UWL Medical Dosimetry Brachy Class 08-09 - Recently Updated Pages

Palladium - 103

JeremiahDonner — Mon, 13 Apr 2009 00:16:07 CDT

Photos:

Relevant Historical Data:	Produced in a reactor by bombarding stable Pd-102 with neutrons.(4)
Chemical/Radioactive Composition:	Matrix consists of a porous and mechanically stable inorganic material(5) A steel-white metal, does not tarnish in air, and is the least dense and lowest melting of the platinum group metals.(6)
Energy Characteristics:	Photon Energy (MeV) 0.021 avg(1,4) Average gamma energy of 20-23 keV(5)
Exposure Rate Constant:	1.48c (Rcm2/mCi-h)(1,4)
Half-life Properties:	17.0 days(1,4) Pd-103 decays 4% per day and delivers 90% dose in 2 months (56 day).(4) Decays by electron capture to rhodium-103, emitting gamma-rays with 21 keV's of energy. (2)
Forms available for use:	Seeds: Palladium-103 - consists of laser-welded titanium tube containing two graphite pallets plated with Palladium-103. There is a lead marker between the pallets that provides radiographic identification.(1) *See Figure labeled 15.5 Brachytherapy optic plaques are sewn to the episclera to cover the base of the intraocular tumor. This is used for uveal melanoma.(7)
HVL in lead:	0.008 mm lead(1)
Measurement/Calibrations/QA:	Pd-103; available activities up to 2 mCi (2.2U) & produce initial dose rates up to 20cGy/hr.(4)
Used in formula/calculation:	The Modular Dose Calculation Modiel: TG-43. The effects of several physical factors on dose rate disribution are considered separately. (0 is used in place of theta, A is used for dose rate constant) The dose rate, D (r, 0) at point P with polar coordinates (r,0) in a medium from the center of a source of air kerma strength Sk can be expressed as: D(r,0)=ASk ((G(r,0))/(G(1,pi/2))(F(r,0))(g(r)) A is the dose rate constant, defined as the dose rate per unit air kerma strength (U) at 1cm along the transverse axis of the seed and has units of cGyh(-1)U(-1): A=D(1,pi/2)/Sk G(r,0) is the geometry factor that accounts for the geometric falloff of the photon fluence with distance from the source and depends on the distribution of radioactive material. For a point source, G(r,0)=1/rsquared and for unifomly distributed line source, G(r,0)=(02-01)/Ly5. F(r,0) is the anisotropy factor normalized at 0=pi/2, with the geometric factor factored out: F(r,0)=(D(r,0)G(r,pi/2))/(D(r,pi/2)G(r,0)) The anisotropy factor accounts for the angular dependence of photon absorption and scatter in the encapsulation and the medium. The radial dose function, g(r), accounts for radial dependence of photon absorption and scatter in the medium along the transverse axis and is given by: g(r)= (D(r,pi/2)G(1, pi/2))/(D(1, pi/2)G(r,pi/2)) Again the geometric factor is factored out from the dose rates in defining g(r). (1) Due to pd-103 source design and low energy x-ray emitted the "anisotropy" is high and the dosimetry is inherently complex. (11)
Uses in Radiation Oncology:	Pd-103 is used in treatment of high grade, permanent "prostate" seed implants.(2,4) It seems to be gaining popularity in see implants.(11) Activity of Pd-103 used for prostate cancer is 1.32mCi (range 0.50 to 1.90mCi) (3); higher initial dose rate compared to I-125 (this is due to the shorter T1/2 : 17 day vs. 59.4 days. (4) Ophthalmic plaque radiation therapy is the most commonly used "eye and vision-sparing" treatment for "choroidal melanoma" (around the world).(9) and/or "Uveal Melanoma" (2) Pd- 103 is also used as a ophthalmic plaque brachytherapy for intraocular melanoma. (7) This is also known as uveal melanoma, as mentioned above. Used for Localization of Non-Palpable tumors - The purpose of radioactive seed localization (RSL) of non-palpable lesions is to localize suspicious tissues for excision with the use of radioactive seeds. RSL uses radioactive seeds previously approved for the treatment of cancerous tumors. For instance, typically, iodine-125 and palladium-103 seeds between 200 – 300 μCi/seed are implanted into a breast lesion using a standard 18-gauge needle. These seeds are normally implanted within mammography or ultrasound suites and removed within surgical suites between 2 and 5 days post implantation. The radioactive seed(s) can be easily located with appropriate instrumentation (using a technique with which surgeons are familiar because of its similarity to sentinel lymph node biopsy and radioguided parathyroidectomy) and surgically removed with minimal injury to non-affected tissue. The seed(s) may be removed from the tissue specimen in surgery, or the tissue specimen containing the seed(s) can be sent to pathology for removal of the seed and analysis of the tissue.(10)
Treatment Planning:	Dosimetry for Palladium 103 is sparse.(1) prescription dose for Prostate cancer with Pd-103 in monotherapy brachytherapy is 125Gy and 100Gy if used as a boost following pelvic EBRT of 40-50Gy. (3) For opthalmic plaque brachytherapy, plaques are sewn to the episclera to cover the base of the intraocular tumor. Treatment involved delivery of a mean apical radiation dose of 80.5 Gy during 5-7 days' continuous treatment. (7)
One other interesting fact:	Palladium -103 may have a biological advantage in permanent implants because the dose is delivered at a faster rate than with Iodine-125.(1) Palladium-103 decays by "electron capture" with the emission of characteristic x-rays in the range of 20 to 23 keV (average energy 20.9 keV) and "Auger electrons".(1) Palladium-103 may be created from palladium-102.(2) The photon fluence distribution around the source is "anisotropic" due to the self-absorbtion by the source pallets, welds, and the lead x-ray marker.(1) Pd-103 is most effective against dedifferentiated tumors (3) Cold working increases its strength and hardness. It is used in some watch springs. (6) The study, "Palladium-103 Brachytherapy Versus Radical Prostatectomy in Patients with Clinically Localized Prostate Cancer: A 12-Year Experience From A Single Group Practice," showed that high-risk prostate cancer patients treated with brachytherapy using palladium-103 experienced greater success than patients treated with prostatectomy. In fact, high-risk patients treated with seeding showed an 88% cure rate vs. a 43% cure rate obtained with surgery at 12 years. Similarly, the results for intermediate-risk patients were also impressive, with 12-year data reflecting a success rate of 89% with seed therapy vs. a 58% success rate with surgery. In addition, low-risk patients demonstrated comparable results with those treated with seeds experiencing a 99% success rate vs. a 97% success rate with surgery at 10 years. (11)

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Links:
1. Palladium-103; Wikipedia - http://en.wikipedia.org/wiki/Palladium-103

2. Eye Plaques - http://www.eyecancer.com/Research/Research.aspx?nID=47&Research=About+Iodine-125+and+Palladium-103+Plaques&nResearchCategoryID=1&sResearchCategory=Articles

3. Palladium 103 seeds - BARD. http://images.google.com/imgres?imgurl=http://www.bardurological.com/resources/productImages/b_020_pd.jpg&imgrefurl=http://www.bardurological.com/products/loadProduct.aspx%3FprodID%3D231&usg=__rhz9S969smomBSF94eASlxhAOWk=&h=223&w=172&sz=11&hl=en&start=16&sig2=4S1rhn4KJeAdr9qVheGh1g&um=1&tbnid=clLhCUiTLMT2DM:&tbnh=107&tbnw=83&prev=/images%3Fq%3Dpalladium%2B103%26hl%3Den%26sa%3DN%26um%3D1&ei=8GfdSbTGGI34Mf_hrOQN

4. External Beam along with Brachytherapy-http://www.medicalnewstoday.com/articles/66101.php

References:
1. Khan, Faiz M. The Physics of Radiation Therapy. 3rd Edition. Philadelphia: Lippincott Williams & Wilkins; 2003: p. 358, 364-365,373-375.

2. Wikipedia. Palladium103. Available at: http://en.wikipedia.org/wiki/Palladium-103. Accessed: 11 March 2009.

3. Devlin, Phillip M. Brachytherapy Applications and Techniques. 1st Edition. Philadelphia: Lippincott Williams & Wilkins; 2007: p. 184-187.

4. "Session: 7.05 – Source of Permanent Implants. Stanford Web-Based Dosimetry Training Tool. http://www.dosimetrytrainingtool.com. Accessed: 8 March 2009.

5. Medical radioactive palladium-103. Available at http://www.freepatentsonline.com/EP1008995.html. Accessed on March 30, 2009.

6. Radiation Glossary N.P. Radiation Protection. Available at http://www.epa.gov/radiation/glossary/termnop.html#p. Accessed on April 4, 2009.

7. Palladium-103. Available at http://www.ncbi.nlm.nih.gov/pubmed/12459367. Accessed on April 4, 2009.

8. "Session: 12.03 – Activity Conversions. Stanford Web-Based Dosimetry Training Tool. http://www.dosimetrytrainingtool.com. Accessed: 8 March 2009.

9. Eye Cancer Network. About Iodine 125 and Palladium 103 Eye Plaques. Available at: http://www.eyecancer.com/Research/Research.aspx?nID=47&Research=About+Iodine-125+and+Palladium-103+Plaques&nResearchCategoryID=1&sResearchCategory=Articles Accessed: 6 April 2009.

10. Iodine-125 and Palladium-103 Low Dose Rate Brachytherapy Seeds. Used for Localization of Non-Palpable Lesions. Available at: http://www.nrc.gov/materials/miau/med-use-toolkit/seed-localization.html. Accessed on 8 April 2009.

11. Prostate Cancer - Brachytherapy with Palladium-103 Better Than or Equal to Prostatectomy. Available at: http://www.medicalnewstoday.com/articles/20904.php. Accessed on 8 April 2009.

Group Colors:
Theresa, Brandie, Christy, Jeremiah

Cobalt - 60

JeremiahDonner — Mon, 13 Apr 2009 00:12:27 CDT

Photos:

Relevant Historical Data:	Cobalt was discovered in 1735 by Georg Brandt, a Swedish chemist.(5) Non-Radioactive Cobalt: occurs naturally in various minerals and has long been used as a blue coloring agent for ceramic and glass. (2) People previously thought the blue color in the colored glass was bismuth, which occurs in nature with cobalt. (7) Radioactive Co-60: produced commercially through linear acceleration for use in medicine and industry. (2) Radioactive CO-60 was discovered by Glenn T. Seaborg and John Livingood at the University of California - Berkeley in the late 1930's. (7) Co-60: can also be a byproduct of nuclear reactor operations, when metal structures, such as steel rods, are exposed to neutron radiation.(2) Produced by bombarding stable Co-59 with neutrons in a nuclear reactor.(6) The first source of Co-60 for medical use was produced in 1951 in Canada and was used by Johns and Coworkders in the first Co-60 teletherapy machine for external beam therapy in 1952. (3)
Chemical/Radioactive Composition:	A radioactive isotope, Cobalt-60 (with gamma ray emission 25 times that of radium), is prepared by neutron bombardment.(5) Metallic solid that can become magnetically charged. (2) Solid under normal conditions and is generally similar to iron and nickel in its properties. (7)
Energy Characteristics:	Beta decay to Ni-60 Beta energy is 0.097 MeV (9) Gamma energy is 2.5 MeV. This comes from emitting a beta particle with two energetic gamma rays (one has and energy of 1.2 MeV and the other an energy of 1.3 MeV). (9) Decay Properties: Decay by Beta particles and gamma radiation; gamma radiation in the energy of 1.17 & 1.33 Mev.(1,2,6) The beta decay to Ni-60 is non radioactive. (7) Activity 1,100 Ci/g (9)
Exposure Rate Constant:	13.07 c (Rcm2/mCi-h) (1,6)
Half-life Properties:	Half Life: 5.26 yr (1,6) Biological: 0.5 day (transfer compartment), 6 days (0.6 in all tissues), 60 days (0.2 in all tissues), 800 days (0.2 in all tissues) (8) This half life is short enough to make isolation a useful treatment strategy for contaminated areas. Waiting 10 to 20 years will allow for sufficient decay to make the site acceptable for use again. (7)
Forms available for use:	"Solid Material" -may appear as small metal disks or in a tube, enclosed at both ends, that holds the small disks.(2) "Powder" if the solid sources have been ground or damaged.(2) "Opthalmic Plaques"; used in recent years for treatment of ocular melanomas - these are stored and reused for years.(3) Remote Afterloading; usually in the shape of "capsules" or "pellets" with an outer diametr of 2.5mm.(6) Cobalt brachytherapy sources are usually fabricated in the form of a wire that is encapsulated in a sheath of platinum iridium or stainless steel.(1) Cobalt-60 is used in many common industrial applications, such as in leveling devices and thickness gauges, and in radiotherapy in hospitals. Large sources of cobalt-60 are increasingly used for sterilization of spices and certain foods. The powerful gamma rays kill bacteria and other pathogens, without damaging the product. After the radiation ceases, the product is not left radioactive. This process is sometimes called "cold pasteurization." (7)
HVL in lead:	11 mm lead (1,6)
Measurement/Calibrations/QA:	The National Institute of Standards and Technology (NIST) established exposure rate calibration standards for some of the brachytherapy sources including Co-60. Its method consists of calibrating a working standard of each type using open air geometry and a series of spherical graphite cavity chambers. A given source is then calibrated by intercomparison with the working standard using a 2.5 liter spherical aluminum ionization chamber, positioned at a distance of about 1m. (1) The NRC requires that, for Afterloading HDR units, the reproducibility of the source positioning be checked each day of use with a precision of 1mm. To ensure this precision, you may use a television system along with a transparent jig to visually confirm the positioning. You may also use autoradiography to confirm position. (10)
Used in formula/calculation:	Time = prescribed dose dose rate (ref) x area factor (3) Dose rate at Dmax = time x dose rate (ref) x area factor (3)
Uses in Radiation Oncology:	Main uses for 60Co: (11) As a tracer for cobalt in chemical reactions, Sterilazation of medical equipment, Radiation source for medical radiotherapy. Radiation source for industrial radiography, Radioactive source for leveling devices and thickness gauges, As a radioactive source for food irradiation and blood irradiation, and As a radioactive source for laboratory use. Co-60 is used medically for radiation therapy as implants and as an external source of radiation exposure. (2) Co-60 is used at a medical tracer. A medical tracer is a material that is introduced into the body to make possible the observation of chemical, physical or biological processes in the body, (8) Total Body Irradiation: Gamma Knife Radiosurgery: gamma knife device contains 201 cobalt 60 sources of approximately 30 curies each, placed in a circular array in a heavily shielded assembly. The device aims gamma radiation through a target point in the patient's brain. The patient wears a specialized helmet that is surgically fixed to their skull so that the brain tumor remains stationary at target point of the gamma rays. An ablative dose of radiation is thereby sent through the tumor in one treatment session, while surrounding brain tissues are relatively spared.(4) Gamma knife radiosurgery has proven effective for patients with benign or malignant brain tumors, vascular malformations such as an arteriouvenous malformation (AVM), and pain.(4) Co-60 has been used in opthalmic plaques for the treatment of ocular melanomas, which are stored and reused over several years. (3)
Treatment Planning:	The exposure rate distribution can be calculated using the Sievert integral. This method consists of dividing the line source into small elementary sources and applying inverse square law and filtration corrections for each. Several other additional corrections are applied to compute the exposure rate accurately using the Sievert integral. A correction for self-absorption and wall thickness as well. An effective attenuation coefficient is needed and varies with filter thickness. Because the Sievert integral uses the energy absorption coefficient, the underlying assumption is that the emitted energy fluence is exponentially attenuated by the filter thickness traversed by the photons. However, the Monte Carlo simulations have shown that beyond the end of the active source region, the Sievert approach introduces significant errors and practically breaks down in the extreme oblique directions. (1)
One other interesting fact:	Co-60 is a hard, gray-blue metal. It resembles iron or nickel.(2) In the periodic table it occupies a position between iron and nickel in the third period.(5)* see photo Atomic number 27; atomic weight 58.9332; melting point 1,495°C; boiling point 2,900°C; specific gravity 8.9; valence 2, 3.(5) It is also used industrially in leveling gauges and to x-ray welding seams and other structural elements to detect flaws. Co-60 also is used for food irradiation, a sterilization process. (2) After entering a living mammal (such as a human), most of the 60Co gets excreted in feces. A small amount is absorbed by liver, kidneys, and bones, where the prolonged exposure to gamma radiation can cause cancer. (11) Gastrointestinal absorption from food or water is the principal source of internally deposited cobalt in the general population. (9)

Links:
1. Centers for Disease Control and Prevention (CDC) - http://www.bt.cdc.gov/radiation/isotopes/cobalt.asp

2. Cobalt-60; Wikipedia - http://en.wikipedia.org/wiki/Cobalt-60

3. Cobalt-60 Fact Sheet - http://www.doh.wa.gov/EHP/RP/factsheets/factsheets-pdf/fs26co60.pdf

References:
1. Khan, Faiz M. The Physics of Radiation Therapy. 3rd Edition. Philadelphia: Lippincott Williams & Wilkins; 2003: p.367, 358, 361, 369-371.

2. Radioisotope Brief: Cobalt-60 (Co-60). Centers for Disease Control and Prevention (CDC). Available at: http://www.bt.cdc.gov/radiation/isotopes/cobalt.asp. 11 March 2009.

3. Bentel, Gunilla C. Radiation Therapy Planning. 2nd Edition. New York: The McGraw-Hill Companies; 1996: p. 61, 22, 536.

4. Wikipedia. Gamma knife. Available at: http://en.wikipedia.org/wiki/Gamma_knife. Accessed: 12 March 2009.

5. Cobalt. Answers.com. Available at: http://www.answers.com/topic/cobalt. Accessed: 12 March 2009.

6. "Session: 7.06 – Sources for Remote Afterloading Devices. Stanford Web-Based Dosimetry Training Tool. http://www.dosimetrytrainingtool.com. Accessed: 8 March 2009.

7. Cobalt. Radiation Protection. Available at http://www.epa.gov/radiation/radionuclides/cobalt.html#discovered. Accessed on April 4, 2009.

8. Cobalt -60. Fact Sheet. Available at http://www.doh.wa.gov/EHP/RP/factsheets/factsheets-pdf/fs26co60.pdf. Accessed on April 4, 2009.

9. Cobalt -60. Human Health Fact Sheet. Available at http://www.ead.anl.gov/pub/doc/Cobalt.pdf. Accessed on April 4, 2009.

10. Martinez, Orton, and Mould. Brachytherapy HDR and LDR. Colombia: Nucletron Corporation; 1990. p. 138-142.

11. Wikipedia. Co-60. Available at: http://en.wikipedia.org/wiki/File:Cobalt-60_Decay_Scheme.svg Accessed: 6 April 2009.

Group Colors:
Theresa. Brandie, Christy, Jeremiah

Radium - 226

olson.lind — Sun, 12 Apr 2009 18:10:49 CDT

. Photos:

Image 1. Natural cycle of Radium-226. (4)

Image 2. Radium 226 decay (9)

Marie and Pierre Curie Research (13)

Relevant Historical Data:	Radium 226 is a naturally occurring radionuclide that was discovered in 1898 by Marie and Pierre Curie along with Henri Becquerel when they isolated it from Uranium pitch blende ore. (8) Radium 226 was one of the first radionuclides utilized for clinical brachytherapy applications and was the radionuclide of choice in the early days of development of brachytherapy. (8) Radium 226, the earliest and once most commonly used radioactive isotope in brachytherapy, has been replaced by artificially produced isotopes such as Cs-137 and Ir-192. (5)(8) Radium 226 was originally used to define the unit Curie (Ci) with 1 Ci being the number of disintegrations of a 1g radium source. (8)
Chemical/Radioactive Composition:	Chemical Symbol: Ra Atomic number (Z, # of protons) = 88 Mass number (A, # of protons + neutrons) = 226 Radium 226 is the sixth member of the uranium series which begins with U-238 and ends with Pb-206. (8) Radium is supplied mostly in the form of radium sulfate or radium chloride. It is then mixed with an inert filler and loaded into cells about 1cm long and 1mm in diameter. The cells are made of 0.1-0.2mm thick gold foil and are sealed to prevent leakage of radon gas. They are then loaded into a sealed platinum sheath. (6) Radium 226 disintegrates very slowly to form radon, a hazardous radioactive gas. (5) When radium is placed in a sealed container it achieves secular equilibrium with its daughter products approximately one month from the time of encapsulation. (6)
Energy Characteristics:	At the end of the decay process from radium to stable lead at least 49 gamma rays are produced with energies ranging from 0.047 to 2.45 MeV. (6)(8) The average energy of the gamma rays from radium 226 in equilibrium with its daughter products and filtered by 0.5mm of platinum is 0.83 MeV. (6) Beta particles, ranging in energy from 0.017 MeV-3.3 MeV, are also emitted in the disintegration of Ra-226 to stable Pb-208. (8) Gamma rays are the only rays used for therapy, the alpha and most of the beta particles emitted are absorbed by the 0.5mm platinum source case. (6)
Exposure Rate Constant:	8.25 Rcm2/mCi-h (when filtered by 0.5mm Pt or when in equilibrium with its daughter products) (6) The exposure rate constant decreases by about 2% for each additional 0.1 mm of Pt added to the 0.5 mm Pt encapsulation and increases by 2% for each 0.1 mm of Pt less than 0.5 mm. (8)
Half-life Properties:	T 1/2 1600 years loses about 1% of activity in 25 years decay to form daughter sources that are unstable (5)
Forms available for use:	Despite double encapsulation, the risk of radium escaping from the source poses a very seriuos risk. This, in addition to the fact that the availability of reactor produced isotopes has increased, had led to the decline of radium in brachytherapy cases. (5)
HVL in lead:	HVL in lead varies from .5mm for a 100 kev source to 12mm for cobalt (1) Because of its relatively high energy (2.45 MeV) Radium 226 has the highest half value layer (HVL) in lead of any brachytherapy source, ranging from 12mm-16mm. (6)(7)(8)
Measurement/Calibrations/QA:	Measurements Even though Radium 226 is no longer used in the field of radiation therapy there are other isotopes that are used in its place that are less toxic. Radium 226, however, set the basis for the measurement of other isotopes that we currently use today. For instance, milligram radium equivalent is the unit used for specifying the source of photon-emitting brachytherapy. It is the amount of Ra 226 filtered by .5 mm thick of Pt that produces the same exposure rate at 1 meter in air as that of the given source. (10) Calibrations The National Institute of Standards and Technology (NIST) have established exposure rate calibration standards for Radium 226. The NIST method consists of calibrating a working standard of each type using open-air geometry and a series of spherical graphite cavity chambers. A given source is then calibrated by intercomparison with the working standard using a 2.5-liter spherical aluminum ionization chamber, positioned at a distance of about 1 m. A similar procedure is used for calibrating a radium source except that the working standards of radium have been calibrated in terms of actual mass of radium. Calibrations of clinical sources should be directly traceable to the NIST or one of the AAPM-ADCLs. This means that the sources are calibrated by direct comparison with a NIST or ADCL calibrated source of the same kind, same radionuclide, same encapsulation, size and shape. If a well-type ionization chamber is used, it should bear a calibration factor determined with a NIST or ADCL calibrate source of the same kind.(6) Quality Assurance Testing It is very important that an acceptance test be performed prior to the use of the source. The purpose of acceptance testing of brachytherapy equipment is to ensure that the source and the associated equipment meet the user’s specifications. A wipe test must be performed at the time of acceptance and every 6 months to verify that everything is correct. Also the physical length, serial number and color-coding of all sources should be checked. Documentation of the source use, strength, removal of the sources from storage and the actual return of source is very important for the accuracy and integrity of the program. Geiger Muller counters and other surveyors would be needed to track the isotope if any were to be misplaced and to take a reading of the patient. (11)
Used in formula/calculation:	What is the activity of 1 g of Ra226? Half life is 1,622 years Λ=.693/T ½ = 0.693 (1,622 years) (3.15 x 10 ^7 sec/year) =1.356 x 10^ -11/sec Activity= 2.66 x 10^21 x 1.356 x 10^-11 dps/g =3.61 x 10^10 dps/g =.975Ci/g (6)
Uses in Radiation Oncology:	In the U.S., nasal radium irradiation was administered to children to prevent middle ear problems or enlarged tonsils from the late 1940s through early 1970s. Radium (usually in the form of radium chloride) is used in medicine to produce radon gas which in turn is used as a cancer treatment. The isotope 223Ra is currently under investigation for use in medicine as cancer treatment of bone metastases. (1)
Treatment Planning:	Historically, the external use of radium was focused on the treatment of malignant disease. Internal use of radium-226 occurred between 1905-1930 through ingestion of soluble radium salts. Before the advent of cobalt and cesium teletherapy machines in the 1950s, all external beam radiotherapy machines made use of radium-226 ("teleradium machines"). With the invention of the Cobalt teletherapy machine, teleradium machines were no longer used. Although, radium still proved to be effective for brachytherapy procedures by inserting it into body cavities or tumors for a specified period of time. Radium's use in brachytherapy was discontinued because of the health risks of its daughter product Radon-222, its high cost for extraction, and its low specific activity compared to other safer, cheaper, isotopes. (12)
One other interesting fact:	Radium is about one million times more active than uranium. The lab notebooks used by the Curies are too highly contaminated to be safely handled today. (2) Radium has been added to the tips of lightening rods, improving their effectiveness by ionizing the air around it. (3)

Links:
Wikipedia. http://en.wikipedia.org/wiki/Radium
Jefferson Lab. http://education.jlab.org/itselemental/ele088.html
United States Environmental Protection Agency. http://www.epa.gov/rpdweb00/radionuclides/radium.html#use
Gamma Dating Center. http://geo.ku.dk/english/gdc/
Radium Deacy. http://langitselatan.com/2008/01/23/begini-cara-kerja-bintang-bagian-2-sumber-energi-bintang/
Proposed Regulation... http://www.leg.state.nv.us/Register/2008Register/R185-08P.pdf
National Science Foundation. http://www.atomicarchive.com/Bios/CuriePhoto.shtml

References:
1. Wikipedia. http://en.wikipedia.org/wiki/Radium. Accessed March 16, 2009.
2. Jefferson Lab. http://education.jlab.org/itselemental/ele088.html Accessed March 16, 2009.
3. United States Environmental Protection Agency http://www.epa.gov/rpdweb00/radionuclides/radium.html#use Accessed March 16, 2009.
4. Gamma Dating Center. http://geo.ku.dk/english/gdc/ Accessed March 16, 2009.
5. Bentel, Gunilla C. Radiation Therapy Planning. 2nd Edition. McGraw-Hill Companies Inc.; 1996: 533-561.
6. Khan, Faiz M. The Physics of Radiation Therapy. 3rd Edition. Philadelphia: Lippincott Williams & Wilkins; 2003: 357-400.
7. Khan, Faiz M. Treatment Planning in Radiation Oncology. 2nd Edition. Philadelphia: Lippincott Williams & Wilkins; 2007: 212-257.
8. Session: 7.4 – Sources for Temporary Implants. Web-Based Dosimetry Training Tool. Retrieved March 16, 2009. Available at:http://www.dosimetrytrainingtool.com
9. Radium Deacy. Available at:http://langitselatan.com/2008/01/23/begini-cara-kerja-bintang-bagian-2-sumber-energi-bintang/. Accessed March 18, 2009.
10. DTT, Module 07.02-Dosimetric Parameters Used for the Characterization of Brachytherapy Sources. Accessed March 23, 2009, Stanford Web-Based Dosimetry Training Tool. Available at http:// www.dosimetrytrainingtool.com
11. Proposed Regulation of the State Board of Health LCB radium-226 and americium-241; adopting by reference certain federal regulations; ... of the filter paper after the dry wipe test must be measured by a ...Accessed March 23, 2009. Available at www.leg.state.nv.us/Register/2008Register/R185-08P.pdf
12. Podgoršak, Ervin. Radiation Physics for Medical Physicists. Birkhauser Publishing; 2006: 319-320.
13. National Science Foundation. Marie and Pierre Curie. Accessed April 8, 2009. Available at: http://www.atomicarchive.com/Bios/CuriePhoto.shtml

Group Colors:
Jen
Lindsey
Dawn
Robin

Phosphorus - 32

olson.lind — Sun, 12 Apr 2009 18:04:36 CDT

Photos:	Measuring beta radiation from a sample of phosphorus-32. (3)
	Galileo™ centering catheter and radioactive phosphorus-32 wire source used in prevention of restenosis. The catheter is inserted in the femoral artery and fed to the coronary artery, where the gold markers can be viewed on an angiogram. The product of the source dose rate and the dwell time in the lesion determines the dose to the arterial wall. (11)

Relevant Historical Data:	Phosphorus 32 is an artificially produced isotope that is used for therapeutic purposes. (1) In 2000 Louis Granados filed for a patent for the use of P-32 as a temporary intravascular implant for brachytherapy and as a radioactive stent for balloon angioplasty to help prevent restenosis. (9)(2)
Chemical/Radioactive Composition:	Chemical Symbol: P Atomic number (Z, # of protons) = 15 Mass number (A, # of protons + # of neutrons) = 32 Phosphorus-32 is a reactor product and is produced by bombarding Phosphorus-31 with neutrons in a reactor. (4) P-32 is available as a soluble phosphate solution and is generally administered to the patient either intravenously or orally. (4) Typical administered activity of P-32 for bone pain palliation ranges from 5-10 mCi (185-370 MBq). (4)
Energy Characteristics:	Phosphorus-32 (P-32) is a pure β-emitter with peak energy of 1.7 MeV and an average energy of 0.694 MeV. (4) P-32 being a β-emitter is best shielded with a low Z material such as plexiglass or acrylic.(4)
Exposure Rate Constant:	Since P-32 is a pure beta emitter it has no exposure rate constant.
Half-life Properties:	T1/2 14.3 days Decays by beta-minus emission (1) Decays about 5% a day (4)
Forms available for use:	Used in the form of sodium phosphate for polycythemia vera, chronic myelocytic leukemia, and chronic lymphocytic leukemia. Used as a tracer in the studies of metabolism of nucleic acids and phospholipids. (5)
HVL in lead:	2mm of water or tissue. Lead is not used as shielding due to the production of Bremsstrahlung x-rays. (6)
Measurement/Calibrations/QA:	A comprehensive QA program should assure accurate and safe delivery of intravascular brachytherapy. In addition it should be designed to satisfy the relevant regulations of the NRC or state it is designated as an Agreement State. AAPM G-60 is who the QA reports are most pertinent to involving intravascular brachytherapy. There are certain recommendations of this report such as: document radiation source properties, develop protocols for receipt of sources, acceptance testing, and commissioning procedures are jus a few of them. A comprehensive QA program should assure accurate and safe delivery of intravascular brachytherapy. In addition it should be designed to satisfy the relevant regulations of the NRC or state it is designated as an Agreement State. AAPM G-60 is who the QA reports are most pertinent to involving intravascular brachytherapy. There are certain recommendations of this report such as: document radiation source properties, develop protocols for receipt of sources, acceptance testing, and commissioning procedures are jus a few of them.(7)
Used in formula/calculation:	What is the final activity after decay using the information given below? A=A(initial) x e -ln2t/T1/2 ln2=.693 T1/2=14 days t=1 A(initial)= 40.0 mCi A=40.0 mCi x e -.693t/14 days =40.0 mCi x e -.495 =40.0 mCi x .951 =95.1 is the final activity (8)
Uses in Radiation Oncology:	Phosphorus-32 is used to treat painful bone metastases for palliation. Typically a 5-10mCi source is used. It is available as a soluble phosphate solution and is generally administered intravenously or orally. Phosphorus is also used to treat polycythemia vera (a disorder characterized by an overproduction of RBCs generally accompanied by an increase in the number of platelets and WBSc), cystic craniopharyngiomas, cystic astrocytomas(8), and chronic myelocytic and chronic lymphocytic leukemias. (5) Phosphorus-32 is also used for intravascular brachytherapy, explained below. (2)
Treatment Planning:	The Guidant GALILEO System uses P-32 for intravascular brachytherapy. The source is sealed in the distal tip of a flexible nitinol wire, which can navigate through arteries. This type of system is a remote afterloading device and a treatment planning system is provided to calculate dwell times required to deliver the prescribed dose. (2) Another way P-32 is used for intravascular brachytherapy is in a radioactive liquid form, the Beta-emitting liquid-filled balloon. The advantages of the balloon are inherent source centering and dose uniformity to the vessel wall, the prescription point. The major disadvantages of this technique are higher ratio of surface/adventitial dose compared to the catheter-based gamma source systems and the possibility of balloon rupture, although rare. (2) Permanent stents can also be rendered radioactive with P-32. After balloon angioplasty, as many as half of the patients may experience restenosis. By inserting a radioactive stent with P-32 into the artery, surgery and irradiation are combined into one procedure. (2) P-32 is also used in colloidal form by injection into the serous cavities (pleural and peritoneal) in order to control the malignant accumulation of fluid. (12)
One other interesting fact:	Even though the beta particles emitted by P-32 decay have a high amount of energy (1.7MeV), they cannot pass through the layer of dead cells on the skin surface. This means that there is a minimal exposure risk to the radiation unless it is directly applied to the skin or ingested. Most of the risk is eliminated by wearing a lab coat and gloves when working with the isotope. P-32 was also used in the famous Hershey-Chase experiment in 1952 which proved that DNA, not protein, is the carrier of genetic information. (10)

Links:
Human Radiation Experiments. http://www.hss.energy.gov/healthsafety/ohre/roadmap/roadmap/index.html
Angioplasty radiation therapy to prevent restenosis. http://www.freepatentsonline.com/6755776.html
Phosphorus 32. http://medical-dictionary.thefreedictionary.com/phosphorus-32
Phosphorus 32. http://dept.kent.edu/ors/ORSContent/ORSBulletins/Rad/SB_P32.pdf
Everything2. http://everything2.com/title/phosphorus-32
Physics Today on the Web. Available at: http://www.aip.org/pt/apr00/coursey.html

References:
1. Bentel, Gunilla C. Radiation Therapy Planning. 2nd Edition. McGraw-Hill Companies Inc.; 1996: 537-538. 537
2. Khan, Faiz M. The Physics of Radiation Therapy. 3rd Edition. Philadelphia: Lippincott Williams & Wilkins; 2003: 357-400.
3. United States Department of Energy. Human Radiation Experiments. Retrieved April 1, 2009. Available at http://www.hss.energy.gov/healthsafety/ohre/roadmap/roadmap/index.html
4. Session: 7.7 – Non sealed Radionuclides for Systemic Therapy. Web-Based Dosimetry Training Tool. Retrieved March 16, 2009. Available at:http://www.dosimetrytrainingtool.com
5. The Free Dictionary. Phosphorus 32. Available at: http://medical-dictionary.thefreedictionary.com/phosphorus-32. Accessed March 18, 2009.
6. Phosphorus 32. Available at:http://dept.kent.edu/ors/ORSContent/ORSBulletins/Rad/SB_P32.pdf. Accessed March 17, 2009.
7. Khan, Faiz M. Treatment Planning in Radiation Oncology. 2nd Edition. Philadelphia: Lippincott Williams & Wilkins; 2007: 558-559.
8. Web Based Dosimetry TrainingTool. Radioactive Decay Session 12.04 slide 1. Accessed March 24, 2009. Available at www.dosimetrytrainingtool.com.
9. United States Patents. Angioplasty radiation therapy to prevent restenosis. Retrieved April 1, 2009. Available at: http://www.freepatentsonline.com/6755776.html
10. Everything2. Available at: http://everything2.com/title/phosphorus-32. Accessed April 1, 2009.
11. Physics Today on the Web. Available at: http://www.aip.org/pt/apr00/coursey.html. Accessed April 1, 2009.
12. Lenards, N. D2L Brachytherapy Glossary. Available at: https://uwlax.courses.wisconsin.edu. Accessed April 4, 2009.

Group Colors:
Lindsey
Robin
Dawn
Jen

Strontium - 89

angie garner — Sun, 12 Apr 2009 16:14:50 CDT

Photos:
	Fig. 1 Strontium diagram 5	Fig. 2 Strontium 6

Relevant Historical Data:	-Strontium 89 (Metastron) has been used around the world for some time, but it is only recently available in Australia.1 -Strontium was discovered in 1798 by Thomas Charles Hope. 3 -The element was named in 1808 by English chemist Humphry Davy, who isolated it by electrolysis after Strontian, a mining location in Scotland, where it was first found. 4 -Strontium is one of the most effective modern therapeutic radioisotopes. 12
Chemical/Radioactive Composition:	Chemical symbol: Sr Atomic number (Z): 38 Mass number (A): 89 -Sr-89 is produced in a nuclear reactor by bombarding enriched Sr-88 with neutrons.7
Energy Characteristics:	-Pure beta emitter 1 -Maximum beta energy is 1.463 MeV 2 -Maximum range of β- from Strontium-89 in tissue is approximately 8 mm 2
Exposure Rate Constant:	-8.1585E-05 Rem per hour (Rem/hr) at a distance of one (1) meter from a one (1) curie point source. 8
Half-life Properties:	-50days 1 -Strontium-89 decays by beta emission with a physical half-life of 50.5 days 2 -Decays to Y-89 a stable isotope.12
Forms available for use:	-Strontium 89 is manufactured as a soluble chloride salt. When dissolved in saline, it can be injected intravenously. 3 -Strontium "imitates" the behaviour of calcium: ie. is taken up and incorporated into bone. There is preferential retention in metastatic lesions compared to normal bone. It is not known why this occurs. The total body retention of strontium 89 therefore depends on the extent of the metastatic bone disease. 4 -Distribution in bone is identical to technezium which is used in bone scans.10
HVL in lead:	-Since Sr-89 is a pure beta emitter, it is best shielded with materials with a low atomic number such as acrylic or plexiglass. High atomic number materials, such as lead, are generally not used for shielding beta emitters due to the production of bremsstrahlung radiation. About 7mm is the maximum range of Sr-89 in plexiglass. 7
Measurement/Calibrations/QA:	-Indications for patient treatment should conform to the Therapeutic Goods Administration in force at the time of patient treatment. 11 -Effective dose is estimated to be 310 mSv/100 MBq. Organ absorbed doses are as follows bone surfaces 1700 mGy/100 MBq, red bone marrow 1100 mGy/100 MBq, lower large intestine 470 mGy/100 MBq and bladder wall mGy/100 MBq. 11 SR-89 is standardized by high-efficiency liquid-scintillation counting with a relative expanded uncertainty.
Used in formula/calculation:	Mean Life (T avg)= 1.44 T1/2 Mean Life= 1.44 x 50.5 days = 72.7 days
Uses in Radiation Oncology:	-Therapeutic approach for bone pain in patients with painful skeletal metastases1,2 -Used in sclerotic metastases from other primaries including prostate, breast, and unknown primary 1,3 -Administered as an intravenous injection of an aqueous solution 1 -Not only is effective in treating painful metastases but also has a therapeutic effect on metastases that have not yet become painful. This is evident as a reduction in the appearance of new sites of skeletal pain in the short term following Strontium 1 -Cancer patients typically are treated with a dose of 150 MBq for bony metastases.3 -Contradindications to using SR-89 are prior administration within 3 months, spinal cor compression, platelet count less than 100,000/mm3, total white cell count less than 3,000/mm3 and wide field RT within the last four weeks.11 Clincal benefits of SR-89 are not apparent for 3-4 weeks, so it should not be considered for a patient with a life expectancy significantly less than 3 months.11 -The maximum range of beta particles of SR-89 does not exceed 7mm, so its radiation effects are isolated to the small area of the skeleton and its radiation burden on the marrow and nearby soft tissue are not significant.12 Clinical tests show 65-76% of patients have a great reduction in pain. About 20% have a full anaesthetic effect from the SR-89.12
Treatment Planning:	-Should be given in the context of overall patient management which takes into account the current clinical picture, previous radiotherapy and alternate treatment options appropriate at that time. A multidisciplinary and consultative approach must be adopted, and the patient must be properly assessed and followed up after the Strontium-89 has been given. 9 -Administration of Strontium-89Chloride Injections: Adults: I.V.: 148 megabecquerel (4 millicurie) administered by slow I.V. injection over 1-2 minutes or 1.5-2.2 megabecquerel (40-60 microcurie)/kg; repeated doses are generally not recommended at intervals <90 days; measure the patient dose by a suitable radioactivity calibration system immediately prior to administration.13 Autoradiography can be performed on sections of bones to study the pattern of deposition.14
One other interesting fact:	-One of the most dangerous products of the nuclear industry; fission products in nuclear explosions and in the reactors of nuclear power plants. 4 -Costing more than $2000 per dose 1 -It is excreted in the urine (90%) and bile (10%). The majority of the dose is excreted in the first 48 hours after injection. 1

Links:
1. Guidelines for the Therapeutic Administration of Strontium 89. Available at: http://www.health.vic.gov.au/environment/downloads/guidelines_strontium.pdf. Accessed on April 2, 2009.
2. Strontium. Available at: http://www.ithyroid.com/strontium.htm. Accessed April 7, 2009.
3. Efficiency of strontium-89 for the palliation of painful bone metastases in prostate cancer. Available at: http://images.katalogas.lt/maleidykla/AML2008-2/113-117.pdf. Accessed April 7, 2009.

References:
1. Medicineau.net. Strontium-89. Available at: http://www.medicineau.net.au/clinical/palliative/strontium.html. Accessed on March 16, 2009.
2. Rxlist.com. Strontium-89. Available at: http://www.rxlist.com/metastron-drug.htm. Accessed on March 16, 2009.
3. Wikipedia. Strontium. Available at: http://en.wikipedia.org/wiki/Strontium. Accessed: March 16, 2009.
4. The Free Dictionary by Farlex. Available at: http://encyclopedia.farlex.com/strontium+89. Accessed on March 16, 2009.
5. Strontium. Available at: http://www.chemistryexplained.com/elements/P-T/Strontium.html. Accessed on March 17, 2009.
6. Strontium. Available at: http://theodoregray.com/PeriodicTable/Elements/038/data.s7.html. Accessed on March 18, 2009.
7. Module 7, Session 7, pp.12-14. Accessed March 26, 2009. Stanford Web-Based Dosimetry Training Tool. Available at: http://www.dosimetrytrainingtool.com.
8. Gamma Ray Dose Constants. Accessed March 26, 2009. Available at: http://www.iem-inc.com/toolgam.html.
9. Guidelines for the Therapeutic Administration of Strontium 89. Available at: http://www.health.vic.gov.au/environment/downloads/guidelines_strontium.pdf. Accessed on April 2, 2009.
10. Perez CA, Brady LW, Halperin EC, Schmidt-Ullrich R, Principles and Practices of Radiation Oncology. Philadelphia: 4 ed. Lippincott Williams & Wilkins; 2004.
11. Guideline for the Theraputic Administration of Strontium-89. Available at http:www.dept.ofhumanservices. Accessed on April 2, 2009.
12. Method of Strontium-89 Radioisotope Production. Available at: http://patentstorm.us/patents/6456680/description/html. Accessed on April 3, 2009.
13. UMM.edu. Strontium-89. Available at: http://www.umm.edu/altmed/drugs/strontium-89-118650.htm. Accessed on April 8, 2009.
14. A Direct Measurement of Strontium-89 Activity in Bone Metastases. Available at: http://cat.inist.fr/?aModele=afficheN&cpsidt=3581199. Accessed on 4-2-2009.
Color Codes:
Purvi - Orange
Alia - Green
Angie - Blue
Tracey -Red.

Gold - 198

danacole — Sun, 12 Apr 2009 10:55:57 CDT

Photos: Photo #1	Photo #2: Gold radioactive recovery
	Photo #3: Gold seeds
	Photo # 4: Au-198 sources placed in the eyeball.

Relevant Historical Data:	An attractive and highly valued metal, gold has been known for at least 5500 years.³ Gold seeds replaced radon seeds for many years, until iodine 125 gained more widespread acceptance.²
Chemical/Radioactive Composition:	Chemical Symbol : Au Atomic Number : 79 Atomic Mass : 196.96655amu.⁴ Au-197 is bombarded with neutrons, when a neutron is absorbed, it becomes Au-198, then decays to Hg-198, a stable form of mercury. 8
Energy Characteristics:	Monoenergetic energy of 412 kev.¹ Beta rays of maximum energy 0.96MeV are also emitted but are absorbed by the platinum wall.²
Exposure Rate Constant:	Exposure Rate Constant : 2.35 R-cm^2 / mCi-hr Air-Kerma Strength : 2.06 cGy-cm^2 / mCi-hr (2.06 U)²
Half-life Properties:	Half-Life: 2.69 days¹ This short half-life is a limiting factor for source transportation to reach the site and/or patient within a useful time frame.²
Forms available for use:	Cylindrical grains or seeds encapsulated in 0.1 mm thick platinum wall.¹ A gold seed is typically 2.5mm long with an outer diameter of 0.8mm.²
HVL in lead:	2.5 mm²
Measurement/Calibrations/QA:	Gold seeds are shipped with very high activities, and by the time ready to be used they have an activity range of 5mCi/seed.¹ Ten percent of the seeds to be used for an implant should be drawn at random and assayed before use to verify the manufacturer's calibration. The results should agree with the manufacturer within +/-3 %. It is also important to maintain a seed count during the procedure at all times. An inventory of the seeds must be done post implantation to ensure all seeds are accounted for. A complete radiation survey of the patient, floor, linen, and personnel should be performed as well and documented in the patient chart. 7
Used in formula/calculation:	106 mCi of Au-198 is implanted into a pelvic mass. Determine the emitted radiation. Mean life of Au-198 = 1.44 times 2.7days=3.888days Emitted radiation= 106mCi x 3.888days= 412.128mCi-days
Uses in Radiation Oncology:	High dose rate therapy. Prostate seed implant.¹ Interstitial permanent implants.² Useful for applications requiring a high dose in a short amount of time, since initial dose rates can be up to 100cGy/hr. 7
Treatment Planning:	In 1972, an open-surgical, retro-pubic brachytherapy method with permanent implants used for the radiation source was introduced by Carlton at Memorial Sloan-Kettering using gold-198 in combination with external beam radiation therapy. Gold-198 has been used as a permanent implant either alone or as adjunct to another. The theoretical advantage of a gold-198 implant is rapid delivery of radiation at a very high dose rate, thus potentially avoiding some of the radio-biologic problems associated with iodine. The higher energy of the source, however, results in less sparing of adjacent normal tissue, thereby limiting the dose that can be prescribed without complications occurring. An additional disadvantage of this isotope is the risk of radiation exposure to staff performing the implantation. Because of this radiation protection problem, gold-198 implantation has fallen out of favor at many centers.⁵ Brachytherapy using Au-198 grains to treat choroidal malignant melanoma study. Radioactive sources were placed into surgically constructed scleral pockets, see photo 4. The radiation dose was 120Gy at the apex of the tumor, which slowly became smaller and completely disappeared at one year and 10 months after treatment.This technique permits the tumor to be treated without the loss of the eye.⁶
One other interesting fact:	There is roughly 1 milligram of gold dissolved in every ton of seawater, although extracting it currently costs more than the gold is worth. It has been estimated that all of the gold that has currently been refined could be placed in a cube measuring 20 meters on a side.³

Links:1. http://www.3rd1000.com/nuclear/halflife.htm

References:
1. Washington CM, Leaver DT. Aspects of brachytherapy. In: Principles and Practice of Radiation Therapy Physics, Simulation, and Treatment Planning. St.Louis, MO: Mosby_year Book, Inc.; 1996:39.
2. Khan Faiz. The Physics of Radiation Therapy. Third Edition. Philadelphia, PA: Lippincott Williams & Wilkins; 2003:p. 358,361.
3. http://education.jlab.org/itselemental/ele079.html Accessed 3/20/09
4. http://chemistry.about.com/od/elementfacts/a/gold.htm Accessed 4/2/09
5. http://caonline.amcancersoc.org/cgi/reprint/45/3/165.pdf Accessed 4/2/09
6. Kawamura T, Koga S, Nomura T et al. Brachytherapy of a choroidal melanoma using radioactive gold grains: a long term follow up study. In Radiation Medicine. 1999:17(3),243-246.
7. http://www.dosimetrytrainingtool.com
8. http://mysite.du.edu/~jcalvert/phys/scat.htm

Photo references:
#1cornerstonegoldrefining.com/History.html.
#3http://www.orau.org/ptp/collection/brachytherapy/seeds.htm Accessed 4/2/09
#4 Kawamura T, Koga S, Nomura T et al. Brachytherapy of a choroidal melanoma using radioactive gold grains: a long term follow up study. In Radiation Medicine. 1999:17(3),243-246.
Authors:
Denise,Michelle, Dana

Ruthenium - 106 / Rhodium - 106

cmcculler — Fri, 10 Apr 2009 12:14:31 CDT

Photos:	Ruthenium 106 eye plaques	Different Brands of Eye Plaques[6]
		Example of seeds in plaque which can be Ru-106, I-125 or Pd-103 [6]

Relevant Historical Data:	Ruthenium was discovered and isolated by Russian scientist Karl Klaus in 1844 in Kazan University, Kazan. Klaus showed that ruthenium oxide contained a new metal and obtained 6 grams of ruthenium from the part of crude platinum that is insoluble in aqua regia. The name derives from Ruthenia, the Latin word for Rus', a historical area which includes present-day western Russia, Ukraine, Belarus, and parts of Slovakia and Poland. Karl Klaus named the element in honor of his birthland. (2) The discovery of rhodium has been attributed to William Hyde Wollaston who discovered it in England in 1803. He successfully isolated it from a crude ore shortly after having discovered palladium. The name rhodium is derived from the Russian word “rhodon” which means rose. [14]
Chemical/Radioactive Composition:	Chemical Symbol: Ru Atomic number (Z, # of protons)=44 Mass number (A, # of protons + neutrons) = 106 A member of the Platinum family, Uranium-235 decays down to Ruthenium-106, a high energy beta emitter. Ruthenium-106 decays to daughter Rhodium- 106, which decays to Palladium 100.[3] Ruthenium fission only yields .38%. Ru-106 has a maximum energy of 3.5 Mev.[4]
Energy Characteristics:	Beta particle energy 3.5 MeV maximum for Ru-106.[9] The mean and maximum energy of 106Rh beta radiation is 1.412 MeV and 3.54 MeV, respectively. The mean energy of gamma radiation is 0.5988 MeV, where the greatest yields belong to 0.512, 0.622, and 1.05 MeV transitions. [8] The maximum range of 106Ru/106Rh electrons in water is roughly 16 mm thus the rest of the dose in greater distances is due to 106Rh photons and bremsstrahlung.[8]
Exposure Rate Constant:	A fission product with a yield of 0.3912%. The activity used for eye plaques ranges from 0.3-1.4 mCi with a surface dose rate up to 70cGy/hr. Exposure rate constant: Rh-106 - 0.138158. [15] Because Ru-106 is a beta emitter, it does not have an exposure rate constant.
Half-life Properties:	Ru -106 half-life 373.6 days Rh-106 half-life 29.8 seconds Both are Beta emitters.[1]
Forms available for use:	Usually embedded in a thin foil of metal such as silver and used for eye applicators which are used for treating choroidal/ocular melanoma.
HVL in lead:	HVL in water or tissue is 2.5mm.[4] Could not find HVL in lead, however it will be minimal considering the HVL depth in water.
Measurement/Calibrations/QA:	Ruthenium-106 emits beta particles with a maximum energy of 39 keV, and can be counted by itself only with a detector sensitive to very low-energy beta particles. Its rhodium-106 daughter, however, emits energetic beta particles and gamma rays that can be measured with most beta or gamma detectors. [16] QA for any brachytherapy includes time, distance and shielding. Keep as much distance as possible from the source. Limit the time spent exposed to the source. Varify the use of proper shielding of the source.[10] Temporary implant needs a decay factor calculation (which is e(-.693/373.6 days) = .998/day or a decay of approximately .2% per day). This is used to calculate the dose from the dose at shipment of the source to the time of implantation. A measurement is taken of the source upon delivery by placing the source in a well counter to varify the dose at shippment.[11] After removal of the plaque with the Ru-106 seeds, standare brachy procedures are used for release of the patient. The room is surveyed with a GM counter to reassure that no radioactive contamination is left behind.[10]
Used in formula/calculation:	The Monte Carlo technique provides a powerful tool for calculation of the dose and dose distributions which helps to predict and determine the doses from different shapes of various types of eye applicators more accurately.[8] The Monte Carlo code MCNPX has been used to calculate dose distributions from a COB-type 106Ru/106Rh ophthalmic applicator manufactured by Eckert & Ziegler BEBIG GmbH.[8] Several dose distributions are calculated: a distribution on a spherical surface 1 mm above the surface and three planar distributions on planes XY (horizontal plane), XZ (vertical plane passing the cut-out), and a plane just in front of the applicator parallel to the plane YZ.[8] All values were normalized to the value on the central axis at the distance of 1 mm above the surface.[8] Mean life = 1.44 (T1/2) =1.44 x 373.6 days =537.98 days Decay constant = 0.693/373.6 days =.0018 per day
Uses in Radiation Oncology:	Ru-106 is used in eye plaques and attached to the retina of the eye to deliver a dose of brachytherapy radiation. This procedure is done to treat opthalmic melanoma.[4] A typical total dose of 85 Gy is delivered to the tumor. Plaques are designed custom fitted to the shape of the treatment area in the range of 12 to 22 mm. Calculations are done using a Plaque Simulator treatment planning software to deliver the dose to the apex of the tumor.[7] Dose rate during plaque treatment at the center applicator surface can be as high as 100 cGy/second. The dose rate may vary greatly across the applicator. The dose rate from a beta applicator decreases to about 5% of the surface dose rate at a depth of 4mm, the depth of the lens below the cornea.[9] The plaques are usually made of attenuation material such as a gold alloy, and a means for attaching seed inside the plaque. The gold shell limits the dose to uninvolved strutures of the eye, by providing some limited collimation. The plaque also protects other organs, as well as persons in the vicinity of the patient. The plaque is ordinarily left in place for up to a week while the treatment id delivered.[9]
Treatment Planning:	Beta-ray emitting Ru-106/Rh-106 ophthalmic applicators have been used for close to 4 decades in the treatment of ophthalmic melanoma. The form factor of these applicators is a spherically concave silver bowl with an inner radius of curvature between 12 and 14 mm, and a total shell thickness of 1 mm. The radioactive nuclide is deposited in a layer 0.1 mm below the concave surface of the applicator. Calculation of dose distributions for clinical treatment planning purposes is complicated by the concave nature of the distributed source, the asymmetric shape of the active region of some applicators, imperfections in the manufacturing process which can result in an inhomogeneous distribution of activity across the active surface, and absorption and scatter in the 0.1 mm layer of silver which seals and protects the radioactive layer. A semi-empirical method of calculating dose distributions for these applicators is described which is fundamentally compatible with treatment planning systems that use the AAPM TG43 Brachytherapy formalism. [12]
One other interesting fact:	Fountain pen nibs are frequently tipped with alloys containing ruthenium. From 1944 onward, the famous Parker 51 fountain pen was fitted with the "RU" nib, a 14K gold nib tipped with 96.2% ruthenium and 3.8% iridium. [13] Rhodium is used for jewelry, for decoration, and as a catalyst. Forty four isotopes and isomers are now known. Rhodium metal (powder) costs about $300/g (99.9% pure). [17]

Links:
http://www.iop.org/EJ/article/1742-6596/102/1/012021/jpconf8_102_012021.pdf?request-id=a5d11cdc-b78a-482b-8b6b-6648809b0f64

References:
1. The Berkley Laboratory Isotopes Projects. Available at: http://ie.lbl.gov/education/isotopes.htm, Accessed March 17, 2009.
2. Wikipedia. Ruthenium 106. Available at:http://en.wikipedia.org/wiki/Ruthenium. Accessed March 19, 2009
3. Platinum Group Metals. Available at: http://books.google.com/books?id=sJsrAAAAYAAJ&pg=PA42&dq=rhodium-106&ei=T-HQSdeBM5O-M7HmudAO. Accessed March 30, 2009.
4. T. Wiegel, N. Bornfeld, W. Hinkelbein, M.H. Forester, Radiotherapy of Ocular Disease, 1997, volume 30, Karger publishing.
5. Absolute Astronomy. Ruthenium-106. Available at: http://www.absoluteastronomy.com/topics/Ruthenium-106. Accessed on April 1, 2009.
6. Eye Physics web site. Available at: www.eyephysics.com. Accessed April 2, 2009.http://bjr.birjournals.org/cgi/content/abstract/76813976v1
7. The British Journal of Radiology. Available at: http://bjr.birjournals.org/cgi/content/abstract/76813976v1, Accessed April 2, 2009.
8. Third McGill International Workshop. Journal of Physics: Conference Series 102 (2008) 012021. Monte Carlo calculation of dose to water of a 106Ru COB-type ophthalmic plaque. Available at: http://www.iop.org/EJ/article/1742-6596/102/1/012021/jpconf8_102_012021.pdf?request-id=57710980-ec10-47cb-9b24-899bcd1d0308. Accessed April 3, 2009.
9. Hendee, William R., Ibbott, Geoffrey S., Radiation Therapy Physics, second edition, Mosby publishing,1996, p. 369, 409.
10. University of Wisconsin- LaCross, D2L DOS 400, Brachytherapy for Medical Dosimetrists, accessed April 6, 2009.
11. Don Thompson MMP, Physicist, United Radiation Oncology, Lexington, KY, April 6, 2009.
12. Chao, KS., Perez, Carlos A., Brady, Luther W. Radiation Oncology Management Decisions, 2nd ed. Philadelphia: Lippincott Williams & Wilkins; 2002. pp. 511-518
13. Ruthenium 106. Available at:http://en.wikipedia.org/wiki/Ruthenium. Accessed March 15, 2009
14. Azom. com. Rhodium- Discovery, Occurrence, Production, Poperties, and Application. Available at: http://www.azom.com/Details.asp?ArticleID=3483. Accessed on April 7, 2009.
15. Integrated Environmental Management, Inc. Gamma Ray Dose Constants. Available at: http://www.iem-inc.com/toolgam.html. Accessed on April 7, 2009.
16. Kahn B, Choppin GR, Taylor JG. User's Guide for Radioactivity Standards. Tennessee: United States Atomic Energy Commission; 1967.
17. Mr. Everett's Web Page. Rhodium. Available at:http://www.mrteverett.com/Chemistry/pdictable/q_elements.asp?Symbol=Rh. Accessed on April 7, 2009.

Color Codes:
Candice - Orange
Sherri - Green
Robin B.- Blue
Allan -Red

Iodine - 125

angie garner — Fri, 10 Apr 2009 09:53:43 CDT

Photos:	Figure 1. Iodine-125 Seeds	Figure 2. Interstitial prostate seed implant CT - Iodine-125
	Fig. 3 Iodine Diagram 6	Figure 4. I-125 prostate implant

Relevant Historical Data:	-Natural abundance is effectively 0%. 1 -Approximately 30 radioactive isotopes of iodine have been made artificially. 6 -In 1946 Allen Reid and Albert Keston discovered Iodine-125, which became important in the field of radioimmunoassay. 13 -Grayish-black non-metallic element, a member of a Halogen group. 9 -Critical organ of I-125 is the thyroid, it is the biological destination. 14
Chemical/Radioactive Composition:	Chemical symbol: I Atomic number (Z): 53 Mass number (A): 125 -I-125 is produced in a nuclear reactor by bombarding Xe-124 with neutrons, which decays via electron capture to I-125. 3 -Electron configuration: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p5 4 -Decay of Xe-125 leads to I-125. 7
Energy Characteristics:	-Emits gamma rays with maximum energies of 35.5 keV (7% emitted, 93% internally converted to: 27keV, 31keV, and 27-32 keV some of which are internally converted to x-rays). 1 -Average energy is 28.5 keV. 9
Exposure Rate Constant:	-Exposure rate constant is 1.46 R-cm2/mCi-hr. 2 -The air-kerma strength is 1.27 cGy-cm2/mCi-hr (1.27U). 3
Half-life Properties:	-The half-life of Iodine-125 is 59.4 days. 1,2 -Decays by about 1.2% in one day. 3 -Half-life of Iodine-125 is 60days 15
Forms available for use:	-Commercially available in dilute NaOH solution as [125I]iodide 1 -Seeds 2 -Seed design contains a silver wire that is visible on radiographs, which helps show seed position as well as orientation. 2 -Sources are widely available as seeds or strands for use in interstitial implants 10 -Widely available as seeds with different designs and consists of I-125 sources encapsulated in a titanium shell 10 -To isolate radioiodine capsule is cooled and Xe gas is allowed to escape. 7
HVL in lead:	-0.025 mm Pb 1 -<0.0001 Pb 15 -TVL=.08 mm Pb
Measurement/Calibrations/QA:	-Air kerma strength standards are maintained for I-125 seeds. These standards are developed by performing measurements in large volume ion chambers such as the spherical carbon wall ion chamber and the wide angle free air chamber. The calibration of all clinically used brachytherapy sources should be directly traceable to the National Institute of Standards and Technology (NIST) or the Accredited Dosimetry Calibration laboratory (ADCL). 8 -Iodine 125 seeds are calibrated in terms of exposure rate in free space at 1m using a free-air ionization chamber at the NIST. A well-type ionization chamber, whose calibration is maintained by a free-air chamber as the primary standard, is used for routine calibrations. 2 -The process of determining the dose distribution obtained from I-125 seeds is complex and uncertain. However, the development of TLD detectors for dosimetry and computational techniques based on Monte Carlo methods have led to a better understanding of the dosimetry of low energy brachytherapy sources such as I-125 10
Used in formula/calculation:	Mean Life (T avg)= 1.44 T1/2 Mean Life= 1.44 x 59.4 days= 85.5 days Dc= Do x Tavg Dc= 20 cGy/hour x 24 hours/day x 85.5 days= 41,040 cGy 41,040 cGy is the total cumulative dose for a permanent Iodine-125 implant with an initial dose rate of 20 cGy/hour.2 Specific Activity: 1739 Ci/g 16
Uses in Radiation Oncology:	-Prostate cancer and brain tumors 1, ocular melanoma, head and neck cancers (high activity seeds) 3 -Commonly used for temporary brachytherapy applications 3 -Used in studies of the pancreas, blood flow, thyroid, liver, take-up of minerals in bones, and loss of proteins in the body. 6 -Used as an alternative to Iridium-192 for soft tissue sarcoma in pediatric patients. Iodine-125 reduces exposure to caregivers and critical anatomic structures, such as gonads, thyroid, and bony growth plates when compared to Iridium-192. 11 -Used for treating thyroid cancers 12 -Monoclonal antibodies radiolabeled with I-125 have also been used for treatment of high grade gliomas. 12 -Organically bound I-125 solution injected into an inflatable balloon catheter (placed in the tumor cavity) is also being employed for treatment of brain tumors. 12 -Used in permanent low dose radiation brachytherapy. Radioactive pellets filled with iodine are permanently implanted into the prostate cancer patient’s prostate gland. Iodine has a longer half life than palladium-103 which is the other substance used in LDR brachytherapy. Iodine emits lower levels of radioactive energy but gives off energy for longer than the palladium. 14
Treatment Planning:	-Pre-planned or intraoperatively planned 5 -Postplanning can also be done to envision the resultant dose distribution.11 -Planning is much more complex than conventional interstitial sources.2 -The anisotropy (differences in dose distribution around the seed) is higher due to differential attenuation of the low-energy x-ray emissions caused by the seed encapsulation 10 -Planning is done after mapping out the prostate several weeks before the implant procedure with trans rectal ultrasound. A specialized computer program is used to determine the number, strength and placement pattern of the seeds.Typically about 110 seeds are used but the number can vary between 80 -150 seeds. The seeds are inserted using thin each needles. Each needle holds 2 to 6 and the accuracy of the needle placement is monitored directly by transrectal ultrasound and fluoroscopy (x-ray). 17
One other interesting fact:	-Has a neutron capture cross section of 900 barns. During a long irradiation part will be converted to Iodine126. 7 -The Iodine 125 seeds lose 50% of their strength every 2 months and the effective treatment time is about 6 months. By one year from implant their radiation is minimal (<1%). 17

Links:
1. Bardurological.com. Iodine-125 seeds. Available at: http://www.bardurological.com/products/loadProduct.aspx?prodID=232. Accessed on March 12, 2009.
2. Nature.com. Iodine seed prostate brachytherapy. Available at: http://www.nature.com/pcan/journal/v7/n3/fig_tab/4500727f2.html. Accessed on March 12, 2009.
3. Iodine-125 Handling Precautions. Available at: http://las.perkinelmer.com/content/TechnicalInfo/TCH_Iodine125.pdf. Accessed April 7, 2009.

References:
1. Wikipedia.com. Iodine-125. Available at: http://en.wikipedia.org/wiki/Iodine-125. Accessed on March 12, 2009.
2. Khan, Faiz M. The Physics of Radiation Therapy. 3rd Edition. Philadelphia: Lippincott Williams & Wilkins; 2003. pp. 358, 367, 545.
3. Module 7, Session 4, pp.29-35. Accessed March 16, 2009, Stanford Web-Based Dosimetry Training Tool. Available at: http://www.dosimetrytrainingtool.com.
4. Radioactive Elements. Available at: http://theodoregray.com/PeriodicTable/Elements/053/data.s7.html. Accessed on March 17, 2009.
5. Medscape Today. Available at: http://www.medscape.com/viewarticle/561945_10. Accessed on March 17, 2009.
6. Iodine. Available at: http://www.chemistryexplained.com/elements/C-K/Iodine.html. Accessed on March 17, 2009.
7. Wikipedia.com Iodine-125. Available at http://en.wikipedia.org/wiki/Iodine-125. Accessed on March 18,2009.
8. Module 7, Session 3, pp3.. Accessed March 18, 2009. Stanford Web-Based Dosimetry Training Tool. Available at: http://www.dosimetrytrainingtool.com.
9. Leibel Steven, Phillips Theodore. Textbook of Radiation Oncology. Philadelphia: W.B. Saunders Company; 1998. p.152.
10. Module 7, Session 4, pp29-33.. Accessed March 19, 2009. Stanford Web-Based Dosimetry Training Tool. Available at: http://www.dosimetrytrainingtool.com.
11. Devlin, Phillip M. Brachytherapy Applications and Techniques. Philadelphia: Lippencott Williams & Wilkins; 2007. pp.45, 283.
12. Module 7, Session 7, pp6. Accessed March 27, 2009. Stanford Web-Based Dosimetry Training Tool. Available at: http://www.dosimetrytrainingtool.com.
13. InteractiveSNM.org. Iodine-125. Available at: http://interactive.snm.org/index.cfm?PageID=1107&RPID=10. Accessed on March 27, 2009.
14. Prostate Cancer Treatment Guide. Iodine-125 in Prostate Cancer Brachytherapy. Available at: http://www.prostate-cancer.com/prostate-cancer-glossary/iodine-125.html. Accessed on April 6, 2009.
15. Ajronline.org. Iodine-125 Source in Interstitial Tumor Therapy. Available at: http://www.ajronline.org/cgi/reprint/123/1/163.pdf. Accessed on April 9, 2009.
16. Khan, Faiz. The Physics of Radition Therapy, 3rd ed. (2003). pp531, 540-2.
17. brachytherapy.co.nz. Prostate Implants New Zealand Ltd. Available at: http://www.brachytherapy.co.nz/brachytherapy.php. Accessed on April 9, 2009.

Color Codes:
Purvi - Orange
Alia - Green
Angie - Blue
Tracey -Red

Strontium - 90 / Yttrium - 90

mattys29 — Wed, 08 Apr 2009 14:26:08 CDT

Photos:	Robot manipulator holding a vial of Yttrium-90 in a hot cell. Image 1

Image 2.

Relevant Historical Data:	In 1970 Adair Crawford and William Cruishank first detected non-radioactive strontium in the mineral strontianite in Scotland. Radioactive Sr-90, like many other radionuclides, was discovered in the 1940's in nuclear experiments connected to the development of the atomic bomb. (4) Strontium-90 is a byproduct of the fission of uranium and plutonium in nuclear reactors, and in nuclear weapons. It was found in the waste. Large amounts of Sr-90 were produced during atmospheric nuclear weapons tests conducted in the 1950's and 1960's and dispersed worldwide. (4) Sr-90 decays to a daughter element called Yttrium-90 by emmitting a beta particle <0.5MeV in energy. (5)
Chemical/Radioactive Composition:	Sr 90: atomic number = 38; atomic mass 90.(8). Chemically reactive; can create halide, oxide, and sulfide compounds Sr-90 decays to yttrium 90 (Y-90), which in turn decays by beta radiation so that wherever Sr-90 is present Y-90 is also present. Because of the beta radiation, Y-90 poses a risk of burns to the eyes and on the skin from external exposure. (1)
Energy Characteristics:	They are both beta emitters with a maximum energy of 2270 keV an average energy of 970 keV. (6). maximum energy values are 546 and 2226 keV. Sr-90 decays via -ve beta emission to Y-90, Max beta Energy= 0.546 MeV. Y-90 decays via -ve beta emission to stable Zr-90. MAx beta energy = 2.283MeV. Only small gamma radiations accompanies these dacays (9)
Exposure Rate Constant:	It doesn't have an exposure rate constant. (7)
Half-life Properties:	Sr-90 = 28years (3), pure Y 90= 2.67 days
Forms available for use:	Sr-90 is a soft metal. It can be present in dust from nuclear fission after detonation of nuclear weapons or a nuclear power plant accident.(1). Y-90: liquid used for lymphoma salvage, Zevalin monoclonal antibody
HVL in lead:	It doesn't have a HVL in lead. It's penetrability is very shallow. (7). Sr-90 =0.125 in tissue.(9)
Measurement/Calibrations/QA:	The principles of Time, Distance, and shielding should be observed with all radioctive isotopes. Y-90. Warnings The contents of the vial are intended for use in the preparation of radiolabelled monoclonal antibodies. The contents of the vial are NOT to be administered directly to patients. Adverse Reactions None known. Adequate shielding should be used with this beta-emitter, in accordance with institutional good radiation safety practices. The absorption of high energy beta particles in matter gives rise to the production of electromagnetic radiation (bremsstrahlung). This radiation is more penetrating that the beta particles which produce it. Therefore, it is essential to reduce the bremsstrahlung production to a minimum for efficient shielding against beta particles. This is done using materials of low atomic number. Plexiglass of thickness 0.1 inch will absorb all beta particles with energies up to 1 MeV. Dosage and Administration This product is used to prepare Yttrium-90 radiolabelled monoclonal antibodies. The patient dose should be measured by a suitable radioactivity calibration system prior to administration. Directions for Preparation. Use aseptic technique and wear waterproof gloves throughout the entire preparation procedure. Make all transfers of radioactive solutions with an adequately shielded syringe and maintain adequate shielding around the vial during the useful life of the radioactive product. Do not use if the solution contains particulate matter or is not a clear solution. How Supplied Yttrium-90 Chloride Sterile Solution is supplied as a sterile , non-pyrogenic solution in 2 mL borosilicate vials with teflon-faced chlorobutyl rubber closures. Each vial contains 52 mCi (1924 MBq) of yttrium-90 as of 1200h ET on the intended day of use. Storage Yttrium-90 Chloride Sterile Solution is to be stored at 15-30°C. Expiry Yttrium-90 Chloride Sterile Solution expires 5 days after the date of calibration. Do not use after the expiry date printed on the package. (11)
Used in formula/calculation:	Y-90- A preplan is performed for a yttrium-90 ocular treatment. 1 source is required and 2 were ordered. If the procedure has to be delayed by 1 day, and the same source is to be used, the number of sources now required would be_____. Using the Activity formula of At=Ao e^ -(.693 x time/half-life) the half-life of yttrium-90 is 2.76 days so now insert the given information into the formula. 1x (.693 x 1/2.67) now because it is delayed the e^(.693 x 1/2.67) is not negative. The answer is 1.29 sources will be required.
Uses in Radiation Oncology:	Excluding intravascular brachytherapy, the common use of Strontium-90 is in ophthalmic applicators. These applicators are commonly used to treat pterygia and corneal vaculations by direct application of several hundred cGy of radiation to the eye in periods of typically several seconds to one or two minutes, depending on the activity of the applicator.(12) Is used as a temporary implant for treating pterygium, a benign growth of the conjuctiva of the eye. Sr-90 is employed in ophthalmic surface applicators which typicaly provides 20 -80cGy/sec surface dose. 90 Sr/ 90 Y has also been employed for intravascular brachytherapy applications to inhibit restenosis on coronary lesions (re-closure of the artery after angioplasty). (3). 90Sr/90Y applicators are used in the treatment of skin haemangiomas. Y90- is used as selective internal radi therapy for the treatment of several cancers e.g. hepatic cancer, pancreatic cancer and advance neuroendocrine cancers. (9).
Treatment Planning:	The beta particles from Yttrium-90 are ideal for the treatment of superficial lesions of the eye. The dose falls very rapidly away from the applicator and is approximately 20 percent at 2mm-depth in tissue. The dose rate on the surface of such an applicator is in the range of 100 cGy/s; thus each treatment is delivered in seconds. Since the half-life is quite long, stontium 90 applicators are stored and used over many years.(7)
One other interesting fact:	Because Sr-90 generates heat as it decays, it is used as a power source for space vehicles, remote weather stations, and navigational beacons. It also is used in industrial gauges and medically, in a controlled manner, to treat bone tumors. (1) Strontium 90 is probably the most-feared fission product. Chemically similar to calcium, it is absorbed along with calcium by the human system and deposited in the bones, where its persistent radioactivity (half-life 28 years) may cause cancer. (2) Stontium was discovered by a Scottish man named Adair Crawford in 1790. It was named after a city in Scotland called Strontianite. Strontium is also used in flares, fireworks and crimson color. Group in Periodic Table: 2 ;Period in Periodic Table: 5;Group Name: Alkaline Earth Metal; Melting Point: 769 degrees Celsius; Boiling Point: 1384 degrees Celsius ;Color when first cut: silvery white; Color after cut: yellowish. (8) It is primarily the 90Y betas that are used for therapy, as the 90Sr betas are mostly absorbed by the stainless steel encapsulation and the surrounding catheter. The 90Sr system (Beta-Cath System) contains sources that are 2.5 mm in length. Source trains of 12 (30 mm), 16 (40 mm) and 24 seeds (60 mm) are commercially available. The sources are stored in a hand-held transfer device and are advanced by a closed loop hydraulic system, which uses sterile water to advance (and then retract) the sources. The advantage of the 90Sr system is the relatively short treatment times (3-5 minutes) and the absence of radiation protection concerns associated with the use of a beta emitter. 90Sr/Y is one of the most energetic beta emitters, which helps reduce the luminal surface dose. The long half-life of the isotope permits the sources to be exchanged on a 6-month basis with no need to change the treatment times during that 6-month period. The disadvantage of this isotope is the potential for attenuation of the betas by calcifications or stents. The Strontium90 vascular brachytherapy system was designed specifically for use in the cath lab and utilizes a patented hydraulic system to deliver the Strontium90 radiation source train into the coronary artery. Strontium90 is an ideal isotope for vascular brachytherapy and the cath lab because it is easy to shield, there is no additional radiation exposure to the cath lab staff and the isotope's 28.8 year half-life means that the treatment times remain consistent from day-to-day use. The multiple radiation source trains (30 mm, 40 mm and 60 mm) allow appropriate radiation coverage of the entire injured area to ensure good clinical outcomes.(10)

Links:
1.Ultrasound guided internal radiotherapy using Y 90: http://jnm.snmjournals.org/cgi/reprint/38/7/1169.pdf
2. Strontium-90 information.http://en.wikipedia.org/wiki/Strontium

References:
1. Centers For disease Control and Prevention. Radioisotope Brief: Strontium-90 (Sr-90). Available at: http://www.bt.cdc.gov/radiation/isotopes/strontium.asp. Accessed on March 19, 2009.

2. Time. Man an Strontium-90. Available at: http://www.time.com/time/magazine/article/0,9171,809133,00.html. Accessed on March 19, 2009.

3. Sources for Temporary Implants. Dosimetry Taining Tool. Available at: www.dosimetrytrainingtool.com. Accessed on March 21, 2009.

4. United States Environmental Protection Agency. Available at www.epa.gov/rpdweb00/radionuclides/strontium.html. Accessed on March 24, 2009.

5. Radioisotopes and Dosimetry in Vascular Brachytherapy. Available at www.content.Karger.com. Accessed on March 24, 2009.

6. Khan, Faiz M. The Physics of Radiation Therapy, Third Edition. Lippincott Williams & Wilkins. 2003. pg. 550.

7. Bentel, Guinilla C. Radiation Therapy Planning, Second Edition. McGraw-Hill. !996. Pg. 534-536.

8. Health Physics society: http://www.hps.org/publicinformation/ate/q429.html

9. Shirish K. Jani, Shirish Jani, K. Handbook of Dosimetery Data of Radiotherapy, illustrated. CRC press1993. pg. 158

10. Strontium-90 brachytherapy uses. Available at:http://www.medscape.com/viewarticle/462111. Accessed on March 25, 2009.

11. Yttrium-90 calibrations. Available at:http://www.mds.nordion.com/documents/products/Package-Insert-Y90-Canada.pdf. Accessed on April 3,2009.

12. VanDyk, Jacob. The Modern Technology of Radiation Oncology. Medical Physics Publishing;1999: pg. 703.

Images: 1. www.radiochemistry.org/.../hanford.htm
2. strontium-90. Available at: www.invasivecardiology.com/article/1917. Accessed 4/8/2009.

Color Code:
Mat C.
Francine
Amy
Kehkashan

Ytterbium - 169

ronken.alia — Wed, 08 Apr 2009 14:00:25 CDT

Mould

Photos:	Fig. 1 Ytterbium 3
	Fig. 3 Ytterbium source seeds 10	Fig. 2 Ytterbium diagram 4

Relevant Historical Data:	-Ytterbium-169 was developed mainly to improve isodose distribution available with iodine-125 or palladium-103 seeds. With a half-life of 32 days, Ytterbium-169 improves the initial dose rate which is achieved in permanent implants with iodine-125. In this respect, Ytterbium-169 has no advantage over palladium-103, which has a half-life of 17 days. Another reason for the development of Ytterbium-169 was to provide a replacement for iridium-192 as a source for high dose rate (HDR) and low dose rate (LDR) treatments. The reduction in energy with Ytterbium-169 simplifies the design and cost of remote afterloading equipment. There is also a cost savings in the reduced shielding requirements for brachytherapy rooms. 5
Chemical/Radioactive Composition:	Chemical symbol: Yb Atomic number (Z): 70 Mass number (A): 169 -Neutron activation of ytterbium oxide in a nuclear reactor produces Y-169. 9 -Geological specimens are known in which the element has an isotopic composition outside the limits for normal material. 3
Energy Characteristics:	-63-308 KeV 1 -Emits photons with energies ranging from 50 to 308 keV 2 (average energy of 93 keV) (excluding energies less than 10 keV) 2 -Gives off gamma radiation 4
Exposure Rate Constant:	-Analytic calculations based on the primary photon spectrum of 169Yb (excluding energies less than 10 keV) yield an air-kerma rate constant of 0.0427 cGy cm2 h-1 MBq-1, and an exposure rate constant of 1.80 R cm2 mCi-1 h-1 for this radionuclide. 2
Half-life Properties:	-32 days 1
Forms available for use:	-Seeds. 2 -The Yb-169 seed is about 5 mm in length with an outer diameter of 1 mm in diameter and contains 0.5 mm diameter ytterbium oxide spheres encapsulated in a cylindrical titanium shell. 9 -The SENTINELTM range of double encapsulated special form sealed source assemblies caters to most industrial applications using gamma radiography. -A choice of isotopes provides solutions for the widely varying requirements demanded by differ ent materials and site conditions. Sources with outputs ranging from less than one curie up to several hundred are available-all precision con structed to ensure the highest possible specific activities and the smallest focal spot sizes. 10 -Ytterbium-169 sources are available in spherical and right circular cylinder focals, housed in a welded titanium alloy capsule 10
HVL in lead:	-The first half-value layer in lead is 0.2 mm; the first tenth-value layer is 1.6 mm 2
Measurement/Calibrations/QA:	-Standardization of brachytherapy source strength in terms of exposure rate has been performed by the National Institute of Standards and Technology. A seed submitted for calibration is placed at the bottom of the re-entrant tube for measurement of its source strength. Exposure rate at 1meter with a stated overall uncertainty of 2%. 7 -The source strength can be measured directly with an ion chamber or calculated indirectly from the source radioactivity [Bq] with corrections for encapsulation. 14
Used in formula/calculation:	Mean Life (T avg)= 1.44 T1/2 Mean Life= 1.44 x 32 days = 46.08 days Dc= Do x Tavg Dc= 10 cGy/hour x 24 hours/day x 46.08 days= 11,059 cGy 11,059 cGy is the total cumulative dose for a permanent Ytterbium-169 implant with an initial dose rate of 10 cGy/hour.8
Uses in Radiation Oncology:	-Used as a substitute for Cs-137 and Ir-192 for temporary implants due to its relatively lower energy emissions.2 -Has also been considered as a replacement for I-125 and Pd-103 in permanent implants. 6,13 Can possibly provide comparable tumor control in slowly proliferating tumors. 6 -Is a promising new radionuclide for intravascular radiotherapy (IVBT). It has a much better penetrating power through calcified plaques and stents compared with the low-energy source Iodine-125. It also provides easier radiation protection measures for cardiac cathlab personnel than the high-energy source Iridium-192, while preserving a favorable dose distribution in tissues surrounding an arterial vessel. 11
Treatment Planning:	-Monte Carlo simulation is an accurate and powerful tool for dosimetric characterization of brachytherapy sources in this energy range. 12 -In spite of the uncertainties in the parameters necessary for an accurate radiobiological modelling, the linear quadratic model can be useful in the comparative evaluation of the radiotherapeutic merit of similar implants. 13
One other interesting fact:	-Radiation protection is not as easily achieved for permanent implants with 169Yb because of the higher energy emissions 2 -For temporary implants, Ytterbium-169 may prove to be a useful substitute for 192Ir or 137Cs because of its relatively lower energy emissions 2

Links:
1. Gamma Ray Sources. Available at: http://onlineshowcase.tafensw.edu.au/ndt/content/radiographic/task2/accessible.htm. Accessed April 7, 2009.
2. Ytterbium-169 Sources. Available at: http://www.entsys-tech.com/ndt/group1radiographicsystems/ytterbium-169.htm. Accessed April 7, 2009.
3. Ytterbium-169: Calculated physical properties of a new radiation source for brachytherapy. Available at: http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=MPHYA6000019000003000695000001&idtype=cvips&gifs=yes. Accessed April 7, 2009.
4. Modern Advances in Prostate Brachytherapy. Available at: http://www.aapm.org/meetings/05SS/program/ProstateAdvances_lief.pdf. Accessed April 7, 2009.

References:

1. Sentinel.thomasnet.com. Ytterbium-169. Available at: http://sentinel.thomasnet.com/item/sources-source-holders/sources/pn-1255?&seo=110. Accessed on March 16, 2009.
2. Pubmed.gov. Ytterbium-169. Available at: http://www.ncbi.nlm.nih.gov/pubmed/1508110. Accessed on March 16, 2009.
3. Radioactive Elements. Available at: http://theodoregray.com/PeriodicTable/Elements/070/data.s7.html. Accessed on March 17, 2009.
4. Ytterbium. Available at: http://www.chemistryexplained.com/elements/T-Z/Ytterbium.html. Accessed on March 17, 2009.
5. Mould, R.F., Battermann, J.J., Martinez, A.A. Brachytherapy from Radium to Optimization. Wageningen,The Netherlands: Veenman Drukkers; 1994. pp. 379-382.
6. IOP.org. Analysis of Radiobiology of Ytterbium-169 and Iodine0125 Permanent Brachytherapy Implants. Available at http://iop.org/EJ/abstract. Accessed on March 18, 2009.
7. Leibel Steven, Phillips Theodore. Textbook of Radiation Oncology. Philadelphia, Pennsylvania: W.B. Saunder Company; 1998.
8. Khan, Faiz M. The Physics of Radiation Therapy. 3rd Edition. Philadelphia: Lippincott Williams & Wilkins; 2003. p. 545.
9. Module 7, Session 9, pp.11-15. Accessed March 26, 2009, Stanford Web-Based Dosimetry Training Tool. Available at: http://www.dosimetrytrainingtool.com.
10. Sentinal.thomasnet.com. Ytterbium 169. Available at: http://sentinel.thomasnet.com/item/sources-source-holders/sources/pn-1255?&seo=110. Accessed on March 27, 2009.
11. Science Direct. Ytterbium-169: A promising new radionuclide for intravascular brachytherapy. Available at: http://www.sciencedirect.com/science?_ob=Article. Accessed on March 30, 2009.
12. Biomed Experts. Dosimetric characteristics, air-kerma strength calibration and verification of Monte Carlo simulation for a new Ytterbium-169 brachytherapy source. Available at: http://www.biomedexperts.com/Abstract.bme/8138449/Dosimetric_characteristics_air-kerma_strength_calibration_and_verification_of_Monte_Carlo_simulation_for_a_new_Ytterbium. Accessed on March 30, 2009.
13. IOP Electronic Journals. Analysis of the radiobiology of ytterbium-169 and iodine-125 permanent brachytherapy implants. Available at: http://www.iop.org/EJ/abstract/0031-9155/42/9/005. Accessed on April 6, 2009.
14. Research Gate Scientific Network. Radioactivity measurements of ytterbium-169 brachytherapy sources. Available at: https://www.researchgate.net/publication/13651733_Radioactivity_measurements_of_ytterbium-169_brachytherapy_sources. Accessed on April 6, 2009.

Color Codes:
Purvi - Orange
Alia - Green
Angie - Blue
Tracey -Red

Cesium-137

danacole — Mon, 06 Apr 2009 21:18:27 CDT

Photos:	Image 1
	Image 2
	Image3

Relevant Historical Data:	In 1860, Gustav Kirchhoff and Robert Bunsen discovered nonradioactive cesium in mineral water in Germany. Radioactive cesium-137, and many other radionuclides that are used in nuclear medicine, was discovered in the late 1930s by Glenn T. Seaborg and his coworker, Margaret Melhase.¹ Cs-137 in our environment came mostly from nuclear weapons testing in the 1950's and 1960's.8
Chemical/Radioactive Composition:	Cesium is produced in nuclear reactor fuel as a natural by-product of nuclear fission. It can be chemically separated from spent nuclear fuel and is widely available.2. Radioactive Cesium is distributed as an insoluble powder or ceramic microsphere matrix enclosed in stainless steel needles or tubes.4
Energy Characteristics:	Photon energy of 662 keV which is comparable to the average photon energy of radium(830keV).² Gamma Factor for Cs-137:³ The gamma rays from Cesium have almost the same penetrating power as radium in tissue.7
Exposure Rate Constant:	The exposure rate constant of Cs-137 is 3.28 R-cm2/mCi-hr.4
Half-life Properties:	The half-life of cesium-137 is 30.22 years.¹
Forms available for use:	Wide variety of needle or tube configurations.² Insoluble powder or ceramic microsphere matrix enclosed in stainless steel needles or tubes.4
HVL in lead:	The HVL in lead for Cesium-137 is 6.5 mm.³
Measurement/Calibrations/QA:	They decay about 2% per year.2. Cs-137 decays by β-emission to a metastable state of Ba -137m which subsequently undergoes isomeric transition from Ba-137m to Ba-137 resulting in the emission of a single 0.662 MeV β-rays and a small number of 35 keV characteristic x-rays resulting from internal conversion.4 A Cesium source can be used clinically for about 7 years due to the long half life.7 A decay chart should be available to the treatment planner so that the correct source activity is used for the time of the procedure. The source loading, number of sources used, along with the total source strength should be documented. A 'Radioactive Materials' sign must be posted on the patient's door, and visitor time and distance from the patient restricted. After removal of the sources, the patient must be surveyed to ensure they were indeed removed completely.4
Used in formula/calculation:	A vaginal cylinder is loaded with 20-15-20 mg Raeq sources of Cs-137. What is the total number of mCi of Cs-137? (Exposure rate constant Cs-137=3.26) 20+15+20=55mgRaeq total 55mgRaeq x 8.25Rcm2/mCihr = 139.2 3.26Rcm2mCihr
Uses in Radiation Oncology:	Cs-137 sources are extensively used for intracavitary implants for the treatment of gynecological cancers.4 A system consisting of a tandem and two ovoids is the most frequently used afterloading apparatus in the treatment of carcinoma of the uterine cervix.5 Cs-137 is only used for low dose rate brachytherapy due to its low specific activity.4
Treatment Planning:	In a typical tandem and ovoid application, only the segment of the tandem lying within the uterine canal should be loaded. The keel on the tandem will indicate where the external cervical os is located and on a lateral radiograph one can measure the length of the tandem lying within the uterus. The distal source should extend to but not beyond the keel, and if this requires more than three sources, nylon spacers of appropriate size can be added either at the proximal end of tandem or between the sources. The desired dose distribution is approximately pear shaped in the anterior view, with the widest part near the cervix. Typically, the tandem is loaded with a 15-mg source at the proximal end, a 12-mg source in the center, and a 10-mg source in the distal end, which is in the cervix. Selection of source strength in the ovoids depends on their diameter and the seperation between them. Ovoid diameter size depends on the patient's vaginal vault size. Selection of source strength also depends on rectal and bladder dose. Typical source strengths are 10-mg in miniovoids and 15, 20, and 25 mg in small, medium, and large ovoids respectively.5 Currently the standard unit is the centigray to a specific anatomical point or isodose line. The anatomical points used for cervical and uterine treatment are points A and B. Point A is located 2 cm superior and 2cm lateral to the center of the cervical canal ( at the cervical os) in the plane of the uterus. Point B was originally 3 cm lateral to point A, but is currently noted as being 1cm lateral to the medial aspect of the pelvic side wall. The dose at point B is typically about one third that at point A.2
One other interesting fact:	Advantages: · Cesium has a half-life of 30 years thus causing only a 2% change in dose-rate over one year. Hence a Cs-137 source can be used in a clinical setting for up to 8-10 years. · Cs-137 has dosimetric properties similar to Ra-226 and has been adopted as a "radium substitute" for clinical brachytherapy applications · -ray as compared to 0.830 MeV for Ra-226gCs-137 sources emit a 0.662 MeV thus leading to lower shielding costs associated with its clinical use. · Disposal of Cs-137 sources is relatively easier as compared to Ra-226.4 Disadvantages: · Low specific activity for Cs-137 precludes the use of Cs-137 for high dose rate applications in clinical brachytherapy.4 It is a soft, silvery-gold alkali metal with a melting point of 28 degrees C, making it one of only five metals that are liquid at room temperatures.6 This fact makes it capable of becoming a water contaminant.

Links:

References:
1. http://www.epa.gov/rpdweb00/radionuclides/cesium.html#whodiscovered Accessed 3/10/09

2. Washington CM, Leaver DT. Aspects of brachytherapy. In: Principles and Practice of Radiation Therapy Physics, Simulation, and Treatment Planning. St.Louis, MO: Mosby_year Book, Inc.; 1996:39,44.

3. http://www.rpdinc.com/html/cesium-137.html Accessed 3/1709

4. http://www.dosimetrytrainingtool.com

5. Bentel GC. Dose calculations in brachytherapy. In: 2nd ed. Radiation Therapy Planning. New York, NY: McGraw-Hill; 1996:566-569.

6. http://en.wikipedia.org/wiki/Caesium

7. Khan, FM. The Physics of Radiation Therapy. 3rd ed. Philadelphia, PA: Lippincott Williams and Wilkins; 2003: 360-397.

8. http://www.epa.gov/radiation/radionuclides/cesium.html

Images:
Image 1. http://www.npp.hu/mukodes/beta-e.htm
Image 2 & 3 Bentel GC. Dose calculation in brachytherapy. In: 2nd ed. Radiation Therapy Planning. New York, NY: McGraw-Hill; 569,572.

Authors:
Denise,Michelle, Dana,

Samarium - 153

cmcculler — Mon, 06 Apr 2009 15:02:09 CDT

Photos:	Samarium a rare earth metal.[4]	Quadramet IV [5] Bone Scan [5]

Relevant Historical Data:

Samarium-153 lexidronam (chemical name Samarium-153-ethylene diamine tetramethylene phosphonate, abbreviated Samarium-153 EDTMP, trade name Quadramet [1]

Chemical/Radioactive Composition:

Samarium-153 lexidronam is a complex of a radioisotope of the lanthanide element samarium with the chelator EDTMP which is used to treat pain when cancer has spread to the bone. It is injected into a vein and distributes throughout the body. It homes in on areas where cancer has invaded the bone. Once there, the radioisotope emits beta particles (electrons) which kill the nearby cancer cells.[1]

Quadramet Chemical Structure [7]

Energy Characteristics:

Samarium-153 is produced in high yield and purity by neutron irradiation of isotopically enriched samarium Sm 152 oxide (152Sm2O3). It emits both medium-energy beta particles and a gamma photon. Samarium-153 has average and maximum beta particle ranges in water of 0.5 mm and 3.0 mm, respectively. [2]

	Radiation Energy (keV)*	Abundance
Beta	640	30%
Beta	710	50%
Beta	810	20%
Gamma	103	29%
* Maximum energies are listed for the beta emissions, the average beta particle energy is 233 keV.

Exposure Rate Constant:

0.46 R/mCi-hr at 1cm [3]

Half-life Properties:

46.3 hours (1.93 days)[1]

Forms available for use:

IV injectable, Quadramet comes in 1.0 mCi/kg. injected through a catheter over a period on 1 minute, followed by an injection of saline flush. Quadramet injections are supplied frozen in a single-dose vial containing 3 mL with 5550 MBq (150 mCi) of samarium-153 at [3]

HVL in lead:

The half-value thickness of lead (Pb) for samarium-153 is approximately 0.10 mm. The use of 1 mm of lead will decrease the external radiation exposure by a factor of approximately 1,000.[3]

Measurement/Calibrations/QA:

Measurement/Calibrations:[8]
All radioactivity is calibrated to the reference date and time on the vial.
The dose should be measured by a suitable radioactivity calibration system, such as a radioisotope dose calibrator, immediately before administration. The dose of radioactivity to be administered and the patient should be verified before administering. Patients should not be released until their radioactivity levels and exposure rates comply with federal and local regulations.

Thaw at room temperature before administration and use within 8 hours of thawing.The drug product expires 48 hours after the time of calibration noted on the label, or 8 hours after thawing, whichever is earlier.

Storage: Store frozen at -10° to -20°C in a lead shielded container.
Storage and disposal should be controlled in a manner that complies with the appropriate regulations of the government agency authorized to license the use of this radionuclide.

QA:[9]

Time-minimize the time spent working with radioactive materials without compromising the quality of care.

Distance-maximize the distance between the source and the workers.

Shielding-proper shielding should be used to limit exposure. The half value layer (HVL) is the amount of shielding required to limit the exposure by half of its magnitude. It could take several HVLs to reduce radiation exposure to personnel within limits.

Used in formula/calculation:

For Quadramet injections it is supplied frozen in a single-dose glass vial containing 3 mL with 5550 MBq (150 mCi) of samarium-153 at calibration Samarium-153 has average and maximum beta particle ranges in water of 0.5mm and 3.0mm, respectively.[3] The specific gamma-ray constant for samarium-153 is 0.46 R/mCi-hr at 1 cm (1.24x10-5 mSv/MBq-hr at 1 meter).[3] All Radioactivity is calibrated to the reference date and time on the vial. Physical Decay Chart Half Life 46.3 hrs.[3]

Time (hour)	Factor	Time ( hour)	Factor
-48	2.05	+1	.99
-36	1.71	+2	.97
-24	1.43	+3	.96
-20	1.35	+4	.94
-16	1.27	+6	.91
-12	1.20	+8	.89
-8	1.13	+12	.84
-6	1.09	+16	.80
-4	1.06	+20	.74
-3	1.05	+24	.70
-2	1.03	+36	.58
-1	1.02	+48	.49

Uses in Radiation Oncology:

A radioactive isotope used in the treatment of bone cancer and bone metastases. Samarium 153 is a radioactive form of the element samarium. It collects in bone, where it releases radiation that may kill cancer cells.[2]

Treatment Planning:

The recommended dose of Quadramet is 1.0 mCi/kg, administered intravenously. Dose adjustment in patients at the extremes of weight have not been studied. Caution should be exercised when determining the dose in very thin or very obese patients.
Patients should not be released until their radioactivity levels and exposure rates comply with federal and local regulation.[3]

One other interesting fact:

Samarium-153 is a compound that will accumulate particularly in osteoblastic or mixed metastatic lesions, with greater uptake in diseased bone than in normal bone. Sixty-five percent of the dose injected will be taken up by the skeleton, and most of that radioactivity will be cleared from the blood in about 30 minutes. Thirty-five percent of the dose is excreted in the urine, and most of that urinary excretion will be completed within 6 hours. [6]

The estimated absorbed radiation doses to an average 70 kg adult patient from an i.v. injection are shown in Table 7.[8] Radiation exposure is based on a urinary voiding interval of 4.8 hours.[8]

ABLE 7: RADIATION ABSORBED DOSES

	70 kg ADULT
Target Organ	Rad/mCi	mGy/MBq
Bone Surfaces	25.0	6.76
Red Marrow	5.70	1.54
Urinary Bladder Wall	3.60	0.097
Kidneys	0.065	0.018
Whole Body	0.040	0.011
Lower large intestine	0.037	0.010
Ovaries	0.032	0.0086
Muscle	0.028	0.0076
Small Intestine	0.023	0.0062
Upper Large Intestine	0.020	0.0054
Testes	0.020	0.0054
Liver	0.019	0.0051
Spleen	0.018	0.0049
Stomach	0.015	0.0041

Links:
http://www.cytogen.com/professional/quadramet/pi.php
http://www.rxlist.com/quadramet-drug.htm
http://www.medicinenet.com/samarium_sm-153lexidronam-injection/article.htm
http://www.pslgroup.com/dg/68bb6.htm
http://www.hps.org/publicinformation/ate/q2052.html

References

1.Samarium-153,wikipedia. Available at: wikipedia.org/wiki/Samarium-153 lexidronam. Accessed on March 10,2009.
2.National Cancer Institute. Samarium-153. Available at: www.cancer.gov. Accessed on March7,2009.

3. Cytogen. Health Care Professional Information Center. Quadramet-prescribing information. Available at: http://www.cytogen.com/professional/quadramet/pi.php. Accessed on March 21, 2009.
4. Web elements website. Available at: http://www.webelements.com/samarium/pictures.html. Accessed March 23, 2009.
5. Quadramet website. Available at: http://www.ansto.gov.au/commercial_services/health/ari/products/radiopharmaceuticals/quadramet/quadramet. Accessed March 23, 2009.
6. Perez, CA. Other Options Available for the Palliation of Pain Secondary to Bone Metastases. Medscape. 2007. Available at: http://www.medscape.com/viewarticle/551143. Accessed on March 30, 2009.
7. Goeckeler, WF. Quadramet Overview. Cytogen. 2005. Available at: http://www.secinfo.com/d14D5a.z5kHq.d.htm. Accesed on March 31, 2009.
8. RxList. Quadramet- Samarium 153 Injection. Available at: http://www.rxlist.com/quadramet-drug.htm. Accessed on March 31, 2009.
9. University of Wisconsin-LaCrosse Dosimetry Program. Brachytherapy QA D2L notes. Available at: www.uwlax.edu. Accessed on April 3, 2009.

Color Codes:
Candice - Orange
Sherri - Green
Robin B.- Blue
Allan -Red

Iodine - 131

cmcculler — Sun, 05 Apr 2009 17:41:55 CDT

Photos:	How were people exposed to Iodine 131 from Hanford?[15]	Radioactive iodine uptake test is a type of nuclear test performed to evaluate thyroid function. The patient ingests radioactive iodine (I-123 or I-131) capsules or liquid. After a time (usually 6 and 24-hours later), a gamma probe is placed over the thyroid gland to measure the amount of radioactivity in the thyroid gland. The values are then compared.[14]
		[16]

Relevant Historical Data:	Iodine- 131 is a radioisotope of iodine- an altered form of the element that is chemically the same but is radioactive. I-131 is found as fallout from atmospheric nuclear bomb explosions, along with a variety of other radioactive substances such as strontium-90. People were exposed by drinking contaminated milk, where is was absorbed by the cows in the pastures. Also contaminated were eggs and leafy vegetables. I-131 has been of the greatest concern because it concentrates in the thyroid, particularly in children, and may increase the risk for thyroid cancer. There appears to be little risk for people exposed as adults. Because iodine concentrates in the thyroid, high doses of I-131 are used to treat some types of benign thyroid diseases as well as thyroid cancer.[1] In 1811, Bernard Courtois discovered natural iodine in water that was used to dissolve certain parts of seaweed ash for use. Radioactive iodine-131 was discovered by Glenn T. Seaborg and John Livingood at the University of California - Berkeley in the late 1930's.[8]
Chemical/Radioactive Composition:	Stable iodine (iodine-127) is naturally present in seaweeds, sponges, other materials, and also found in Chilean saltpeter, caliche, and brine associated with salt deposits. It is present in nature in various materials, with soil, rock, and all living organisms containing low concentrations. Radioactive isotopes of iodine are produced by nuclear fission. When an atom of uranium-235 (or other fissile nuclide) fissions, it generally splits asymmetrically into two large fragments – fission products with mass numbers in the range of about 90 and 140 – and two or three neutrons. (The mass number is the sum of the number of protons and neutrons in the nucleus of the atom.) Iodine-129 and iodine-131 are two such products. The fission yield of iodine-129 is about 1% and the yield of iodine-131 is close to 3%. That is, about one atom of iodine-129 and three atoms of iodine 131 are produced per 100 fissions. [5] Pure I-131 is a non-metallic, purplish-black crystalline solid. However, because it readily binds with other elements, I-131 usually is found as a compound rather than in its pure form.9]
Energy Characteristics:	I-131 decays with a half-life of 8.02 days with beta and gamma emissions. This nuclide of iodine atom has 78 neutrons in nucleus, the stable nuclide 127I has 74 neutrons. On decaying, 131I transforms into 131Xe:The primary emissions of I-131 decay are 364 keV gamma rays (81% abundance) and 606 keV beta particles (89% abundance).[3] Mean beta energy is 192 keV.[10]
Exposure Rate Constant:	2.3 R/Hr at 1cm per mCi [4]
Half-life Properties:	8 Days [4] Biological Half-Life: 138 days* Effective Half-Life: 7.6 days* * These are “generic” biological and effective half-lives; the specific labeled compound may alter.[11]
Forms available for use:	Derived from Iodine into a liquid form which is swallowed.[2] I-131 is also available in capsule form.[10]
HVL in lead:	.31 cm [4] HVL of 6.3 cm in water.[10]
Measurement/Calibrations/QA:	Survey Instrumentation [11] Survey meter equipped with a G-M pancake or thin-window probe is efficient for detecting the betas from I-131. Survey meters equipped with a NaI scintillation probe is suitable for detection of the I-131 gamma. Either a gamma counter or a liquid scintillation counter can be used to detect removable I-131 contamination on wipe tests smears. Calibration [12] Begins with a radioactive preparation- commonly in solution- of the radionuclides in a stable chemical form. Specific activity of the solution must not be modified by any change other than the normal radioactive decay of the nuclide. Then the specific activity of the solution is determined (number of disintegrations per second which take place in the solution per unit of mass). The preparation is then enclosed in a sealed ampoule and dispatched to the requesting lab. The distributor gives a certificate of the specific activity of the sample at a date (reference date) some days after the sample is due to reach the client- usually about a week later. This ensures that the receiving lab will be able to do its work with the sample on that date. QA [13] At the designated time, the dose to be administered is brought on a cart to the patient's room in its shielded shipping container. All contamination precautions must be observed, If liquid I-131 is used for therapy, appropriate use of a closed-circuit liquid delivery system may limit or eliminate contamination of the ambient air and skin and the possibility of any accidental spillage.
Used in formula/calculation:	Typical dosage for hyperthyroidism is 5-10 mCi of I-131 sodium iodide. Typical dosage for thyroid cancer is 100 -200 mCi of I-131 sodium iodide.[10]
Uses in Radiation Oncology:	Mostly used for the treatment of hyperthyroidism, which can be caused by Graves disease. This is an overactive thyroid problem or caused by nodules within the gland producing too much thyroid hormone. This is usually treated by a nuclear medicine department. Iodine-131 is also used to treat thyroid cancer.[2]
Treatment Planning:	This procedure is primarily done in nuclear medicine departments. Treatment planning information could not be obtained. Most nuclear physicians prefer fixed dose I-131 therapy without actually calculating the dosimetry for ablation. The treatment dose variances among different centers are wides with a range of 25-200 mCi, depending on whether it is given for residual functioning thyroid tissue in the the neck or for metastases detected locally in the neck or in various organs as well as the age and gender of the patient. First doses as high as 300mCi have been given in some centers on the basis of assumption that metastases may lose their ability to concentrate iodine. With high-dose therapy, the dose to the blood should be less than 200 rad to reduce bone marrow toxicity. The total whole body retained dose at 48 hours should be less than 120 mCi in widespread metastatic thyroid carcinoma and 80 mCi in the presence of lung metastases. The latter is a precaution to avoid inducing pulmonary fibrosis. [13]
One other interesting fact:	Iodine- 131 is a decay product of Te-131 (beta-) and decays down to Xe-131 (beta-).[6] Half Value Thickness in water is 6.3 cm. Iodine is a nonmetallic, purplish-black crystalline solid. It has the unusual property of ‘sublimation,' which means that it can go directly from a solid to a gas, without first becoming liquid. It sublimes to a deep violet vapor at room temperature. This vapor is irritating to the eyes, nose and throat. Iodine dissolves in alcohol and in water. It melts at 236 °F.[8] I-131 dissolves easily in water or alcohol. I-131 readily combines with other elements and does not stay in its pure form once released into the environment.[9]

Links:
http://www.bt.cdc.gov/radiation/isotopes/iodine.asp
http://www.epa.gov/rpdweb00/radionuclides/iodine.html
http://www.ead.anl.gov/pub/doc/Iodine.pdf
http://www.iodine131.org
http://en.wikipedia.org/wiki/Iodine-131
References:
1. National cancer institute. Available at: http://www.cancer.gov/cancertopics/factsheet/I131qa. Accessed March 16, 2009.
2. Radiology Info. Available at: http://www.radiologyinfo.org/en/info.cfm. Accessed March 16, 2009.
3. Iodine 131. Radioactive Isotopes. Availabe at http://ie.lbl.gov/decay.html. Accessed March 15, 2009.
4. Bentel, G. Radiation Therapy Planning. 2nd Ed.NewYork:Macgraw-Hill:1992. pp.534-535.
5. Argonne National Laboratory, EVS. Iodine. Human Health Fact Sheet. August 2005. Available at: http://www.ead.anl.gov/pub/doc/Iodine.pdf. Accessed March 17, 2009.
6. Wiipedia. Available at: http://en.wikipedia.org/wiki/Iodine-131. Accessed March 17, 2009.
7. Argonne National Laboratory. Available at: http://www.ead.anl.gov/pub/doc/tbl2-rad-prop.pdf. Accessed March 17, 2009.
8. U.S. Environmental Protection Agency. Radiaton Protection. Iodine. Available at: http://www.epa.gov/rpdweb00/radionuclides/iodine.html. Accessed on March 19, 2009.
9. Centers for Disease Control and Prevention. Iodine 131. Available at: http://www.bt.cdc.gov/radiation/isotopes/iodine.asp. Accessed on March 19, 2009.
10. Jani, Shirish K. Handbook of Dosimetry Data for Radiotherapy. CRC Press, Inc., 1993, p. 149.
11. University of Cincinatti. Radiation Safety:I-131. Available at: http://researchcompliance.uc.edu/radsafety/isotope/isds-I131.html. Accessed on March 19, 2009.
12. International Atomic Energy Agency. Calibrated Nuclides-An IAEA Service. Available at: www.iaea.org/Publications/Magazines/Bulletin/Bull062/06206802325.pdf. Accessed on March 19, 2009.
13. Al-Shakhrah, IA. Radioprotection using Iodine-131 for Thyroid Cancer and Hyperthyroidism: A review. Clinical Journal of Oncology nursing. 2008; 12: 905-912.
14. New York Times. Radioactivity Test. Available at: http://www.cdc.gov/.../htdsweb/Iodine131_Exposure.htm. Accessed on March 23, 2009.
15. Then Handford Tyroid Disease Study. Iodine 131 Exposure. Available at: www.cdc.gov/.../htdsweb/Iodine131_Exposure.htm. Accessed on March 23, 2009.
16. Chemical Forums: A Socratic Model of Chemical EducationAvailable at: www.chemicalforums.com/index.php?topic=15248.0. Accessed on March 23, 2009.

Color Codes:
Candice - Orange
Sherri - Green
Robin B.- Blue
Allan -Red

Iridium - 192

LaRosa.Fran — Sun, 05 Apr 2009 13:48:13 CDT

Photos:	Iridium powder	Iridium Source
	Ribbons containing Iridium-192

Relevant Historical Data:

Iridium was discovered in 1803 by Smithson Tennant among insoluble impurities in natural platinum from South America. It is one of the rarest elements in the Earth's crust, with annual production and consumption of only three tonnes. However, iridium does find a number of specialized industrial and scientific applications. Iridium is employed when high corrosion resistance and high temperatures are needed, as in spark plugs, crucibles for recrystallization of semiconductors at high temperatures, electrodes for the production of chlorine in the chloralkali process, and radioisotope thermoelectric generators used in unmanned spacecraft. Iridium compounds also find applications as catalysts for the production of acetic acid.(2)

Iridium has been linked with the extinction of the dinosaurs and many other species 65 million years ago. The unusually high abundance of iridium in the clays of the K–T geologic boundary was a crucial clue that led to the theory that the extinction was caused by the impact of a massive extraterrestrial object with Earth—the so-called Alvarez hypothesis. Iridium is found in meteorites with an abundance much higher than its average abundance in the Earth's crust. It is thought that due to the high density and siderophilic ("iron-loving") character of iridium, most of the iridium on Earth is found in the inner core of the planet.(2)

Chemical/Radioactive Composition:

Name: Iridium-192
Symbol: Ir-192
Atomic Number: 77
Atomic Mass: 192.217
Classification: Transition Metal. (1)
Iridium-192 undergoes beta decay(3)

One of the lesser-known members of the platinum group metals, iridium is white, resembling platinum, but with a slight yellowish cast. It possesses quite remarkable chemical and physical properties. Due to its hardness, brittleness, and very high melting point (the tenth highest of all elements), solid iridium is difficult to machine, form, or work, and thus powder metallurgy is commonly employed instead. It is the only metal to maintain good mechanical properties in air at temperatures above 1600 °C. Iridium has a very high boiling point (11th among all elements) and becomes a superconductor under 0.14 K.(2)

Energy Characteristics:

Iridium-192 undergoes beta decay and has an energy of 370 keV.(3). Ir -192 decays via negative beta emission(95.6%) to Pt-192 and via electron capture (4.4%) to Os-192. (6) They emit a low-energy gamma ray and x-rays with energies below .0355 MeV. The low energy allows local shielding with metal foils only a few tenths of a millimeter thick and allows numerous applications not available with other radionuclides. (

Exposure Rate Constant:

4.69 Rcm squared / mCi-h

Half-life Properties:

Iridium-192 has a half life of 74 days, and it decays to stable platinum-192 and osmium-192 by emitting a beta particle and by electron capture; most of these decays (95%) are by beta emission.(1)

Forms available for use:

Ir-192 used in medicine is in the form of tiny seeds, each about the size of a grain of rice. Industrial gauges hold pencil-like metal sticks of solid Ir-192 or small pencil-like tubes that contain pellets of Ir-192. (4)

HVL in lead:

~ 3 mm lead. (6)

Measurement/Calibrations/QA:

A well-type chamber is most commonly used to calibrate Ir-192 seeds. The energy-response stability as well as the linearity of the well-type chamber are checked with the Ir-192 HDR source itself. This type of check is performed at least once at the end of the normal use of the source before its replacement by a new source.(10)

A type of calibration that can be performed is with a free-air ionization chamber. This type of chamber is also used for measuring soft x-rays. You need an array of four to six seeds to enhance the ionization-current-to-background-current ration. Placement is very important because of the ionization that takes place to obtain a correct reading. Important factors in the use of this type of chamber are the defined air volume of the chamber and the mean background current. For the readings to be correct there needs to be no more than a 10% background correction and a source-to-chamber distance of no less than .25m. (8)

Another study that was reported on calibration on Iodine-125 is using GAFCHROMIC film. A single seed source and a train of six seeds spaced 1mm apart enclosed by a nylon ribbon was evaluated. Each source was placed in a homogeneous solid water phantom directly below a stack of the films. The density on the films was then scanned five days after being exposed to the Iridium-192 with a microdensitometer. Isodose curve plots were then used to evealuate the results.(9)

Used in formula/calculation:

Basically the dose rate in water is calculated by the inverse square law with smalll corrections for absorption, scattering, and anisotrophy. There is no correction for the inhomogeneity of the patients' tissues.(10)

The formula uses:
air kerma strength
dose rate constant
geometry factor
radial dose function
anisotrophy function

The accepted tolerance is 3% from the calibration source vs. the sources to be used in treatment.(10)

Uses in Radiation Oncology:

Iridium-192 is used medically in brachytherapy to treat various types of cancer. (Brachytherapy is a method of radiation treatment in which sealed sources are used to deliver a radiation dose at a distance of up to a few centimeters by surface, intracavitary, or interstitial application.) Iridium-192 implants are used especially in the head and breast. They are produced in wire form and are introduced through a catheter to the target area. After being left in place for the time required to deliver the desired dose, the implant wire is removed.

Treatment Planning:

A 60-year-old woman presented to the dermatologist with multicentric, purple–red nodules spreading widely over the parietal scalp. A bleeding ulcer was found in the center of the conglomerated nodule. A bulky skip lesion formed an exophytic mass, 5 cm in diameter, located in the left temporal region. The patient recalled hitting her head on an iron pole 3 months before the visit, resulting in a head injury. Histological examination of an excision biopsy specimen made the diagnosis of malignant hemangioendothelioma. No lymph node or distant organ metastasis was found in image studies including chest radiography, ultrasonography of the neck, gallium scintigram and computed tomography (CT) of the head and neck. Platelet counts were less than 30 000/mm3. Blood coagulation tests showed prolongation of prothrombin time (PT), partial prothrombin time (PTT) and increased fibrin/fibrinogen degeneration products (FDP) and D-dimer. Frequent blood platelet transfusion resulted in only a small temporary recovery.

As immunotherapy by systemic injection of interleukin 2 failed to improve coagulopathy, radiotherapy was added using a 6 MeV electron beam by a single field, 20 x 20 cm in size, covering the entire scalp skin from the top of the head. The prescription dose per fraction was 3 Gy, four fractions per week. It was discontinued when a total of 39 Gy had been delivered over 20 days because the left temporal tumor progressed in size and coagulopathy still remained unchanged. The isodose distribution calculated by a three-dimensional treatment-planning device (Cadplan version 3.3, Varian) revealed a significant underdosage in the growing tumor (Fig. 1). We then decided to adopt the iridium-192 surface mold technique to avoid the underdosage. To make the surface mold close to the entire tumor, the thickness of the lesion should be as even as possible. We then delivered further electron beam irradiation on the parietal and left temporal areas separately with each portal(s), 10 cm x 10 cm in size, at 2 Gy/fraction, five fractions/week, a total of 20 Gy over 13 days. Although the left temporal tumor ceased to grow, the prepared therapy flattened the targeted tumor far less than expected. We made a helmet with a heat-moldable plastic facemask instead of the plaster casting tape described originally (8). The left temporal part of the mask was cut to prevent its separation from the skin surface due to the exophytic tumor. Fourteen flexible polyethylene tubes of 5 Fr. gauge were fixed in parallel along the sagittal plane on the inner surface of the mask. For delivery on the left temporal tumor exposed beyond the mask, four other guide tubes were separately arranged on the mask (Fig. 2). Treatment planning was performed on a device (PLATO-BPS version 13.1, Nucletron) using the CT images obtained as the mold put on her head. Active source dwell positions were determined to cover the entire tumor at 5 mm intervals in each applicator. The reference points were set at 20 mm beneath the surface of the tumor. For the left temporal tumor, the depths were increased to 30 mm. Geometric optimization in volume was calculated to obtain a uniform dose distribution (Fig. 3). From the next day to the end of electron radiotherapy, a total of 12 fractions, three fractions per week, a total of 36 Gy was delivered over 33 days. The total dose used in brachytherapy was limited because it had already reached the threshold dose for skin at the end of the electron beam radiotherapy and the brain was also considerably irradiated in this method. The tumor showed an apparent decrease in volume during the treatment, especially in the left temporal portion, which became almost flat.

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Figure 1. Isodose distribution on a coronal plane of the scalp by electron beam irradiation. Underdosage is apparent in the area angled too far away from perpendicular incidence. The lower pole of the left temporal tumor was not adequately irradiated.

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Figure 2. (a) A view of the inner surface of the surface mold from the bottom. The left temporal part of the mask was cut and tubes were separately arranged along the axial plane crossing the hole. (b) Arrangement of applicators for brachytherapy in anterior–posterior view reconstructed by computer.

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Figure 3. Isodose distribution in a coronal plane of the scalp by brachytherapy. The entire tumor is irradiated with at least 3 Gy/fraction.

The patient complained of pain in the irradiated area of the head and needed analgesics for several months after the completion of the treatment. About 2 weeks after the end of therapy, the blood platelet count began to increase and it reached a normal value in 2 months. At the same time, FDP and D-dimer decreased. The tumor had almost disappeared 3 months after the brachytherapy (Fig. 4). Alopecia occurred and was irreversible in the irradiated area.

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Figure 4. Appearance of the patient’s head (a) before and (b) after the radiotherapy.

One year later, a metastatic nodule, 4 x 3 cm in size, developed at the lower pole of the parotid gland. It was treated by 4 MV photon irradiation with anterior–posterior opposed pair portals of 3 Gy/fraction, four fractions/week, a total dose of 60 Gy over 46 days. The tumor showed almost complete regression at the end of therapy.
Two years later, several dusky, purple–red plaques appeared on the skin of the right temporal area, bordering the bold parietal skin previously irradiated; 4 MV electron beam irradiation of 3 Gy/fraction, four fractions/week and a total dose of 60 Gy over 29 days, was delivered by a 15 x 15 cm single portal with 5 mm bolus. At the end of this treatment the plaques became flat and they disappeared in 3 months. The patient is alive and free from disease now, 6 months after the last radiotherapy and 3 years after initial treatment. Recent plain radiography and MRI of the head did not indicate any damage to the skull or brain.(5)

One other interesting fact:

Source : Neutron bombardment of 99.9% iridium metal
> 450 Ci/g for standard specific activity material
> 1000 Ci/g for high specific activity material Iridium can be taken into the body by eating food, drinking water, or breathing air. Gastrointestinal absorption from food or water is the likely source of internally deposited iridium in the general population. After ingestion or inhalation, most iridium is excreted from the body and never enters the bloodstream; only about 1% of the amount taken into the body by ingestion is absorbed into the blood. Twenty percent of the iridium that reaches the blood is excreted right away, 20% deposits in the liver, 4% deposits in the kidney, 2% deposits in the spleen, and the remaining 54% is evenly distributed among other organs and tissues of the body. Of the iridium that deposits in any organ or tissue, 20% leaves the body with a biological half-life of 8 days and 80% clears with a biological half-life of 200 days. On the basis of animal studies, retention of iridium was determined to be the same for all age groups. Most inhaled iridium compounds appear to clear the lungs quite rapidly.(1)

Links:
CDC Radioisotope Brief
Calibration of Ir-192
Lost Iridium-192 Source

References:
1. Human Health fact sheet: http://www.ead.anl.gov/pub/doc/Iridium.pdf
2. Iridium-192. Available at: http://en.wikipedia.org/wiki/Iridium. Accessed March 17, 2009.
3. Washington, C Leaver, D. Principles and Practice of Radiation Therapy. 2nd ed. St. Louis,MO: Mosby Inc;2004: p-324-325
4. CDC. Radioisotope Brief:Iridium-192 (IR-192). Available at:http://www.bt.cdc.gov/radiation/isotopes/iridium.asp. Accessed March 21 2009.
5. Oxford Jounals. Iridium-192 Brachytherapy for Hemorrhagic Angiosarcoma of the Scalp. Available at:http://jjco.oxfordjournals.org/cgi/content/full/33/4/198. Accessed March 21, 2009.
6. Shirish K. Jani, Shirish Jani, K. Handbook of Dosimetery Data of Radiotherapy, illustrated. CRC press1993. pg. 150
7. VanDyk, Jacob. The Modern Technology of Radiation Oncology. Medical Physics Publishing:1999: pg 704.
8. Journal of Research of the National Institute of Standards and Technology. Available at www.findarticles.com/p/articles. Accessed on April 3, 2009.
9. PubMed. Available at www.ncbi.nlm.nih.gov/pubmed.com. Accessed on April 2, 2009.
10.Dosimetry and Quality Assurance in High Dose Rate Brachytherapy with Iridium - 192. Available at www.sgsmp.ch/r13hdr-e.pdf. Accessed on April 2, 2009.

Color Code:
Mat C.
Francine
Amy

Americium - 241

amyremer — Fri, 03 Apr 2009 13:58:35 CDT

Photos:

The reason alpha decay occurs is because the nucleus has too many protons which cause excessive repulsion. In an attempt to reduce the repulsion, a Helium nucleus is emitted. The way it works is that the Helium nuclei are in constant collision with the walls of the nucleus and because of its energy and mass, there exists a nonzero probability of transmission. That is, an alpha particle (Helium nucleus) will tunnel out of the nucleus. Here is an example of alpha emission with americium-241.(6)

Relevant Historical Data:

First produced in 1944 Americium (isotope Am-241) was discovered by nuclear chemist Glenn Seaborg and his colleagues(13) during the Manhattan Project at the University of Chicago's Metallurgical Labratory by bombarding plutonium with neutrons. It was the fourth transuranic element to be discovered. (12)Created by bombarding Plutonium-239 with high energy neutrons to create Plutonium-240. Plutonium-240 is bombarded with high energy neutrons to create Plutonium-241 which then decays to Am-241 through beta decay. Am-241 did not receive a name until 1946 in honor of the continent where it was discovered.

Chemical/Radioactive Composition:

Chemical Symbol : AM -241, Am241 Specific Activity : 3.5 Ci/g
Atomic number : 95
Physical appearance: silver metal that tarnishes slowly in air and is soluble in acid.
AmO2 = Americium oxide

Energy Characteristics:

Principle Emission
Type	Energy	Percentage
Alpha	5485 keV	84.5
Alpha	5443 keV	13.0
Gamma	59.5 keV	35.9
Gamma	26.3 keV	2.4
Gamma	13.9 keV	42
Beta	52 Kev	-

It decays primarily by alpha particle emission to neptunium-237. Its alpha emmission is approximately three times that of radium. Gram quantities of Am-241 emits alpha particles and low-energy gamma rays (60KeV, giving a dose of .0011mSv/yr at 1m).

Exposure Rate Constant:

The "Specific Gamma Ray Dose Constant", sometimes known as the "Gamma Factor", is the dose rate at a specific distance from a given amount of a photon-emitting radionuclide. These constants are used frequently for radiation protection purposes. The following is a listing of Specific Gamma Ray Dose Constants for a variety of radionuclides, in units of Rem per hour (Rem/hr) at a distance of one (1) meter from a one (1) curie point source of that radionuclide.(5)

Americium

Am-241 - 0.313723
Am-242 - 0.202612
Am-242m - 0.18315
Am-243 - 0.312872
Am-244 - 1.17216
Am-245 - 0.086617
Am-246 - 0.079513 (5)

Half-life Properties:

Half-life 432.2 years(2) , Biological half-life of Am-241 following injestion or inhalation is 50 years in bone, 20 years in liver, and permanent in gonadal tissues. Am-241 emits both alpha and gamma radiation (alpha radiation is utilized in AmBe "chemical" neutron sources), but here we are interested in low energy or "soft" gamma rays. Am-241 produces 59.5 keV gammas with a 36% probability of decay, and 14 keV gammas with a 43% probability of decay.(7) Decays to Np-237, decaying in turn to Pa-233 and U-233. (8)

Forms available for use:

In aqueous systems the most common oxidation state is +3. It is very much harder to oxidize Am(III) to Am(IV) than it is to oxidise Pu(III) to Pu(IV).(2)
Currently the solvent extraction chemistry of americium is important as in several areas of the world scientists are working on reducing the medium term radiotoxicity of the waste from the reprocessing of used nuclear fuel.
See liquid-liquid extraction for some examples of the solvent extraction of americium.
Americium, unlike uranium, does not readily form a dioxide americyl core (AmO2).(2) This is because americium is very hard to oxidise above the +3 oxidation state when it is in an aqueous solution. In the environment, this americyl core could complex with carbonate as well as other oxygen moieties (OH-, NO2-, NO3-, and SO4-2) to form charged complexes which tend to be readily mobile with low affinities to soil.

AmO2(OH)+1
AmO2(OH)2+2
AmO2CO3+1
AmO2(CO3)2-1
AmO2(CO3)3-3(2)

HVL in lead:

0.01cm (1)

Measurement/Calibrations/QA:

Prototype tests for calibration or reference sources containing americium-241
An applicant for a license pursuant to Sec. 32.57 shall, for any
type of source which is designed to contain more than 0.005 microcurie
of americium-241, conduct prototype tests, in the order listed, on each
of five prototypes of such source, which contains more than 0.005
microcurie of americium-241, as follows:
(a) Initial measurement. The quantity of radioactive material
deposited on the source shall be measured by direct counting of the
source.
(b) Dry wipe test. The entire radioactive surface of the source
shall be wiped with filter paper with the application of moderate finger
pressure. Removal of radioactive material from the source shall be
determined by measuring the radioactivity on the filter paper or by
direct measurement of the radioactivity on the source following the dry
wipe.
(c) Wet wipe test. The entire radioactive surface of the source
shall be wiped with filter paper, moistened with water, with the
application of moderate finger pressure. Removal of radioactive material
from the source shall be determined by measuring the radioactivity on
the filter paper after it has dried or by direct measurement of the
radioactivity on the source following the wet wipe.
(d) Water soak test. The source shall be immersed in water at room
temperature for a period of 24 consecutive hours. The source shall then
be removed from the water. Removal of radioactive material from the
source shall be determined by direct measurement of the radioactivity on
the source after it has dried or by measuring the radioactivity in the residue
obtained by evaporation of the water in which the source was immersed.
(e) Dry wipe test. On completion of the preceding test in this
section, the dry wipe test described in paragraph (b) of this section
shall be repeated.
(f) Observations. Removal of more than 0.005 microcurie of
radioactivity in any test prescribed by this section shall be cause for
rejection of the source design. Results of prototype tests submitted to
the Commission shall be given in terms of radioactivity in microcuries
and percent of removal from the total amount of radioactive material
deposited on the source. (9)

Methods of detection (in order of preference)
(Radiation detectors will detect americium-241. Most detection will be based on detection of the 59.5 keV gamma).
1. A radiation survey meter equipped with an energy-compensated Geiger Mueller detector.
2. Ion chamber survey meter – tends to be less sensitive than a Geiger Mueller survey meter but is able to respond more precisely in higher radiation fields.
3. Gamma scintillation detector – very sensitive but is also energy dependent. Must be calibrated for Am-241 before it can be used for dose assessment surveys. (1)

QA:

Always use the principles of time, distance and shielding to minimize dose
Engineering Controls: Sealed radioactive sources used in industrial applications should always be within a protective source housing to minimize radiation dose and to protect the source capsule from damage.
Personal Protective Equipment (for normal handling of unsealed sources only. Always wear disposable gloves, safety glasses, personal protective equipment and clothing as appropriate to the material handled). No special PPE required. No Special Storage Requirements. (1)

Used in formula/calculation:

Radioactive decay problem:

Americium-241 is used in some smoke detectors. It is an alpha emitter with a half-life of 432 years. How long will it take for 43.0 % of an Am-241 sample to decay?

Use the formula

A=Pe^(-rt)

and r=ln2/halflife

r=ln2/432=0.0016

Let P(the starting amount) be equal to 100

If 43% will be decayed the remainig will be 57

Substituting it in the expression

57=100e^(-0.0016t)

ln (57/100)=ln e^(-0.0016t)

ln (57/100)=-0.0016t

t=ln (57/100)/-0.0016

t=350.34 years Reference (10)

Calculation:

Question:

I need the exposure rate in mR/hr for a 500 mCi 241Am source at a distance of 30 feet. I'm using the formula D=6*C*E/d2. What is E (energy of gamma in MeV) for 241Am. Where can I find this information or other ways to make this calculation?

Answer:

The energy and intensity of the gamma or x rays of 241Am can be found in tables in the NUDAT retrieval program made available on the Internet by Brookhaven National Laboratory.
A form will open asking various parameters. Fill in the mass number, nuclide, and radiation. (The radiation is G.) On the pull down for sort order, select the option beginning with intensity and energy of radiation. The sort will be ascending by intensity, so the most important contributions to exposure, most intense, will be at the bottom of the list. You will find these three photons:

Energy (MeV)	Intensity (%)
0.0139	37.0
0.0263	2.4
0.0595	35.9

All other photons are negligible relative to these three, so substituting the energy values in your equation will give the exposure from 241Am. The formula you propose will give a larger number of photons at 30 feet the correct value because attenuation in air was not considered. Nevertheless, because incorrect energy absorption coefficients are used, the formula predicts less energy will be deposited per unit volume and the resulting exposure rate will be too low. The formula you propose should not be used for the case of 241Am. The formula will give the answer of 0.093 mR/h. The actual result is higher, as will be shown below. The distance of 30 feet (9.144 m) in air attenuates these photons significantly. The mass energy absorption coefficients (mE) to estimate the attenuation can be obtained from the National Institute of Science and Tachnology. It will be necessary to interpolate the coefficients for the 241Am energies. The exposure rate by the simple formula should be reduced for each photon energy by the attenuation of 30 feet of air. The result must then be increased using the appropriate attenuation factor for the energy deposited in a unit volume. Rather than attempting to correct a simple approximation formula, it is better to perform the full analysis. The analysis below is intended for use in a spreadsheet.

Mev	Intensity	Photons/s	Photons/s-cm2at 914.4 cm	Attenuated Photons/s-cm2	Photons Absorbed/s-cm3	MeV/s-cm3
0.0139	0.370	7.90E+09	7.52E+02	117	0.219845	0.003056
0.0263	0.024	4.44+08	4.23+01	32	0.00854	0.000225
0.0595	0.359	6.44E+09	6.32+02	617	0.022544	0.001341

The photons/s value for each energy is the intensity x 0.5 Ci x 3.7 x 1010 disintegrations/Ci.

The photons/s-cm2 at 914.4 cm for each energy is the previous column divided by 4 π 914.42.

The attenuated photons/s-cm2 is the previous column times exp (-μE 914.4).
The photons absorbed/s-cm3 is the previous column times 1-exp (-μE1).
The MeV absorbed/s-cm3 is the previous column times the first column.
The total MeV absorbed/s-cm3 must be converted to MeV/h-kg by totaling the last column, multiplying by 3,600 s/h, dividing by 0.001205 g air/cm3, and then multiplying by 1,000 g/kg.
MeV/h-kg is converted to eV by multiplying by 1 x 106 to ion pairs/h-kg by dividing by 33.7 eV/ion pair.
Coulomb/kg-h is obtained by dividing ion pairs/h-kg by 6.24 x 1018 ion pairs/coulomb, then R/h is finally obtained by dividing 2.58 x 10-4 coulomb/R.
The result is 0.254 mR/h.

A method to obtain mrad/h is to continue the above table after attenuated photons/s-cm2 with the following:

Kerma coefficient (pGy cm2)	Kerma/s (pGy/s)	mrad/h
3.7	432.1	0.156
0.96	30.8	0.011
0.28	174.7	0.0629

The kerma coefficient for each energy was interpolated from Table A-1 of ICRU Report 57, "Conversion Coefficients for use in Radiological Protection Against External Radiation," 1998.
The kerma/s equals the product of the previous two columns.
The mrad/h (in air) was converted from pGy/h (kerma/s times 3600 s/h).
The total is 0.253 mrad/h.

Note: The result will be dependent upon the interpolated values. Also, buildup was not considered in these calculations and will likely increase the result about 30 percent.

Uses in Radiation Oncology:

Small amount is used in an ionization chamber inside the detector

Treatment Planning:

There is no treatment planning currently being done because it is still being studied and is not commercially available to this date. (11)

One other interesting fact:

Americium-241 does not occur in nature; however, some americium may be found in the environment as the result of atmospheric testing of nuclear weapons and improper disposal of wastes.
Americium-241 is commonly found in ionizing smoke alarms. Even though it is radioactive, it is not very dangerous. A piece of paper, a few centimeters of air, or even the layer of dead cells on your skin are adequate shielding. About the only way this could hurt is as if a person ingest it.

It is one of the nine reactor produced isotopes that is at risk of being used in bombs for terrorist attacks. (12)

Americium-241 is the only isotope of americium to have widespread commercial use. It is the radiation source for a number of applications:

medical diagnostic devices
research
fluid-density gauges
thickness gauges
aircraft fuel gauges
distance-sensing devices, all of which utilize its gamma radiation.

A mixture of americium-241 and beryllium provides a neutron source for industrial devices that monitor product quality. Two examples are devices for nondestructive testing of machinery and gauges for measuring the thickness of glass and other products. (13)

There are tests that reliably measure the amount of americium in a urine sample, even at very low levels. Using these measurements, scientists can estimate the total amount of Am-241 present in the body. Other tests can measure Am-241 in soft tissues (such as body organs) and in feces, bone, and milk. None of these tests are routinely available in a doctor's office because they require special laboratory equipment.(13)

It is the only synthetic element that has found its way into households. There is one type of common smoke detector that contains a small amount of the substance, only .2 micrograms. (12)

Links:
Decay Radiation Search
X-Ray Mass Attenuation Coefficients
http://en.wikipedia.org/wiki/Americium

References:
1. Radioiactive Material Safety Data Sheet. Available at: http://www.safety.uncc.edu/Forms/Nuclide%20Safety%20Data%20Sheets%20NIH/Americium%20241.pdf. Accessed March 15, 2009.
2. Americum. Available at:http://en.wikipedia.org/wiki/Americium. Accessed March 16, 2009.
3. Health Physics Society. Dose and dose calculations. Available at: http://www.hps.org/publicinformation/ate/q1488.html. Accessed March 16, 2009
4. Radioactive material safety data sheet : http://www.stuarthunt.com/Downloads/RMSDS/Am241.pdf
5. Americum. Available at http://www.iem-inc.com/toolgam.html. Accessed March 17, 2009.
6. Americum Images. Available at:www.impcas.ac.cn/.../prc/radiation_types.html.Accessed March 17, 2009.
7. Analog. Gamma Ray Detector Calibration. Available at: http://www.logwell.com/tech/nuclear/GR_cal.html. Accessed on March 21, 2009.
8. Princeton University. Contained Source Radiation. Available at:http://web.princeton.edu/sites/ehs/ContainedSources/AmBeSource/ambesource.htm. Accessed on March 21,2009.
9. Title 10: Energy. Nuclear Regulatory Commission. Available at: http://edocket.access.gpo.gov/cfr_2005/janqtr/10cfr32.102.htm. Accessed March 21 2009.
10. Yahoo Answers. Ask.Answer.Discover. Available at: http://answers.yahoo.com/question/index?qid=20070217085004AAgZR9y. Accessed March 21,2009
11.Perez, Carlos A., Halperin, Edward C., Brady, Luther W., Schmidt-Ullrich, Rupert K.. Principles and Practice of Radiation Therapy, Fourth Edition. Lippincott Williams & Wilkins. 2004. pg 479-480.
12.Wikipedia. Available at www.wikipedia.org/Dirty_bomb. Accessed on March 24, 2009.
13. Radiation Protection. Americum. Available at: http://www.epa.gov/radiation/radionuclides/americium.html. Accessed March 30,2009.

Color code:
Francine
Mat C.. . .

UWL Medical Dosimetry Brachy Class 08-09 Home

RobinCarter — Thu, 19 Mar 2009 09:04:33 CDT

This wiki is our meeting place to plan and discuss isotopes for this course.

Check back regularly to update with new information and to collaborate with your class.

Click the Play button

Assignments

nlenards — Wed, 25 Feb 2009 12:31:22 CST

Instructions:
1. Find your group/name on the list below and see which isotopes you have been assigned to.
2. Go to the menu on the left upper corner and find that isotope page.
3. When you get to that page, there is a button at the top of the page called "easy edit"; click on this and then you will be in the edit mode. You can type your information into the boxes or spaces provides, and insert your pictures where instructed to do so. I have started the Ruthenium-106 page, but all of you are responsible for finishing it.
4. All areas are editable by everyone; therefore if you see something incorrect, you can change it in a different color and include a note to others.
5. You can use your email accounts or "discussions" to share information for this project.
6. If you have questions, problems, etc. - just let me know and I can help.

This project is a way of achieving group collaboration, research and learning at a higher level, and a published study guide for you to study for exam preparation.

Isotope	Group
Cesium-137	Red
Radium-226	Blue
Iodine-125	Green
Cobalt-60	Purple
Americium-241	Yellow
Iodine-131	Pink
Gold-198	Red
Phosphorus-32	Blue
Ytterbium-169	Green
Palladium-103	Purple
Iridium-192	Yellow
Samarium-153	Pink
Strontium-89	Green
Strontium-90/Yttrium-90	Yellow
Ruthenium-106/Rhodium-106	Pink