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Strontium - 89
| 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.
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angie garner |
Latest page update: made by angie garner
, Apr 12 2009, 5:14 PM EDT
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