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Radium Used in Cancer Treatment
Posted on February 7th, 2013

RSCS will be training radiopharmaceutical technicians about the hazards associated with alpha-emitting radionuclides in support of a newly developed cancer treatment using Radium-223.  The new treatment has been going through an FDA fast-track approval process due to its clinical success for increasing life spans for patients with Castration-Resistant Prostate Cancer and Bone Metastases.

This radionuclide is naturally occurring in the U-235 decay chain; however, its natural abundance is so low that it is economically constraining to extract it from its natural state for commercial and pharmaceutical purposes.  Therefore, it is produced by neutron activation of Ra-226 and subsequent decay into Ra-223 as shown below.


For the medical administration, the Ra-223 is chemically separated from its predecessors and then continues to decay with a half-life of about 11 days.  For decay of Ra-223, 4 alpha particles, 2 gamma rays (through the emission of over 13 different energies), and 2 beta particles (over 6 energy levels) are emitted.  The administered Ra-223 preferentially concentrates in bone and in the prostate cancer cells, and the emitted alpha energy is deposited locally in these cancers and has little detrimental impact on the surrounding healthy tissues.

Although this alpha emitter is about 1000 times less radiotoxic as compared to the transuranic radionuclides (i.e. Americium, Curium, Plutonium, and Neptunium) sometimes found at nuclear power plants, it is more than 5000 times more radiotoxic than some of the common isotopes used in diagnostic radiology such as Tl-201 and Tc99m.  This characteristic makes it an excellent choice for cancer treatment, but it does require an understanding of its characteristics to adequately control and monitor for contamination for the medical staff.

Our support in providing this special training is a result of the work we have done for operating and decommissioning nuclear power facilities in North America that have transuranic contamination that require special precautions for control and monitoring for occupational workers.  We find this unique use of Ra-223 an exciting and effective use of Radium and radioactive materials.  In fact, additional research is being done to embed alpha-emitting radionuclides into gold nano-spheres for targeted delivery to other diseased organs of the body.  More information on this can be found at: http://www.eurekalert.org/pub_releases/2013-02/uom-msb020413.php.

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