Tuesday, August 17, 2010

The isotopes are back!

Nope, not those Isotopes...

After last year's fallout, the 53-year old Chalk river reactor is back up and running after almost a year and a half offline due to a heavy water leak.

So, how exactly do these isotopes work for cancer diagnosis?

Nuclear imaging
is the most advanced imaging technology and provides detailed views of the body. Patients are inhale, ingest or are injected with a minute amount of radioactive material which then sends radiation beams from the inside of the body. A scanner or camera is then able to pick up these beams from specific organs to capture detailed images. Nuclear imagining is commonly used in making diagnosis of cancers, tumors and cardiovascular disease.

Because most medical isotopes have short half-lives, they can't be stockpiled like other more stable products, such as vaccines. The half-life of Molybdenum-99 (the isotope used to produce Tc-99m) is 66 hours. The half-life of Tc-99m is 6 hours. Generators, containers that encase Molybdenum-99 degrading to Tc-99m, expire after two weeks.

Are there alternative technologies for these diagnosis tools/isotopes?

Alternative isotopes that can be used with existing cameras (SPECT and gamma cameras) offer advantages because they can use existing infrastructure. The alternative isotopes are produced by small accelerators, called cyclotrons, and are not reliant on nuclear reactors.

* Thallium-201 is approved as an alternative for most heart tests, which account for approximately half of all Tc-99m procedures in Canada.
* Iodine-123 is approved to image kidneys. It can also be used to image the thyroid gland, and can be made available by request from a physician or through clinical trials.
* Gallium-67 is approved for detection of Hodgkin's disease and lymphomas, among other types of cancers.

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