Tc-99m Shortage
An article about the shortage of Tc-99m popped in my Twitter feed via Salon. The original article is Inside The Global Race To Deliver A Vital Radioactive Isotope Used To Detect Cancer by Sarah Varney at Kaiser Health News.
Although the shortage isn’t anything new (I wrote about it back in 2012), coincidentally my order for Tc-99m for this past Wednesday was canceled because the supplier couldn’t get their generator.
So what is Tc-99m and what’s the big deal? Tc-99m is a radioactive isotope of technetium. The “m” is for metastable. Tc-99m is produced by the radioactive decay of Mo-99 (molybdenum-99). Mo-99 is traditionally made from highly enriched uranium (HEU) U-235. Tc-99m is used in SPECT imaging (you can read more below). For example, if you get a cardiac stress test, chances are, they will inject you with sestamibi, which is a compound labeled with Tc-99m. The SPECT image with sestamibi identifies regions of dead/damaged heart tissue, e.g., where you had blocked blood flow during a heart attack. There are other compounds labeled with Tc-99m for bone scans, tumor scans, etc.
One of the advantages of Tc-99m, is that it has a 6 hr half-life. That can be a disadvantage for delivery and production but it’s an advantage in the sense that the patient is essentially non-radioactive after 2.5 days. Iodine-125, on the other hand, has a half-life of 59 days, so it takes 1.6 years to be essentially free of the radiation (unless of course, it’s biologically cleared from your body). Part of the problem with production of Mo-99 is that it also has a relatively short half-life, 66 hours.
The article talks about how there are basically only 5 reactors in the world that produce Mo-99 and none are in the USA. So the USA ships U-235 to these countries for production of Mo-99 to be shipped back to the USA. Many of these reactors are decades (like 50 years) old.
The Kaiser Health News article is news, only in that one solution to the shortage has an update. There are three alternative methods to producing Mo-99 that are relevant to the article. Two of the methods are being pursued by NorthStar and the other is being pursued by SHINE Medical Technologies. SHINE is close to finally opening a production facility in Wisconsin, hence the “news” about the shortage.
Here’s the Salon article that I saw.
Inside The Global Race To Deliver A Vital Radioactive Isotope Used To Detect Cancer
Sarah Varney at Kaiser Health News
I’m linking the Ars Technica version because the photo in the Salon article is irrelevant and suggests pollution or something. I don’t know.
If you’re interested in the SHINE method:
https://phys.org/news/2015-06-lab-commercial-method-medical-isotope.html
More details about Tc-99m/Mo-99 production:
The Medical Isotope Crisis: How We Got Here and Where We Are Going
Thomas J. Ruth
J. Nucl. Med. Technol. December 1, 2014 vol. 42 no. 4 245-248
http://tech.snmjournals.org/content/42/4/245.full
and more info on SPECT imaging
Medical Imaging 101 pt 7: SPECT
Well!
Interesting update, NorthStar Medical Radioisotopes has just received FDA and NRC approval for their method of producing Mo-99/Tc-99m.
prnewswire.com – FDA and NRC pave way for the first domestic supply of the most commonly used medical isotope in diagnostic imaging
Jajajja
Chad Haney, whew