Goodness, that turned out to be a little picture. Oh well. That's our friend Thallous Chloride. I'm gonna tell you all about him!
We have had some bad news here in the world of nuclear pharmacy. We have a continuing shortage of our radioactive material. It's a world-wide problem. And just when things straighten out a little bit, another reactor goes down.
We have a few little tricks we can pull out of the bag when things get really short. We can lighten up the activity for each dose. We can make multiple deliveries to our customers so that there is less activity needed to make the dose (since the drug is radioactive, it is constantly decaying down; less time between the filling of the dose & delivery means less initial activity needed). I'm sure this is all as clear as mud & that you probably aren't very interested but all of this makes my nerdy little heart go pit-a-pat. Certain parts of my job are extremely intriguing to me. Anyway, another trick we can pull out of the bag when needed is to use another isotope. This is especially helpful for cardiac tests (a large portion of our business). When we can't get Technetium 99-m (Tc-99m) we can use Thallous Chloride (Tl-201). They don't function exactly the same way, but they both can make pictures of heart function. Mission accomplished!
My main concern in the difference between Tc-99m & Tl-201 is the difference in half-life. This is the amount of time it takes for the radioactivity to decay down by one half. For Tc-99m, the half-life is six hours. If I have 10 mCi at 8:00 a.m., I will have 5 mCi at 2:00 p.m. For Tl-201, the half-life is just short of 3 DAYS. As a result, when drawing up doses of Tl-201, I have to be very, very, very, very careful not to contaminate anything. When you contaminate an area you have to clean up the removable contamination & then wait a period of 10 half-lifes for the area to decay down to background (normal). This makes drawing Tl-201 doses a little bit scary, but it also makes it very exciting. I have only been able to draw up Tl-201 on two different occasions, one day last week & this afternoon. Both times (thank God!) I didn't get anything hot (i.e. contaminated). Since we only have two dose drawing hoods in our lab we can't really afford to leave one out of use for 30 days.
I am really grateful for these little adventures into something new at my job. I have been very blessed with this position & this company, but it's painful to be in a place where your skills don't get challenged. Every once in a while it's good to get pushed to a place where your hands get a little shaky & you sweat - just a 'lil!