Tuesday, January 22, 2008

Nuclear Medicine Step 1--Tracer Dose of Radioactive Iodine

OK, so here is the first step. I am at Emory. The first room in the Nuclear Medicine unit is where they give out radioactive iodine. Just me and a small lead container sitting on the floor waiting.

In comes the doctor.

The process is pretty simple.

He opens a small container. Think of a powered sugar container--the metal kind with the holes on the top. But, this container is missing the holes.

Out comes a cardboard tube with a lid. He pops it off.

He pours two capsules into a plastic medicine cup. He says "swallow these".

In front of me is a cup containing radiation. I am supposed to swallow it. Who cares about suncreen or not sitting in front of the microwave. Just swallow some radioactive pills. We are such primitive savages. Jump to year 2030--"Steve, you have a type of cancer that is all throughout your body. It was given to you a long time ago because you voluntarily swallowed radiation. We were just too stupid to know back then". I do hope I live that long.

I open my mouth, pour in the two capsules, and swallow.

What did I take?

4 millicuries of radioactive iodine. A millicurie is 1/1000 of a curie. That's all you need to know. We can't see or weigh radiation like we do with medicines. Radiation is something that will create an image on film (x-ray, CT-scan) or, in a more powerful dose, kill the cell (or cause more cancer!). Think of a laser. You can buy one for $10.00 that you can point on the ground for your dogs to chase, or you can spend $30,000,000 and create a vaporizing laser that will knock out a missle in the air. Well, I just took a very small dose of radiation. It is about 1/30 or 1/40th of the dose used for therapy, the effort to treat or kill the cancer. The radioactive iodine that I took is just enough to light me up inside. My starving thyroid cells, looking for iodine, will absorb the iodine. Just enough to be seen with a special scan that will take place on Friday. This will be a whole body scan--about an hour. It will look for thyroid cells that have absorbed the iodine. When the doctor finds the thyroid cells, he will make a determination. I could have no visible cells, some in one area, a mass in one area, a combination, or my body could be infested. Depending on how much is found, this will determine the dosage of radioactive iodine.

[A curie is a unit of radioactivity equal to the amount of a radioactive isotope that decays at the rate of 37,000,000,000 disintegrations per second. For those interested, Emory uses I-131 for both the scan and the therapy. ]

Why is the room the first room in the unit?

Duh, to run out as soon as I take the dose so I don't have to be near anyone else.

What precautions do I take at home?

Sleep alone for a week.
Private bath.
Disposible dishes.
Wash utensils and other dishes alone.
Wash my clothes alone.
Flush the toilet 2-3 times.
Stay away from anyone by several feet when possible.
OK to hug the kids after the tracer dose, but better to stay 3 feet apart.
OK to eat at the table.

All of this for the rest of my life! Just kidding. For me, with you kids. It will be for 1.5 weeks total--including a week after my therapeutic dose.

Where does the radioactive iodine go?

I-131 has a 8 day half-life. This means after 4 days, it is 1/2 gone. After 4 more days, there is 1/4 remaining. After 4 more days, there is 1/8 remaining. I am told that it is OK to be near people after a week--sleeping or touching them, but--hmm, it sounds like it should be longer....I guess at some point, the radiation is minimal. Where does it go? It is excreted in the urine and sweat, in general, but that which is lodged in my thyroid cells, trapped in my body somewhere, does not "go anywhere". It decays--the atoms disentegrate, so that they no longer exist. Nuclear activity going on in my body.