Radiation Therapy 101

Today was a good day. I am slightly fatigued right now, but not too bad.

In tonight's post I have decided to finally answer all your questions about the radiation side of my treatment. Feel free to post extra questions to the comments section and I'll do my best to try to answer them.

1. What exactly is radiation therapy?
Radiation therapy is the medical practice of using radiation to control cancer cells. In my most basic understanding, the radiation beams are directed at specific tissues and the beams break apart DNA of all cells. When the DNA is ripped apart in this manner, the cancer cells cannot successfully copy themselves and so they die. If you remember from my chemo post, the chemo drugs bind to dividing DNA and make it impossible for the DNA to split/copy itself. This is why combining the chemo with the radiation works so well. Normal cells also die, but are able to find new ways to make new cells. The cancer cells cannot.

2. But if your cancer has been removed (i.e. doesn't show up on any scans) what are they radiating?
Maybe this is obvious to some people, but this was the question I had for my doctors. Even with the most accurate PET/CT technology, when scans are taken, the machines only take pictures in 7mm increments. If the cancer cells fall between a scan, then they won't show up in the results. It takes over 50 million cancer cells in order to make a 7mm diameter tumor, but it only takes 1 cancer cell to knock me out of remission. Obviously we can't see where any of these potential cancer cells are, but we can take some good guesses. Even though I had clear margins, any of my original tumor sites (right tongue, left lymphnode) could have cancer cells surrounding the removed area. Think of like a wet tennis ball hitting the court. If you really examine it, does the water just make a perfect circle or are there little droplets that go to the sides and don't touch the main mark. That kinda how the tumors are. They do take quite a bit of extra around the tumor site, but they still might miss a cancer cell or two. Also, despite being at one of the best surgical centers, cancer cells can remain on surgical instruments and get caught along the scar lines in my neck. Remember it only takes 1 cell. They could also be somewhere in transit along my lymphnode drainage system from my tongue to my lymphnodes. These are all the areas they will be targeting.


3. What type of treatment are you getting? What is IMRT?
My treatment is taking place on a TomoTherapy HiArt® (highly integrated and adaptive radiotherapy) treatment system, one of only a handful in the country. TomoTherapy is a way to easily combine treatment plans, position, and radiation delivery all in one. It is the newest advancement in IMRT (intensity modulated radiation therapy) which is just what it sounds like...shaping the intensity of the radiation to deliver different amounts to different tissues, sparing specific areas. I am receiving 33 doses giving up to 66 grays to the main target areas as I talked about in question 2. That means up to 2 grays (or 200 rads) per treatment. I have treatment every Monday through Friday for 6.5 weeks. They have tailored my program specifically to avoid my right cheek salivary gland, my larynx, pharynx, and most of my jaw.


4. Are you radioactive? Do you have super powers?
No, the radiation does not make me radioactive. As soon as the machine is off, I'm safe to be around. Also, despite some of my coworkers claiming I must have superpowers for having such a strong sense of smell and being able to taste metal, I do NOT have any super powers.

5. How does it feel being radiated?
Aside from the awkward/claustrophobic feelings brought on by having my feet strapped together (so I don't accidentally cross them and misalign myself to the machine) and having my head fully locked into place by the mask, I don't "feel" anything. There are a bunch of clicking noises and as I've described in earlier posts, there is a 1-2 second smell/taste at the beginning of the radiation beams starting up. In total the process probably takes about 15 minutes from the CT scan, waiting for the scan to match itself to the original treatment plan, the technicians moving the table I'm on a few mm up/down & left/right based on the results, and then the radiation beams themselves.