Getting irradiated

Insurance aside, radiation treatment deserves attention in its own right. Even after MRI’s, CT scans, and a PET scan, radiation still strikes me as the most science-fictional experience I’ve had as a cancer patient.

The basic problem with radiation is also its strength: radiation destroys cells. If it hits cancer cells intensely enough, it's likely to destroy them. If it hits healthy cells intensely enough, it's likely to destroy them too. (Incidentally, this doesn't have to be done just in one session; the doses add up, which is why my treatment will consist of 15 separate sessions lasting till mid-July.) So the job of radiation treatment is to find a way to concentrate as much as possible on the cancer cells while sparing the healthy cells nearby. In my case, that means sparing both the healthy parts of my liver (still chugging away with blood test numbers almost entirely back in the normal range). It also means sparing the important organs nearby, notably the stomach and the intestine.

There seem to be two basic ways of making sure the radiation hits just its true target, or rather does so as much as possible -- absolute perfection doesn’t seem to be attainable. The first method is by very carefully shaping the radiation beam; the second is by making sure the beam is as precisely aimed at the tumors it is meant to target as possible. 

As the patient, I don’t have anything to do with shaping the radiation beam. That’s a technological feat that the machinery is designed for, and the operators of the machinery carefully manage. 

The basic idea, as explained on a National Cancer Institute website, is to deliver beams of radiation from many directions, so as to “conform[] to the shape of the tumor” – hence the name “3-D conformal radiation.” Further refinement of the shaping of the beam can come from a version of 3-D conformal radiation called “intensity-modulated radiation therapy” or IMRT; again according to the National Cancer Institute website, “IMRT uses many more smaller beams than 3-D conformal and the strength of the beams in some areas can be changed to give higher doses to certain parts of the tumor.” Finally, in stereotactic body radiation therapy (SBRT), the same website explains that “many small beams of radiation are aimed at the tumor from different directions. Each beam has very little effect on the tissue it passes through, but a precisely targeted dose of radiation is delivered to the site where all the beams come together.” My understanding is that IMRT and SBRT are overlapping terms, and that they describe what I’m receiving.

All that, again, is the work of the machinery and the medical staff. Meanwhile my contribution is to assist with the aiming of all these beams. My assistance isn’t very dramatic: my assignment is to lie in a mold that was prepared at my “simulation” session three weeks ago and that holds me in a particular position, and then to follow instructions meant to get my position even more precisely set. I start my assignment by lying down on the narrow table where I’ll be during the radiation. Then the medical staff take over; at this preparatory stage I'm supposed to be a dead weight, and not try to help the staff, who will move me to exactly where they want me.

Then my job is to breathe. This is a lot harder than it sounds. Most of the radiation seems to be sent my way while I hold my breath; that’s because breathing itself moves the organs inside you quite a bit. But naturally people hold their breath to different degrees at different moments, and the radiation staff want me at exactly the right point. So I take a breath, then they tell me to let just a little breath out, then a little more, then breathe in just a bit … and then, when I’ve got just the right amount of breath in me, they start the actual radiation. Only by then I’ve already used up quite a bit of the oxygen from that first breath, and now I don’t get to breathe again till they’re done! Two or three times they took me right to my limit, with my chest beginning to shake as I needed more and more urgently to breathe. I wasn’t sure whether that would be an aiming problem itself, but they told me afterwards that I’d done a good job – so I hope they got the targeting they needed. I also hope I’ll be a better breather today (Monday, June 25), when I go for my second session.

But I haven’t yet said what really seems so futuristic about this process. I lie on the table, with a linear accelerator behind me that’s producing the radiation beams. (A linear accelerator!) Meanwhile three lenses, all quite large – maybe two or three square feet – revolve around me. I wasn't quite sure where they were coming from or going to, because I was in the body mold on the table and could only look up, but it appears that the group of lenses can revolve at least part way under the table on which I’m lying. The whole apparatus looks something like this picture (which happens to be of a Varian Medical Systems machine -- I'm not sure which brand Sloan Kettering is using):

One of these lenses, perhaps the biggest, is round (you can see it near the top of the photo). The round lens is the source of the radiation beams and has cross-hairs embedded in it that I think are used for targeting. There are also laser beams, apparently coming from the walls of the room, that help in the targeting too; I’m guessing these are aimed at the tattoos that I was given during the “simulation” session. 

The other two lenses are rectangular and are used for taking x-rays as the process goes along, to make sure that everything looks right inside me. (They're visible sticking out on the sides of the machine in the picture.) There was a moment during my first session, this past Friday, when everything paused, while the doctor reviewed the images they had so far, I guess to make sure that in fact everything did look right. Fortunately it did, and then my actual treatment started. In the future, I think the treatment will get underway at once, so the whole process will be quicker, maybe 20 minutes of actual time being treated per day. 

The lenses revolve very near me – the medical staff assured me that I would never actually be hit by one, and this proved to be true, but they’re still really close – and they do so quite silently. Meanwhile I’m listening to music; they told me I could choose anything and I had a good time with Beatles songs I hadn’t heard in years. So as I’m working on being a good breather these big lenses are quietly revolving around me, and it looks like something out of 2001.

And I say: great!