But first, I asked about how often they calibrate the machine (which, by the way, is a Varian Systems Clinac iX Linear Accelerator) and the answer was: Daily. But OK... I didn't ask how that was done. But according to the technician, a great many of the errors that were possible early on in the IMRT history have been fixed by updates to the machines and software. The machine itself is huge... I'll post some pictures on the next page... and I would love to see it with the covers off. Not likely to happen.
The doctor's office I go to has a special section for patients getting radiation treatments that has a set of small changing rooms, some semi-comfy chairs, a card table with a jigsaw puzzle on it, and a closed-circuit camera that someone down the hall monitors. So, you just walk in, change into the uniform, and wait until someone comes to get you. It's kind of nice... as long as you're OK with waiting a bit. Machines, being what they are, have some glitches sometimes. Personally, I'm just fine with waiting until they're working properly. Like I'm fine with the pilot who wants ALL the engines to work before taking off.
The first thing that happens, after getting on the table and lying down (with the requisite paper drape) is they get me aligned using the tatoos on my hips. Anthony usually says "lie heavy" which I take to mean "don't help me move you" rather than tell him some heavy-duty lie from my past. He scoots me a bit, and once I'm in position, he leaves the room. Today I asked about the need to have clothing out of the way, and Anthony told me that some material causes the sensors to register a kind of false signal... like thick skin, so the machine compensates with more radiation. They don't want that, hence the drawing back of the clothes and the paper drapes.
Next..
The machine starts rotating, counterclockwise from my point of view. Arms come out from each side, and the rotation stops with a head positioned at 12 and 6 o'clock, and they take a picture. (I need to find out how this is done... not a fluoroscope thing.) Here's a picture of the accelerator (from the Varian website) of the machine, with the imaging arms extended.
Next, the machine rotates around me, so the head that was above me is now on my right, and the one that was under me is on my left... just like in the picture here. Then, a brief pause while another picture is taken, and the arms retract. The big head of the machine then rotates clear around, so that it is at 6 o'clock... under me, and I can hear some clicking as the multi-leaved collimator part of it adjusts. The light on the wall, indicating radiation X-ray activity, flashes for about 30 seconds and stops. More clicking, and then another sequence of the light flashing. That same (or similar) sequence is repeated as the machine rotates to several positions around me... about 4:30, 2:30, 1:30 then 11:30, 10:30 and 8:30... then it goes back to right over me and we're done.
All in all, it's pretty quick. The funny part is, each evening after starting this, I've taken a nap when I get home. Maybe it's just that I'm listening more when I'm tired... and giving in rather than fighting it. And I've been heading to bed earlier. Who knows? It's so hard to tell where the tiredness is coming from. After all, the hormones are still running their course, and they've got that side-effect too.
Here are the other shots of the machine... one that kind of provides some idea of scale. This position must be showing the image-taking sequence, because in my short experience, when the radiation sequence is taking place, the extendable arms are retracted.
This one, from the overview on the Varian website is more of a conceptual schematic... but interesting.
The rounded area just over the platform is what houses the collimator... which is part of what shapes and focuses the beam.
An interesting sequence, overall, and now I'm feeling fairly nappy. I think it's time for a little "lie-down".
No comments:
Post a Comment