Collimators

Collimators??? Well, now I have an explanation as to why the zapping sounds like a demented carrot grater rather than some of the noises out of Star Wars! The reason is because of what are called "Multi-leaf collimators". You can read the complete guide here: http://www.aapm.org/meetings/99AM/pdf/2787-9625.pdf if you really have to.

Basically, it's a really clever device that blocks bits of the beam while you're being zapped to ensure that bits that shouldn't be zapped, aren't. And it moves around really quickly and, in my case, makes sure that my eyeballs aren't x-rayed, for example. This isn't the same as getting an MRI scan where your eyeballs are safe!

Anyway, I'm now a third of the way through the treatment and not feeling any ill effects except for the bleedin' journey...