I posted a reply to a question about radiotherapy, but info like this is hard to go back and find on this site, so I thought I'd copy it to my blog, so I can point other people to it when I see similar questions.
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Here's my recollection of the sequence of events of radiotherapy on my brain tumour. Perhaps others will comment if they had different experiences, or if I got anything wrong. I must say all the staff were very pleasant throughout alll my treatment.
I don't know if as a child you ever had a torch with interchangeable fronts that cast a beam in for example the shape of a duck or a butterfly the like on your bedroom wall, well this is the principle here. So if viewed from a certain direction your mum's tumour happened to look butterfly shaped, then they would arrange the equipment to shine the right shaped beam from the right direction. So now the problem is to work out generally about 3 different beam angles.
They work out beam angles for more than one direction because the x rays have to pass through good tissue before they hit the tumour, so this way the good tissue gets a low dose of radiation, and the nasty stuff gets as good a roasting as they can possibly give it. Some of the good tissue has to be taken special care of because of what it does, for instance the nerves from the back of the eye or the brain stem are things you really don't want to give too much dose to.
For me the angles and intensities for the beams were decided using two different sorts of images. Mostly people have MRI scans to detect tumours, because thats the kind of scan that the doctors can see best with. Your mum's probably already had at least one of these, it's the one where it sounds like a children lacking a sense of rhythm trying to form a steel band using dustbin lids. Once they have decided to do radiotherapy they will also take a CT scan.
I found the CT scan a real breeze after the 10 or so MRI scan's I'd had before. The CT scan is done a) because they need to know exactly where all the bits and bobs in your brain are, and MRI doesn't tell you that well enough; and b) because it tells the doctors exactly how much of the beam passing through the head will be absorbed by every little point in the head. It's only when they know this that they can work out how much dose would be given to the tumour and the other vital bits by any particular arrangement of beams.
So after the CT scan I had to wait a week or so before I went back to try out the beam angles they had worked out for me. They did this on a simulator, which is much like the equipment for actually delivering the dose. I guess the delay is because it takes someone quite a bit of time to use the MRI and CT scans together to do all the complex mathematics that results in your tailor made treatment.
Once they've done all this number crunching they have to have a way of making sure you are lying on the treatment couch in exactly the right position, otherwise they could end up shining the carefully shaped beam at the wrong bit of brain. For me they did this by making a transparent plastic face cast. It took about 20 minutes with, if I recall correctly, a fabric bandage coated in gooey stuff that started off the consistency of butter cream, and after about 10 minutes of it feeling quite warm, it hardened up, and could be taken off to a back room somewhere, where someone turned it into a mask.
The simulator is used to check that the treatment plan works in practise, without taking up time in the real treatment room. My guess is that this might vary a bit from hospital to hospital so it may not be exactly like this for you. The simulator room and the treatment room both have lasers in the walls in exactly corresponding positions. You lay on a table and they put your mask on. The mask has some kind of device for clipping it to the table in a way that can be done to give exactly the same position day after day. Once they have moved you to the right position they mark your mask where the lasers shine on it, and they record some numbers for the table arrangements. You'll get very used to these numbers, as they get called out every time you go in for a zap, as they adjust the table millimetre by millimetre to line you up.
You then get a timetable of treatments. I had 30; one every weekday for 6 weeks. As it was explaind to me, they "fractionate", or split up the whole dose over say 30 days because cells that are in the process of dividing (i.e. the tumour cells) are affected more by the x-rays than those which are not. So in this way you have more chance of catching the little blighters at it.
I arranged a rota of friends to drive me to the hospital, because my previous surgery meant I could no longer drive. I was asked for a preference of time of day before they made up my timetable, and I was glad that I asked for early morning. You tend to get most of your appointments for roughly the same time every day, but some will be different when the machinery has to be taken out of service. For me the appointment times were very precise times, e.g. 8:53 to 9:05. The later your appointment in the day the more chance that there will have been delays and you could be sitting for an hour or so waiting.
The treatments are pretty easy really. You lay on the bed, they put the mask over your face, clip it into place on the table, and you wiggle about a bit to make it comfortable, by which point you should be in the right position. They then move the table electronically, and call out those numbers I mentioned. All being well, when they have moved the table to the right place, then the lasers are shining directly at the marks on your mask.
If you can look up into the "linear accelerator" you'll see a shape formed by a device made up of lots of metal "leaves" next to one another, that can be moved in and out by the machinery. The shape is unlikely to be butterfly shaped, but it will be the shape that your tumour has, when looked at from that angle. There is only one machine for delivering the dose, so each treatment involves a couple of short waits for repositioning the beam. They leave the room for about a minue whilst each zap is happening. The only sensation I recall is a slightly odd taste on the tip of my tongue, a bit like testing a half dead battery by putting the terminals on your tongue.
Now and again they do a belt and braces double check during the treatment to see that everything is exactly as it should be by taking a picture of your treatment. This works because some of the x-rays they are zapping will go straight through you and come out the other side. If they use these to capture a picture, they can do some more number crunching using the original MRI and CT images to work out exactly what that picture should look like.
I found that after about 4 or 5 weeks I started to get quite tired and needed to sleep a lot. This was when the early appointments weren't quite so welcome, but on balance I think I'd rather go earlier than later. It was also about this time that my hair started falling out. It fell out over the course of about 3 or 4 days, mostly when I was washing my hair. I distinctly remember having to clear the bath plug hole of a handful of it - quite a low point in the process.
It was a bit of a surprise to me how big the circles of baldness were. Given that my tumour was about the size of a hen's egg, the patches of missing hair above each ear were about the size of a tea plate. I now have a pretty good covering of hair again.
The benefit of radiotherapy is I think undeniable, but I have to say that my memory after radiotherapy is not as good as it was. I've had psychological tests recently to understand my memory problems, but they aren't a lot of good without the people testing you knowing what your memory was like before treatment. I don't know if it's possible, but if you are in a job where your mental faculties are your livelihood, it may be worth finding out about getting a baseline test before treatment.
For me, I hesitated to make a point of this before treatment and at again later at the psychological tests. I have a Ph.D. and a first class honours degree, but in the company of surgeons and the like I felt this was irrelevant so I didn't mention it. Now I am having trouble returning to my occupation, but the broad brush tests for memory problems suggested that I should be able to get back to my occupation, without them really knowing what that occupation is.
