Monday 5 April 2021

Prostate Cancer: IGRT & the linear accelerator

Of all the scanners I've been put under or pushed through, the linear accelerator has to be the most impressive.


With its 4 'arms' rotating around your body, its half Swiss Army knife and half curious robot.

I can't help wondering if they ever go berserk, pick up the patient, spin them around a couple of times, and then dump them into a bin, saying "Sorry mate, you are beyond help!"

I've now completed just 3 of my 37 radiotherapy sessions while laying under a Linear Accelerator (or LINAC). My local hospital has 2 LINACs and for each machine they book patients in 12 minute intervals, which gives you some idea of how quick the treatment session is. The whole process is pretty slick.

My sessions are scheduled for each day, except weekends and Bank Holidays.

Upon arrival, I phone reception from my car to 'clock in' and then wait for someone to call me back when they are ready for me. They then give me a changing room number and in I go.

Each changing room has an entry door and a treatment door. So once inside, I remove my shoes and my trousers and put on my dressing gown. When they are ready for me, they open the treatment door and I make my way to the LINAC room carrying my own blue slip-mat.


The LINAC's main head is fixed to the gantry, but the other 3 are on articulated arms.

The slip-mat is placed on the bed and I lay down on top, sunny side up, having first removed my gown. I have 3 tiny tattoo dots which were made earlier, at a pre-radiotherapy session. By pulling the slip-mat, the therapists align me to the LINAC, making sure me and my 3 dots are in the correct position to be zapped.

Once all 3 members of the team are happy with my position, they all quickly get-the-hell out of the room (I guess they are scared that the LINAC might pick one of them up and dump them in the bin!).

In the ceiling I noticed a cross shaped hole had been cut in one of the ceiling tiles to expose (what I think is) a laser transponder. Sometimes a green laser line stretches across the ceiling aligned with this 'cross'.

The front of the machine carrying the 4 'heads' slowly rotates, stopping, restarting and reversing from time to time. Sometimes the main head disappears out of my sight-line while one of the articulated arms moves its sensor very close to me, as if taking a curious look at some peculiar specimen.

I haven't found a good description of how this machine works, but I know it provides 3D images to the operators hiding in their control room. So I'd guess that the three articulated arms are responsible for imaging, hence the Image Guided Radiotherapy (IGRT), the gold fiducials and my newly acquired tattoos.

After a few of minutes of operation, the LINAC's arms stop circling me, and I'm free to go. First stop is the toilet, as an hour or so earlier it was my duty to fill my bladder with 450ml (about a pint) of water.

food, drink & side-effects

I'll have to revisit this topic when I get further into my treatment, but for now I understand I can expect to feel more tired, my skin may get sore wherever the radiation enters or leaves the body, and I may suffer from bladder problems or diarrhea.

At an earlier consultation, I was told to drink 2.5litre of fluid each day but not drink tea and coffee, although Rooibos (red bush) tea is allowed. I didn't question this at the time, but it appears that tea and coffee irritate the bowel, probably resulting in diarrhea. Although I'm getting used to Rooibos tea, its not enjoyable and is no substitute for 'builders tea'. I am allowed to drink alcohol in moderation.

Drinking 2.5litres per day is not a problem for me. The problem is trying to space it out throughout the day between (say) 8am and 6pm, as there is no point in drinking the full quota in a couple of hours. I also note each [450ml] drink that I consume via the 'notes' app on my phone.

Its all about maintaining hydration and (on the day of radiotherapy) drinking a pint first thing in the morning, then a second pint 50 mins before treatment to ensure the bladder is full.

I haven't had any guidance on what I can or can't eat. If tea & coffee is a problem, you can bet there are things I should also avoid eating. Spicey food is probably out (Hurrah! I don't like it anyway), but I may need to experiment with the things that I do like if I encounter any problems.


Next prostate cancer post:-

Ring That Bell!

Click on the "Health" tab at the top of the page to find more posts on my experience of prostate cancer.

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