New Tattoos

So I'm to have radiotherapy.

Dr Carnell has prescribed 50.4 Gy ("Gray") to be given via Intensity Modulated Radiation Therapy (IMRT) in 28 fractions, at 1.8 Gy each time.

First, some definitions.

Gray: according to Wikipedia, one gray is the absorption of one joule of energy, in the form of ionising radiation, per kilogram of matter. The unit is named after the British physicist Louis Harold Gray (1905 - 1965)  whose work in the 1930's, 40's and 50's laid down much of the groundwork underpinning modern radiation therapy. A whole body exposure of 5 Gy generally leads to death within about 14 days: I'm only having a small part of my body treated, and although the local area will be damaged, it will eventually recover. I hope.

 IMRT: this is a kind of high-precision radiation treatment delivered using a linear accelerator (linac). The intensity of the radiation can be changed during the treatment to allow a more intense dosage to the tumour cells whilst sparing adjoining healthy tissue. The targeting of the radiation beams conforms to a precise 3-D image of the tumour cells. Shaped radiation beams are aimed from several angles of exposure to intersect at the tumour. This provides a much larger absorbed dose there than in the surrounding, healthy tissue, allowing higher dosages to be given with fewer side effects.The radiation beams may be moved during treatment, and the intensity changed,  dozens or even hundreds of times.

Fractions: the dose of radiation required is spread out over days or weeks, with the patient receiving a fraction of the total dose on each visit. This allows healthy cells to recover somewhat between sessions, whereas tumour cells are generally less capable of repairing themselves. Despite the high degree of precision allowed by the IMRT machine, it is inevitable that the radiation beams will affect healthy tissue as well as tumour cells. In my case, the beams have to go in through skin, fat, muscle, and bone before they even get to the treatment area. Then out the other side. There will be some damage to healthy cells, but this should repair.

That's the theory.

Now the practice:
Here's a nice little video, courtesy of UCLH, as an introduction to radiotherapy planning and treatment at UCLH.

Radiotherapy at UCLH

For me, the process started on 17th August with treatment planning. There are practical considerations. Delivering the treatment requires repeated visits, with the patient in exactly the same position each time so that the doctor can locate the target for the IMRT, again and again. This requires the correct alignment of the patient in relation to the linac. Even a slight movement of the body relative to the equipment can cause the radiation beams to go off target. Then there are theoretical considerations: the IMRT machine is a hugely flexible tool, but three dimensional planning for this type of conformal radiation is much more complex than for traditional one-slice radiation therapy. Calculating how to do all this takes time and care. There are various techniques to ensure the correct alignment including laser lights, field lights, skin markers and stereotactic modelling, but the first task is to ensure that the patient stays still within the machine, in the same position each time. In my case, this required making a body mould.

A friendly and kind technician called Colin led me into a room containing a couch with a solid surface and notches round the edge, designed to hold a variety of fittings. It was set up for me, with a metal frame at the head end. In front of this was a bright blue bag, which looked like a large, under filled bean bag. Colin explained the treatment process, with particular emphasis on the side effects for my skin. I'm going to get a sunburn-like effect across the right side of my chest. He warned me to avoid perfume or deodorant on the skin until it heals, to stay out of the sun for a year after treatment, and to steer clear of astringent soaps. I need to use aqueous cream to clean and condition my skin for the forseeable: and he gave me a big 100g tube to take home with me.

I lay on the couch with my head on the bean bag and my hands grasping handles behind my head. Colin and his colleague adjusted my position a few times, checked that I was comfortable, then pumped all the air out of the bean bag. This made the whole thing solid, preserving the indentations produced by my head and arms. The bag actually contained polystyrene beads, which lock together when the air is removed so instantly creating a custom made portable, lightweight and rigid piece of apparatus.This will follow me to each of the radiotherapy sessions, ensuring that the alignment of my upper body stays the same.

R/T Mould

The second task was more complex. The target zone of the radiotherapy is inside my lungs which is a) invisible from the outside and b) moving constantly, as I breathe. The radiographers needed to make visible marks on my skin which can be used to align me on each treatment, and to model my breathing so as to fine tune the IMRT as much as possible with my natural movements. So I and the body mould were taken to the radiotherapy planning department.

There were two radiographers, both called Jo, taking me through this stage. I went into a room labelled "CT Simulator" which was confusing as there was a real CT machine in there. Maybe it simulates something else, like radiotherapy. Anyway, the body mould was placed in position at the head of the machine, and I was asked to undress my upper body and get onto the couch. I then lay down with my head and arms held in position by the mould.

I couldn't really see what was going on, but apparently thin green laser beams lined up on my body along the midline and across my chest forming cross hairs. A small oblong white plastic box with black ends was taped to my abdomen aligned to the longitudinal beam, presumably to monitor the rise and fall of my stomach as I breathe. Pen marks were made on either side of my chest, and at the site of the cross hairs. Godfrey and the Jo's left the room and I lay in that position for several minutes while the Jo's monitored my breathing from a side room. Then the machine started up, and I had yet another CT scan.

After the scan, one of the Jo's came out and checked the pen marks she had made. Seeming satisfied, she got some ink, and a needle, and made them permanent. These can now be aligned with laser lights on the linac, ensuring I haven't rolled slightly, or moved down the couch. I and my cancerous cells will be exactly where the accelerator expects them to be, enabling optimum zapping.

3 little scratches, 3 new tattoos. Brings my total to four, so far. The first one's still my favourite!

Four Tattoos and some freckles

That was it, I was done. The treatment itself starts on the 3rd September, so I have a few weeks of normal life before then. Although it was overcast, the day was growing warm and so Godfrey and I headed off to the Founder's Arms on the banks of the Thames for well deserved sandwich and a pint. Just as we arrived the sky cleared and we sat there in beautiful sunshine, with a refreshing breeze blowing in off the water. Lovely.