This week, I had my perspex shell made and fitted. It will keep me in exactly the same place for the 30 radiotherapy sessions.
The process was somewhat like the one described in Wikipedia’s entry on Lifecasting. In a special Mould Room at the hospital, lying flat with my head tilted as far back as possible (so important stuff will stay out of the beam) my head and neck were smeared with vaseline, then (apart from my face) covered with blue alginate gel and plaster of paris bandages to add strength. After five minutes of setting, the whole thing was peeled off.
While I was gone, they filled it was more plaster of paris to make a bust, and the reversed it again by vacuum-moulding a plastic sheet around the bust. The result was trimmed, and a hole was cut for my face. Now, after a second fitting and the addition of extra shoulder restraints and clips, they can use the resulting shell to pin me to a table in such a way that I can only move a couple of mm each way. Impressive :-)
There don’t seem to be good photos on the web; I’ll see if I can take some when I start treatment at the end of the month.