This is a hard one! Why? Because we have no computer to help us! 3DCRT is just you, your imagination and then you get started. But if you can get through the process here and produce a plan, well, IMRT will be a breeze.
Firstly, if you have rushed here because you think that the answer to your problem is here, just stop and take a deep breath. Have you already worked through how to make a proper GTV, make a proper CTV, and make a proper PTV?
If you haven't, go and do these first. There is some really good material there and it will make producing a plan so much more fulfilling. Yes, and looking at properly assess a plan might also be a useful thing to do as it tells you something about the format of what you are going to produce.
Secondly, being able to do this is very much dependent on your planning computer. I am using Pinnacle at the moment, but sadly I can tell you that making plans on the different systems is very different. I have been able to achieve similar plans on Pinnacle, Xio and Eclipse. You will just need to ask your planners lots of "how do I …" questions until you know your way around the system you have.
There are at least two available planning systems to play on:
- one is a piece of Mac software found here, but sadly which I couldn't get to work and runs on old Mac hardware
- the other is the PLUNC software found here. This is functional and used for planning in different places. I haven't played with it yet.
Principles of 3DCRT.
- complete your voluming!
- check your voluming!
- there is no problem that cannot be answered with a 5 field approach
- no beam enters through a critical structure unless inevitable
- dose inhomogeneity between 95% and 107% is IRRELEVANT
- the distance between the PTV edge and shielding edge is about 0.7cm ON ALL MACHINES (this is the physical penumbra and cannot be altered)
- beam arrangements should respect the spatial arrangement of tumour volumes AND critical structures
So let us attempt a couple of 3DCRT cases! (Be patient, I have to find and collate images to demonstrate so you will just have to wait.)
- Prostate Cancer planning case
- Head & Neck planning case