Question: What kind of radiation do you use and why?

Rob Brass answered on 13 Jun 2016:

This is a great question!

We normally treat using high energy x-ray photons – about 6 million volts! Photons are little packets of light energy. We can also treat using a beam of high energy electrons but only use this in a few cases.

We need our photons to have such a high energy in order for them to travel deeper into the patient before they deliver their dose, the higher the energy the further they can travel. We sometimes use even higher energies (about 10 MV) if a tumour is quite deep within the patient.

Electrons dont travel as deep as electrons as they interact more with the patient and lose their energy more quickly.

We couldnt use alpha particles as they wouldnt get past the skin!

We also have the UKs first proton treatment facility at Clatterbridge, however we only use it to treat eye tumours. This fires a beam of high energy protons generated in a cyclotron. Protons have the advantage that they tend to deliver most of their dose over a very short distance at the end of their range, so if you can position that range within the tumour then the dose you give to other healthy tissues is tiny. However with our cyclotron we can only use them for eyes as we cant get the energy required to go deeper into the body.

I tried to keep it brief, let me know if youd like any more detail on anything!