Mikey,
I posted a link to this on the other thread, but perhaps you didn't read it:
What is radiation therapy?
Radiation therapy uses ionising radiation to kill cancer cells while causing minimal damage to surrounding healthy tissues. The type of radiation most commonly used is high energy X-rays which are capable of penetrating tissue to reach deep tumours. While X-rays cause damage at the target region, they also damage healthy tissue either in front of, or behind, the tumour. Many of the developments in X-ray therapy have sought to get more of the radiation to the tumour and less to the healthy tissue. The Christie has been at the forefront of research into this. We are leaders in the delivery of advanced radiotherapy. This includes stereotactic radiotherapy and intensity modulated radiotherapy, both of which reduce side effects. We treat more patients with advanced radiotherapy than any other UK centre.
Why proton beam therapy?
Proton beam therapy is a different type of radiotherapy. It uses a high energy beam of protons rather than high energy X-rays to deliver a dose of radiotherapy for patients with cancer.
Like X-rays, a beam of high energy protons penetrates tissue to reach deep tumours. However, the ionisation behaviour of a proton beam is fundamentally different to that of an X-ray beam. This is because protons produce more ionisation (and therefore cause more cellular damage) at one particular depth that is strongly dependant on the energy of the proton. This means that, compared to X-rays, protons cause less damage to healthy tissue lying in front of the tumour, and no damage at all to healthy tissue lying behind the tumour. This greatly reduces the side effects of radiation therapy.
Proton beam therapy gives us the potential to reduce the long-term side effects of radiation treatment, which is especially important in children. It also enables us to increase the dose to certain tumours, in particular those resistant to radiation, while sparing the healthy tissue. This is particularly useful for tumours near the spine or at the bottom of the skull where there are sensitive structures, such as the brain and spinal column, nearby.