Conventional radiotherapy uses high energy beams of x-rays to destroy cancerous cells. Whilst modern radiotherapy techniques allow the radiation dose to accurately target the tumour, some radiation is deposited in surrounding healthy tissue. This leads to treatment-related side effects impacting on patient’s quality of life. The use of high energy protons has the potential to reduce this radiation dose to surrounding tissues which reduces the risk of side-effects.
Proton therapy was first suggested in 1946 and delivered clinically in California in 1954 and Sweden in 1957. The US now has 34 operational centres with another18 at the stages of planning and development.
The first hospital-based proton unit was in the UK at Clatterbridge in 1989, for the treatment of ocular cancers. Despite this, development of proton therapy in the UK has been slower than in Europe and the US for a number of reasons, including higher cost and a lack of clinical evidence of benefit.
With conventional photon radiotherapy, the location of dose delivery can be inferred through measuring the x-rays that exit through the patient.