Case Study

Dr Tristan Pryer

Mathematical modelling of proton therapy

Conventional radiotherapy uses high energy beams of x-rays, or photons, 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 the patient’s quality of life. Proton Beam Therapy promises to be a revolutionary treatment for certain difficult cancers, where conventional radiotherapy beams are unable to adequately avoid irradiation of surrounding critical tissues, such as paediatric cancers, the base of the skull and complex head and neck cancers.

One aspect of this project is to investigate the mathematical modelling of proton therapy treatment planning, improving the likelihood of eradicating the tumour and reducing radiation dose to surrounding healthy tissue. With conventional photon radiotherapy, the location of dose delivery can be inferred by measuring the X-rays that exit through the patient. Proton therapy treatment verification is much more challenging, and currently not available, as the majority of the radiation dose, and the proton beam itself remains within the patient.

A potential solution to this issue is to measure the small amount of radiation that does escape from the patient during proton treatment. This radiation is a result of nuclear interactions and de-excitations and is released as high energy prompt-gamma radiation. Several research groups worldwide are developing detector systems that can measure this radiation. However, due to the sparsity of data, the current measurement of the prompt-gamma radiation alone does not assure that the intended radiation dose was delivered as intended. This project will provide accurate methods based on numerical and stochastic analysis of the Boltzmann transport equation with the overarching goal of deriving the radiation dose distribution from measurements of emitted prompt-gamma photons.