Imaging of prompt emissions during proton cancer therapy for geometric and dosimetric verification

Proton Beam Therapy is a type of radiotherapy, which uses a precision high-energy beam of particles to destroy cancer cells. The treatment is particularly suitable for complex childhood cancers, increasing success rates and reducing side- effects, such as deafness, loss of IQ and secondary cancers. It can also used to treat brain cancers and head and neck cancers. It is crucial that there is clear knowledge of the quantity of radiation required and also delivered to a patient during treatment. This proposal "Imaging of prompt gamma emissions during proton cancer therapy for geometric and dosimetric verification", aims to develop an optimised detector and methodology to allow real time verification of radiation delivery.
This task is an essential part of the radiotherapy process, however this is significantly more challenging for protons than for high energy photons (which are utilised in existing facilities). The proposal brings together experts in radiation sensors from the University of Liverpool, imaging experts from University College London (UCL) and University College London Hospital (UCLH) and Radiation therapy professionals from the Clatterbridge Cancer Centre. UCLH will be the home of one of the two new proton therapy centres to be built in England, Clatterbridge houses the only existing proton therapy facility in the
UK.

Robust in vivo dosimetry provides absolute confirmation that radiotherapy is delivered as intended and is recommended by both professional bodies and the UK National Patient Safety Agency (9). Radiation overdose to normal tissues resulting either from calculation errors or geographical missing of the tumour has serious consequences for patients, as does tumour underdose, leading to treatment failure and avoidable disease progression. Reported radiotherapy incidents that have led to patient deaths or severe treatment-related side-effects (10) could, in the vast majority of cases, have been prevented had in vivo dosimetry been performed. Diode and portal-imaging based methods are commonly used for in vivo dosimetry in photon radiotherapy, however neither method is adequate, if possible at all, for proton therapy. Deriving delivered dose via PG imaging has the potential to fill this important role in the safe delivery of proton radiotherapy.