ProBE: Proton boosting extension for imaging and therapy

Proton beam therapy has been shown to be a promising alternative to traditional radiotherapy, especially for paediatric malignancies and radio-resistant tumours. Allowing a highly precise tumour irradiation, it is currently limited by range verification. Several imaging modalities can be utilised for treatment planning, but typically X-ray CT is used. CT scans require conversion from Hounsfield units to estimate the proton stopping power (PSP) of the tissue being treated, and this produces inaccuracy. Proton CT (pCT) measures PSP and is thought to allow an improvement of the treatment accuracy. The Christie Hospital will use a 250 MeV cyclotron for proton therapy, in this paper a pulsed linac upgrade is proposed, to provide 350 MeV protons for pCT within the facility. Space contraints require a compact, high gradient (HG) solution that is reliable and affordable.