Citation: Australasian Physical and Engineering Sciences in Medicine. 2019, 42(1), 329
Author: Yap J.S.L. (Jacinta.yap@cockcroft.ac.uk); Schnuerer R. (Roland.schnuerer@cockcroft.ac.uk); Welsch C.P. (carsten.welsch@cockcroft.ac.uk); Hentz M. (m.hentz.13@ucl.ac.uk); Jolly S. (s.jolly@ucl.ac.uk); Kacperek A. (andrzej.kacperek@nhs.net))
Abstract: Introduction The Clatterbridge Cancer Centre (CCC) in the United Kingdom is the world's first hospital proton beam therapy facility, providing successful treatments for the past 30 years. A 60 MeV beam of protons is produced and transported through a passive delivery system enabling the precise delivery of uniform dose to ocular tumour sites. The QUASAR group is developing an online beam monitor based on LHCb VErtex LOcator (VELO) detector technology for implementation into the CCC clinical proton beamline. The design of the monitoring system allows real time measurements by correlation of the beam halo with the beam current. In order to investigate the capability of the system as a dose monitor, accurate and validated simulations are needed for the integration of the detector and also for the full characterisation of the beam. Method A model of the beamline has been developed using the Monte Carlo simulation toolkit GEANT4 which describes the treatment line starting from the vacuum tube containing the double scattering foils, through to the nozzle. The geometry of the delivery system components are accurately defined, along with the VELO sensors positioned within a designated integration zone between the modulator box and treatment head. The simulation model has been validated against experimental data, including depth dose and transverse profiles. Results The CCC beamline model is described in detail and experimental measurements are presented alongside simulated results achieved with the validated Geant4 model. The integration of the VELO detectors within the delivery system and recent progress to correlate halo measurements with delivered dose is also shown. Conclusion An accurate and validated simulation model of the CCC beamline is essential to investigate the implementation of the VELO detector system and its viability as a candidate for online dose monitoring. This will also facilitate future work into radiobiological studies and facility upgrades.
