Proton imaging for cancer treatment using a high proton flux: deaveraging calorimetry

Protons are beneficial for cancer treatment due to their potential of targeting the tumor site more precisely than photons, thereby causing less damage to the surrounding healthy tissue. Currently, however, the protons are shot blindly without any feedback. Proton computed tomography, creating cross-sectional images, offers a potential route to reducing range uncertainties for proton therapy treatment planning. The existing commercial clinical facilities usually have a high proton flux. To measure the resulting energy changes in the protons, a relatively inexpensive scintillator-based calorimeter is being proposed within the context of the OPTIma (Optimising Proton Therapy through Imaging) consortium and associated system. Due to the high flux this will only report the integrated energy deposited by all protons within a bunch. Here we present a mathematical method that deaverages the deposited energy by reconstructing the individual contributions. The method is tested by GEANT4 Monte Carlo simulations, and the results illustrate that the artefacts due to the averaging are almost completely eliminated by applying this method [1]. 

Left: ideal system; middle: system with integrated proton energies; right: restored system due to the de-averaging algorithm

[1] A. Winter, B. Vorselaars, M. Esposito, A. Badiee, T. Price, P. P. Allport and N. Allinson, OPTIma: simplifying calorimetry for proton computed tomography in high proton flux environments, Phys. Med. Biol., 69 055034 (2024).