title: A theoretical framework to predict the most likely ion path in particle imaging.
abstract: In this work, a generic rigorous Bayesian formalism is introduced to predict the most likely path of any ion crossing a medium between two detection points. The path is predicted based on a combination of the particle scattering in the material and measurements of its initial and final position, direction and energy. The path estimate's precision is compared to the Monte Carlo simulated path. Every ion from hydrogen to carbon is simulated in two scenarios, (1) where the range is fixed and (2) where the initial velocity is fixed. In the scenario where the range is kept constant, the maximal root-mean-square error between the estimated path and the Monte Carlo path drops significantly between the proton path estimate (0.50 mm) and the helium path estimate (0.18 mm), but less so up to the carbon path estimate (0.09 mm). However, this scenario is identified as the configuration that maximizes the dose while minimizing the path resolution. In the scenario where the initial velocity is fixed, the maximal root-mean-square error between the estimated path and the Monte Carlo path drops significantly between the proton path estimate (0.29 mm) and the helium path estimate (0.09 mm) but increases for heavier ions up to carbon (0.12 mm). As a result, helium is found to be the particle with the most accurate path estimate for the lowest dose, potentially leading to tomographic images of higher spatial resolution.
authors.affiliation: Département de physique, de génie physique et d'optique et Centre de recherche sur le cancer, Université Laval, Québec, Canada. Département de radio-oncologie et CRCHU de Québec, CHU de Québec, QC, Canada. Department of Radiation Oncology, Francis H. Burr Proton Therapy Center Massachusetts General Hospital (MGH), Boston, MA, United States of America.
authors.forename: Charles-Antoine
authors.initials: CA
authors.lastname: Collins-Fekete
authors.forename: Lennart
authors.initials: L
authors.lastname: Volz
authors.forename: Stephen K N
authors.initials: SK
authors.lastname: Portillo
authors.forename: Luc
authors.initials: L
authors.lastname: Beaulieu
authors.forename: Joao
authors.initials: J
authors.lastname: Seco
mesh_terms: D001499:Bayes Theorem; D002244:Carbon; D006371:Helium; D006801:Humans; D008962:Models, Theoretical; D057054:Molecular Imaging / Q000379:methods*; D009010:Monte Carlo Method; D011522:Protons; D012542:Scattering, Radiation; D014054:Tomography
chemical_list: D011522:Protons; D006371:Helium; D002244:Carbon