Comparative study of the performance of proton imaging set-ups in terms of spatial resolution - CNRS - Centre national de la recherche scientifique Accéder directement au contenu
Poster De Conférence Année : 2017

Comparative study of the performance of proton imaging set-ups in terms of spatial resolution

Résumé

Proton imaging (PI) has long been proposed as alternative or complementary imaging modality in ion beam therapy offering a direct probe of the relative stopping power. However, it is not yet integrated into the clinical work flow. PI suffers from limited spatial resolution due to multiple Coulomb scattering (MCS). MCS causes protons to traverse matter on non straight stochastic trajectories leading to spatial blurring in PI. The most likely path (MLP) is a statistical estimate of proton trajectories based on information about position and angle of the protons before and after the imaged volume. We have extended and devised the mathematical framework of the MLP. To account for beam geometry we have introduced a cone beam system of reference. We have further included expressions to describe the uncertainty on the proton position and angle. We solved convolution integrals analytically. As a quantitative figure of merit for the intrinsic spatial resolution we use the average width of the uncertainty envelope around the MLP. Based on this, we compare typical types of PI set-ups (PIS). The spatial resolution of a PIS with passive field and pixel detector is only 5 times lower compared to single tracking (ST) device, provided the protons' entry and exit angles are measured accurately. For an uncertainty of +/- 1 degree, ST is comparable to a set-up combining pencil beam scanning (PBS) and a pixel detector. PBS in combination with a range telescope is limited by beam spot size for thinner phantoms (<20 cm), but comparable to a passive field coupled to a pixel detector for thick (>20 cm) phantoms. The derived expression for the MLP is compact and easy to implement numerically. Through numerical parameters in the expression, different kinds of PIS can conveniently be analyzed without the need to re-derive any formulae. The comparison study helps to select an appropriate PIS depending on the requirements on spatial and water equivalent thickness resolution.
Fichier non déposé

Dates et versions

hal-01795560 , version 1 (18-05-2018)

Identifiants

  • HAL Id : hal-01795560 , version 1

Citer

Nils Krah, Mattia Fontana, Ilaria Rinaldi. Comparative study of the performance of proton imaging set-ups in terms of spatial resolution. 2017 IEEE NSS/MIC/RTSD, Oct 2017, Atlanta, United States. 2017. ⟨hal-01795560⟩
28 Consultations
0 Téléchargements

Partager

Gmail Facebook X LinkedIn More