The impact of tracking system properties on the most likely path estimation in proton CT
Résumé
Proton CT nowadays aims at improving hadron therapy treatment planning
by mapping the stopping power of materials. In order to optimize a spatial
resolution of the reconstructed images, the most likely path (MLP) of each
proton can be computed. We investigated the errors in the computation of
this path due to the configuration of the system, i.e. the spatial resolution of
the tracking planes, their material budget, and their positioning. A method
for computing the uncertainty in the estimated paths for a given system was
derived. The uncertainties upon the entrance and exit of the object were
propagated analytically in the path computation. This procedure was then
used to evaluate the impact of each parameter, and to compare different
systems. We show that the intrinsic characteristics of the system generate
an uncertainty in the positions and directions of the particles propagated
during the MLP computation. The spatial resolution and material budget of
the trackers in particular may affect the path estimation, and thus the spatial
resolution of an image.