  Physical and biological range uncertainties limit the clinical potential of
Proton Beam Therapy (PBT). In this proceedings, we report on two research
projects, which we are conducting in parallel and which both tackle the problem
of range uncertainties. One aims at developing software tools and the other at
developing detector instrumentation. Regarding the first, we report on our
development and pre-clinical application of a GPU-accelerated Monte Carlo (MC)
simulation toolkit Fred. Concerning the letter, we report on our investigations
of plastic scintillator based PET detectors for particle therapy delivery
monitoring. We study the feasibility of Jagiellonian-PET detector technology
for proton beam therapy range monitoring by means of MC simulations of the
$\beta^+$ activity induced in a phantom by proton beams and present preliminary
results of PET image reconstruction. Using a GPU-accelerated Monte Carlo
simulation toolkit Fred and plastic scintillator based PET detectors we aim to
improve patient treatment quality with protons.
