Measuring Multiple Coulomb Scattering for Proton Computed Tomography*

Proton Computed Tomography (PCT) has the potential to be a very powerful and insightful medical imaging technique, but is currently limited in our ability to accurately measure the Multiple Coulomb Scattering (MCS) that occurs when a proton beam passes through material. Our approach aims to use a digital camera to capture a fraction of the light emitted when protons pass through a 1mm thick scintillator after they exit a target. In combination with data provided by the therapeutic proton beam at the Mayo Clinic Arizona facility, our goal is to accurately measure the MCS distribution to estimate the energy loss and trajectory of a therapeutic proton beam as it passes through a target. Preliminary data taken at the Mayo Clinic Arizona facility used a 221.3 MeV proton beam passing through 5cm, 10cm, and 15cm acrylic phantoms as well as muscle-equivalent and bone-equivalent phantoms and provides promise for this method to be used in conjunction with a PCT algorithm and encourages further study.