title: Software platform for simulation of a prototype proton CT scanner.
abstract: OBJECTIVE
  Proton computed tomography (pCT) is a promising imaging technique to substitute or at least complement x-ray CT for more accurate proton therapy treatment planning as it allows calculating directly proton relative stopping power from proton energy loss measurements. A proton CT scanner with a silicon-based particle tracking system and a five-stage scintillating energy detector has been completed. In parallel a modular software platform was developed to characterize the performance of the proposed pCT.
  
  
  METHODS
  The modular pCT software platform consists of (1) a Geant4-based simulation modeling the Loma Linda proton therapy beam line and the prototype proton CT scanner, (2) water equivalent path length (WEPL) calibration of the scintillating energy detector, and (3) image reconstruction algorithm for the reconstruction of the relative stopping power (RSP) of the scanned object. In this work, each component of the modular pCT software platform is described and validated with respect to experimental data and benchmarked against theoretical predictions. In particular, the RSP reconstruction was validated with both experimental scans, water column measurements, and theoretical calculations.
  
  
  RESULTS
  The results show that the pCT software platform accurately reproduces the performance of the existing prototype pCT scanner with a RSP agreement between experimental and simulated values to better than 1.5%.
  
  
  CONCLUSIONS
  The validated platform is a versatile tool for clinical proton CT performance and application studies in a virtual setting. The platform is flexible and can be modified to simulate not yet existing versions of pCT scanners and higher proton energies than those currently clinically available.
authors.affiliation: Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia.|Division of Radiation Research, Department of Basic Sciences, Loma Linda University, Loma Linda, CA, USA.
authors.forename: Valentina
authors.initials: V
authors.lastname: Giacometti
authors.affiliation: Division of Radiation Research, Department of Basic Sciences, Loma Linda University, Loma Linda, CA, USA.
authors.forename: Vladimir A
authors.initials: VA
authors.lastname: Bashkirov
authors.affiliation: Department of Radiation Oncology, University of California San Francisco, CA, USA.
authors.forename: Pierluigi
authors.initials: P
authors.lastname: Piersimoni
authors.affiliation: Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia.
authors.forename: Susanna
authors.initials: S
authors.lastname: Guatelli
authors.affiliation: Santa Cruz Institute for Particle Physics, Santa Cruz, CA, USA.
authors.forename: Tia E
authors.initials: TE
authors.lastname: Plautz
authors.affiliation: Santa Cruz Institute for Particle Physics, Santa Cruz, CA, USA.
authors.forename: Hartmut F-W
authors.initials: HF
authors.lastname: Sadrozinski
authors.affiliation: Santa Cruz Institute for Particle Physics, Santa Cruz, CA, USA.
authors.forename: Robert P
authors.initials: RP
authors.lastname: Johnson
authors.affiliation: Santa Cruz Institute for Particle Physics, Santa Cruz, CA, USA.
authors.forename: Andriy
authors.initials: A
authors.lastname: Zatserklyaniy
authors.affiliation: Department of Radiation Oncology, Heidelberg University Clinic, Heidelberg, Germany.|Department of Medical Physics, Ludwig-Maximilians Universität München, Munich, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Tessonnier
authors.affiliation: Department of Medical Physics, Ludwig-Maximilians Universität München, Munich, Germany.|Heidelberg Ion Beam Therapy Center, Heidelberg, Germany.
authors.forename: Katia
authors.initials: K
authors.lastname: Parodi
authors.affiliation: Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia.
authors.forename: Anatoly B
authors.initials: AB
authors.lastname: Rosenfeld
authors.affiliation: Division of Radiation Research, Department of Basic Sciences, Loma Linda University, Loma Linda, CA, USA.|Department of Radiation Oncology, University of California San Francisco, CA, USA.
authors.forename: Reinhard W
authors.initials: RW
authors.lastname: Schulte
mesh_terms: D000465:Algorithms; D002138:Calibration; D002648:Child; D003198:Computer Simulation; D004867:Equipment Design; D006257:Head / Q000000981:diagnostic imaging; D006801:Humans; D008953:Models, Anatomic; D008962:Models, Theoretical; D061766:Proton Therapy / Q000295:instrumentation / Q000379:methods; D011522:Protons; D012984:Software; D013909:Thorax / Q000000981:diagnostic imaging; D014054:Tomography / Q000295:instrumentation* / Q000379:methods*; D014867:Water
chemical_list: D011522:Protons; D014867:Water
keywords: Geant4; image reconstruction; proton computed tomography; stopping power