Sensitivity Study for Evaluating the Extracted Beam Parameters of the LLUMC Proton Therapy Synchrotron

The MINOS nonlinear constrained optimization program, working in concert with the beam optics code TRANSPORT, has been shown in recent work to provide a fast, efficient and reliable procedure for determining the parameters of the beam extracted from the Loma Linda University Medical Center (LLUMC) proton therapy synchrotron. MINOS and TRANSPORT work together as Modules of the Particle Beam Optics Laboratory (PBO Lab ™) software. The software was used to determine the parameters of the beam extracted from the synchrotron accelerator that best fit the extensive beam profile data used to monitor the LLUMC proton therapy beamlines. Additional constraints have been utilized with the procedure, and the parametric dependence upon certain parameters has been examined, in order to evaluate the sensitivity of the best fit extracted beam parameters to various assumptions. In this paper two examples of these sensitivity studies are reported. The sensitivity of the results to the momentum spread assumed for the beam is explored by carrying out parametric optimizations. Second, the character of the optimizer solutions under the imposition of additional constraints upon the emittance values is examined. The methods used for the calculations are outlined and selected results are presented.