title: Therapeutic step and shoot proton beam spot-scanning with a multi-leaf collimator: a Monte Carlo study.
abstract: In step and shoot spot-scanning, a small-diameter proton beam is magnetically swept and varied in energy in order to cover the tumour. Initial estimates of the beam size indicate that additional collimating hardware will be needed for lower energy proton beams in order to achieve a clinically acceptable lateral dose falloff at the edge of the proton beam. In this report, we present dosimetric data from Monte Carlo simulations with a model of a simple multileaf collimator which indicate that such a device may be used to improve the lateral dose falloff. The dosimetric quantities relevant to the clinical usefulness of the device are studied, including lateral penumbra, leaf transmission and scalloping effect. Multileaf collimation is compared with a differential spot-weighting technique of sharpening the lateral dose falloff.
authors.affiliation: The University of Texas M. D. Anderson Cancer Center, Department of Radiation Physics, 1515 Holcombe Blvd., Unit 94, Houston, Texas 77030, USA. mbues@mdanderson.org
authors.forename: M
authors.initials: M
authors.lastname: Bues
authors.forename: W D
authors.initials: WD
authors.lastname: Newhauser
authors.forename: U
authors.initials: U
authors.lastname: Titt
authors.forename: A R
authors.initials: AR
authors.lastname: Smith
mesh_terms: D001822:Body Burden; D003198:Computer Simulation; D006801:Humans; D008954:Models, Biological; D015233:Models, Statistical; D009010:Monte Carlo Method; D061766:Proton Therapy; D011835:Radiation Protection / Q000379:methods*; D011874:Radiometry / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods* / Q000592:standards; D020266:Radiotherapy, Conformal / Q000295:instrumentation* / Q000379:methods*; D012062:Relative Biological Effectiveness; D018570:Risk Assessment / Q000379:methods; D012307:Risk Factors; D012542:Scattering, Radiation; D012986:Software Validation; D011522:Protons
chemical_list: D011522:Protons