title: Non-uniform depth scanning for proton therapy systems employing active energy variation.
abstract: In proton scanning systems that employ active energy variation for depth modulation, a switch of the particle energy might typically require 1-2 s. For plans comprising many energy slices, these seconds could sum up to a non-negligible fraction of the total treatment duration. We have applied the Nyquist-Shannon sampling theorem to determine an efficient spatial arrangement of Bragg peaks in a target volume. This pre-determined schedule of increasing energy spacing with higher energy allows us to reduce the number of used energy slices without compromising the physical dosimetric quality of a plan. Our results suggest that the advantage of such a simple implementation would be especially significant for larger, deep-seated tumors such as the prostate; the number of energy slices was cut by a factor of 2-6.
authors.affiliation: Department of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany. j.kang@dkfz.de
authors.forename: Joanne H
authors.initials: JH
authors.lastname: Kang
authors.forename: Jan J
authors.initials: JJ
authors.lastname: Wilkens
authors.forename: Uwe
authors.initials: U
authors.lastname: Oelfke
mesh_terms: D001331:Automation; D004867:Equipment Design; D006801:Humans; D008297:Male; D008962:Models, Theoretical; D016011:Normal Distribution; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011522:Protons; D018787:Radiation Oncology / Q000379:methods; D011874:Radiometry / Q000295:instrumentation / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000295:instrumentation* / Q000379:methods*; D012984:Software; D013997:Time Factors
chemical_list: D011522:Protons