Non-uniform depth scanning for proton therapy systems employing active energy variation

• Published in: Physics in medicine & biology Vol. 53; no. 9; pp. N149 - N155
• Main Authors: Kang, Joanne H, Wilkens, Jan J, Oelfke, Uwe
• Format: Journal Article
• Language: English
• Published: England IOP Publishing 07.05.2008
• Subjects: Automation; Equipment Design; Humans; Male; Models, Theoretical; Normal Distribution; Prostatic Neoplasms - radiotherapy; Protons; Radiation Oncology - methods; Radiometry - instrumentation; Radiometry - methods; Radiotherapy Dosage; Radiotherapy Planning, Computer-Assisted - instrumentation; Radiotherapy Planning, Computer-Assisted - methods; Software; Time Factors
• ISSN: 0031-9155; 1361-6560
• DOI: 10.1088/0031-9155/53/9/N01

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.