Evaluation of spot size using volumetric repainting technique on a ProteusPLUS PBS Proton Therapy System

S. Rana, J. Bennouna, A. Gutierrez, A. Rosenfeld

Research output: Contribution to journalConference articlepeer-review

3 Scopus citations


Volumetric repainting is considered as one of the techniques for motion mitigation in proton therapy. Faster layer switching time to deliver a volumetric repainting proton plan is very critical to reduce the overall treatment time. Recently, IBA (proton therapy vendor at the Miami Cancer Institute) has implemented a "field regulation"-a new feature to reduce the switching time between layers by applying a magnetic field setpoint to specific groups of magnets. In order to investigate the impact of field regulation and volumetric repainting technique on the spot size, several spot maps were generated. The spot sizes were measured at the isocenter and four off-Axis points using the Lynx 2D scintillation detector. The average difference in spot size between two delivery sequences ("down"vs. "up"directions) for given energy at all five locations was 0.6 0.5%. The measurement results from the current study demonstrated that the impact of field regulation on the spot size was very minimal, and this was true for both the volumetric and non-volumetric techniques on a ProteusPLUS proton system with a PBS dedicated nozzle.

Original languageEnglish (US)
Article number012027
JournalJournal of Physics: Conference Series
Issue number1
StatePublished - Oct 16 2020
Externally publishedYes
Event20th Biannual Micro-Mini and Nano Dosimetry and Innovative Technologies in Radiation Oncology, MMND ITRO 2020 - Wollongong, Australia
Duration: Feb 10 2020Feb 16 2020

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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