The Influence of Motion on the Delivery Accuracy When Comparing Actively Scanned Carbon Ions versus Protons at a Synchrotron-Based Radiotherapy Facility

Franciska Lebbink, Markus Stock, Dietmar Georg, Barbara Knäusl*

*Corresponding author for this work

Research output: Journal article (peer-reviewed)Journal article

7 Citations (Scopus)

Abstract

Motion amplitudes, in need of mitigation for moving targets irradiated with pulsed carbon ions and protons, were identified to guide the decision on treatment and motion mitigation strategy. Measurements with PinPoint ionisation chambers positioned in an anthropomorphic breathing phantom were acquired to investigate different tumour motion scenarios, including rib and lung movements. The effect of beam delivery dynamics and spot characteristics was considered. The dose in the tumour centre was deteriorated up to 10% for carbon ions but only up to 5% for protons. Dose deviations in the penumbra increased by a factor of two when comparing carbon ions to protons, ranging from 2 to 30% for an increasing motion amplitude that was strongly dependent on the beam intensity. Layer rescanning was able to diminish the dose distortion caused by tumour motion, but an increase in spot size could reduce it even further to 5% within the target and 10% at the penumbra. An increased need for motion mitigation of carbon ions compared to protons was identified to assure target coverage and sparing of adjacent organs at risk in the penumbra region and outside the target. For the clinical implementation of moving target treatments at a synchrotron-based particle facility complex, time dependencies needed to be considered.

Original languageEnglish
Article number1788
JournalCancers
Volume14
Issue number7
DOIs
Publication statusPublished - 31 Mar 2022
Externally publishedYes

Keywords

  • 4D
  • breathing motion
  • motion mitigation
  • particle therapy

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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