Impact of Intrafractional Bowel Gas Movement on Carbon Ion Beam Dose Distribution in Pancreatic Radiotherapy
- Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba (Japan)
- Hospital, National Institute of Radiological Sciences, Chiba (Japan)
- Accelerator Engineering Corporation, Chiba (Japan)
Purpose: To assess carbon ion beam dose variation due to bowel gas movement in pancreatic radiotherapy. Methods and Materials: Ten pancreatic cancer inpatients were subject to diagnostic contrast-enhanced dynamic helical CT examination under breath-holding conditions, which included multiple-phase dynamic CT with arterial, venous, and delayed phases. The arterial-venous phase and arterial-delayed phase intervals were 35 and 145 s, respectively. A compensating bolus was designed to cover the target obtained at the arterial phase. Carbon ion dose distribution was calculated by applying the bolus to the CT data sets at the other two phases. Results: Dose conformation to the clinical target volume was degraded by beam overshoot/undershoot due to bowel gas movement. The D95 for clinical target volume was degraded from 98.2% (range, 98.0-99.1%) of the prescribed dose to 94.7% (range, 88.0-99.0%) at 145 s. Excessive dosing to normal tissues varied among tissues and was, for example, 12.2 GyE/13.1 GyE (0 s/145 s) for the cord and 38.8 GyE/39.8 GyE (0 s/145 s) for the duodenum. The magnitude of beam overshoot/undershoot was particularly exacerbated from the anterior and left directions. Conclusions: Bowel gas movement causes dosimetric variation to the target during treatment for radiotherapy. The effect of bowel gas movement varies with beam angle, with greatest influence on the anterior-posterior and left-right beams.
- OSTI ID:
- 21172694
- Journal Information:
- International Journal of Radiation Oncology, Biology and Physics, Vol. 73, Issue 4; Other Information: DOI: 10.1016/j.ijrobp.2008.10.055; PII: S0360-3016(08)03725-5; Copyright (c) 2009 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0360-3016
- Country of Publication:
- United States
- Language:
- English
Similar Records
Online adaptive radiotherapy of the bladder: Small bowel irradiated-volume reduction
Magnitude of Residual Internal Anatomy Motion on Heavy Charged Particle Dose Distribution in Respiratory Gated Lung Therapy