A 4D-optimization concept for scanned ion beam therapy.

Graeff C, Lüchtenborg R, Eley JG, Durante M, Bert C
Radiother Oncol. 2013 109 (3): 419-24

PMID: 24183865 · DOI:10.1016/j.radonc.2013.09.018

BACKGROUND AND PURPOSE - Scanned carbon beam therapy offers advantageous dose distributions and an increased biological effect. Treating moving targets is complex due to sensitivity to range changes and interplay. We propose a 4D treatment planning concept that considers motion during particle number optimization.

MATERIAL AND METHODS - The target was subdivided into sectors, one for each motion phase of a 4D-CT. Each sector was non-rigidly transformed to its motion phase and there targeted by a dedicated raster field (RST). Therefore, the resulting 4D-RST compensated target motion and range changes. A 4D treatment control system (TCS) was needed for synchronized delivery to the measured patient motion. 4D-optimized plans were simulated for 9 NSCLC lung cancer patients and compared to static irradiation at end-exhale. A prototype TCS was implemented and successfully tested in a film experiment.

RESULTS - The 4D-optimized treatment plan resulted in only slightly lower dose coverage of the target compared to static optimization, with V 95% of 97.9% (median, range 96.5-99.4%) vs. 99.3% (98.5-99.8%), with negligible overdose. The conformity number was comparable at 88.2% (85.1-92.5%) vs. 85.2% (79.9-91.2%) for 4D and static, respectively.

CONCLUSION - We implemented and tested a 4D treatment plan optimization method resulting in highly conformal dose delivery.

Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

MeSH Terms (10)

Carcinoma, Non-Small-Cell Lung Four-Dimensional Computed Tomography Heavy Ion Radiotherapy Humans Ions Lung Neoplasms Motion Radiotherapy, Conformal Radiotherapy Dosage Radiotherapy Planning, Computer-Assisted

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