Limited Impact of Setup and Range Uncertainties, Breathing Motion, and Interplay Effects in Robustly Optimized Intensity Modulated Proton Therapy for Stage III Non-small Cell Lung Cancer

Tatsuya Inoue, Joachim Widder, Lisanne V van Dijk, Hideki Takegawa, Masahiko Koizumi, Masaaki Takashina, Keisuke Usui, Chie Kurokawa, Satoru Sugimoto, Anneyuko I Saito, Keisuke Sasai, Aart A Van't Veld, Johannes A Langendijk, Erik W Korevaar

OnderzoeksoutputAcademicpeer review

52 Citaten (Scopus)

Samenvatting

Purpose: To investigate the impact of setup and range uncertainties, breathing motion, and interplay effects using scanning pencil beams in robustly optimized intensity modulated proton therapy (IMPT) for stage III non-small cell lung cancer (NSCLC).

Methods and Materials: Three-field IMPT plans were created using a minimax robust optimization technique for 10 NSCLC patients. The plans accounted for 5- or 7-mm setup errors with +/- 3% range uncertainties. The robustness of the IMPT nominal plans was evaluated considering (1) isotropic 5-mm setup errors with +/- 3% range uncertainties; (2) breathing motion; (3) interplay effects; and (4) a combination of items 1 and 2. The plans were calculated using 4-dimensional and average intensity projection computed tomography images. The target coverage (TC, volume receiving 95% of prescribed dose) and homogeneity index (D-2 - D-98, where D-2 and D-98 are the least doses received by 2% and 98% of the volume) for the internal clinical target volume, and dose indexes for lung, esophagus, heart and spinal cord were compared with that of clinical volumetric modulated arc therapy plans.

Results: The TC and homogeneity index for all plans were within clinical limits when considering the breathing motion and interplay effects independently. The setup and range uncertainties had a larger effect when considering their combined effect. The TC decreased to 98% for robust 7-mm evaluations for all patients. The organ at risk dose parameters did not significantly vary between the respective robust 5-mm and robust 7-mm evaluations for the 4 error types. Compared with the volumetric modulated arc therapy plans, the IMPT plans showed better target homogeneity and mean lung and heart dose parameters reduced by about 40% and 60%, respectively.

Conclusions: In robustly optimized IMPT for stage III NSCLC, the setup and range uncertainties, breathing motion, and interplay effects have limited impact on target coverage, dose homogeneity, and organ-at-risk dose parameters. (C) 2016 Elsevier Inc. All rights reserved.

Originele taal-2English
Pagina's (van-tot)661-669
Aantal pagina's9
TijdschriftInternational Journal of Radiation Oncology Biology Physics
Volume96
Nummer van het tijdschrift3
DOI's
StatusPublished - 1-nov.-2016

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