PMID- 24506612 OWN - NLM STAT- MEDLINE DCOM- 20140928 LR - 20220331 IS - 2473-4209 (Electronic) IS - 0094-2405 (Print) IS - 0094-2405 (Linking) VI - 41 IP - 2 DP - 2014 Feb TI - On the interplay effects with proton scanning beams in stage III lung cancer. PG - 021721 LID - 10.1118/1.4862076 [doi] LID - 021721 AB - PURPOSE: To assess the dosimetric impact of interplay between spot-scanning proton beam and respiratory motion in intensity-modulated proton therapy (IMPT) for stage III lung cancer. METHODS: Eleven patients were sampled from 112 patients with stage III nonsmall cell lung cancer to well represent the distribution of 112 patients in terms of target size and motion. Clinical target volumes (CTVs) and planning target volumes (PTVs) were defined according to the authors' clinical protocol. Uniform and realistic breathing patterns were considered along with regular- and hypofractionation scenarios. The dose contributed by a spot was fully calculated on the computed tomography (CT) images corresponding to the respiratory phase that the spot is delivered, and then accumulated to the reference phase of the 4DCT to generate the dynamic dose that provides an estimation of what might be delivered under the influence of interplay effect. The dynamic dose distributions at different numbers of fractions were compared with the corresponding 4D composite dose which is the equally weighted average of the doses, respectively, computed on respiratory phases of a 4DCT image set. RESULTS: Under regular fractionation, the average and maximum differences in CTV coverage between the 4D composite and dynamic doses after delivery of all 35 fractions were no more than 0.2% and 0.9%, respectively. The maximum differences between the two dose distributions for the maximum dose to the spinal cord, heart V40, esophagus V55, and lung V20 were 1.2 Gy, 0.1%, 0.8%, and 0.4%, respectively. Although relatively large differences in single fraction, correlated with small CTVs relative to motions, were observed, the authors' biological response calculations suggested that this interfractional dose variation may have limited biological impact. Assuming a hypofractionation scenario, the differences between the 4D composite and dynamic doses were well confined even for single fraction. CONCLUSIONS: Despite the presence of interplay effect, the delivered dose may be reliably estimated using the 4D composite dose. In general the interplay effect may not be a primary concern with IMPT for lung cancers for the authors' institution. The described interplay analysis tool may be used to provide additional confidence in treatment delivery. FAU - Li, Yupeng AU - Li Y AD - Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030 and Applied Research, Varian Medical Systems, Palo Alto, California 94304. FAU - Kardar, Laleh AU - Kardar L AD - Department of Industrial Engineering, The University of Houston, Houston, Texas 77204. FAU - Li, Xiaoqiang AU - Li X AD - Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030. FAU - Li, Heng AU - Li H AD - Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030. FAU - Cao, Wenhua AU - Cao W AD - Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030 and Department of Industrial Engineering, The University of Houston, Houston, Texas 77204. FAU - Chang, Joe Y AU - Chang JY AD - Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030. FAU - Liao, Li AU - Liao L AD - Department of Industrial Engineering, The University of Houston, Houston, Texas 77204. FAU - Zhu, Ronald X AU - Zhu RX AD - Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030. FAU - Sahoo, Narayan AU - Sahoo N AD - Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030. FAU - Gillin, Michael AU - Gillin M AD - Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030. FAU - Liao, Zhongxing AU - Liao Z AD - Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030. FAU - Komaki, Ritsuko AU - Komaki R AD - Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030. FAU - Cox, James D AU - Cox JD AD - Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030. FAU - Lim, Gino AU - Lim G AD - Department of Industrial Engineering, The University of Houston, Houston, Texas 77204. FAU - Zhang, Xiaodong AU - Zhang X AD - Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030. LA - eng GR - P30 CA016672/CA/NCI NIH HHS/United States GR - CA016672/CA/NCI NIH HHS/United States PT - Journal Article PT - Research Support, N.I.H., Extramural PT - Research Support, Non-U.S. Gov't PL - United States TA - Med Phys JT - Medical physics JID - 0425746 SB - IM MH - Carcinoma, Non-Small-Cell Lung/diagnostic imaging/*pathology/*physiopathology/*radiotherapy MH - Dose Fractionation, Radiation MH - Four-Dimensional Computed Tomography MH - Humans MH - Lung Neoplasms/diagnostic imaging/*pathology/physiopathology/*radiotherapy MH - Movement MH - Neoplasm Staging MH - Proton Therapy/*methods MH - Radiotherapy Planning, Computer-Assisted MH - Radiotherapy, Intensity-Modulated/*methods MH - Respiration PMC - PMC4108709 EDAT- 2014/02/11 06:00 MHDA- 2014/10/01 06:00 PMCR- 2015/02/01 CRDT- 2014/02/11 06:00 PHST- 2014/02/11 06:00 [entrez] PHST- 2014/02/11 06:00 [pubmed] PHST- 2014/10/01 06:00 [medline] PHST- 2015/02/01 00:00 [pmc-release] AID - 040402MPH [pii] AID - 1.4862076 [pii] AID - 10.1118/1.4862076 [doi] PST - ppublish SO - Med Phys. 2014 Feb;41(2):021721. doi: 10.1118/1.4862076.