PMID- 24125432 OWN - NLM STAT- MEDLINE DCOM- 20150109 LR - 20220318 IS - 1748-717X (Electronic) IS - 1748-717X (Linking) VI - 8 DP - 2013 Oct 14 TI - Single arc volumetric-modulated arc therapy is sufficient for nasopharyngeal carcinoma: a dosimetric comparison with dual arc VMAT and dynamic MLC and step-and-shoot intensity-modulated radiotherapy. PG - 237 LID - 10.1186/1748-717X-8-237 [doi] AB - BACKGROUND: The performance of single arc VMAT (VMAT1) for nasopharyngeal carcinoma (NPC) on the Axesse linac has not been well described in previous studies. The purpose of this study is to assess the feasibility of VMAT1 for NPC by comparing the dosimetry, delivery efficiency, and accuracy with dual arc VMAT (VMAT2), dynamic MLC intensity-modulated radiotherapy (dIMRT), and step-and-shoot intensity-modulated radiotherapy (ssIMRT). METHODS: Twenty consecutive patients with non-metastatic NPC were selected to be planned with VMAT1, VMAT2, dIMRT and ssIMRT using Monaco 3.2 TPS on the Axesse linear accelerator. Three planning target volumes (PTVs), contoured as high risk, moderate risk and low risk regions, were set to receive median absorbed-dose (D50%) of 72.6 Gy, 63.6 Gy and 54 Gy, respectively. The Homogeneity Index (HI), Conformity Index (CI), Dose Volume Histograms (DVHs), delivery efficiency and accuracy were all evaluated. RESULTS: Mean HI of PTV72.6 is better with VMAT1(0.07) and VMAT2(0.07) than dIMRT(0.09) and ssIMRT(0.09). Mean HI of PTV63.6 is better with VMAT1(0.21) and VMAT2(0.21) than dIMRT and ssIMRT. Mean CI of PTV72.6 is also better with VMAT1(0.57) and VMAT2(0.57) than dIMRT(0.49) and ssIMRT(0.5). Mean CI of PTV63.6 is better with VMAT1(0.76) and VMAT2(0.76) than dIMRT(0.73) and ssIMRT(0.73). VMAT had significantly improved homogeneity and conformity compared with IMRT. There was no significant difference between VMAT1 and VMAT2 in PTV coverage. Dose to normal tissues was acceptable for all four plan groups. VMAT1 and VMAT2 showed no significant difference in normal tissue sparring, whereas the mean dose of the parotid gland of dIMRT was significantly reduced compared to VMAT1 and VMAT2. The mean delivery time for VMAT1, VMAT2, dIMRT and ssIMRT was 2.7 min, 3.9 min, 5.7 min and 14.1 min, respectively. VMAT1 reduced the average delivery time by 29.8%, 51.1% and 80.8% compared with VMAT2, dIMRT and ssIMRT, respectively. VMAT and IMRT could all be delivered accurately based on our quality assurance standards. CONCLUSIONS: In the treatment of NPC using the Axesse linear accelerator, single arc VMAT has shown superiority to double arc VMAT, dIMRT and ssIMRT in delivery efficiency, without compromise to the PTV coverage. However, there is still room for improvement in terms of OAR sparing. FAU - Ning, Zhong-Hua AU - Ning ZH AD - Department of Radiation Oncology, The Third Affiliated Hospital, Soochow University, 185 Juqian Road, Changzhou 213003, China. JianXue.Jin@elekta.com. FAU - Mu, Jin-Ming AU - Mu JM FAU - Jin, Jian-Xue AU - Jin JX FAU - Li, Xiao-Dong AU - Li XD FAU - Li, Qi-Lin AU - Li QL FAU - Gu, Wen-Dong AU - Gu WD FAU - Huang, Jin AU - Huang J FAU - Han, Yang AU - Han Y FAU - Pei, Hong-Lei AU - Pei HL LA - eng PT - Comparative Study PT - Journal Article DEP - 20131014 PL - England TA - Radiat Oncol JT - Radiation oncology (London, England) JID - 101265111 SB - IM MH - Carcinoma MH - Humans MH - Nasopharyngeal Carcinoma MH - Nasopharyngeal Neoplasms/*radiotherapy MH - Radiometry MH - Radiotherapy Dosage MH - Radiotherapy Planning, Computer-Assisted/*methods MH - Radiotherapy, Intensity-Modulated PMC - PMC3854543 EDAT- 2013/10/16 06:00 MHDA- 2015/01/13 06:00 PMCR- 2013/10/14 CRDT- 2013/10/16 06:00 PHST- 2013/05/27 00:00 [received] PHST- 2013/10/05 00:00 [accepted] PHST- 2013/10/16 06:00 [entrez] PHST- 2013/10/16 06:00 [pubmed] PHST- 2015/01/13 06:00 [medline] PHST- 2013/10/14 00:00 [pmc-release] AID - 1748-717X-8-237 [pii] AID - 10.1186/1748-717X-8-237 [doi] PST - epublish SO - Radiat Oncol. 2013 Oct 14;8:237. doi: 10.1186/1748-717X-8-237.