Physics·Biology·Technique
A study of finite discontinuity-volumetric modulated arc therapy for mid-and distal-Esophageal Carcinoma
Wang Qingxin, Jiang Bo, Sun Jiana, Zhao Lujun, Yuan Zhiyong, Xu Liming, Wang Wei
Published 2016-11-15
Cite as Chin J Radiat Oncol, 2016,25(11): 1238-1243. DOI: 10.3760/cma.j.issn.1004-4221.2016.11.020
Abstract
ObjectiveTo implement the finite discontinuity-volumetric modulated arc therapy (FD-VMAT) in the Pinnacle planning system, and to investigate its clinical significance.
MethodsEight patients with thoracic esophageal cancer in our hospital were enrolled as subjects. FD-VMAT was fulfilled in the Pinnacle planning system using a developed program. FD-VMAT, VMAT, and fixed-field intensity-modulated radiotherapy (IMRT) plans were designed for each patient. The conformity index (CI) and homogeneity index (HI) of the planning target volume (PTV), doses to organs at risk, passing rate for plan verification, number of monitor units, and treatment time were used to evaluate the plans. Comparison between different plans was made by paired t test.
ResultsFor the PTV, there was no significant difference in CI between FD-VMAT and VAMT (P=0.186); FD-VMAT had a significantly worse HI than VMAT (P=0.001); however, both the CI and HI were significantly improved in FD-VMAT than in IMRT (P=0.006, 0.002). Compared with IMRT, FD-VMAT, retaining the advantage of VMAT, had pulmonary V20 and V30 significantly reduced by 19.79% and 20.32%, respectively (P=0.000, 0.000). For the pulmonary low-dose regions (≤V5), FD-VMAT retained the advantage of IMRT and had lower doses than VMAT.Particularly, pulmonary V2 was significantly reduced by 16.79%(P=0.000). The mean lung dose was significantly lower in FD-VMAT than in VMAT or IMRT (P=0.001, 0.000). There were no significant differences in D1cc to spinal cord PRV, heart V30, or passing rate for plan verification between the three therapies. The heart V40 and mean heart dose in FD-VMAT were similar to those in VMAT (P=0.175, 0.468), but significantly lower than those in IMRT (P=0.021, 0.002). FD-VMAT had a larger number of monitor units and longer treatment time than VMAT.Compared with IMRT, the number of monitor units and treatment time were reduced by 13.6% and 49.6% in FD-VMAT, respectively.
ConclusionsCompared with VMAT and IMRT, the application of the developed FD-VMAT in the treatment of thoracic esophageal cancer can further reduce the lung dose while keeping the PTV coverage, protection of the heart and spinal cord, and high efficacy. FD-VMAT is a new therapy available for thoracic esophageal cancer.
Key words:
Finite discontinuity-volumetric modulated arc therapy; Volumetric-modulated arc therapy; Intensity-modulated radiotherapy; Pinnacle treatment planning system; Esophageal Neoplasm
Contributor Information
Wang Qingxin
Department of Radiation Oncology, Tianjin Medical University Cancer Institute and Hosptial, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin 300060, China
Jiang Bo
Department of Radiation Oncology, Tianjin Medical University Cancer Institute and Hosptial, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin 300060, China
Sun Jiana
College of Mathematics and Physics, University of South China
Zhao Lujun
Department of Radiation Oncology, Tianjin Medical University Cancer Institute and Hosptial, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin 300060, China
Yuan Zhiyong
Department of Radiation Oncology, Tianjin Medical University Cancer Institute and Hosptial, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin 300060, China
Xu Liming
Department of Radiation Oncology, Tianjin Medical University Cancer Institute and Hosptial, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin 300060, China
Wang Wei
Department of Radiation Oncology, Tianjin Medical University Cancer Institute and Hosptial, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin 300060, China