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Significant decrease in the radiation low-dose delivered to normal tissue in a novel cervical cancer VMAT plan using sub-arc collimator angle optimization
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C. Chen   , W. Xu , J. Shen , C. Xie , Y. Zhou , X. Wang , J. Zhang , D. Jiang , Y. Zhong , H. Liu , H. Yu |
| Department of Radiation and Medical Oncology, Hubei Key Laboratory of Tumor Biological Behaviors, Hubei Cancer Clinical Study Center, Zhongnan Hospital of Wuhan University, 169 Donghu Street, Wuhan, China , doctorzyh73@163.com |
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Abstract: (53 Views) |
Background: Traditionally, volumetric modulated arc therapy (VMAT) plans have depended on a predefined gantry range and a fixed collimator angle. Herein, we develop a novel sub-arc collimator angle optimization (SACAO) method for VMAT in cervical cancer. Materials and Methods: Twenty patients with cervical cancer were retrieved in the retrospective planning study. Two plans for traditional optimization were generated using dual arcs with two static collimator angles of 0˚ and 45˚ (named VMAT_0 and VMAT_45, respectively). A new plan was also developed using SACAO (named VMAT_SACAO). The dynamic gantry range segmentation of the full arc was calculated according to the continuity of the best conformity index (CI). The dose-volumetric parameters, average x-jaw size, and total monitor units (MUs) were compared. Results: The HI (uniformity index) and CI (conformity index) were improved in VMAT_SACAO compared to VMAT_0 and VMAT_45. The average x-jaw size of VMAT_SACAO was lower than VMAT_0 and VMAT_45 (18.7 ± 0.9 cm2, 20.7 ± 1.1 cm2, and 20.2 ± 1.0 cm2), as well as the total MUs (402 ± 19.0, 450 ± 18.8, and 432 ± 18.5). The average low-dose delivered to normal tissue was lowest in VMAT_SACAO compared to VMAT_0 and VMAT_45 (15.8 ± 0.4 Gy, 18.6 ± 0.3 Gy, and 17.0 ± 0.4 Gy). Conclusion: Compared to the two VMAT plans, the VMAT_SACAO improved the HI and CI, decreased the low-dose delivered to normal tissue, the V50, V45, and V15 of the small bowel, and the total MUs when applied in treating cervical cancer patients. |
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| Keywords: Radiotherapy, cervical cancer, volumetric modulated arc therapy, collimator angle optimization, normal tissue protection. |
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Full-Text [PDF 882 kb]
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Type of Study: Original Research |
Subject:
Radiation Biology
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