Ueda Yoshihiro1,2, Ohira Shingo1,3, Isono Masaru1, Miyazaki Masayoshi1, Konishi Koji1, Kamiura Shoji4, Sumida Iori2, Ogawa Kazuhiko2, Teshima Teruki1. 1. 1 Department of Radiation Oncology, Osaka International Cancer Institute, Osaka Japan. 2. 2 Department of Radiation Oncology, Graduate School of Medicine, Osaka University, Osaka, Japan. 3. 3 Department of Medical Physics and Engineering, Osaka University Graduate School of Medicine, Osaka, Japan. 4. 4 Department of Gynaecology, Osaka International Cancer Institute, Osaka, Japan.
Abstract
OBJECTIVE: To reduce the ovarian dose with volumetric modulated arc therapy (VMAT), an original VMAT was designed with two types of arcs to restrict angles and fields (R-VMAT). METHODS: The subjects were 11 patients who underwent ovarian transposition with clips left by a surgeon. Three methods, intensity-modulated radiotherapy (IMRT), standard VMAT (S-VMAT) and R-VMAT, were optimized for assessment of the ovarian dose with the target coverage kept high. RESULTS: The homogeneity and conformity indexes for the planning target volume (PTV) were similar for the three methods. However, the average ± SD of the ovarian mean dose (OMD) was 5.0 ± 1.5, 4.9 ± 1.9 and 3.5 ± 1.4 Gy, and the percentage of ovarian volume exceeding 5 Gy (V5) was 41.5 ± 34.1%, 34.1 ± 38.05% and 8.4 ± 20.5% for IMRT, S-VMAT and R-VMAT, respectively. The OMD and V5 were significantly smaller for R-VMAT than for the other plans (p < 0.01). Correlation values between the OMD and the lateral distance from the ovaries to the PTV surface were 0.86, 0.81 and 0.82 for IMRT, S-VMAT and R-VMAT, respectively. CONCLUSION: These findings suggest that R-VMAT delivered the lowest dose to the ovaries. To reduce the OMD to less than 3 Gy, ovaries should be transposed laterally 6.1 cm away from the PTV surface when R-VMAT is used. Advances in knowledge: When organs with high susceptibility to radiation, such as ovaries, are near the PTV, R-VMAT is superior to IMRT and S-VMAT.
OBJECTIVE: To reduce the ovarian dose with volumetric modulated arc therapy (VMAT), an original VMAT was designed with two types of arcs to restrict angles and fields (R-VMAT). METHODS: The subjects were 11 patients who underwent ovarian transposition with clips left by a surgeon. Three methods, intensity-modulated radiotherapy (IMRT), standard VMAT (S-VMAT) and R-VMAT, were optimized for assessment of the ovarian dose with the target coverage kept high. RESULTS: The homogeneity and conformity indexes for the planning target volume (PTV) were similar for the three methods. However, the average ± SD of the ovarian mean dose (OMD) was 5.0 ± 1.5, 4.9 ± 1.9 and 3.5 ± 1.4 Gy, and the percentage of ovarian volume exceeding 5 Gy (V5) was 41.5 ± 34.1%, 34.1 ± 38.05% and 8.4 ± 20.5% for IMRT, S-VMAT and R-VMAT, respectively. The OMD and V5 were significantly smaller for R-VMAT than for the other plans (p < 0.01). Correlation values between the OMD and the lateral distance from the ovaries to the PTV surface were 0.86, 0.81 and 0.82 for IMRT, S-VMAT and R-VMAT, respectively. CONCLUSION: These findings suggest that R-VMAT delivered the lowest dose to the ovaries. To reduce the OMD to less than 3 Gy, ovaries should be transposed laterally 6.1 cm away from the PTV surface when R-VMAT is used. Advances in knowledge: When organs with high susceptibility to radiation, such as ovaries, are near the PTV, R-VMAT is superior to IMRT and S-VMAT.
Authors: David Palma; Emily Vollans; Kerry James; Sandy Nakano; Vitali Moiseenko; Richard Shaffer; Michael McKenzie; James Morris; Karl Otto Journal: Int J Radiat Oncol Biol Phys Date: 2008-05-01 Impact factor: 7.038
Authors: Hanzi Xu; Chang Guo; Xiuming Zhang; Yaqin Wu; Biqing Zhu; Emei Lu; Zhihua Sun; Dan He; Fei Deng; Juan Lv; Zhen Gong Journal: Ann Transl Med Date: 2021-12