Radiotherapy
Clinical application of radiotherapy based on UIH linear accelerators to in vivo dose verification
Xie Jiacun, Li Liang, Liang Hengpo, Li Yaqiong, Wang Zhibin
Published 2023-05-25
Cite as Chin J Radiol Med Prot, 2023, 43(5): 357-361. DOI: 10.3760/cma.j.cn112271-20221106-00432
Abstract
ObjectiveTo explore the clinical application of the electronic portal imaging device (EPID) based on the linear accelerator produced by Shanghai United Imaging Healthcare Co., Ltd. (UIH) to in vivo dose verification.
MethodsA total of 68 patients (32 cases with head and neck tumors, 16 cases with chest tumors, and 20 cases with abdomen and pelvis tumors) who were treated with volumetric modulated arc therapy (VMAT) in the Henan Provincial People′s Hospital were selected in this study. Each patient underwent the pre-treatment dose verification using an Arccheck device (Pre Arccheck), the pre-treatment dose verification using an EPID (Pre EPID), and the in vivo dose verification using an EPID (In vivo EPID). Moreover, the position verification based on fan beam computed tomography (FBCT) was also performed for each patient in the first three treatments and then once a week. The patients were treated when the setup error in any direction (x: left-right, y: head-foot, z: vertical) was less than 3 mm; otherwise, position correction would be conducted. The three-dimensional setup deviation d was calculated according to setup errors x, y, and z.
ResultsThe γ passing rates of dose verifications Pre EPID and In vivo EPID of 68 patients were (99.97±0.1)% and (94.15±3.84)%, respectively, significantly different from that (98.86±1.48)% of the Pre Arccheck dose verification (t = -6.12, 9.43; P < 0.05). The γ passing rates of the chest, abdomen and pelvis, and head and neck in the In vivo EPID dose verification showed no significant differences (P > 0.05). The difference in the γ passing rates (5.56±3.72)% between dose verifications Pre EPID and first In vivo EPID was unrelated to the three-dimensional setup deviation d (1.46±1.51 mm) (P > 0.05). As the treatment proceeded, the γ passing rate of In vivo EPID gradually decreased from (94.15±3.84)% in the first week to (92.15±3.24)% in the fifth week. From the third week to the fifth week, the γ passing rates of In vivo EPID were significantly different from those in the first week (t = 2.48, 2.75, 3.09, P < 0.05).
ConclusionsThe setup errors within 3 mm do not affect the γ passing rate of in vivo dose verification. The clinically acceptable threshold for the γ passing rate of in vivo EPID needs to be further determined. In addition, in vivo dose verification can support the clinical application of adaptive radiotherapy to a certain extent.
Key words:
In vivo dose verification; γ passing rate; Electronic portal imaging device; Setup error
Contributor Information
Xie Jiacun
Department of Cancer Center, Henan Provincial People′s Hospital, People′s Hospital of Zhengzhou University, People′s Hospital of Henan University, Zhengzhou 450003, China.
Li Liang
Department of Cancer Center, Henan Provincial People′s Hospital, People′s Hospital of Zhengzhou University, People′s Hospital of Henan University, Zhengzhou 450003, China.
Liang Hengpo
Department of Cancer Center, Henan Provincial People′s Hospital, People′s Hospital of Zhengzhou University, People′s Hospital of Henan University, Zhengzhou 450003, China.
Li Yaqiong
Department of Cancer Center, Henan Provincial People′s Hospital, People′s Hospital of Zhengzhou University, People′s Hospital of Henan University, Zhengzhou 450003, China.
Wang Zhibin
Department of Cancer Center, Henan Provincial People′s Hospital, People′s Hospital of Zhengzhou University, People′s Hospital of Henan University, Zhengzhou 450003, China.
