Impact of the Varian real-time position management respiratory gating system on radiotherapy planning dosimetry
10.3760/cma.j.cn112271-20220516-00207
- VernacularTitle:瓦里安呼吸门控实时位置管理系统对放射治疗计划剂量学的影响
- Author:
Fang ZHENG
1
;
Heli ZHONG
;
Hongtao CHEN
;
Longxing LI
;
Ding ZHANG
;
Xin FU
;
Yabin SHI
;
Zihuang LI
Author Information
1. 深圳市人民医院 暨南大学第二临床医学院 南方科技大学第一附属医院肿瘤放疗科，深圳 518020
- Keywords:
Real-time position management respiratory gating;
Portal Dosimetry;
Chest and abdominal tumors;
Radiotherapy plan verification
- From:
Chinese Journal of Radiological Medicine and Protection
2022;42(9):685-690
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To study the impact of the Varian real-time position management (RPM) respiratory gating system on radiotherapy planning dosimetry.Methods:The radiotherapy plans of 40 cases with thoracic or abdominal tumors were retrospectively selected in this study. The motion phantom for quality control was adopted to generate respiratory gating signals, and the 30%-60% stable phase at the end of expiratory was selected as the respiratory gating window. The dose verification for the abovementioned radiotherapy plans was performed using the Portal Dosimetry (PD) system under RPM respiratory gating mode with the Edge accelerator. Afterwards, dose analysis was performed with different γ passing rate criteria and the distribution characteristics of γ values were analyzed. Finally, the verification results between the non-gating mode and the gating mode were compared.Results:Under the respiratory gating mode, the passing rates of all intensity-modulated radiation therapy/volumetric-modulated arc therapy (IMRT/VMAT) plans with or without flattening filters were over 95.5% by γ criteria of (3%, 3 mm) or (3%, 2 mm) and were over 90% by stricter γ criteria of (2%, 2 mm). All plans met the clinical requirements recommended by the American Association of Physicists in Medicine (AAPM). The passing rates of dose verification under non-gating mode were slightly better than those under respiratory gating mode, and the differences between the two modes were statistically significant (3%/3 mm, Z =-1.45; 3%/2 mm, Z =-2.86; 2%/2 mm, Z =-3.70; 1%/1 mm, Z =-4.52; P<0.05). There was no significant difference in the minimum and maximum values of γ and the share of γ > 1.5 of plan verification result under the two modes. However, the average value and standard deviation of the γ were generally smaller under the non-gating mode. Conclusions:The impact of the introduction of RPM respiratory gating technology on dose is clinically acceptable, and the execution of these plans in this gating mode is safe and reliable.
