The effect of respiratory motion states on dynamic IMRT dose distribution
10.3760/cma.j.issn.0254-5098.2019.03.007
- VernacularTitle:呼吸运动状态对动态调强放疗剂量分布影响的研究
- Author:
Xianxiang WU
1
;
Zhenyang NIU
;
Zhenle FEI
;
Lingling LIU
;
Xiangli CUI
;
Min WEI
;
Lei WANG
Author Information
1. 安徽医科大学生命科学学院生物医学工程系
- Keywords:
Respiratory motor;
Target volume;
γ-passing rate;
Dose distribution;
Dynamic intensitymodulated radiation therapy
- From:
Chinese Journal of Radiological Medicine and Protection
2019;39(3):197-201
- CountryChina
- Language:Chinese
-
Abstract:
Objective To investigate the effect of respiratory movement of different amplitude,period and direction on the dose distribution of target area in dynamic intensity modulated radiation therapy.Methods A total of 30 cases of lung cancer were selected and divided into three groups according to the volume size of the target area,including groups A (72.0-200.2 cm3),B (271.7-380.0 cm3) and C (498.9-684.9 cm3).The average volume was 151.5,327.1 and 583.3 cm3,respectively.Breathing motion simulation platform was used to drive the mode body with two-dimensional ionization chamber matrix along the Gun-Target direction,then turn the collimator to 0° and 90°,respectively.The doses were collected at the central level in different amplitudes of 0,4,8,12 and 15 mm,periodic respiratory movement at the intervals of 3,4 and 5 s and respiratory motion measurement with a cycle of 4 s 5 times.The difference of dose distribution between the collected dose and TPS output was analyzed by taking the absolute dose and γ-passing rate (3 mm/3％) as indicators.Results In the two-sided upward,respiratory movement reduced the dose at the medial edge of the target area and increased the dose at the lateral edge of the target area.The difference of γ-passing rate between respiration cycle was up to 3.54％ (t=2.301,P＜0.05),and when the respiration movement was more than 8 mm,the γ-passing rate was less than 90％ and decreased with the increase of amplitude.The difference of γ-passing rate between static and respiratory motion was negatively correlated with the volume of target area,and the average γ-passing rate of A,B and C three groups increased gradually.The γ-passing rate of 5 composited dose was higher than that of single dose,and the difference was statistically sigificant(t=-9.36--5.95,P＜0.05).Conclusions The dose distribution of dynamic IMRT target area is mainly influenced by respiration range and its own volume,and the respiration cycle has an effect on dose distribution under partial amplitude.After implementing the multiple doses,some single dose implementation errors can be eliminated.Physicians need to expand the target area reasonably according to the range of respiratory movement,and optimize the amount of marginal tissue in the target area in the direction of respiratory movement.For patients with small target volume and large respiratory movement,respiratory management technology should be adopted to improve the accuracy of target dose implementation.
