Effect of density heterogeneity on absorbed dose with CyberKnife Synchrony Respiratory Tracking System
10.3760/cma.j.issn.1004-4221.2017.10.020
- VernacularTitle:射波刀追踪治疗中组织密度不均匀对吸收剂量影响的评估
- Author:
Hongyuan LIU
1
;
Zhiyong YANG
;
Zhiwen LIANG
;
Jing YANG
;
Bin HU
;
Junping CHENG
;
Ting CAO
;
Qin LI
Author Information
1. 华中科技大学同济医学院附属协和医院肿瘤中心
- Keywords:
CyberKnife;
Synchrony system;
Tissue heterogeneous;
Absorbed dose
- From:
Chinese Journal of Radiation Oncology
2017;26(10):1204-1208
- CountryChina
- Language:Chinese
-
Abstract:
Objective To measure the actual absorbed dose of the target in the QUASAR Respiratory Motion Phantom using the CyberKnife Synchrony Respiratory Tracking System, and to evaluate the effect of density heterogeneity on the absorbed dose of tumor gross target volume ( GTV ) . Methods Nine groups were obtained by making different patterns of QUASAR phantom:rib thickness of 0, 20, and 50 mm, and motion amplitudes of 0, 10, and 15 mm. The nine groups were treated with static computed tomography (CT) in different time phases of four-dimensional CT (4DCT) plan, with the same beam and number of monitor units, and the 4D accumulated dose was calculated. The doses of static and 4D plans were calculated using Ray-tracing and Monte Carlo algorithms, and the absorbed doses of GTV in the nine groups were measured at the same time. Results There were a decrease in calculated absorbed dose of GTV and an increase in deviation between the planned and actual dose, with the increases in simulated rib thickness and motion amplitude. Conclusions The density heterogeneity has an impact on the absorbed dose of GTV. Both static CT and 4DCT plan can evaluate the absorbed dose of GTV in case of small rib thickness and motion amplitude, and 4DCT plan with Monte Carlo algorithm may be the optimal method for evaluation of the absorbed dose of GTV in case of large rib thickness and motion amplitude ( deviation<3%)
