Verification of photon beam field absorbed dose and two-dimensional dose distribution in intensity modulated radiotherapy in Sichuan province
10.3760/cma.j.issn.0254-5098.2018.02.011
- VernacularTitle:四川省调强放疗光子线束吸收剂量和二维剂量分布验证研究
- Author:
Qiao MA
1
;
Ran LIU
;
Deming LIU
;
Bo HU
;
Suming LUO
Author Information
1. 610059 成都理工大学地学核技术四川省重点实验室;四川省疾病预防控制中心职业与辐射卫生所
- Keywords:
Thermoluminescent dosimeter;
Film;
Intensity modulated radiotherapy;
Absorbed dose;
Two-dimensional dose distribution
- From:
Chinese Journal of Radiological Medicine and Protection
2018;38(2):134-137
- CountryChina
- Language:Chinese
-
Abstract:
Objective To measure absorbed dose and verify two-dimensional dose distribution from IMRT MLC using thermoluminescence dosimeters (TLDs) and films.Methods The teflon phantom was scanned by CT and its images were transmitted to TPS for planning.The 6 Gy-corresponding MUs were calculated at 90 cm SSD and 10 cm depth and on 5 cm × 5 cm radiation field.All the plans were implemented at 7 medical linear accelerators,which were produced by Varian,Elekta and Siemens and selected from 7 third-grade first-class hospitals according to the technical conditions of various regions in Sichuan province.The homogeneous solid phantoms used in hospitals were covered by 30 cm × 30 cm and 25 cm × 25 cm films.Then,the films were covered by thicker-than-20 cm phantoms.Finally,the plans were implemented by aligning the center of beams to the films center.Results The relative deviations of the measured absorbed dose to TPS-planned dose were 1.4％,3.7％,-2.5％,-0.3％,4.9％,4.9％,5.0％ for TLDs and 4.7％,4.3％,1.5％,3.9％,-1.6％,3.3％,-1.3％ for films,respectively,all consistent with the limit of less than 5％.The passing rates of 2D dose distribution (3 mm/3％) were 99.9％,98.5％,98.5％,97.9％ and 70.0％ for 5 accelerators,with only one not consistent with the requirements.Conclusions It is convenient to measure the absorbed dose to photon beam field and verify two-dimensional dose distribution using TLDs and films,which can provide quality assurance for radiation treatment plans.
