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National Remote Quality Audit of LINAC-Based Radiotherapy in Korea

H Chung1*, H Kim1 , M Song1 , K Kim2 , S Han2 , S Choi2 , K Kim2 , G Cho2 , (1) Korea Institute of Nuclear Safety, Daejeon, Korea ,(2) Korea Institute of Radiological and Medical Sciences, Seoul, Korea


(Sunday, 7/14/2019)  

Room: ePoster Forums

Purpose: To analyze the results of the national remote audit of LINACs for radiotherapy in Korea. This study was performed to understand current state of quality management of LINAC-based radiotherapy in Korea.

Methods: Korea Institute of Nuclear Safety (KINS) and Korea Institute of Radiological and Medical Sciences (KIRAMS) are developing quality audit program for external radiation therapy from 2017. As part of the study, postal audit was conducted for verification of dosimetric and mechanical accuracy of 164 LINACs in 91 hospitals in Korea from 2017 to 2018. Standard phantoms were developed for the measurement of output dose from photon beam and mechanical accuracy. Each hospitals performed the established QA procedures with the mailed standard phantoms including glass dosimeters and radiochromic film. The irradiated glass and film dosimeters were scanned and analyzed in KIRAMS.

Results: Percent difference between dose at dmax from the glass dosimeter and dose at dmax reported by the hospitals was calculated as -2.96%±0.83% for 6 MV, -0.19%±1.77% for 10 MV, and -0.27%±1.85% for 15 MV. The number of each beam energy was 161 for 6 MV, 98 for 10 MV, 59 for 15 MV for the 164 LINACs. Mechanical accuracy evaluated as distance differences which were -0.4mm±0.75mm in X and 0.14mm±0.63mm in Y compare to 10cm X 10cm field size, 0.51mm±0.31mm for couch rotation isocenter, 0.55mm±0.43mm for collimator rotation isocenter, and 0.89mm±0.47mm for gantry rotation isocenter.

Conclusion: Several dosimetric and mechanical accuracy values exceeded tolerance level due to human error or unknown causes. After re-performance of postal audit of the LINACs which showed the exceeded values, most of the dosimetric and mechanical accuracy values were within the tolerance level. However, two LINACs still showed mechanical accuracy values exceeded the tolerance level. Remote quality audit program for tomotherapy and CyberKnife will developed and performed for further study.


Quality Assurance, Linear Accelerator, Dosimetry


Not Applicable / None Entered.

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