Oncotarget

Research Papers:

Gamma analysis with a gamma criterion of 2%/1 mm for stereotactic ablative radiotherapy delivered with volumetric modulated arc therapy technique: a single institution experience

Jung-In Kim, Minsoo Chun, Hong-Gyun Wu, Eui Kyu Chie, Hak Jae Kim, Jin Ho Kim and Jong Min Park _

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Oncotarget. 2017; 8:76076-76084. https://doi.org/10.18632/oncotarget.18530

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Abstract

Jung-in Kim1,2,3, Minsoo Chun1,2,3, Hong-Gyun Wu1,2,3,4, Eui Kyu Chie1,2,3,4, Hak Jae Kim1,2,3,4, Jin Ho Kim1,2,3 and Jong Min Park1,2,3,5

1Department of Radiation Oncology, Seoul National University Hospital, Seoul, Republic of Korea

2Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Republic of Korea

3Biomedical Research Institute, Seoul National University College of Medicine, Seoul, Republic of Korea

4Department of Radiation Oncology, Seoul National University College of Medicine, Seoul, Republic of Korea

5Center for Convergence Research on Robotics, Advanced Institutes of Convergence Technology, Suwon, Republic of Korea

Correspondence to:

Jong Min Park, email: [email protected]

Keywords: 2D gamma evaluation, pre-treatment patient-specific quality assurance, volumetric modulated arc therapy, stereotactic ablative radiotherapy, gamma criterion

Received: January 31, 2017     Accepted: June 02, 2017     Published: June 16, 2017

ABSTRACT

To report a single-institution experience of gamma evaluations with 2%/1 mm for stereotactic ablative radiotherapy (SABR) delivered with volumetric modulated arc therapy (VMAT) technique, from January 2014 to January 2016. A total of 168 SABR VMAT plans were analyzed with a gamma criterion of 2%/1 mm, a threshold value of 10%, and a tolerance level of 90%. Of the 168 cases, four cases failed with 2%/1 mm. The average passing rate was 97.0% ± 2.5%. Three of the four failed cases showed passing rates higher than 90%, which was achieved by shifting the measuring device by 1 mm in the left-to-right or anterior-to-posterior directions. One failed case showed a passing rate higher than 90%, which was achieved by changing the threshold value from 10% to 5%, leading to an increase in the number of tested points from 26 to 51. Concerns regarding the high susceptibility of the gamma criterion of 2%/1 mm to setup errors of the measuring device are unnecessary based on our two-year experience, since only four cases failed with the 2%/1 mm from a total of 168 clinical cases. Therefore, the gamma criterion of 2%/1 mm could be successfully applied in the clinic with its high sensitivity to detect errors in VMAT plans.


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