HOME > Research


 
작성일 : 17-01-06 17:01
Feasibility Study of Patient-specific Quality Assurance System for High-dose-rate Brachytherapy in Patients with Cervical Cancer
 글쓴이 : 관리자
조회 : 6,115  


 This study was conducted for the purpose of establishing a quality-assurance (QA) system for brachytherapy that can ensure patient-specific QA by enhancing dosimetric accuracy for the patient’s therapy plan. To measure the point-absorbed dose and the 2D dose distribution for the patient’s therapy plan, we fabricated a solid phantom that allowed for the insertion of an applicator for patient-specific QA and used an ion chamber and a film as measuring devices. The patient treatment plan was exported to the QA dose-calculation software, which calculated the time weight of dwell position stored in the plan DICOM (Digital Imaging and Communications in Medicine) file to obtain an overall beam quality correction factor, and that correction was applied to the dose calculations. Experiments were conducted after importing the patient’s treatment planning source data for the fabricated phantom and inserting the applicator, ion chamber, and film into the phantom. On completion of dose delivery, the doses to the ion chamber and film were checked against the corresponding treatment plan to evaluate the dosimetric accuracy. For experimental purposes, five treatment plans were randomly selected. The beam quality correction factors for ovoid and tandem brachytherapy applicators were found to be 1.15 and 1.10 ? 1.12, respectively. The beam quality correction factor in tandem fluctuated by approximately 2%, depending on the changes in the dwell position. The doses measured by using the ion chamber showed differences ranging from ?2.4% to 0.6%, compared to the planned doses. As for the film, the passing rate was 90% or higher when assessed using a gamma value of the local dose difference of 3% and a distance to agreement of 3 mm. The results show that the self-fabricated phantom was suitable for QA in clinical settings. The proposed patient-specific QA for the treatment planning is expected to contributeto reduce dosimetric errors in brachytherapy and, thus, to enhancing treatment accuracy. 

Boram Lee
Department of Bio-convergence Engineering, Korea University, Seoul 02841, Korea, and
Department of Radiation Oncology, Samsung Medical Center,
Sungkyunkwan University School of Medicine, Seoul 06351, Korea
Sung Hwan Ahn, Hyeyoung Kim, Youngyih Han and Seung Jae Huh
Department of Radiation Oncology, Samsung Medical Center,
Sungkyunkwan University School of Medicine, Seoul 06351, Korea
Jin Sung Kim
Department of Radiation Oncology, Yonsei University College of Medicine, Yonsei Cancer Center, Seoul 03722, Korea
Dong Wook Kim
Department of Radiation Oncology, Kyung Hee University Hospital at Gangdong, Seoul 05278, Korea
Jina Sim and Myonggeun Yoon?
Department of Bio-convergence Engineering, Korea University, Seoul 02841, Korea

Journal of the Korean Physical Society, Vol. 68, No. 8, April 2016