Gha-Jung Kim ¹, Joon-Koo Choi ¹, Dong-Hee Hong ¹, Hyeong-Gyun Kim ¹, Geum-Mun Beak ²

Affiliations
1 Department of Radiology Science, Far East University, Chungbuk, KR
2 Department of Radiation Oncology, College of Medicine, University of Ulsan, Asan Medical Center, Seoul, KR

Abstract

Background/Objectives: This study focuses on radiation therapy planning according to flattening filter or flattening filterfree in high-energy X-ray therapy. Methods/Statistical Analysis: VMAT (Volumetric Modulated Arc Therapy) planning was built subject to 5 patients and the CI (Conformity Index) and HI (Homogeneity Index) values were comparatively analyzed using DVH (Dose Volume Histogram). Therapy plans were made with simple fractionation for 2 patients and VMAT therapy plans according to usage of flattening filter or flattening filter-free through SBRT therapy plans were made for 3 patients. Findings: For the therapy plan for the first brain patient, CI values according to use of flattening filter or flattening filter-free were both shown to be 0.95, and HI values were shown to be 1.09 and 1.10. For the second lung cancer patients, CI values according to use of flattening filter or flattening filter-free were both shown to be 0.95, and HI values were both shown to be 1.09. For the third lung cancer patients, CI values according to use of flattening filter or flattening filter-free were shown to be 0.95 and 0.96, and HI values were shown to be 1.08 and 1.07. For the Fourth liver cancer patients, CI values according to use of flattening filter or flattening filter-free were shown to be 0.94 and 0.95, and HI values were shown to be 1.11 and 1.12. For the Fifth liver cancer patients, CI values according to use of flattening filter or flattening filter-free were shown to be 0.94 and 0.96, and HI values were shown to be 1.10 and 1.09. As a result of comparison, mean CI values according to use of flattening filter or flattening filter-free were shown to be 0.946 and 0.954(p= 0.135), and HI values were both shown to be 1.094(p=0.549). Improvements: In this study, results of radiation therapy planning according to use of flattening filter or flattening filter-free in high-energy X-ray equipment were shown to be similar and usability could be found in using flattening filter- free that can reduce therapy time by minimizing reduction of radiation output dose.

Keywords

CI (Conformity Index), DVH (Dose Volume Histogram), Flattening-Filter Free (FFF), HI (Homogeneity Index), Radiation Therapy, VMAT (Volumetric Modulated Arc Therapy).

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