Anisotropy in a Few mm Regions from an Ir192 High Dose Rate Source Measured with a GafChromic Film in Acrylic Phantom

Hyun Do Huh*; Seong Hoon Kim; Jin Ho Choi; Byung Chul Cho; Dong Oh Shin; Soo il Kwon; Ha Chung Chun; John J K Loh*; Woo Chul Kim*

Article

Original Article

Korean Journal of Medical Physics 2004; 15(2): 94-99

Published online June 25, 2004

Anisotropy in a Few mm Regions from an Ir192 High Dose Rate Source Measured with a GafChromic Film in Acrylic Phantom

아크릴 팬톰에서 GafChromic 필름을 이용한 고선량률 근접 치료용 Ir-192 선원의 근접 거리에서 비등방성 측정

Hyun Do Huh*^∥, Seong Hoon Kim^†, Jin Ho Choi^‡, Byung Chul Cho^§, Dong Oh Shin^¶, Soo il Kwon^∥, Ha Chung Chun^†, John J K Loh*, and Woo Chul Kim*

허현도*^∥·김성훈^†·최진호^‡·조병철^§·신동오^¶·권수일^∥·전하정^†·노준규*·김우철*

Author Info ⁺

*Department of Radiation Oncology, College of Medicine, Inha University, ^†Department of Radiation Oncology, College of Medicine, Hanyang University, ^‡Department of Radiation Oncology, Gachon, Medical school, Gil Medical Center, ^§Department of Radiation Oncology, Hallym University College of Medicine, ^∥Department of Medical Physics, Kyonggi University, ^¶Department of Radiation Oncology, Medicine, College of Medicine, KyungHee University

*인하대학교 의과대학 방사선종양학교실, ^†한양대학교 의과대학 방사선종양학교실, ^‡가천의과대학교 방사선종양학교실, ^§한림대학교 성심병원 방사선종양학교실, ^∥경희대학교 의과대학 방사선종양학교실, ^¶경기대학교 의학물리학과

Abstract

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Abstract

Radiochromic film has several advantages; high spatial resolution, relatively low spectral sensitivity, near tissue equivalence and requires no special development procedure. The object of this study was to measure the anisotropy of an Ir-192 source (microSelectron manufactured by Nucletron) in a few mm regions from the source, using the GafChromic film. The GafChromic film was calibrated in the range of 0∼105 Gy, using a 4 MV photon beam, and the anisotropy function measured in an acrylic phantom using the GafChroimic film. The data obtained gave agreement to within 4.4% of the Monte Calro calculation, by J. F. Williamson, at a radial distance of 2.5 mm with polar angles of 50 to 130^o, while a maximum deviation of 17.6% was observed at angles near 140^o and agreement within 3.7% at a radial distance of 5 mm at polar angles between 35 to 160^o and a maximum deviation of 7.6% was observed at angles near 30^o. A GafChromic film can be used as a more efficient detector for measuring the anisotropy of an HDR ¹⁹²Ir source at close distances than any other detector.

KeywordsGafChromic film, anisotropy function, Ir-192 source