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Original Article

Korean Journal of Medical Physics 2014; 25(4): 255-263

Published online December 30, 2014

Copyright © Korean Society of Medical Physics.

Feasibility Study of the microDiamond Detector for Measurement of Small Field Photon Beam

Chang Yeol Lee*, Woo Chul Kim*, Hun Jeong Kim*, Young Hoon Ji, Kum Bae Kim, Sang Hoon Lee, Chul Kee Min§, Gwang Hwan Jo§, Dong Oh Shin, Seong Hoon Kim, Hyun Do Huh

*Department of Radiation Oncology, College of Medicine, Inha University, Incheon,
Research Institute of Radiological and Medical Sciences, Korea Institute of Radiological and Medical Sciences, Seoul, Department of Radiation Oncology, College of Medicine, Kwandong University, Gangneung, §Department of Radiation Oncology, College of Medicine, Soonchunhyang University, Cheonan, Department of Radiation Oncology, College of Medicine, Kyunghee University, Seoul, Department of Radiation Oncology, College of Medicine, Hanyang University, Seoul, Korea

Received: November 11, 2014; Revised: November 26, 2014; Accepted: November 28, 2014

Abstract

The dosimetry of very small fields is challenging for several reasons including a lack of lateral electronic equilibrium, large dose gradients, and the size of detector in respect to the field size. The objective of this work was to evaluate the suitability of a new commercial synthetic diamond detector, namely, the PTW 60019 microDiamond, for the small field dosimetry in cyberknife photon beams of 6 different collimator size (from 5 mm to 30 mm). Measurements included dose linearity, dose rate dependence, output factors (OF), percentage depth doses (PDD) and off center ratio (OCR). The results were compared to those of pinpoint ionization chamber, diamond detector, microLion liquid Ionization chamber and diode detector. The dose linearity results for the microDiamond detector showed good linearly proportional to dose. The microDiamond detector showed little dose rate dependency throughout the range of 100∼600 MU/min, while microLion liquid Ionization chamber showed a significant discrepancy of approximately 5.8%. The OF measured with microDiamond detector agreed within 3.8% with those measured with diode. PDD curves measured with silicon diode and diamond detector agreed well for all the field sizes. In particular, slightly sharper penumbras are obtained by the microDiamond detector, indicating a good spatial resolution. The results obtained confirm that the new PTW 60019 microDiamond detector is suitable candidate for application in small radiation fields dosimetry.

KeywordsmicroDiamond detector, Small field, Dosimetry

Korean Society of Medical Physics

Vol.35 No.2
June 2024

pISSN 2508-4445
eISSN 2508-4453
Formerly ISSN 1226-5829

Frequency: Quarterly

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