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Beam Quality Conversion Factor of a MicroDiamond Detector in Flattened and Un-Flattened High-Energy Photon Beams

T Saitou*1,2, K Hirayama1,2,3, M Shimizu2, Y Morishita2, K Okudaira4, T Kamomae5, H Oguchi5, M Sato1, M Hoshina1, (1) Komazawa University, Setagaya, Tokyo, (2) National Metrology Institute of Japan, Tsukuba, Ibaraki, (3) National Cancer Center Hospital East, Kashiwa, Chiba, (4) Nagoya University Hospital, Nagoya, Aichi, (5) Nagoya University Graduate School of Medicine, Nagoya, Aichi


(Tuesday, 7/16/2019) 3:45 PM - 4:15 PM

Room: Exhibit Hall | Forum 3

Purpose: In order to use a microDiamond detector for absorbed dose determination, we experimentally determined the beam quality conversion factor (kQ) of the microDiamond detector using a graphite calorimeter.

Methods: Two microDiamond detectors (PTW TN-60019) were calibrated in a Co-gamma ray and flattened high-energy photon beams by National Metrology Institute of Japan (PSDL in Japan). The microDiamond detectors were also calibrated for un-flattened high-energy photon beam from a CyberKnife at Nagoya university hospital. The absorbed dose to water in un-flattened high-energy photon beam was determined using a compact graphite calorimeter in a water phantom. The kQ of the microDiamond detectors were determined as a ratio of the calibration coefficients for the Co-60 gamma ray and the high-energy photon beams.

Results: The experimental results of kQ of the microDiamond detectors was 0.9847±0.0055 (k=1) at the TPR20,10 range from 0.64 to 0.76. The present results were observed to constant for the flattened and un-flattened high-energy photon beams. The present results were in good agreement with the Coste’s calculation results.

Conclusion: The kQ of two microDiamond detectors was experimentally determined in the flattened and un-flattened high-energy photon beams. The beam quality dependence of the microDiamond detectors is smaller than a relative standard uncertainty of present kQ (0.6 %) within the TPR20,10 range from 0.64 to 0.76.


Dosimetry, Semiconductor Detectors


TH- Radiation dose measurement devices: diodes/solid state

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