
Diamond detector in absorbed dose measurements in high‐energy linear accelerator photon and electron beams
Author(s) -
Ravichandran Ramamoorthy,
Binukumar John Pichy,
Amri Iqbal Al,
Davis Cheriyathmanjiyil Antony
Publication year - 2016
Publication title -
journal of applied clinical medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.83
H-Index - 48
ISSN - 1526-9914
DOI - 10.1120/jacmp.v17i2.5690
Subject(s) - dosimetry , absorbed dose , dosimeter , diamond , detector , dose profile , reproducibility , ionization chamber , materials science , optics , irradiation , linear particle accelerator , radiation , nuclear medicine , physics , chemistry , beam (structure) , nuclear physics , ion , ionization , medicine , chromatography , quantum mechanics , composite material
Diamond detectors (DD) are preferred in small field dosimetry of radiation beams because of small dose profile penumbras, better spatial resolution, and tissue‐equivalent properties. We investigated a commercially available ‘microdiamond’ detector in realizing absorbed dose from first principles. A microdiamond detector, type TM 60019 with tandem electrometer is used to measure absorbed doses in water, nylon, and PMMA phantoms. With sensitive volume 0.004 mm 3 , radius 1.1 mm, thickness 1 × 10 − 3 mm , the nominal response is 1 nC/Gy. It is assumed that the diamond detector could collect total electric charge (nC) developed during irradiation at 0 V bias. We found that dose rate effect is less than 0.7% for changing dose rate by 500 MU/min. The reproducibility in obtaining readings with diamond detector is found to be ± 0.17 % (1 SD) ( n = 11 ) . The measured absorbed doses for 6 MV and 15 MV photons arrived at using mass energy absorption coefficients and stopping power ratios compared well with N d , water calibrated ion chamber measured absorbed doses within 3% in water, PMMA, and nylon media. The calibration factor obtained for diamond detector confirmed response variation is due to sensitivity due to difference in manufacturing process. For electron beams, we had to apply ratio of electron densities of water to carbon. Our results qualify diamond dosimeter as a transfer standard, based on long‐term stability and reproducibility. Based on micro‐dimensions, we recommend these detectors for pretreatment dose verifications in small field irradiations like stereotactic treatments with image guidance. PACS number(s): 87.56.Da