Butson Martin J, Cheung Tsang, Yu Peter K N
Department of Physics and Materials Science, City University of Hong Kong, Kowloon Tong, Hong Kong.
Phys Med Biol. 2006 Dec 7;51(23):N417-21. doi: 10.1088/0031-9155/51/23/N03. Epub 2006 Nov 8.
SIRAD badge dosimeters are a new type of personal dosimeter designed to measure radiation exposure up to 200 R and give a visual qualitative measurement of exposure. This is performed using the active dosimeter window, which contains a radiochromic material amalgamated in the badge assembly. When irradiated, the badges active window turns blue, which can be matched against the given colour chart for a qualitative assessment of the exposure received. Measurements have been performed to analyse the absorption spectra of the active window, and results show that the window automatically turns a blue colour upon irradiation and produces two peaks in the absorption spectra located at 617 nm and 567 nm. When analysed with a common computer desktop scanner, the optical density response of the film to radiation exposure is non-linear but reproducible. The net OD of the film was 0.21 at 50 R exposure and 0.31 at 200 R exposure when irradiated with a 6 MV x-ray energy beam. When compared to the calibration colour strips at 6 MV x-ray energy the film's OD response matches relatively well within 3.5%. An approximate 8% reduction in measured OD to exposure was seen for 250 kVp x-rays compared to 6 MV x-rays. The film provides an adequate measurement and visually qualitative assessment of radiation exposure for levels in the range of 0 to 200 R.
SIRAD徽章剂量计是一种新型个人剂量计，设计用于测量高达200伦琴的辐射暴露，并对暴露情况进行视觉定性测量。这是通过有源剂量计窗口来实现的，该窗口包含一种融合在徽章组件中的放射变色材料。受到照射时，徽章的有源窗口会变成蓝色，可与给定的色标进行比对，以对所接受的暴露进行定性评估。已进行测量以分析有源窗口的吸收光谱，结果表明该窗口在受到照射时会自动变成蓝色，并在吸收光谱中产生位于617纳米和567纳米处的两个峰值。用普通的计算机桌面扫描仪进行分析时，胶片对辐射暴露的光密度响应是非线性的，但具有可重复性。当用6兆伏X射线能量束照射时，胶片在50伦琴暴露时的净光密度为0.21，在200伦琴暴露时为0.31。与6兆伏X射线能量下的校准色条相比，胶片的光密度响应在3.5%的范围内匹配得相对较好。与6兆伏X射线相比，250千伏峰值X射线的测量光密度对暴露的降低幅度约为8%。该胶片可为0至200伦琴范围内的辐射暴露水平提供充分的测量和视觉定性评估。
