In an x-ray diagnosis, it is important to evaluate the entrance dose rate, as the dose rate of exposure becomes highest in that position. To investigate the effect of the entrance dose rate of x-ray CT scanners, a dose-rate dosimeter comprising a silicon x-ray diode (Si-XD), a CMOS dual operational amplifier, resistors, capacitors, and a mini-substrate measuring 20 × 17 mm² were developed. The Si-XD is desirable for measuring the changing entrance dose rate, as it enables the reduction of the response time, dimensions, and cost of the dosimeter. The dosimeter was connected to a microcomputer (mbed), and the output voltages from the dosimeter were measured using an analog–digital converter in the mbed. The output voltages were proportional to the tube currents at a constant tube voltage of 100 kV using an industrial x-ray tube, and the calibrated dose rates corresponded well to those obtained using a commercially available semiconductor dosimeter. However, owing to the energy dependence of the dosimeter, the calibrated dose rate was ∼10% higher than that of a commercially available semiconductor dosimeter at the lower tube voltage. In the angular dependence of the dosimeter, the flatness measured from 60° to 120° was ∼103% in this study. A fundamental study for measuring the dose-rate variations with rotation was performed. The results showed a different profile than the angular dependence due to the distance from the source and the complex factors of the scattered radiation.

中文翻译：

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基于硅X射线二极管的X射线CT扫描仪剂量率剂量计的研制

在 X 射线诊断中，评估入口剂量率很重要，因为该位置的暴露剂量率最高。为了研究 X 射线 CT 扫描仪入口剂量率的影响，剂量率剂量计包括硅 X 射线二极管 (Si-XD)、CMOS 双运算放大器、电阻器、电容器和微型基板测量20 × 17 毫米²被开发。Si-XD 可用于测量不断变化的入口剂量率，因为它可以减少剂量计的响应时间、尺寸和成本。剂量计与微型计算机 (mbed) 相连，剂量计的输出电压使用 mbed 中的模数转换器进行测量。输出电压与使用工业 X 射线管在 100 kV 恒定管电压下的管电流成正比，校准的剂量率与使用市售半导体剂量计获得的剂量率相当。然而，由于剂量计的能量依赖性，在较低的管电压下，校准的剂量率比市售的半导体剂量计高约 10%。在剂量计的角度依赖性中，在这项研究中，从 60° 到 120° 测量的平坦度为~103%。进行了测量随旋转的剂量率变化的基础研究。由于与源的距离和散射辐射的复杂因素，结果显示出与角度依赖性不同的轮廓。