Instituto de Investigación Biosanitaria, Ibs.Granada. Hospital Universitario Clínico San Cecilio, 18160 Granada, Spain.
ECsens, Department of Electronics and Computer Technology, Sport and Health University Research Institute (iMUDS), University of Granada, 18071 Granada, Spain.
Sensors (Basel). 2020 Mar 11;20(6):1568. doi: 10.3390/s20061568.
Safe quality control of radiotherapy treatments lies in reliable dosimetric sensors. Currently, ionization chambers and solid-state diodes along with electrometers as readout systems are accomplishing this task. In this work, we present a well-known and low-cost semiconductor sensor, the light-dependent resistor (LDR), as an alternative to the existing sensing devices for dosimetry. To demonstrate this, a complete characterization of the response to radiation of commercial LDRs has been conducted in terms of sensitivity, reproducibility and thermal correction under different bias voltages. Irradiation sessions have been applied under the common conditions in radiotherapy treatments using a hospital linear accelerator. Moreover, the same electrometer used for the ionization chamber has also been successfully used for LDRs. In comparison with the sensitivity achieved for the ionization chamber (0.2 nC/cGy at 400 V bias voltage), higher sensitivities have been measured for the proposed LDRs, ranging from 0.24 to 1.04 nC/cGy at bias voltages from 30 to 150 V, with a reproducibility uncertainty among samples of around 10%. In addition, LDR temperature dependence has been properly modeled using the simple thermistor model so that an easy thermal drift correction of dose measurements can be applied. Therefore, experimental results show that LDRs can be a reliable alternative to dosimetric sensors with the advantages of low size, affordable cost and the fact that it could be adopted with minimal changes in routine dosimetry quality control since the same readout system is fully compatible.
放射治疗的安全质量控制依赖于可靠的剂量传感器。目前，电离室和固态二极管以及作为读出系统的静电计正在完成这项任务。在这项工作中，我们提出了一种众所周知且低成本的半导体传感器，即光敏电阻（LDR），作为现有剂量测量传感设备的替代方案。为了证明这一点，我们对商用 LDR 的辐射响应进行了全面的特性描述，包括在不同偏置电压下的灵敏度、可重复性和热校正。使用医院直线加速器在放射治疗中的常见条件下进行了辐照实验。此外，还成功地将用于电离室的相同静电计用于 LDR。与为电离室实现的灵敏度（400V 偏置电压下为 0.2nC/cGy）相比，所提出的 LDR 的灵敏度更高，从 30V 到 150V 的偏置电压范围内，其灵敏度范围为 0.24 到 1.04nC/cGy，样品之间的重现性不确定性约为 10%。此外，LDR 的温度依赖性已通过简单的热敏电阻模型进行了适当建模，以便可以应用简单的热漂移剂量测量修正。因此，实验结果表明，LDR 可以成为可靠的剂量传感器替代方案，具有尺寸小、价格低廉的优势，并且由于相同的读出系统完全兼容，因此可以在常规剂量质量控制中进行最小的更改采用。
