Light-Dependent Resistors as Dosimetric Sensors in Radiotherapy

Abstract

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.

Floating-Gate MOS Transistor with Dynamic Biasing as a Radiation Sensor

“…Various semiconductor components are widely used as a radiation sensors and have many applications, such as PIN diodes [1], PIN photodiodes [2], phototransistors [3,4], Light-Dependent Resistors (LDR) [5], PMOS [6][7][8] and VDMOS transistors [9,10].…”

Gerenciamento De Dados Coletados De Sensores Iot Utilizando Computação Em Nuvem

“…O LDR (Light Dependent Resistor), também conhecido como célula fotocondutiva, é um dispositivo semicondutor eletrônico, que tem como principal característica apresentar mudança em sua resistência elétrica proporcionalmente à quantidade de luz que incide sobre ele (ROMÁN-RAYA et al, 2020).…”

Commercial photodiodes and phototransistors as dosimeters of photon beams for radiotherapy

“…These limitations have been addressed by proposing the use of low‐cost commercial optoelectronic detectors such as light‐dependent resistors 5–7 and, considering current‐mode devices, phototransistors and photodiodes, in some cases along with custom‐made affordable readout systems 8 . Despite the vast majority of analyzed detectors are silicon‐based devices, diamond detectors and SiC Schottky diodes present good dosimetric performance as well 9–14 .…”

“…Commercial dosimetric systems based on diodes are always polarized at 0 V. Detectors and electrometers, although very reliable equipment, can be considered expensive items with costs well above several thousands of dollars depending on the model. These limitations have been addressed by proposing the use of low-cost commercial optoelectronic detectors such as light-dependent resistors [5][6][7] and, considering current-mode devices, phototransistors and photodiodes, in some cases along with custom-made affordable readout systems. 8 Despite the vast majority of analyzed detectors are siliconbased devices, diamond detectors and SiC Schottky diodes present good dosimetric performance as well.…”