Current mode response of phototransistors to gamma radiation

Andjelković, Marko; Ristić, Goran S.

doi:10.1016/j.radmeas.2015.03.005

Cited by 16 publications

(42 citation statements)

References 16 publications

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“…To a greater extent, most of the semiconductor-based photodiodes and LEDs consist of silicon PN junctions. Today, photodiodes are typically used for signal detection [9,14,15,16] while LEDs are principally used for luminescence [13]. However, some novel studies have directly manipulated LEDs for electromagnetic radiation detection (sensing) [11,17,18,19,20].…”

Section: Photodiodes/ledsmentioning

confidence: 99%

“…Due to this energy absorption, electrons overcome the depletion region’s electric field potential thus formulation of recombinations. From Equation (1) [16], an electrical current (I) is a result of summing up (integrating) all the small charges, (dq), flowing per unit time (dt). The current (I) can also be defined as the rate of charge flow.…”

Section: Photodiodes/ledsmentioning

confidence: 99%

“…However, this is related to an adverse effect of increasing the capacitance [14]. From Equation (2) [16], while assuming a parallel plate capacitor [18] with constant charge, the capacitance is inversely proportional to the applied voltage. It can also be observed from Equation (3) [15,16] that area-A (sensitive area) is directly proportional to the capacitance thus an increase in the area increases the capacitance.…”

Section: Photodiodes/ledsmentioning

confidence: 99%

“…From Equation (2) [16], while assuming a parallel plate capacitor [18] with constant charge, the capacitance is inversely proportional to the applied voltage. It can also be observed from Equation (3) [15,16] that area-A (sensitive area) is directly proportional to the capacitance thus an increase in the area increases the capacitance. Therefore, due to the inverse proportionality between the capacitance and the voltage, there is an output signal-voltage amplitude drop associated with an increase in the area [14].…”

Section: Photodiodes/ledsmentioning

confidence: 99%

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A Review: Photonic Devices Used for Dosimetry in Medical Radiation

Damulira

Yusoff

Omar

et al. 2019

Sensors

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Numerous instruments such as ionization chambers, hand-held and pocket dosimeters of various types, film badges, thermoluminescent dosimeters (TLDs) and optically stimulated luminescence dosimeters (OSLDs) are used to measure and monitor radiation in medical applications. Of recent, photonic devices have also been adopted. This article evaluates recent research and advancements in the applications of photonic devices in medical radiation detection primarily focusing on four types; photodiodes – including light-emitting diodes (LEDs), phototransistors—including metal oxide semiconductor field effect transistors (MOSFETs), photovoltaic sensors/solar cells, and charge coupled devices/charge metal oxide semiconductors (CCD/CMOS) cameras. A comprehensive analysis of the operating principles and recent technologies of these devices is performed. Further, critical evaluation and comparison of their benefits and limitations as dosimeters is done based on the available studies. Common factors barring photonic devices from being used as radiation detectors are also discussed; with suggestions on possible solutions to overcome these barriers. Finally, the potentials of these devices and the challenges of realizing their applications as quintessential dosimeters are highlighted for future research and improvements.

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Section: Photodiodes/ledsmentioning

confidence: 99%

Section: Photodiodes/ledsmentioning

confidence: 99%

Section: Photodiodes/ledsmentioning

confidence: 99%

Section: Photodiodes/ledsmentioning

confidence: 99%

See 2 more Smart Citations

A Review: Photonic Devices Used for Dosimetry in Medical Radiation

Damulira

Yusoff

Omar

et al. 2019

Sensors

View full text Add to dashboard Cite

show abstract

“…The cost of these systems would be significantly reduced provided that commercial devices not specifically manufactured for dosimetry could be used, which has already been addressed for MOSFET transistors [10,11]. Recently, other semiconductor devices have been studied for the same purpose, such as photodiodes and phototransistors [12][13][14], and in some cases the record of absorbed doses has been achieved in radiodiagnosis tests [15]. Some authors have observed that variations of the reverse current arise in certain photodiodes and phototransistors subjected to a field of ionizing radiation, proving that such variations are proportional to the absorbed dose rate [15,16].…”

Section: Introductionmentioning

confidence: 99%

Light-Dependent Resistors as Dosimetric Sensors in Radiotherapy

Román-Raya

Ruiz-García

Escobedo

et al. 2020

Sensors

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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.

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Commercial photodiodes and phototransistors as dosimeters of photon beams for radiotherapy

et al. 2021

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Purpose The response to radiation typically used in radiotherapy treatments has been experimentally evaluated for three samples of two phototransistors (BPW85B and OP505A) and two PIN photodiodes types (VTB8440BH and BPW34S). Methods To that end, a staggered irradiation cycle has been applied which included dose rate values from 0.81 to 4.87 cGy/s, achieving a total absorbed dose of 21.4 Gy. The samples have been irradiated with a linear accelerator and the relations between the induced photocurrent and the average and instantaneous dose rates, and between the accumulated charge and the absorbed dose, have been determined. The radiation‐induced output currents were measured by means of an external interface of the devices to a previously designed readout unit. Results Experimental results of Si PIN photodiode BPW34S have shown a sensitivity of (13.9 ± 0.5) nC/cGy, slight sensitivity dependence on dose rate, and a high linearity of the current with the average and instantaneous dose rate, requiring only 10 V of reverse bias voltage. This device thermal drift has characterized and modeled for temperature effect compensation. Conclusions Silicon PIN photodiode BPW34S, previously tested for X‐rays and Co‐60 gamma ray source, can also be a reliable candidate for dose rate and absorbed skin dose determination in typical radiotherapy treatments irradiations. A low sensitivity loss below 2% up to 21.4 Gy has been measured, allowing its use as an affordable reusable skin dosimeter. Moreover, no significant difference has been observed between its response to dose‐per‐pulse and changing pulse repetition frequency in terms of sensitivity and dependence with dose‐rate value.

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Current mode response of phototransistors to gamma radiation

Cited by 16 publications

References 16 publications

A Review: Photonic Devices Used for Dosimetry in Medical Radiation

A Review: Photonic Devices Used for Dosimetry in Medical Radiation

Light-Dependent Resistors as Dosimetric Sensors in Radiotherapy

Commercial photodiodes and phototransistors as dosimeters of photon beams for radiotherapy

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