Design and optimization of large area thin‐film CdTe detector for radiation therapy imaging applications

Parsai, E; Shvydka, Diana; Kang, Jun

doi:10.1118/1.3438082

Cited by 23 publications

(31 citation statements)

References 33 publications

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“…The development of cadmium telluride (CdTe) energydiscriminating imaging detectors has paved the way for Spectral CT [17][18][19]. Spectral CT with an energy resolved photon counting detector (PCD) is proved to have a number of advantages over dual-energy CT for improving material identification [20,21].…”

Section: Introductionmentioning

confidence: 99%

System-independent material classification through X-ray attenuation decomposition from spectral X-ray CT

Jumanazarov

Koo

Busi

et al. 2020

NDT & E International

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We present a method for material classifications in spectral X-ray Computed Tomography (SCT) taking advantage of energy-resolving 2D detectors to simultaneously extract the energy dependence of a material's linear attenuation coefficient (LAC). The method employs an attenuation decomposition presented by Alvarez et al., and estimates system-independent material properties of electron density (e) and effective atomic number (ef f), independent of the scanner, from the energy-dependent LAC measurements. The method uses a spectral correction algorithm and the energy range is truncated to exclude bins with photon starvation and spectral distortion present even after correction of detector response. A novel technique of energy bin selection is used for optimized classification performance. The method is tested against another SCT classification method called SRZE for inspecting materials in the range of 6 ≤ ef f ≤ 23. Our method aims at an increase in the speed of pot processing workflow after the data acquisition, and it achieves explicitly up to 32 times better time efficiency for the reconstruction with comparable accuracy for a range of materials important in threat detection.

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Section: Introductionmentioning

confidence: 99%

System-independent material classification through X-ray attenuation decomposition from spectral X-ray CT

Jumanazarov

Koo

Busi

et al. 2020

NDT & E International

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“…Thick (5 μm) film photovoltaics have been explored in combination with thin‐film transistor (TFT) backbone forming flexible keV xX‐ray imager (15) operating under moderate external voltage (5‐20 V). Similarly, response of MV X‐ray detector utilizing polycrystalacm20311line CdTe photovoltaic thicker films (10‐1000 μm) have been simulated in combination with various metal plates to enhance the detector signal (18) . However, until now, low‐cost flexible thin‐film photovoltaic sensors, potentially scalable to large‐area array of sensors, have not been experimentally tested in clinical radiotherapy beams.…”

Section: Introductionmentioning

confidence: 99%

Low‐cost flexible thin‐film detector for medical dosimetry applications

Zygmanski

Abkai

Han

et al. 2014

J Applied Clin Med Phys

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The purpose of this study is to characterize dosimetric properties of thin film photovoltaic sensors as a platform for development of prototype dose verification equipment in radiotherapy. Towards this goal, flexible thin‐film sensors of dose with embedded data acquisition electronics and wireless data transmission are prototyped and tested in kV and MV photon beams. Fundamental dosimetric properties are determined in view of a specific application to dose verification in multiple planes or curved surfaces inside a phantom. Uniqueness of the new thin‐film sensors consists in their mechanical properties, low‐power operation, and low‐cost. They are thinner and more flexible than dosimetric films. In principle, each thin‐film sensor can be fabricated in any size (mm2 – cm2 areas) and shape. Individual sensors can be put together in an array of sensors spreading over large areas and yet being light. Photovoltaic mode of charge collection (of electrons and holes) does not require external electric field applied to the sensor, and this implies simplicity of data acquisition electronics and low power operation. The prototype device use for testing consists of several thin film dose sensors, each of about 1.5 cm×5 cm area, connected to simple readout electronics. Sensitivity of the sensors is determined per unit area and compared to EPID sensitivity, as well as other standard photodiodes. Each sensor independently measures dose and is based on commercially available flexible thin‐film aSi photodiodes. Readout electronics consists of an ultra low‐power microcontroller, radio frequency transmitter, and a low‐noise amplification circuit implemented on a flexible printed circuit board. Detector output is digitized and transmitted wirelessly to an external host computer where it is integrated and processed. A megavoltage medical linear accelerator (Varian Tx) equipped with kilovoltage online imaging system and a Cobalt source are use to irradiate different thin‐film detector sensors in a Solid Water phantom under various irradiation conditions. Different factors are considered in characterization of the device attributes: energies (80 kVp, 130 kVp, 6 MV, 15 MV), dose rates (different ms × mA, 100–600 MU/min), total doses (0.1 cGy‐500 cGy), depths (0.5 cm–20 cm), irradiation angles with respect to the detector surface (0°‐180°), and IMRT tests (closed MLC, sweeping gap). The detector response to MV radiation is both linear with total dose (~1‐400 cGy) and independent of dose rate (100‐600 Mu/min). The sensitivity per unit area of thin‐film sensors is lower than for aSi flat‐panel detectors, but sufficient to acquire stable and accurate signals during irradiations. The proposed thin‐film photodiode system has properties which make it promising for clinical dosimetry. Due to the mechanical flexibility of each sensor and readout electronics, low‐cost, and wireless data acquisition, it could be considered for quality assurance (e.g., IMRT, mechanical linac QA), as well as real‐time dose monitoring in challenging setup configuratio...

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“…In proton beam dosimetry, semiconductor-based devices require materials that convert signals into different forms because the energy is generally too strong for direct signals to be received, or a buffer layer is applied in front of the absorber layer to shorten the energy transmission length. Parsai et al developed a CdTe thin film detector using a metal plate to convert a 6 MV photon beam into secondary electrons and then conducted a study on detecting a 6 MV therapy beam [17]. The results of 6 MV percentage depth dose measurement using CdTe cells agreed well with those of a Monte Carlo simulation in an ion chamber.…”

Section: Introductionmentioning

confidence: 82%

Radiation hardness of cadmium telluride solar cells in proton therapy beam mode

et al. 2019

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We evaluated the durability of cadmium telluride (CdTe) solar cells upon proton beam irradiation as well as the possibility of achieving a dosimeter usable in proton beam therapy by applying 100 MeV of pencil beam scanning (PBS) irradiation. Specifically, a 100 MeV proton PBS beam was applied at irradiation doses of 0, 1012, 1013, 1014, and 1015 cm-2. According to the results, the remaining factors (defined as the ratio of the degraded value to the initial value) of open-circuit voltage (Voc), short-circuit current (Jsc), fill-factor (FF), and efficiency (ƞ) which are solar cell performance parameters, were approximately 89%, 44%, 69%, and 30%, respectively, compared to those of the reference cell (without irradiation) at the highest dose of 1×1015 cm-2. In particular, the conversion efficiency, which is the main factor, was approximately 70% of that of the reference cell even at a high fluence of 1×1014 cm-2. In addition, we observed the projected range of the hydrogen atoms based on the PBS beam energy using the Tool for Particle Simulation software and assessed the amount of fluence accumulated in a CdTe cell. As the energy increased, the fluence accumulated inside the cell tended to decrease owing to the characteristics of the Bragg peak of the proton. Thus, the radiation damage to the cell induced by the proton beam was reduced. The results of this study are expected to provide valuable reference information for research on dosimetry sensors composed of thin-film solar cells, serving as the basis for future application in proton beam therapy with CdTe solar cells.

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Design and optimization of large area thin‐film CdTe detector for radiation therapy imaging applications

Abstract: The proposed CdTe-based large area thin-film detector has a potential of becoming an efficient low-cost electronic portal imaging device for radiation therapy applications.

Cited by 23 publications

References 33 publications

System-independent material classification through X-ray attenuation decomposition from spectral X-ray CT

System-independent material classification through X-ray attenuation decomposition from spectral X-ray CT

Low‐cost flexible thin‐film detector for medical dosimetry applications

Radiation hardness of cadmium telluride solar cells in proton therapy beam mode

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