X-ray energy separation method using a CdTe semiconductor X-ray imaging sensor and photon counting method

Tsutsui, Hiroshi; Ohtsuchi, T.; Ohmori, K.; Baba, Sueki

doi:10.1109/23.199485

Cited by 23 publications

(2 citation statements)

References 18 publications

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“…It has a relatively large band gap, 1.47 eV at 300 K, resulting in a small thermal noise. Another outstanding characteristic of this semiconductor material is its high atomic number that enables strong absorption and good detection efficiency for high-energy photons [1,2]. At the same time, CdTe detectors suffer from the crystal impurities such as Te-inclusions, dislocation networks, and twin and subgrain boundaries [3], which affect the detector performance [4,5].…”

Section: Introductionmentioning

confidence: 99%

Modeling the impact of defects on the charge collection efficiency of a Cadmium Telluride detector

Golovleva¹,

Bezak²,

Bharthuar³

et al. 2021

J. Inst.

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Cadmium telluride is a favorable material for X-ray detection as it has an outstanding characteristic for room temperature operation. It is a high-Z material with excellent photon radiation absorption properties. However, CdTe single crystals may include a large number of extended crystallographic defects, such as grain boundaries, twins, and tellurium (Te) inclusions, which can have an impact on detector performance. A Technology Computer Aided Design (TCAD) local defect model has been developed to investigate the effects of local defects on charge collection efficiency (CCE). We studied a 1 mm thick Schottky-type CdTe radiation detector with transient-current technique by using a red laser at room temperature. By raster scanning the detector surface we were able to study signal shaping within the bulk, and to locate surface defects by observing their impact on the CCE. In this paper we present our TCAD model with localized defect, and compare the simulation results to TCT measurements. In the model an inclusion with a diameter of 10 μm was assumed. The center of the defect was positioned at 6 μm distance from the surface. We show that the defect has a notable effect on current transients, which in turn affect the CCE of the CdTe detector. The simulated charge collection at the position of the defect decreases by 80 % in comparison to the defect-free case. The simulations show that the defects give a characteristic shape to TCT signal. This can further be used to detect defects in CdTe detectors and to estimate the overall defect density in the material.

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Section: Introductionmentioning

confidence: 99%

Modeling the impact of defects on the charge collection efficiency of a Cadmium Telluride detector

Golovleva¹,

Bezak²,

Bharthuar³

et al. 2021

J. Inst.

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“…The primary efforts were focused on improving photon counting (PC) detector technology, which was the major problem of PCS-CT for decades. Several prototype PC detectors were developed based on semiconductors Si (Benini et al 1990, Arfelli et al 1997, Arfelli et al 1998, Danielsson et al 2000, Aslund et al 2007, CdTe (Tsutsui et al 1993, Schlomka et al 2008, Barber et al 2009, Cormode et al 2010, and CdZnTe (Tumer et al 2000, Cajipe et al 2004, Le and Molloi 2011, Shikhaliev and Fritz 2011. These detectors were primarily linear array detectors.…”

Section: Introductionmentioning

confidence: 99%

Soft tissue imaging with photon counting spectroscopic CT

Shikhaliev

2015

Phys. Med. Biol.

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The purpose of this work was experimental investigation of photon counting spectroscopic CT (PCS-CT) imaging of anatomical soft tissue with clinically relevant size. The imaging experiments were performed using a spectroscopic CT system based on CdZnTe photon counting detector with two rows of pixels, 256 pixels in each row, 1 × 1 mm(2) pixel size, and 25.6 cm detector length. The detector could split the x-ray energy spectrum to 5 regions (energy bins), and acquire 5 multi-energy (spectroscopic) CT images in a single CT scan. A sample of round shaped anatomical soft tissue of 14 cm diameter including lean and fat was used for imaging. To avoid the negative effect of anatomical noise on quantitative analysis, a spectroscopic CT phantom with tissue equivalent solid materials was used. The images were acquired at 60, 90, and 120 kVp tube voltages, and spectroscopic image series were acquired with 3 and 5 energy bins. Spectroscopic CT numbers were introduced and used to evaluate an energy selective image series. The anatomical soft tissue with 14 cm diameter was visualized with good quality and without substantial artifacts by the photon counting spectroscopic CT system. The effects of the energy bin crosstalk on spectroscopic CT numbers were quantified and analyzed. The single and double slice PCS-CT images were acquired and compared. Several new findings were observed, including the effect of soft tissue non-uniformity on image artifacts, unique status of highest energy bin, and material dependent visualization in spectroscopic image series. Fat-lean decomposition was performed using dual energy subtraction and threshold segmentation methods, and compared. Using K-edge filtered x-rays improved fat-lean decomposition as compared to conventional x-rays. Several new and important aspects of the PCS-CT were investigated. These include imaging soft tissue with clinically relevant size, single- and double-slice PCS-CT imaging, using spectroscopic CT numbers to quantify multi-energy PCS-CT images, application of K-edge filtered x-rays for improved soft tissue decomposition, and several others. The study suggests that the presented PCS-CT technology meets the requirements of a particular clinical application, i.e. dedicated breast CT.

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Radiation detectors

Iwase¹,

Ohmori²

1997

Narrow-Gap II–VI Compounds for Optoelectronic and Electromagnetic Applications

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X-ray energy separation method using a CdTe semiconductor X-ray imaging sensor and photon counting method

Cited by 23 publications

References 18 publications

Modeling the impact of defects on the charge collection efficiency of a Cadmium Telluride detector

Modeling the impact of defects on the charge collection efficiency of a Cadmium Telluride detector

Soft tissue imaging with photon counting spectroscopic CT

Radiation detectors

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