Fisher Information Analysis of Depth-of-Interaction Estimation in Double-Sided Strip Detectors

Salcin, Esen; Barrett, Harrison H.; Barber, H. Bradford; Takeda, S.; Watanabe, Shin; Takahashi, Tadayuki; Furenlid, Lars R.

doi:10.1109/tns.2014.2317454

Cited by 10 publications

(5 citation statements)

References 31 publications

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“…In contrast, the peaks above 20 keV exhibit low-energy tails. This tail structure is caused by the depth dependence of the induced charge due to the charge trapping effect [2,16,17].…”

Section: Anode and Cathode Spectrum Of 241 Ammentioning

confidence: 99%

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Imaging and Spectral Performance of a 60 μm Pitch CdTe Double-Sided Strip Detector

Furukawa,

Nagasawa,

Glesener

et al. 2020

Preprint

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We have evaluated the performance of a fine pitch CdTe Double-sided Strip Detector (CdTe-DSD), which was originally developed for the focal plane detector of a hard X-ray telescope to observe the Sun. The detector has a thickness of 750 µm and has 128 strip electrodes with a 60 µm strip pitch orthogonally placed on both sides of the detector and covers an energy range 4 keV to 80 keV. The study of the depth of photon interaction and charge sharing effects are of importance in order to provide good spectroscopic and imaging performance. We study the tail structure observed in the spectra caused by charge trapping and develop a new method to reconstruct the spectra based on induced charge information from both anode and cathode strips. By applying this method, energy resolutions (FWHM) of 0.76 keV and 1.0 keV can be obtained at photon energies of 14 keV and 60 keV, respectively, if the energy difference between the anode and cathode is within 1 keV. Furthermore, the tail component at 60 keV is reduced, and the energy resolution of the 60 keV peak is improved from 2.4 keV to 1.5 keV (FWHM) if the energy difference is greater than 1 keV. In order to study the imaging performance, we constructed a simple imaging system using a 5 mm thick tungsten plate that has a pinhole with a diameter of 100 µm. We utilize a 133 Ba radioisotope of 1 mm in diameter as a target source in combination with a 100 µm slit made from 0.5 mm thickness tungsten. We imaged the 133 Ba source behind the 100 µm slit using a 30 keV peak, with a 100 µm pinhole placed at the center of the source-detector distance. By applying a charge sharing correction between strips, we have succeeded in obtaining a position resolution better than the strip pitch of 60 µm.

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“…In contrast, the peaks above 20 keV exhibit low-energy tails. This tail structure is caused by the depth dependence of the induced charge due to the charge trapping effect [2,16,17].…”

Section: Anode and Cathode Spectrum Of 241 Ammentioning

confidence: 99%

“…The tail angle θ u is determined as 55.3 • by the PCA on the energy "average vs difference" plot summed over the detector. It is assumed that the tail structure in this case is caused by the events which photons interact very close to the cathode side [16] and the percentage of this event is 5.3%.…”

Section: Reconstruction Algorithm and Improved Spectramentioning

confidence: 99%

Imaging and Spectral Performance of a 60 μm Pitch CdTe Double-Sided Strip Detector

Furukawa,

Nagasawa,

Glesener

et al. 2020

Preprint

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“…[56] These offer much higher stopping power for the isotopes commonly used in preclinical and clinical studies and will be used in CGRI’s next-generation systems. [57]…”

Section: Crossed Strip Semiconductor Detectorsmentioning

confidence: 99%

Molecular imaging in the College of Optical Sciences: an overview of two decades of instrumentation development

et al. 2014

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During the past two decades, researchers at the University of Arizona’s Center for Gamma-Ray Imaging (CGRI) have explored a variety of approaches to gamma-ray detection, including scintillation cameras, solid-state detectors, and hybrids such as the intensified Quantum Imaging Device (iQID) configuration where a scintillator is followed by optical gain and a fast CCD or CMOS camera. We have combined these detectors with a variety of collimation schemes, including single and multiple pinholes, parallel-hole collimators, synthetic apertures, and anamorphic crossed slits, to build a large number of preclinical molecular-imaging systems that perform Single-Photon Emission Computed Tomography (SPECT), Positron Emission Tomography (PET), and X-Ray Computed Tomography (CT). In this paper, we discuss the themes and methods we have developed over the years to record and fully use the information content carried by every detected gamma-ray photon.

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“…One advantage of the DSD configuration compared with the pixel-type detector is that signals can be measured from both anode and cathode strips. Since the µτ products (mobility times lifetime) in CdTe differ by * Email Address: shunsaku.nagasawa@ipmu.jp a factor of ten between holes and electrons, the amounts of signals accumulated on the cathode and anode sides differ according to the depth of the interaction point (DoI) [2,3]. If a photon interacts with the detector at a point close to the anode side, for example, more holes are trapped, and the signal on the cathode side, i.e., the total energy, will be weaker than that on the anode side.…”

Section: Introductionmentioning

confidence: 99%

Wide-gap CdTe Strip Detectors for High-Resolution Imaging in Hard X-rays

Nagasawa¹,

Takahiro²,

Watanabe³

et al. 2023

Preprint

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We propose a new strip configuration for CdTe X-ray detectors, named "Wide-gap CdTe strip detector", in which the gap between adjacent strips is much wider than the width of each strip. It has been known that the observed energies of an incoming photon in adjacent strips can be utilized to achieve a position resolution finer than the strip pitch, if and only if the charge cloud induced by an incoming X-ray photon is split into multiple strips and their energies are accurately measured. However, with existing CdTe strip detectors, the ratio of such charge-sharing events is limited. An idea for a potential breakthrough to greatly enhance the ratio of charge-sharing events is to widen the gaps between strips on the detector. To test the concept, we developed a wide-gap CdTe strip detector, which has 64 platinum strip electrodes on the cathode side with some variations in strip pitches from 60 µm (30 µm strip and 30 µm gap width) to 80 µm (30 µm strip and 50 µm gap width). We evaluated the performance depending on the strip pitches by irradiating X-rays from 241 Am on the detector. The charge loss due to the wider gaps on the detector was found to be significant to the extent that the assumption that the energy of an incoming photon for a charge-sharing event was the simple sum of the energies detected in adjacent strips lead to a significant degradation in the energy resolution in the accumulated spectrum, compared with those obtained with its predecessor having standard gap-widths. We then developed a new energy-reconstruction method to compensate for the charge loss. Application of the method to the data yielded a spectrum with a comparable spectral resolution with that of the predecessor. The ratio of the charge-sharing events for 17.8 keV events was doubled from that of the predecessor, from 24.3 to 49.9 percent. We assessed the results with a theoretical simulation based on the Shockley-Ramo theorem and found that they were in agreement.

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Fisher Information Analysis of Depth-of-Interaction Estimation in Double-Sided Strip Detectors

Cited by 10 publications

References 31 publications

Imaging and Spectral Performance of a 60 μm Pitch CdTe Double-Sided Strip Detector

Imaging and Spectral Performance of a 60 μm Pitch CdTe Double-Sided Strip Detector

Molecular imaging in the College of Optical Sciences: an overview of two decades of instrumentation development

Wide-gap CdTe Strip Detectors for High-Resolution Imaging in Hard X-rays

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