A four-pixel matched collimator for high-sensitivity SPECT imaging

Suzuki, Atsuro; Takeuchi, Wataru; Ishitsu, Takafumi; Tsuchiya, Katsutoshi; Ueno, Yuichiro; Kobashi, Keiji

doi:10.1088/0031-9155/58/7/2199

Cited by 11 publications

(24 citation statements)

References 9 publications

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“…The PSF of each collimator type was obtained by ray-tracing simulation [6,7]. The attenuation factor of the gamma rays in a subject was approximated by an exponential function of the line integral from an image pixel to a detector pixel in an attenuation map.…”

Section: Image Reconstruction Methodsmentioning

confidence: 99%

“…This system is described in detail in previous reports [6,7]. In brief, CdTe-SPECT includes two detector heads.…”

Section: Outline Of Cdte-spectmentioning

confidence: 99%

“…For high-sensitivity imaging, a wide aperture parallel-hole collimator (Fig. 4.1), which we call the "4-pixel matched collimator" (4-PMC), was previously developed [6,7]. The hole size of the 4-PMC is matched to four detector pixels, that is, there are four (2 Â 2) pixels per collimator hole.…”

Section: Outline Of Cdte-spectmentioning

confidence: 99%

“…These features of semiconductor detectors may lead to improved PET and SPECT images. The authors previously developed CdTe semiconductor detector-based PET (CdTe-PET) [1,2] and SPECT (CdTe-SPECT) [6,7]. The physical and clinical performances of the systems were evaluated through phantom, animal, and clinical studies.…”

Section: Introductionmentioning

confidence: 99%

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Semiconductor Detector-Based Scanners for Nuclear Medicine

Takeuchi

Suzuki

Ueno

et al. 2016

Perspectives on Nuclear Medicine for Molecular Diagnosis and Integrated Therapy

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Semiconductor detectors have the potential to improve the quantitative accuracy of nuclear medicine imaging with their better energy and intrinsic spatial resolutions than those of conventional scintillator-based detectors. The fine energy resolution leads to a better image contrast due to better scatter rejection. The fine intrinsic spatial resolution due to a pixelated structure leads to a better image contrast and lower partial volume effect. Their pixelated structures also improve the count-rate capability. The authors developed CdTe semiconductor detectorbased positron emission tomography (CdTe-PET) and single-photon emission computed tomography (CdTe-SPECT) in order to test the potential of using semiconductor detectors in nuclear medicine. The physical performances of both systems were measured in several phantom experiments. The capability of using CdTe-PET

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Section: Image Reconstruction Methodsmentioning

confidence: 99%

“…This system is described in detail in previous reports [6,7]. In brief, CdTe-SPECT includes two detector heads.…”

Section: Outline Of Cdte-spectmentioning

confidence: 99%

Section: Outline Of Cdte-spectmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Semiconductor Detector-Based Scanners for Nuclear Medicine

Takeuchi

Suzuki

Ueno

et al. 2016

Perspectives on Nuclear Medicine for Molecular Diagnosis and Integrated Therapy

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“…For a pixelated detector, a straightforward approach for maximizing sensitivity is to match the collimator holes with detector pixels to obtain a pixel-geometry-matching collimator (PGMC)[9][10]. Detectors combined with PGM-Cs are expected to be more efficient than non-pixel-matching collimations.…”

Section: Introductionmentioning

confidence: 99%

An energy-optimized collimator design for a CZT-based SPECT camera

Weng

Bagchi

Zan

et al. 2016

Nuclear Instruments and Methods in Physics Research Section A:

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In single photon emission computed tomography, it is a challenging task to maintain reasonable performance using only one specific collimator for radio-tracers over a broad spectrum of diagnostic photon energies, since photon scatter and penetration in a collimator differ with the photon energy. Frequent collimator exchanges are inevitable in daily clinical SPECT imaging, which hinders throughput while subjecting the camera to operational errors and damage. Our objective is to design a collimator, which independent of the photon energy performs reasonably well for commonly used radiotracers with low- to medium-energy levels of gamma emissions. Using the Geant4 simulation toolkit, we simulated and evaluated a parallel-hole collimator mounted to a CZT detector. With the pixel-geometry-matching collimation, the pitch of the collimator hole was fixed to match the pixel size of the CZT detector throughout this work. Four variables, hole shape, hole length, hole radius/width and the source-to-collimator distance were carefully studied. Scatter and penetration of the collimator, sensitivity and spatial resolution of the system were assessed for four radionuclides including 57Co, 99mTc, 123I and 111In, with respect to the aforementioned four variables. An optimal collimator was then decided upon such that it maximized the total relative sensitivity (TRS) for the four considered radionuclides while other performance parameters, such as scatter, penetration and spatial resolution, were benchmarked to prevalent commercial scanners and collimators. Digital phantom studies were also performed to validate the system with the optimal square-hole collimator (23 mm hole length, 1.28 mm hole width, 0.32 mm septal thickness) in terms of contrast, contrast-to-noise ratio and recovery ratio. This study demonstrates promise of our proposed energy-optimized collimator to be used in a CZT-based gamma camera, with comparable or even better imaging performance versus commercial collimators such as low-energy high resolution (LEHR) and medium energy general purpose (MEGP) collimators.

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Technical Note: Nuclear imaging with an x‐ray flat panel detector: A proof‐of‐concept study

et al. 2020

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Interventional procedures involving radionuclides (e.g., radioembolization) would benefit from single-photon emission computed tomography (SPECT) performed in the intervention room because the activity distribution could be immediately visualized. We believe it might be possible to perform SPECT with the C-arm cone beam computed tomography (CBCT) scanner present in the intervention room by equipping the x-ray flat panel detector with a collimator. The purpose of this study is to demonstrate the approach and to investigate the achievable SPECT reconstruction quality. Methods: A proof-of-concept experiment was performed to evaluate the possibility of nuclear imaging with an x-ray flat panel detector. The experiment was digitally replicated to study the accuracy of the simulations. Three flat panel configurations (with standard hardware and reconstruction methodology, with sophisticated reconstruction methodology, and with expected future hardware) and a conventional gamma camera were evaluated. The Jaszczak and the NEMA IQ phantom (filled with 99m Tc) were simulated and assessed on resolution and contrast-to-noise ratio (CNR). Results: The proof-of-concept experiment demonstrated that nuclear images could be obtained from the flat panel detector. The simulation of the same configuration demonstrated that simulations could accurately predict the flat panel detector response. The CNR of the 37 mm sphere in the NEMA IQ phantom was 22.8 AE 1.2 for the gamma camera reconstructions, while it was 11.3 AE 0.7 for the standard flat panel detector. With sophisticated reconstruction methodology, the CNR improved to 13.5 AE 1.4. The CNR can be expected to advance to 18.1 AE 1.3 for future flat panel detectors. Conclusions: The x-ray flat panel detector of a CBCT scanner might be used to perform nuclear imaging. The SPECT reconstruction quality will be lower than that achieved by a conventional gamma camera. The flat panel detector approach could, however, be useful in providing a cost-effective alternative to the purchase of a mobile SPECT scanner for enabling interventional scanning.

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A four-pixel matched collimator for high-sensitivity SPECT imaging

Cited by 11 publications

References 9 publications

Semiconductor Detector-Based Scanners for Nuclear Medicine

Semiconductor Detector-Based Scanners for Nuclear Medicine

An energy-optimized collimator design for a CZT-based SPECT camera

Technical Note: Nuclear imaging with an x‐ray flat panel detector: A proof‐of‐concept study

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