Evaluating collimator designs for nuclear breast imaging with High-Purity Germanium detectors

Campbell, Desmond L.; Peterson, Todd E.

doi:10.1109/nssmic.2011.6152960

Cited by 4 publications

(5 citation statements)

References 13 publications

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“…It has been shown that utilising parallel square-hole collimation comprised of tungsten and registered to the detector elements provides the best spatial resolution-sensitivity tradeoff for CZT systems and produces sensitivity gains between a factor of 1.5 and 3 (Weinmann et al 2009). Our initial study for improving the collimator design with HPGe detector by minimising penetration artifacts yielded a collimator with sensitivity gains of a factor of 1.83 over the collimator used in the present study (Campbell and Peterson 2011). We anticipate that applying a registered, tungsten collimator to HPGe detectors may offer further improvements in performance for HPGe systems.…”

Section: Discussionmentioning

confidence: 99%

Simulation study comparing high-purity germanium and cadmium zinc telluride detectors for breast imaging

Campbell¹,

Peterson²

2014

Phys. Med. Biol.

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We conducted simulations to compare the potential imaging performance for breast cancer detection with High-Purity Germanium (HPGe) and Cadmium Zinc Telluride (CZT) systems with 1% and 3.8% energy resolution at 140 keV, respectively. Using the Monte Carlo N-Particle (MCNP5) simulation package, we modelled both 5 mm-thick CZT and 10 mm-thick HPGe detectors with the same parallel-hole collimator for the imaging of a breast/torso phantom. Simulated energy spectra were generated, and planar images were created for various energy windows around the 140-keV photopeak. Relative sensitivity and scatter and the torso fractions were calculated along with tumour contrast and signal-to-noise ratios (SNR). Simulations showed that utilizing a ±1.25% energy window with an HPGe system better suppressed torso background and small-angle scattered photons than a comparable CZT system using a −5%/+10% energy window. Both systems provided statistically similar contrast and SNR, with HPGe providing higher relative sensitivity. Lowering the counts of HPGe images to match CZT count density still yielded equivalent contrast between HPGe and CZT. Thus, an HPGe system may provide equivalent breast imaging capability at lower injected radioactivity levels when acquiring for equal imaging time.

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Section: Discussionmentioning

confidence: 99%

Simulation study comparing high-purity germanium and cadmium zinc telluride detectors for breast imaging

Campbell¹,

Peterson²

2014

Phys. Med. Biol.

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“…The collimator employed in this study has been evaluated previously [22], but we briefly motivate its use here. Septal thickness was first chosen and positioned to shield the gap regions between collection strips in the benchtop HPGe detectors, with additional septa placed to improve geometric spatial resolution.…”

Section: Methodsmentioning

confidence: 99%

“…The collimator length was selected to satisfy the Chicago criterion to ensure artifact-free projections and minimize septa penetration [43]. The mounted square-hole tungsten collimators had a 20-mm length, 2.25-mm hole width, and 0.25-mm septal thickness, providing an angular acceptance of 12.8°, an analytically calculated collimator resolution of 5.31 mm at 10-mm distance from the camera and a 83% increase in sensitivity (4.6×10 4 cpm/MBq) over a low-energy, high-resolution (LEHR) hexagonal-hole lead collimator with 20-mm length, 1.85-mm hole width, and 0.30-mm septal thickness (2.4×10 4 cpm/MBq)) [22]. …”

Section: Methodsmentioning

confidence: 99%

“…For equivalent activity imaged, the HPGe camera provided better relative sensitivity with similar tumor contrast and SNR while suppressing small-angle scatter events and background from the torso [21]. Other simulations investigating the feasibility of the HPGe camera with various parallel-hole collimators for MBI found that our choice of large-bore, square-hole collimation provided an 81% enhancement in count sensitivity and better suppression of events from the torso than the standard hexagonal-hole collimator [22]. …”

Section: Introductionmentioning

confidence: 99%

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Molecular Breast Imaging Using Synthetic Projections From High-Purity Germanium Detectors: A Simulation Study

Campbell

Peterson

2017

IEEE Trans. Radiat. Plasma Med. Sci.

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High-Purity Germanium (HPGe) gamma cameras are an emerging technology for Molecular Breast Imaging (MBI) due to their 2D lateral spatial resolution, depth-of-interaction (DOI) estimation, and superb energy resolution. In this simulation study, we investigate the potential imaging performance of an opposing view dual-head HPGe breast imaging system using a synthetic-projection technique, which utilizes DOI data with varying degrees of overlap in an iterative OSEM reconstruction algorithm to create 3D images from which new 2D projections are then created. The radiation transport simulator Monte Carlo N-Particle was employed to generate projections from 10-mm thick HPGe detectors using tungsten parallel-hole collimators with short and wide holes. Simulations modeling 140-keV emissions from various contrast-detail and breast-torso phantoms were conducted. Synthetic projections were generated along with conjugate-counting images from collected HPGe projections. Tumor contrast, SNR, and hot-spot detection measurements were used to compare images. Results show that the synthetic projections could resolve more low-contrast tumors compared to single-camera projections and conjugate-counting methods. MBI simulations also showed increased contrast and SNR in synthetic projections compared to individual projections. In conclusion, the HPGe imaging system employing a synthetic-projection technique may offer advantages over individual dual-camera projections or conjugate-counting methods in terms of contrast, SNR, and tumor detectability.

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“…All data acquisition, system control, and system monitoring functions are accessed through a single USB-2.0 port. An integrated assembly allows for interchangeable mounting of parallel-hole and pinhole collimators, whose designs were based on simulations for optimizing parallel-hole and single pinhole collimation for small-animal imaging [6], [8].…”

Section: A Ggc Specificationsmentioning

confidence: 99%

Evaluation of a compact, general-purpose Germanium Gamma Camera

Campbell

Hull²,

Peterson

2013

2013 IEEE Nuclear Science Symposium and Medical Imaging Conference (2013 NSS/MIC)

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Technological advances in High-Purity Germanium (HPGe) detectors have given rise to compact, mechanically cooled gamma cameras that do not require bulky liquid nitrogen dewars to operate. When used in the double-sided strip configuration, spatial resolution finer than the strip width can be obtained using pulse signal analysis for position interpolation. With 3D position sensitivity and excellent energy resolution (1% FWHM at 140 keV), HPGe detectors have many possible applications in biomedical imaging. Here, we introduce the Germanium Gamma Camera (GGC1.1), a fully integrated imaging system incorporating a 90-mm diameter, 10-mm thick germanium detector with 16 x 16 orthogonal strips of 5-mm pitch having 0.25-mm wide gaps between the strips. All data acquisition, system control, and system monitoring functions are accessed through a single USB-2.0 port. An integrated assembly also allows for interchangeable mounting of parallel-hole and pinhole collimators. The intrinsic properties of the GGC1.1 detector system are measured according to the NEMA NU 1-2007 standards for gamma cameras, including detector efficiency, spatial resolution, energy resolution, and uniformity. In addition, we demonstrate the planar imaging capabilities of the GGC1.1 with the parallel-hole and pinhole collimators by scanning line sources, as well as a phantom comprised of spherical hot spots in a warm background.

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Evaluating collimator designs for nuclear breast imaging with High-Purity Germanium detectors

Cited by 4 publications

References 13 publications

Simulation study comparing high-purity germanium and cadmium zinc telluride detectors for breast imaging

Simulation study comparing high-purity germanium and cadmium zinc telluride detectors for breast imaging

Molecular Breast Imaging Using Synthetic Projections From High-Purity Germanium Detectors: A Simulation Study

Evaluation of a compact, general-purpose Germanium Gamma Camera

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