Design and assessment of a novel SPECT system for desktop open-gantry imaging of small animals: A simulation study

Zeraatkar, Navid; Farahani, Mohammad Hossein Davood Abadi; Rahmim, Arman; Sarkar, Saeed; Ay, Mohammad Reza

doi:10.1118/1.4947127

Cited by 9 publications

(5 citation statements)

References 56 publications

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“…A detailed description of the program and the parameters used to model analytically a similar AdaptiSPECT-C prototype can be found in Auer et al (2021). The software models analytically the system response by tracing individual rays from the center of each object voxel to interacting with each detector pixel (Zeraatkar et al 2016). The analytic modeling was calibrated against MCS by calculating a sensitivity calibration factor from a high-count VOI-like source distribution in air centered on the VOI.…”

Section: Iterative Image Reconstruction With Attenuation Correction A...mentioning

confidence: 99%

Mesh modeling of system geometry and anatomy phantoms for realistic GATE simulations and their inclusion in SPECT reconstruction

Auer¹,

Könik²,

Fromme³

et al. 2023

Phys. Med. Biol.

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Objective. Monte-Carlo simulation studies have been essential for advancing various developments in SPECT imaging, such as system design and accurate image reconstruction. Among the simulation software available, GATE is one of the most used simulation toolkits in nuclear medicine, which allows building systems and attenuation phantom geometries based on the combination of idealized volumes. However, these idealized volumes are inadequate for modeling free-form shape components of such geometries. Recent GATE versions alleviate these major limitations by allowing users to import triangulated surface meshes. Approach. In this study, we describe our mesh-based simulations of a next-generation multi-pinhole SPECT system dedicated to clinical brain imaging, called AdaptiSPECT-C. To simulate realistic imaging data, we incorporated in our simulation the XCAT phantom, which provides an advanced anatomical description of the human body. An additional challenge with the AdaptiSPECT-C geometry is that the default voxelized XCAT attenuation phantom was not usable in our simulation due to intersection of objects of dissimilar materials caused by overlap of the air containing regions of the XCAT beyond the surface of the phantom and the components of the imaging system. Main Results. We validated our mesh-based modeling against the one constructed by idealized volumes for a simplified single vertex configuration of AdaptiSPECT-C through simulated projection data of 123I-activity distributions. We resolved the overlap conflict by creating and incorporating a mesh-based attenuation phantom following a volume hierarchy. We then evaluated our reconstructions with attenuation and scatter correction for projections obtained from simulation consisting of mesh-based modeling of the system and the attenuation phantom for brain imaging. Our approach demonstrated similar performance as the reference scheme simulated in air for uniform and clinical-like 123I-IMP brain perfusion source distributions. Significance. This work enables the simulation of complex SPECT acquisitions and reconstructions for emulating realistic imaging data close to those of actual patients.

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Section: Iterative Image Reconstruction With Attenuation Correction A...mentioning

confidence: 99%

Mesh modeling of system geometry and anatomy phantoms for realistic GATE simulations and their inclusion in SPECT reconstruction

Auer¹,

Könik²,

Fromme³

et al. 2023

Phys. Med. Biol.

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show abstract

“…We developed a generic GPU-accelerated platform for fast analytic simulation and reconstruction of single and multi-pinhole SPECT geometries (Zeraatkar et al 2016. The software models the geometric and physical properties of AdaptiSPECT-C (e.g., position and orientation of detectors and apertures, pinhole acceptance angle and size) and the object.…”

Section: Analytic Noise-free Simulation and Iterative Image Reconstru...mentioning

confidence: 99%

“…We also make use of the effective diameter for resolution instead of the physical diameter of the pinhole to take the penetration through the aperture edges into account (Accorsi & Metzler 2004). The projector and reconstruction software is based on a single ray-tracing approach described in detail in (Zeraatkar et al 2016). It was demonstrated in this work that the projection into the detector of a given voxel of the image domain passing through the pinhole is circular when the detectors and apertures planes can be considered parallel.…”

Section: Analytic Noise-free Simulation and Iterative Image Reconstru...mentioning

confidence: 99%

Inclusion of quasi-vertex views in a brain-dedicated multi-pinhole SPECT system for improved imaging performance

et al. 2021

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With brain-dedicated multi-detector systems employing pinhole apertures the usage of detectors facing the top of the patient’s head (i.e. quasi-vertex (QV) views) can provide the advantage of additional viewing from close to the brain for improved detector coverage. In this paper, we report the results of simulation and reconstruction studies to investigate the impact of the QV views on the imaging performance of AdaptiSPECT-C, a brain-dedicated stationary SPECT system under development. In this design, both primary and scatter photons from regions located inferior to the brain can contribute to SPECT projections acquired by the QV views, and thus degrade AdaptiSPECT-C imaging performance. In this work, we determined the proportion, origin, and nature (i.e. primary, scatter, and multiple-scatter) of counts emitted from structures within the head and throughout the body contributing to projections from the different AdaptiSPECT-C detector rings, as well as from a true vertex view detector. We simulated phantoms used to assess different aspects of image quality (i.e. uniform activity concentration sphere, and Derenzo), as well as anthropomorphic phantoms with different count levels emulating clinical 123I activity distributions (i.e. DaTscan and perfusion). We determined that attenuation and scatter in the patient’s body greatly diminish the probability of the photons emitted outside the volume of interest reaching to detectors and being recorded within the 15% photopeak energy window. In addition, we demonstrated that the inclusion of the residual of such counts in the system acquisition does not degrade visual interpretation or quantitative analysis. The addition of the QV detectors improves volumetric sensitivity, angular sampling, and spatial resolution leading to significant enhancement in image quality, especially in the striato-thalamic and superior regions of the brain. Besides, the use of QV detectors improves the recovery of clinically relevant metrics such as the striatal binding ratio and mean activity in selected cerebral structures. Our findings proving the usefulness of the QV ring for brain imaging with 123I agents can be generalized to other commonly used SPECT imaging agents labelled with isotopes, such as 99mTc and likely 111In.

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“…Moreover, performance of the detector was evaluated based on NEMA NU-1 2007 [10] standard. The developed gamma detector head is going to be used in a dedicated dual-head fixed 90 • -angle cardiac SPECT and a small-animal pinhole SPECT [11][12][13].…”

Section: Jinst 12 P09008mentioning

confidence: 99%

Development and calibration of a new gamma camera detector using large square Photomultiplier Tubes

et al. 2017

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Large area scintillation detectors applied in gamma cameras as well as Single Photon Computed Tomography (SPECT) systems, have a major role in in-vivo functional imaging. Most of the gamma detectors utilize hexagonal arrangement of Photomultiplier Tubes (PMTs). In this work we applied large square-shaped PMTs with row/column arrangement and positioning. The Use of large square PMTs reduces dead zones in the detector surface. However, the conventional center of gravity method for positioning may not introduce an acceptable result. Hence, the digital correlated signal enhancement (CSE) algorithm was optimized to obtain better linearity and spatial resolution in the developed detector. The performance of the developed detector was evaluated based on NEMA-NU1-2007 standard. The acquired images using this method showed acceptable uniformity and linearity comparing to three commercial gamma cameras. Also the intrinsic and extrinsic spatial resolutions with low-energy high-resolution (LEHR) collimator at 10 cm from surface of the detector were 3.7 mm and 7.5 mm, respectively. The energy resolution of the camera was measured 9.5%. The performance evaluation demonstrated that the developed detector maintains image quality with a reduced number of used PMTs relative to the detection area.

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Design and assessment of a novel SPECT system for desktop open-gantry imaging of small animals: A simulation study

Cited by 9 publications

References 56 publications

Mesh modeling of system geometry and anatomy phantoms for realistic GATE simulations and their inclusion in SPECT reconstruction

Mesh modeling of system geometry and anatomy phantoms for realistic GATE simulations and their inclusion in SPECT reconstruction

Inclusion of quasi-vertex views in a brain-dedicated multi-pinhole SPECT system for improved imaging performance

Development and calibration of a new gamma camera detector using large square Photomultiplier Tubes

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