Implementation and preliminary investigation of analytical methods for correction of distance-dependent resolution variation and uniform attenuation in 3D brain SPECT

Li, J.; Zhang, Liang; Ye, J.; Han, Guoping

doi:10.1109/23.819299

Cited by 5 publications

(4 citation statements)

References 29 publications

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“…Therefore, the orbits of the detectors when using the proposed hybrid collimators may be larger than the conventional noncircular ones and lead to decreased resolution in the images. However, if the spatial detector response of the system can be accurately modeled in image reconstruction [12], [13], the requirement of the orbits due to the image resolution consideration will no longer be the decisive consideration. Orbits that can keep the OOIs in the CV of the hybrid collimators the most will be preferred.…”

Section: Discussionmentioning

confidence: 99%

Hybrid parallel-slant hole collimators for SPECT imaging

Bai

Shao

et al. 2004

IEEE Trans. Nucl. Sci.

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We propose a new collimator geometry, the hybrid parallel-slant (HPS) hole geometry, to improve sensitivity for SPECT imaging with large field of view (LFOV) gamma cameras. A HPS collimator has one segment with parallel holes and one or more segments with slant holes. The collimator can be mounted on a conventional SPECT LFOV system that uses parallel-beam collimators, and no additional detector or collimator motion is required for data acquisition. The parallel segment of the collimator allows for the acquisition of a complete data set of the organs-of-interest and the slant segments provide additional data. In this work, simulation studies of an MCAT phantom were performed with a HPS collimator with one slant segment. The slant direction points from patient head to patient feet with a slant angle of 30 . We simulated 64 projection views over 180 with the modeling of nonuniform attenuation effect, and then reconstructed images using an MLEM algorithm that incorporated the hybrid geometry. It was shown that sensitivity to the cardiac region of the phantom was increased by approximately 50% when using the HPS collimator compared with a parallel-hole collimator. No visible artifacts were observed in the myocardium and the signal-to-noise ratio (SNR) of the myocardium walls was improved. Compared with collimators with other geometries, using a HPS collimator has the following advantages: (a) significant sensitivity increase; (b) a complete data set obtained from the parallel segment that allows for artifact-free image reconstruction; and (c) no additional collimator or detector motion. This work demonstrates the potential value of hybrid geometry in collimator design for LFOV SPECT imaging.Index Terms-Collimator geometry, field of view (FOV), hybrid parallel-slant (HPS) hole collimator, SPECT.

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Section: Discussionmentioning

confidence: 99%

Hybrid parallel-slant hole collimators for SPECT imaging

Bai

Shao

et al. 2004

IEEE Trans. Nucl. Sci.

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“…Extension of the inversion to include distance-dependent PSF has been developed via the frequency-distance relation (FDR) [15]- [21]. Efforts to extend the inversion from parallel-hole collimation to fan-beam geometry have been also reported in the literature [22]- [25].…”

Section: Evaluation Of An Efficient Compensation Methods Formentioning

confidence: 99%

“…A common merit for comparing ROC curves is the AUC . In the binormal model fitting for ROC curves (justified by the central limit theorem when a sufficiently large number of ratings and a sufficiently large sample of images are used), can be calculated by (19) where is the cumulative standard normal distribution of (20) and and are parameters that best fit the equation relating the statistics of TPF and FPF (21) In this study, a total of 1000 projections, (500 with and 500 without the defect) were generated, where the noise level is equivalent to 100 K counts per view. They were reconstructed using each of the two different methods, resulting in a total of 2000 images or samples.…”

Section: B Roc Studymentioning

confidence: 99%

Evaluation of an efficient compensation method for quantitative fan-beam brain SPECT reconstruction

Wen

Han

et al. 2005

IEEE Trans. Med. Imaging

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Fan-beam collimators are designed to improve the system sensitivity and resolution for imaging small objects such as the human brain and breasts in single photon emission computed tomography (SPECT). Many reconstruction algorithms have been studied and applied to this geometry to deal with every kind of degradation factor. This paper presents a new reconstruction approach for SPECT with circular orbit, which demonstrated good performance in terms of both accuracy and efficiency. The new approach compensates for degradation factors including noise, scatter, attenuation, and spatially variant detector response. Its uniform attenuation approximation strategy avoids the additional transmission scan for the brain attenuation map, hence reducing the patient radiation dose and furthermore simplifying the imaging procedure. We evaluate and compare this new approach with the well-established ordered-subset expectation-maximization iterative method, using Monte Carlo simulations. We perform quantitative analysis with regional bias-variance, receiver operating characteristics, and Hotelling trace studies for both methods. The results demonstrate that our reconstruction strategy has comparable performance with a significant reduction of computing time.

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“…It under-recovers the resolution for objects beyond that average distance, and over-recovers the resolution for objects within the average range. Another approach that uses the frequency-distance principle (FDP) (6) can model the depthdependent resolution of the system. However, the integration of this approach is not easy with two other major aspects of SPECT imaging, i.e., non-uniform attenuation and model-based scatter corrections.…”

Section: Methodsmentioning

confidence: 99%

Evaluation of the Image Contrast with a New Depth-Dependent Collimator Resolution Iterative Reconstruction Method

Ahmed¹

2010

The Egyptian Journal Nuclear Medicine

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Iterative reconstruction methods are well suited to improve image quality and clinical performance in SPECT imaging in nuclear medicine. This is done by incorporating internal modeling of the imaging physics in SPECT reconstructions to correct for the major factors affecting image quality. These factors include degradation of spatial resolution with increasing distance of the source from the collimator, Compton scatter and photon attenuation. Since noise suppression approaches degrade the image resolution, a good balance of resolution recovery and noise suppression is desirable. The Astonish software package provides powerful control of the resolution recovery technique and an application-specific optimization of noise suppression. Objectives: The aim of the study is to compare the contrast value of the images resulting from filtering with different available iteration methods with the new depth dependant collimator resolution iteration technique (Astonish) in SPECT imaging. Materials and methods: The study was performed on a Forte dual head gamma camera, using the SPECT phantom. The contrast value is calculated for a specified hot sphere within the cold background by applying the studied reconstruction iterative methods (MLEM, 3D-OSEM and Astonish) with iteration number from 1-15 iterations. The resultant calculated contrast values are then compared for each iteration method. Results: Regarding the MLEM iteration method the average contrast value was [0.8002 ± 0.0304] and for the 3D OSEM iteration method the average contrast value was [0.8662 ± 0.0068]. As regards to the Astonish iteration method the average contrast value was [0.907 ± 0.0394]. There was a statistical significant difference in contrast value between the studied iteration methods (p=4.2E-12). Conclusion:The MLEM iteration method increases the sphere count with increasing the iteration number; and also it increases the background counts with about 3 fold that of the 3D OSEM method, and about 4 folds that of Astonish method. Although both 3D-OSEM and Astonish methods give sphere counts that are almost within the same range but incorporating the depth dependant resolution recovery parameter in the Astonish method leads to decrease in the background count with increasing the iteration number, which in turn enhances the contrast of the resultant image from Astonish iteration method rather than that of both MLEM and 3D-OSEM methods.

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Implementation and preliminary investigation of analytical methods for correction of distance-dependent resolution variation and uniform attenuation in 3D brain SPECT

Cited by 5 publications

References 29 publications

Hybrid parallel-slant hole collimators for SPECT imaging

Hybrid parallel-slant hole collimators for SPECT imaging

Evaluation of an efficient compensation method for quantitative fan-beam brain SPECT reconstruction

Evaluation of the Image Contrast with a New Depth-Dependent Collimator Resolution Iterative Reconstruction Method

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