Three-dimensional geometric point response correction in rotating slant-hole (RSH) SPECT

Bal, Girish; Clackdoyle, Rolf; Zeng, G.L.; Kadrmas, Dan

doi:10.1109/nssmic.1999.842826

Cited by 4 publications

(3 citation statements)

References 10 publications

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“…The point response function is symmetric for the conventional parallel-hole collimator. However, for the slant-hole collimator, the point response function is asymmetric (13). The point response function is elongated in the direction of angle β as shown in Figure 6.…”

Section: Methodsmentioning

confidence: 99%

Geometric Calibration and Image Reconstruction for a Segmented Slant-Hole Stationary Cardiac SPECT System

Mao

Zeng

2015

Journal of Nuclear Medicine Technology

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A dedicated stationary cardiac single-photon emission computed tomography (SPECT) system with a novel segmented slant-hole collimator has been developed. The goal of this paper is to calibrate this new imaging geometry with a point source. Methods Unlike the commercially available dedicated cardiac SPECT systems, which are specialized and can be used only to image the heart, our proposed cardiac system is based on a conventional SPECT system but with a segmented slant-hole collimator replacing the collimator. For a dual-head SPECT system, 2 segmented collimators, each with 7 sections, are arranged in an L-shaped configuration such that they can produce a complete cardiac SPECT image with only one gantry position. A calibration method was developed to estimate the geometric parameters of each collimator section as well as the detector rotation radius, under the assumption that the point source location is calculated using the central-section data. With a point source located off the rotation axis, geometric parameters for each collimator section can be estimated independently. The parameters estimated individually are further improved by a joint objective function that uses all collimator sections simultaneously and incorporates the collimator symmetry information. Results Estimation results and images reconstructed from estimated parameters are presented for both simulated and real data acquired from a prototype collimator. The calibration accuracy was validated by computer simulations with an error of about 0.1° for the slant angles and about 1 mm for the rotation radius. Reconstructions of a heart-insert phantom did not show any image artifacts of inaccurate geometric parameters. Conclusion Compared with the detector’s intrinsic resolution, the estimation error is small and can be ignored. Therefore, the accuracy of the calibration is sufficient for cardiac SPECT imaging.

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Section: Methodsmentioning

confidence: 99%

Geometric Calibration and Image Reconstruction for a Segmented Slant-Hole Stationary Cardiac SPECT System

Mao

Zeng

2015

Journal of Nuclear Medicine Technology

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“…Attenuation and the depth dependent geometric response function (GRF) were modeled in the PH as well as in the FSSH projection data [28] (Fig. 4).…”

Section: B Simulated Phantom Studymentioning

confidence: 99%

“…However, the resolution of the reconstructed images, for the three imaging geometries, was comparable after GRF compensation. The GRF for the FSSH collimator is asymmetric [28] and depends on the direction of the slant angle. The reconstructed images with GRF compensation, corresponding to iteration number 5, 6, and 6 for PH180, FSSH120, and Corresponding slices for the FSSH120 and FSSH180 imaging geometries are given in (b) and (c), respectively.…”

Section: Physical Phantom Studymentioning

confidence: 99%

Cardiac Imaging Using a Four-Segment Slant-Hole Collimator

Bal

DiBella

Gullberg

et al. 2006

IEEE Trans. Nucl. Sci.

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The main objective of this paper is to evaluate foursegment slant-hole (FSSH) SPECT for cardiac imaging. FSSH is a slant-hole collimator that is divided into four segments and arranged such that the photons from the volume of interest (VOI) are projected four times for every location of the detector. These multiple projections help to improve the sensitivity of the photons from the VOI by a factor 4 cos 3 , where is the slant angle of the collimator. Another advantage of FSSH SPECT is a reduction in the total scan time, since a gantry rotation of 2 is sufficient to satisfy Orlov's condition. That means, for a slant angle of 30 , a gantry rotation of 120 is sufficient to satisfy Orlov's condition and obtain a complete dataset. In this paper, we evaluate and compare the reconstructed images obtained using an FSSH collimator, for a gantry rotation of 180 and 120 , with those obtained from a parallel-hole (PH) SPECT system using a 180 acquisition. The reconstructed images from the three imaging geometries were compared in terms of average image noise, contrast, and percentage error, for seven different clinical count levels and for multiple noise realizations in each case. The increase in sensitivity of the FSSH system was found to translate into a proportional decrease in statistical noise for voxels in the VOI of the reconstructed images. Finally, a physical phantom study was performed using a prototype FSSH collimator. Our findings show that FSSH collimators have the potential of being the collimator of choice for cardiac SPECT imaging. Though we explore the potential of FSSH collimators for cardiac imaging in this paper, the concept can be extended for imaging other organs such as the breasts, kidney, and brain.

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