Evaluation of iterative methods for aperture correction in SPECT

Haruta, Nobuhiro; Ogawa, Kōichi

doi:10.1002/scj.20158

Cited by 4 publications

(4 citation statements)

References 14 publications

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“…Computed Tomography for Gases (CTG) is the task of deriving gas distribution models from localized integral concentration measurements (Bennetts et al, 2014;Byer, 1979;Price et al, 2001). CTG models can be either grid-based or parametric: gridbased approaches estimate the concentrations at each cell from a set of integral concentration measurements (Haruta & Ogawa, 2005;Trincavelli et al, 2012), whereas parametric approaches use, e.g. the integral measurements to fit functional parameters of an analytic function, e.g.…”

Section: Related Workmentioning

confidence: 99%

Aerial-based gas tomography – from single beams to complex gas distributions

Neumann

Kohlhoff

Hüllmann

et al. 2019

European Journal of Remote Sensing

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In this paper, we present and validate the concept of an autonomous aerial robot to reconstruct tomographic 2D slices of gas plumes in outdoor environments. Our platform, the so-called Unmanned Aerial Vehicle for Remote Gas Sensing (UAV-REGAS), combines a lightweight Tunable Diode Laser Absorption Spectroscopy (TDLAS) gas sensor with a 3-axis aerial stabilization gimbal for aiming at a versatile octocopter. While the TDLAS sensor provides integral gas concentration measurements, it does not measure the distance traveled by the laser diode's beam nor the distribution of gas along the optical path. Thus, we complement the setup with a laser rangefinder and apply principles of Computed Tomography (CT) to create a model of the spatial gas distribution from a set of integral concentration measurements. To allow for a fundamental ground truth evaluation of the applied gas tomography algorithm, we set up a unique outdoor test environment based on two 3D ultrasonic anemometers and a distributed array of 10 infrared gas transmitters. We present results showing its performance characteristics and 2D plume reconstruction capabilities under realistic conditions. The proposed system can be deployed in scenarios that cannot be addressed by currently available robots and thus constitutes a significant step forward for the field of Mobile Robot Olfaction (MRO).

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Section: Related Workmentioning

confidence: 99%

Aerial-based gas tomography – from single beams to complex gas distributions

Neumann

Kohlhoff

Hüllmann

et al. 2019

European Journal of Remote Sensing

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“…For the iterative reconstruction [14][15][16], we have proposed an analogous two-step deblurring procedure in which the first step is the same, i.e., each projection is deconvolved by the conventional noniterative procedure, but the second step (iterative deconvolution), to suppress the blurring introduced by the lowpass filtering in the first step, is not performed explicitly but is rather merged with the iterative reconstruction procedure itself. The iterative reconstruction algorithm used in this research is multiplicative simultaneous iterative reconstruction technique (MSIRT) [17], and we expect similar results for the other iterative reconstruction techniques. The simulation and EPRI experimental results suggest that the proposed deblurring scheme generates images with substantial improvement in the reconstruction quality for both the FBP and the MSIRT for a variety of imaging parameters including different SNR and gradient strengths.…”

Section: Introductionmentioning

confidence: 56%

“…A detailed comparison of various iterative reconstruction techniques for EPRI is left for further studies. An iteration of MSIRT [17], after taking into account the transfer function, is given by…”

Section: Iterative Reconstructionmentioning

confidence: 99%

Enhanced resolution for EPR imaging by two-step deblurring

Ahmad

Clymer

Vikram

et al. 2007

Journal of Magnetic Resonance

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The broad spectrum of spin probes used for electron paramagnetic resonance imaging (EPRI) result in poor spatial resolution of the reconstructed images. Conventional deconvolution procedures can enhance the resolution to some extent but obtaining high resolution EPR images is still a challenge. In this work, we have implemented and analyzed the performance of a postacquisition deblurring technique to enhance the spatial resolution of the EPR images. The technique consists of two steps; noniterative deconvolution followed by iterative deconvolution of the acquired projections which are then projected back using filtered backprojection (FBP) to reconstruct a high resolution image. Further, we have proposed an analogous technique for the iterative reconstruction algorithms such as multiplicative simultaneous iterative reconstruction technique (MSIRT) which can be a method of choice for many applications. The performance of the suggested deblurring approach is evaluated using computer simulations and EPRI experiments. Results suggest that the proposed procedure is superior to the standard FBP and standard iterative reconstruction algorithms in terms of meansquare-error (MSE), spatial resolution, and visual judgment. Although the procedure is described for 2D imaging, it can be readily extended to 3D imaging.

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“…In the correction of scattered photons we used a model-based method with a scatter response function [17]- [18]. The aperture correction was performed with a method [19] typically used in iterative image reconstruction. And to reduce the effect of quantum noise we used a Butterworth filter.…”

Section: B Performance Of the Spect Systemmentioning

confidence: 99%

Development of a prototype semiconductor gamma-camera system

Ogawa

Ishikawa

Shuto

et al. 2009

2009 IEEE Nuclear Science Symposium Conference Record (NSS/MIC)

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We made a prototype gamma camera system with CdZnTe semiconductor detectors that work at room temperature. The effective field of view of this detector is 195 × 156 mm 2 with a pixel size of 2.46 × 2.46 mm 2 . We evaluated the performance of the detector in terms of the energy resolution, intrinsic spatial resolution, system spatial resolution and system sensitivity. The performance of the detector was evaluated with methods based on the NEMA standard (NU1). The results showed that the mean energy resolution was 5.55 % FWHM for 99m Tc, the intrinsic spatial resolution 2.46 mm FWHM, the system spatial resolutions 7.1 mm FWHM (without scatterer) and 7.4 mm FWHM (with scatterer), and the system sensitivity 46.3 cps/MBq. The performance of the system was also evaluated with some SPECT phantoms and the feasibility of the detector was confirmed with the SPECT images.

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Evaluation of iterative methods for aperture correction in SPECT

Cited by 4 publications

References 14 publications

Aerial-based gas tomography – from single beams to complex gas distributions

Aerial-based gas tomography – from single beams to complex gas distributions

Enhanced resolution for EPR imaging by two-step deblurring

Development of a prototype semiconductor gamma-camera system

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