Iterative correction method for shift-variant blurring caused by collimator aperture in SPECT

Ogawa, Kōichi; Katsu, Haruto

doi:10.1007/bf03165051

Cited by 12 publications

(4 citation statements)

References 6 publications

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“…Methods of correcting the effect of the collimator include a method based on a position-independent deblurring filter [8], correction by iterative approach [9][10][11][12], and a correction procedure in Fourier transform domain intended to achieve position-dependent correction [13][14][15]. In this study, a method of performing attenuation correction and aperture correction at the same time [15] is used.…”

Section: Correction Aperturementioning

confidence: 99%

Analytical correction methods for aperture and attenuation effects in SPECT

Ishikawa

Ogawa

2006

Electron Comm Jpn Pt III

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SUMMARYThis paper is concerned with the lowering of spatial resolution by γ ray attenuation and the collimator aperture, which are serious factors degrading the quantitative performance of SPECT (single-photon emission CT). The limit of analytical correction is investigated from the viewpoint of the aperture angle and noise. The methods considered in this paper are the analytical attenuation correction proposed by Kudo and Saito and the analytical aperture correction based on the stationary phase principle proposed by Lewitt and colleagues. Both of these methods are intended to correct projection data affected by attenuation and aperture blur in the Fourier space. Simulation results show that the correction for the attenuation and the aperture is effective if the single-sided aperture is up to 1°. It is also shown that the statistical noise should be carefully handled in applying the correction.

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Section: Correction Aperturementioning

confidence: 99%

Analytical correction methods for aperture and attenuation effects in SPECT

Ishikawa

Ogawa

2006

Electron Comm Jpn Pt III

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“…Because of this, SPECT images have shift-variants, blurring that differs at the center and periphery of the image. Several methods have been proposed to compensate for this degradation in the collimator's spatial resolution: to apply a filter that removes blurring in a position-independent way [3]; to apply corrections based on Fourier regions, which allows for position-dependent corrections [4][5][6]; or to apply corrections via iterative approximations [7][8][9][10]. Of these, noise resistance is lowest with compensation methods in frequency space, so these are not much used, and iterative methods are often chosen for use in real-world clinical settings.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of iterative methods for aperture correction in SPECT

Haruta

Ogawa

2005

Syst. Comp. Jpn.

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SUMMARYThis paper uses simulations of numerical phantoms to compare the performance of different iterative-approximation methods of aperture correction in single-photon emission computed tomography (SPECT); aperture correction is employed to remove blurrings in the reconstructed image that are caused by the collimator used to acquire SPECT data. The comparisons take the size of the aperture angle, radius of the detector's rotation, and amount of Poisson noise as parameters, and follow quantitative standards as a basis for visually assessing the images obtained from seven different iterative correction methods.

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“…On the other hand, the 3D-FDR method is based on the Fourier transform of a sinogram, which is applied to projected data prior to reconstruction [10]. The 3D-FDR method, which is mainly used for filtered back projection (FBP), can be applied for OSEM [11]. Regarding DaT-SPECT imaging, improvements in image quality produced by spatial resolution correction using 3D-FDR has not been studied.…”

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Impact of Collimator on DaT-SPECT Imaging: Monte Carlo Simulation Study

Takahashi¹,

Himuro²,

Funada³

et al. 2020

RDI

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Aim: The purpose of this study was to assess the impact of the collimator in viewing the dopamine transporter, using 123I ioflupane single-photon emission computed tomography (DaT-SPECT) images utilizing a Monte Carlo simulation. Methods: For the purpose of this study, the Monte Carlo simulation of electrons and photons (MCEP)- SPECT was used. A numerical phantom was created from a real basal ganglia phantom and installed within the code. The specific binding ratios (SBRs) were 5.03 and 2.01 for the background concentration of 7.44 kBq/mL or 7.04 and 3.03 for a background concentration of 5.56 kBq/mL. The simulated images were evaluated using a recovery coefficient (RC). Initially, we simulated the performance of 14 collimators without resolution correction to investigate the impact of the collimator dimension. The effects of two resolution correction methods (collimator broad correction (CBC) and three-dimensional frequency– distance relationship (3D-FDR)) on two reconstruction methods (Ordered-Subsets Expectation Maximization (OSEM) and Filtered back projection (FBP)) was assessed for collimators that demonstrated a better RC value. Results: Five low-energy high-resolution (LEHR) collimators and one medium-energy general-purpose (MEGP) collimator demonstrated superior RC values. These collimators had a high aspect ratio (holelength/hole-diameter). The maximum RC value without resolution correction was 64.9% when the image was reconstructed with OSEM. The RC value improved to 79.7% when the resolution correction of CBC was applied. When the resolution collection was applied, the RCs improved by approximately 1.2 times when compared against those without the resolution correction. In terms of the reconstruction method, the RC obtained using OSEM was statistically insignificant when compared to the RC using FBP. The difference in the RC value with collimators decreased according to resolution correction. Conclusion: The LEHR collimator with a high aspect ratio, and the OSEM with spatial resolution correction were confirmed to be appropriate for DaT-SPECT imaging. In terms of the reconstruction method, CBC was more favourable than FDR.

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Iterative correction method for shift-variant blurring caused by collimator aperture in SPECT

Cited by 12 publications

References 6 publications

Analytical correction methods for aperture and attenuation effects in SPECT

Analytical correction methods for aperture and attenuation effects in SPECT

Evaluation of iterative methods for aperture correction in SPECT

Impact of Collimator on DaT-SPECT Imaging: Monte Carlo Simulation Study

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