Scatter modelling and compensation in emission tomography

Zaidi, Habib; Koral, Kenneth F.

doi:10.1007/s00259-004-1495-z

Cited by 187 publications

(142 citation statements)

References 45 publications

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“…2 showed that the TEW could make it possible. Our method corresponds to Zaidi et al (8) and stresses the importance of comparing clinic results with and without scatter correction. Much research has been done on this subject using phantoms, but there are few studies in clinics.…”

Section: Discussionmentioning

confidence: 99%

“…So after correction, heart defects could be found. Since King MA et al (3) and Zaidi et al (8) brought a ratio of 0.34 for scattered to unscattered (primary) counts, increase of contrast and sharpness after correction could be understood.…”

Section: Discussionmentioning

confidence: 99%

“…ANN method separated the 123I and 99m Tc primary photons well. In a clinical environment Zaidi et al stated, “researcher must be willing to compare clinics results with and without scatter correction.” (8) …”

Section: Introductionmentioning

confidence: 99%

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Scatter Correction for Heart SPECT images Using TEW method

Changizi

Takavar

Babakhani

et al. 2008

J Applied Clin Med Phys

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Radionuclide imaging has the potential to be used in quantitative analysis of the regional function of organs. However, quantification of SPECT images is degraded by many factors such as Compton photon scattering. This could have a destructive effect on clinical reports so it is important to do scatter correction to get better quality SPECT images. We intended to determine how scatter correction with the TEW method can help physicians who look at heart SPECT images, get better reports. This study used the TEW method for scatter correction, which was proposed by Ogawa et al., (9) using the two narrow windows on either side of the photopeak (20% down and 20% up of the photopeak respectively). Injection of radiopharmaceutical 99mTc was used for medical imaging. In the Shariati Hospital, Tehran, we studied a total of 80 patients with heart disease indications (43 men and 37 women) over the ages of 30–80 years. Contrast and sharpness were considerably improved after scatter correction so physicians could look at defects better. In a few cases scatter correction changed heart defect reports to normal. Using TEW, sensitivity and specificity increased from 86% to 94% and from 61% to 84% respectively. This method was simple to use in clinics.PACS numbers: 87.57.uh

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Scatter Correction for Heart SPECT images Using TEW method

Changizi

Takavar

Babakhani

et al. 2008

J Applied Clin Med Phys

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“…Iterative image reconstruction methods for emission tomography were comprehensively reviewed in [18]. Well-aligned anatomical information from hybrid scanners enabled advances of various correction methods such as attenuation corrections [19] and scatter corrections [20,21] for better quantitative and qualitative imaging [12].…”

Section: Introductionmentioning

confidence: 99%

The Use of Anatomical Information for Molecular Image Reconstruction Algorithms: Attenuation/Scatter Correction, Motion Compensation, and Noise Reduction

Chun

2016

Nucl Med Mol Imaging

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PET and SPECT are important tools for providing valuable molecular information about patients to clinicians. Advances in nuclear medicine hardware technologies and statistical image reconstruction algorithms enabled significantly improved image quality. Sequentially or simultaneously acquired anatomical images such as CT and MRI from hybrid scanners are also important ingredients for improving the image quality of PET or SPECT further. High-quality anatomical information has been used and investigated for attenuation and scatter corrections, motion compensation, and noise reduction via post-reconstruction filtering and regularization in inverse problems. In this article, we will review works using anatomical information for molecular image reconstruction algorithms for better image quality by describing mathematical models, discussing sources of anatomical information for different cases, and showing some examples.

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“…There are several parameters that affect the quality and quantitative accuracy of PET images, including positron range [1], the limited spatial resolution and resulting partial volume effect [2], contribution from scattered photons [3], photon attenuation [4], patient motion [5], and the image reconstruction algorithm [6]. Attenuation of photons in vivo degrades the visual quality and quantitative accuracy of PET images, thereby adversely affecting interpretation and quantitation of activity concentration.…”

Section: Introductionmentioning

confidence: 99%

Comparative Assessment of Energy-Mapping Approaches in CT-Based Attenuation Correction for PET

Shirmohammad

Sarkar

et al. 2010

Mol Imaging Biol

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Introduction: Reliable quantification in positron emission tomography (PET) requires accurate attenuation correction of emission data, which in turn entails accurate determination of the attenuation map (µ-map) of the object under study. One of the main steps involved in CTbased attenuation correction (CTAC) is energy-mapping, or the conversion of linear attenuation coefficients (µ) calculated at the effective CT energy to those corresponding to 511 keV. Materials and methods: The aim of this study is to compare different energy-mapping techniques including scaling, segmentation, the hybrid method, the bilinear calibration curve technique and the dual-energy approach to generate the µ-maps required for attenuation correction. In addition, our newly proposed method involving a quadratic polynomial calibration curve was also assessed. The µ-maps generated for both phantom and clinical studies were assessed qualitatively and quantitatively. A cylindrical polyethylene phantom containing different concentrations of K 2 HPO 4 in water was scanned and the µ-maps calculated from the corresponding CT images using the above-referenced energy-mapping methods. The CT images of five whole-body data sets acquired on a GE Discovery LS PET/ CT scanner were employed to generate µ-maps using different energy-mapping approaches that were compared with the µ-maps generated at 511 keV using 68 Ge/ 68 Ga rod sources. In another experiment, the evaluation was performed on PET images of a clinical study corrected for attenuation using µ-maps generated using the above described methods. The evaluation was performed for three different tissue types, namely, soft tissue, lung, and bone. Results and Discussion: All energy-mapping methods yielded almost similar results for soft tissues. The mean relative differences between scaling, segmentation, hybrid, bilinear, and quadratic polynomial calibration curve methods and the transmission scan serving as reference were 6.60%, 6.56%, 6.60%, 5.96%, and 7.36%, respectively. However, the scaling method produced the largest difference (16%) for bone tissues. For lung tissues, the segmentation method produced the largest difference (14.9%). The results for reconstructed PET imagesCorrespondence to: Mohammad R. Ay; e-mail: mohammadreza_ay@tums.ac.ir followed a similar trend. For soft tissues, all energy-mapping methods yield results in nearly the same range. However, in bone tissues, the scaling method resulted in considerable bias in the µ-maps and the reconstructed PET images. The segmentation method also produced noticeable bias especially in regions with variable densities such as the lung, since a single µ is assigned to the lungs. Apart from the aforementioned case, despite small differences in the generated µ-maps, the use of different energy-mapping methods does not affect, to a visible or measurable extent, the reconstructed PET images.

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Scatter modelling and compensation in emission tomography

Cited by 187 publications

References 45 publications

Scatter Correction for Heart SPECT images Using TEW method

Scatter Correction for Heart SPECT images Using TEW method

The Use of Anatomical Information for Molecular Image Reconstruction Algorithms: Attenuation/Scatter Correction, Motion Compensation, and Noise Reduction

Comparative Assessment of Energy-Mapping Approaches in CT-Based Attenuation Correction for PET

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