scholarly journals Transmission Scan

2020 ◽  
Author(s):  
Keyword(s):  
Transmission Scan

PET/MRI/VCT: Restoration of Virtual CT from Transmission Scan on PET/MRI Using Joint-Anisotropic Diffusion

2015 ◽  
pp. 25-33
Author(s):  
Kuangyu Shi ◽  
Xiaoyin Cheng ◽  
Nassir Navab ◽  
Stefan Foerster ◽  
Sibylle I. Ziegler
Keyword(s):  
Anisotropic Diffusion ◽  
Transmission Scan ◽  
Virtual Ct

A Tomographic Segmented Gamma Scanner for the Measurement of Decommissioning Wastes

2003 ◽  
Author(s):  
J. A. Mason ◽  
A. C. Tolchard ◽  
A. C. N. Towner ◽  
K. Burke ◽  
R. A. Price ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Isotopic Ratio ◽  
Source Distribution ◽  
Geometric Transformation ◽  
Measurement Technology ◽  
Emission Data ◽  
Attenuation Coefficients ◽  
Distribution Maps ◽  
Transmission Scan ◽  
The Matrix

The ANTECH Tomographic Segmented Gamma Scanner (TSGS) combines: a) Conventional Segmented Gamma Scanner (SGS) analysis (compliant to ASTM C1133-96), b) Tomographic Gamma Scanner (TGS) analysis providing both attenuation and source distribution maps (effectively 3D images) of the interior of drums, and c) Isotopic ratio analysis for uranium and transuranic elements using PC-FRAM. In SGS mode the drum is rotated and scanned segment by segment along its height. A two-pass measurement, one for transmission and one for emission, results in two spectra for each segment. An assay is made by measuring the intensity of a characteristic gamma ray from each nuclide. Corrections are made for count rate-related losses and attenuation by the item (using a transmission source). Calibration standards are used to provide the relationship between observed gamma-ray intensity and nuclide content. On completion, count rates are summed, and mass values for the nuclides of interest in the entire drum are calculated based on comparisons to appropriate calibration materials. In the case of SGS, the matrix is assumed to be homogeneous on a segment by segment basis. TGS involves measuring drums in segments as for SGS. However, in the case of TGS, while the drum is rotated, it is also moved in the horizontal direction (translated). Also, instead of taking a single large spectrum for each segment, 150 separate spectra are taken as the drum rotates and is translated. These 150 spectra are obtained both for transmission and for emission measurements. The 150 spectra taken for transmission constitute a set of data that can be solved to yield the distribution, or map of attenuation coefficients throughout the segment of the sample or drum. The measurement equations are over specified and the solution uses a maximum likelihood analysis. This results in the determination of a map (after a geometric transformation) of attenuation coefficients in a rectangular grid suitably superimposed on each segment. The attenuation map enables the operator to ‘visulise’ the variation of the density (governed by the collimator size and voxe resolution) in regions of the drum. This serves a non-destructive examination function similar to ‘real time radiography’ but with lower resolution. For the analysis of the emission data, the additional information obtained from the transmission data allows the emission data to be corrected for attenuation. This attenuation correction is the essential and important characteristic of TGS measurements not present in other gamma-ray measurement systems. For the first time in the case of the TGS, the map of attenuation is used to correct the measured source distribution in the matrix (segment by segment). The TSGS extends the range of gamma-ray measurement technology, as it is able to correctly determine the attenuation corrected radionuclide inventory in heterogeneous matrices where previous techniques such as the SGS are only applicable to homogeneous matrices. In the case of TGS a single calibration based on a non-interfering or empty matrix is made and then corrections relating back to this non-interfering matrix are made using the attenuation information determined from the transmission scan.

Attenuation correction of a flat table top for radiation therapy in hybrid PET/MR using CT- and 68Ge/68Ga transmission scan-based μ-maps

2019 ◽  
Vol 65 ◽  
pp. 76-83 ◽  
Author(s):  
Stephan Witoszynskyj ◽  
Piotr Andrzejewski ◽  
Dietmar Georg ◽  
Marcus Hacker ◽  
Tufve Nyholm ◽  
...  
Keyword(s):  
Radiation Therapy ◽  
Attenuation Correction ◽  
Transmission Scan

Diagnostic Value of Blood Pool and Transmission Scan in Cardiovascular and Tissue Pathology of the Thoracic Midline

CHEST Journal ◽  
1975 ◽  
Vol 67 (1) ◽  
pp. 65-68
Author(s):  
M. Demedts ◽  
M. DeRoo ◽  
J. Bruggeman ◽  
J. Rutten ◽  
J. Cosemans
Keyword(s):  
Diagnostic Value ◽  
Blood Pool ◽  
Transmission Scan

Effect of scatter and attenuation correction in ROI analysis of brain perfusion scintigraphy

2007 ◽  
Vol 46 (03) ◽  
pp. 101-106 ◽  
Author(s):  
J. Hashimoto ◽  
K. Ogawa ◽  
A. Kubo ◽  
A. Fukunaga ◽  
S. Onozuka ◽  
...  
Keyword(s):  
Attenuation Correction ◽  
Single Photon ◽  
Scatter Correction ◽  
Photon Emission ◽  
Brain Perfusion ◽  
Projection Data ◽  
Reference Area ◽  
Whole Brain ◽  
Transmission Scan ◽  
Nonuniform Attenuation Correction

SummaryThe aim of this study was to evaluate the effect of scatter and attenuation correction in region of interest (ROI) analysis of brain perfusion single-photon emission tomography (SPECT), and to assess the influence of selecting the reference area on the calculation of lesion-to-reference count ratios. Patients, methods: Data were collected from a brain phantom and ten patients with unilateral internal carotid artery stenosis. A simultaneous emission and transmission scan was performed after injecting 123I-iodoamphetamine. We reconstructed three SPECT images from common projection data: with scatter correction and nonuniform attenuation correction, with scatter correction and uniform attenuation correction, and with uniform attenuation correction applied to data without scatter correction. Regional count ratios were calculated by using four different reference areas (contralateral intact side, ipsilateral cerebellum, whole brain and hemisphere). Results: Scatter correction improved the accuracy of measuring the count ratios in the phantom experiment. It also yielded marked difference in the count ratio in the clinical study when using the cerebellum, whole brain or hemisphere as the reference. Difference between nonuniform and uniform attenuation correction was not significant in the phantom and clinical studies except when the cerebellar reference was used. Calculation of the lesion-to-normal count ratios referring the same site in the contralateral hemisphere was not dependent on the use of scatter correction or transmission scan-based attenuation correction. Conclusion: Scatter correction was indispensable for accurate measurement in most of the ROI analyses. Nonuniform attenuation correction is not necessary when using the reference area other than the cerebellum.

Three-dimensional PET emission scan registration and transmission scan synthesis

1997 ◽  
Vol 16 (5) ◽  
pp. 542-561 ◽  
Author(s):  
Chung-Lin Huang ◽  
Wen-Tsang Chang ◽  
Liang-Chih Wu ◽  
Jiunn-Kuen Wang
Keyword(s):  
Three Dimensional ◽  
Transmission Scan ◽  
Scan Registration

scholarly journals Absolute Quantitation in Neurological PET: Do We Need it?

1991 ◽  
Vol 11 (1_suppl) ◽  
pp. A3-A16 ◽  
Author(s):  
S. C. Strother ◽  
J-S. Liow ◽  
J. R. Moeller ◽  
J. J. Sidtis ◽  
V. J. Dhawan ◽  
...  
Keyword(s):  
Disease Progression ◽  
Region Of Interest ◽  
Immune Deficiency Syndrome ◽  
Deficiency Syndrome ◽  
Image Resolution ◽  
Control Group ◽  
Scaling Effects ◽  
Absolute Quantitation ◽  
Transmission Scan ◽  
Multivariate Procedures

This article addresses the question posed in the title by examining the effects of parameters traditionally associated with improved absolute quantitation, on the analysis of 12 acquired immune deficiency syndrome dementia complex (ADC) patients compared to a normal control group. Results are discussed within the framework of the subprofile scaling model (SSM) for analyzing patterns of regional covariation. It is demonstrated that the ability to extract measures of group discrimination and disease progression are unaffected by (1) limited improvements in image resolution, (2) the use of transmission scan smoothing, (3) the application of a scatter deconvolution correction, and (4) converting region-of-interest measurements of counts per voxel to measurements of regional CMRglc. This “robustness” of the SSM approach is partly due to the extraction of disease-related subject weights, independent of any subject's global scaling effects. It is argued that other analysis techniques that initially reduce intersubject variation (e.g., using regional ratios or normalizing by global metabolic rates before applying traditional multivariate procedures) lack analytic features that may be important to identify multidimensional, disease-related image patterns. Based on the ADC patient data, it is concluded that measures of group discrimination and disease progression will not necessarily benefit from the optimization of parameters traditionally associated with improved absolute quantitation.

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