Optimization of energy window and evaluation of scatter compensation methods in MPS using the ideal observer with model mismatch

2015 ◽  
Author(s):  
Michael Ghaly ◽  
Jonathan M. Links ◽  
Eric Frey
Keyword(s):  
Ideal Observer ◽  
Energy Window ◽  
Model Mismatch ◽  
Scatter Compensation ◽  
Compensation Methods ◽  
The Ideal

Effect of Dual and Triple Energy Window Scatter Correction Methods on Image Quality in Liver Scintigraphy

1998 ◽  
Vol 37 (07) ◽  
pp. 239-244 ◽  
Author(s):  
K. Perisinakis ◽  
N. Karkavitsas ◽  
N. Gourtsoyiannis ◽  
J. Damilakis
Keyword(s):  
Signal To Noise Ratio ◽  
Scatter Correction ◽  
Energy Window ◽  
Planar Imaging ◽  
Signal To Noise ◽  
Liver Scintigraphy ◽  
Scatter Compensation ◽  
Compensation Methods ◽  
Hepatic Imaging ◽  
Noise Ratio

Summary Aim: To investigate the effect of two scatter correction methods on lesion detectability for both planar and tomographic hepatic imaging. Methods: All planar and tomographic acquisitions involved simultaneous collection of photons in the main photopeak window (126-1 54 keV) and three additional windows (92-116, 116-126 and 154-164 keV). Uncorrected and corrected for scatter images were obtained from the same acquisition data. The dual energy window (DEW) and the triple energy window (TEW) scatter compensation methods were used to obtain two sets of corrected images. The DEW method was implemented with main photopeak window 126-154 keV, Compton scatter window 92-126 keVand scatter multiplier k = 0.5. A modified TEW method was also applied with main photopeak window 126-154 keV and scatter subwindows 116-126 keV and 154-164 keV. Phantoms were used to study the effect of scatter correction on contrast and signal-to-noise ratio. The observer’s ability to identify lesions was studied on uncorrected and corrected for scatter patient images. Results: In planar imaging, both scatter compensation methods yielded contrast enhancement. However signal to noise ratio (SNR) was degraded to 0.63 and 0.67 when DEW and TEW were applied respectively. In SPECT images, contrast was increased by a factor of 2.4 and 1.7, while SNR was degraded to 0.60 and 0.64 when DEW and TEW methods were used respectively. Conclusions: Scatter correction using DEW and TEW methods may improve observer’s ability to distinguish lesions in planar (p<0.05 for both methods) and SPECT (p<0.05 for both methods) liver studies.

Model mismatch and the ideal observer in SPECT

2013 ◽  
Author(s):  
Michael Ghaly ◽  
Jonathan M. Links ◽  
Yong Du ◽  
Eric C. Frey
Keyword(s):  
Ideal Observer ◽  
Model Mismatch ◽  
The Ideal

Object Detection Using an Ideal Observer Model

2020 ◽  
Vol 2020 (16) ◽  
pp. 41-1-41-7
Author(s):  
Orit Skorka ◽  
Paul J. Kane
Keyword(s):  
Object Detection ◽  
Matched Filter ◽  
Image Sensors ◽  
Ideal Observer ◽  
Noise Power ◽  
Relative Evaluation ◽  
Detection And Identification ◽  
Cross Correlation Analysis ◽  
Observer Model ◽  
The Ideal

Many of the metrics developed for informational imaging are useful in automotive imaging, since many of the tasks – for example, object detection and identification – are similar. This work discusses sensor characterization parameters for the Ideal Observer SNR model, and elaborates on the noise power spectrum. It presents cross-correlation analysis results for matched-filter detection of a tribar pattern in sets of resolution target images that were captured with three image sensors over a range of illumination levels. Lastly, the work compares the crosscorrelation data to predictions made by the Ideal Observer Model and demonstrates good agreement between the two methods on relative evaluation of detection capabilities.

scholarly journals Tactile orientation perception: an ideal observer analysis of human psychophysical performance in relation to macaque area 3b receptive fields

2015 ◽  
Vol 114 (6) ◽  
pp. 3076-3096 ◽  
Author(s):  
Ryan M. Peters ◽  
Phillip Staibano ◽  
Daniel Goldreich
Keyword(s):  
Cortical Neurons ◽  
Human Performance ◽  
Spatial Perception ◽  
Receptive Fields ◽  
Human Perception ◽  
Ideal Observer ◽  
Orientation Discrimination ◽  
Orientation Perception ◽  
Area 3B ◽  
The Ideal

The ability to resolve the orientation of edges is crucial to daily tactile and sensorimotor function, yet the means by which edge perception occurs is not well understood. Primate cortical area 3b neurons have diverse receptive field (RF) spatial structures that may participate in edge orientation perception. We evaluated five candidate RF models for macaque area 3b neurons, previously recorded while an oriented bar contacted the monkey's fingertip. We used a Bayesian classifier to assign each neuron a best-fit RF structure. We generated predictions for human performance by implementing an ideal observer that optimally decoded stimulus-evoked spike counts in the model neurons. The ideal observer predicted a saturating reduction in bar orientation discrimination threshold with increasing bar length. We tested 24 humans on an automated, precision-controlled bar orientation discrimination task and observed performance consistent with that predicted. We next queried the ideal observer to discover the RF structure and number of cortical neurons that best matched each participant's performance. Human perception was matched with a median of 24 model neurons firing throughout a 1-s period. The 10 lowest-performing participants were fit with RFs lacking inhibitory sidebands, whereas 12 of the 14 higher-performing participants were fit with RFs containing inhibitory sidebands. Participants whose discrimination improved as bar length increased to 10 mm were fit with longer RFs; those who performed well on the 2-mm bar, with narrower RFs. These results suggest plausible RF features and computational strategies underlying tactile spatial perception and may have implications for perceptual learning.

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