13 March 2009 Evaluating low pass filters on SPECT reconstructed cardiac orientation estimation
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Proceedings Volume 7258, Medical Imaging 2009: Physics of Medical Imaging; 72582Q (2009); doi: 10.1117/12.812199
Event: SPIE Medical Imaging, 2009, Lake Buena Vista (Orlando Area), Florida, United States
Abstract
Low pass filters can affect the quality of clinical SPECT images by smoothing. Appropriate filter and parameter selection leads to optimum smoothing that leads to a better quantification followed by correct diagnosis and accurate interpretation by the physician. This study aims at evaluating the low pass filters on SPECT reconstruction algorithms. Criteria for evaluating the filters are estimating the SPECT reconstructed cardiac azimuth and elevation angle. Low pass filters studied are butterworth, gaussian, hamming, hanning and parzen. Experiments are conducted using three reconstruction algorithms, FBP (filtered back projection), MLEM (maximum likelihood expectation maximization) and OSEM (ordered subsets expectation maximization), on four gated cardiac patient projections (two patients with stress and rest projections). Each filter is applied with varying cutoff and order for each reconstruction algorithm (only butterworth used for MLEM and OSEM). The azimuth and elevation angles are calculated from the reconstructed volume and the variation observed in the angles with varying filter parameters is reported. Our results demonstrate that behavior of hamming, hanning and parzen filter (used with FBP) with varying cutoff is similar for all the datasets. Butterworth filter (cutoff > 0.4) behaves in a similar fashion for all the datasets using all the algorithms whereas with OSEM for a cutoff < 0.4, it fails to generate cardiac orientation due to oversmoothing, and gives an unstable response with FBP and MLEM. This study on evaluating effect of low pass filter cutoff and order on cardiac orientation using three different reconstruction algorithms provides an interesting insight into optimal selection of filter parameters.
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Shekhar Dwivedi, "Evaluating low pass filters on SPECT reconstructed cardiac orientation estimation", Proc. SPIE 7258, Medical Imaging 2009: Physics of Medical Imaging, 72582Q (13 March 2009); doi: 10.1117/12.812199; https://doi.org/10.1117/12.812199
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KEYWORDS
Reconstruction algorithms

Linear filtering

Single photon emission computed tomography

Image filtering

Expectation maximization algorithms

Gaussian filters

Visualization

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