New Approaches in SPECT Breast Imaging
Annual summary rept. 1 Jul 2001-30 Jun 2001
DUKE UNIV DURHAM NC
Pagination or Media Count:
Parallel-beam Tilted-Head SPECT TH-SPECT was implemented on a SPECT system for its potential to image breast lesions and nearby axilla of seated, upright women. Breast, liver, and myocardial activity were included in order to simulate direct contamination and Compton scattering expected in clinical scans. Results indicated an increase in axial blurring with greater tilt angle. Reconstructions of combined fillable breast and torso phantoms containing two 1.15 ml lesions were most clearly visible in the 30 reconstructed TH-SPECT images, providing lesion SNR and contrast improvements of nearly three times compared to the high-count planar images Because it is not clear which reconstruction method, if any, is better suited for TH-SPECT data, a geometric derivation of the ramp filter for tilted parallel-beam geometries was explored. A filtered backprojection FBP algorithm, using this filter, was then implemented and compared with an iterative Ordered Subsets Expectation Maximization OSEM algorithm, using TH-SPECT data. Results indicated OSEM SNR and contrast values were higher at all degrees of tilt and may offer better shape and uniform activity distribution of the breast compared to FBP methods.
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