Transverse slat collimation for asymmetric-fan transmission CT
- Rush-Presbyterian-St. Luke`s Med. Center, Chicago, IL (United States); and others
We have recently developed a new asymmetric-fan geometry for transmission CT (TCT) on SPECT systems. This new technique effectively extends the TCT field-of-view (FOV) without causing truncation problem. With an asymmetric-fan collimator (AFC). We have achieved a reconstructed FOV matching the projection width of the camera. However, this geometry is too rigidly defined that its application may have limited flexibility to accommodate very large size patients. Because the sampling of the asymmetric-fan geometry (AFG) is already defined by the location of the transmission source (TS), the role of a collimator is only to block scatters originated form the TS. Since an 1D transverse-slat-collimator (TSC) can also provide the same 2D AFG, it could be an alternative to the 2D AFC. Advantages of the slat collimator are: (1) simple and low cost due to its 1D and parallel features, (2) flexibily providing a AFG. When used in conjunction with a well collimated line source (by another small TSC) to provide co-planar fan-beam flux in all the transverse planes, a TSC could effectively block cross-plane scatters. Only the in-plane scatters could get through to the detector and could be insignificant in quantity in comparison to the directly transmitted photons. We have constructed a pair of TSC and tested its performance. With phantoms imaged on a SPECT system, we have demonstrated that the image quality of TCT derived from the TSC is close to that form an AFC. A carefully designed study to optimized technical parameters is in order. The attraction of the TSC is that the imaging FOV size is flexibly adjustable. It is possible to use two sources, placed at different positions, to extend the imaging FOV beyond the field size of SPECT systems.
- OSTI ID:
- 197904
- Report Number(s):
- CONF-940605--
- Journal Information:
- Journal of Nuclear Medicine, Journal Name: Journal of Nuclear Medicine Journal Issue: Suppl.5 Vol. 35; ISSN JNMEAQ; ISSN 0161-5505
- Country of Publication:
- United States
- Language:
- English
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