Line array transmission sources for SPECT attenuation correction—design and reconstruction

E. G. Hawman; T. D. Rempel; A. H. Vija; J. C. Engdahl

doi:10.1117/12.596081

20 April 2005 Line array transmission sources for SPECT attenuation correction: design and reconstruction

E. G. Hawman, T. D. Rempel, A. H. Vija, J. C. Engdahl

Proceedings Volume 5745, Medical Imaging 2005: Physics of Medical Imaging; (2005) https://doi.org/10.1117/12.596081
Event: Medical Imaging, 2005, San Diego, California, United States

Abstract

Correction for non-uniform attenuation in SPECT generally requires measurements of radiation transmittance through the patient and reconstruction of the data to form an attenuation image, or mu-map. For nuclear cardiac studies it useful if the emission and transmission data for each projection view can be acquired simultaneously using non-overlapping energy windows. This simplifies the registration of the emission and transmission data. Large area transmission sources are desirable to avoid data truncation; however, 2D-planar liquid sources are cumbersome and extended solid area sources of Gd-153 or Am-247 are impractical. Co-57 sheet sources present spectral overlap problems for imaging of Tc-99m tracers. With Gd-153 line arrays, one can achieve the benefits of 2D-planar sources, low truncation and simultaneous emission/transmission measurements, using lightweight static mechanical attachments to the SPECT camera system. A new method is proposed to determine optimal positions for the lines of the transmission array based on maximizing the entropy of the transmitted flux through the patient. Transmission reconstruction using parallel beam filtered back-projection yields attenuation maps with poor spatial resolution and significant aliasing effects. The degradations of image quality become worse as the angular separations of the lines as seen by the detector increase. To improve the reconstruction of line array transmission data a maximum likelihood modified gradient algorithm was derived. The algorithm takes into account emission-to-transmission down scatter as well as the overlapping of radiation patterns of the individual lines. Ordered subset versions of algorithms are explored. Image quality is assessed with simulations based on an attenuation map derived from CT.

Citation Download Citation

E. G. Hawman, T. D. Rempel, A. H. Vija, and J. C. Engdahl "Line array transmission sources for SPECT attenuation correction: design and reconstruction", Proc. SPIE 5745, Medical Imaging 2005: Physics of Medical Imaging, (20 April 2005); https://doi.org/10.1117/12.596081

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available