AN SVD STUDY OF TRUNCATED TRANSMISSION DATA IN SPECT

Even though a noiseless, band-limited function is uniquely determined by its values in a local region, single photon emission computed tomog raphy (SPECT) projections are not band-limited, and unmeasured project ions may not be possible to be exactly estimated from the measured dat a. Projections from all views should be considered simultaneously and are modeled as a set of linear equations. The singular value decomposi tion (SVD) method is used to analyze and solve the equations. It is sh own that truncation does not always result in an underdetermined probl em, yet the problem may be ill-conditioned. An inaccurate pixel model may cause reconstruction artifacts via mismatch between the measured d ata and the modeled projections.