Seven-pinhole tomography--a technical description.

A single-photon emission tomography system was developed and studied. Based upon a seven-pinhile-collimated Anger camera, interfaced to a digital minicomputer, this imaging configuration yielded seven independent, nonoverlapping projection images of the radioactivity in a commonly viewed volume. The computer was used to implement an iterative algorithm that processed these projections to yield a three-dimensional reconstruction of the soruce distribution. The algorithm provudes a nonlinear first approximation to the reconstruction, then use a single iteration technique to reduce errors resulting from that approximation. Point spread functions (PSF) at various distances from the collimator face, and point-source sensitivity (PSS) at a location in the middle of the reconstruction volume were determined. The system was used for thallium-201 imaging, where it was shown to reduce imaging time and increase sensitivity without loss in specificity when compared with standard parallel-hole-collimated imaging. Seven-pinhole tomography is a practical three-dimensional imaging system that has been demonstrated to be useful in the emission cardiology setting.