P-ascorbate was reduced by both dialysis and filtration treatments. Neither S-cobalamin nor S-folate were reduced by dialysis or filtration treatments.

Scattered photons degrade nuclear medicine image contrast and resolution, and preclude simple attenuation corrections. Current scatter correction methods utilize detected events with energies below pulse height analyzer (PHA) window levels, making attenuation corrections source position dependent. This new scatter rejection technique analyzes only the photon signals occurring within the range of standard PHA windows. In real time, at each image location the PHA window energy distribution is analyzed, a scatter fraction determined, and a scatter corrected number of events are output. The method can be adapted to any imaging system which produces event location and energy signals. Attenuation corrections (u=0.15 cm(-1), 140 keV) are within 6% for 2-10 cm depths.

An experimental procedure using edge response functions (ERF) has been devised to rapidly provide modulation transfer function (MTF) values for gamma camera imaging. Both camera intrinsic and system MTFs are generated. This procedure uses a simple test tool to generate the ERF which is then processed by a computer program using a cubic splines differentiation technique and a discrete Fourier transform algorithm to produce the MTF values. An analytic test of the computer algorithms as well as an experimental test using collimator data from the Bureau of Radiological Health is presented to confirm the accuracy of the procedure.

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