IMAGING PROPERTIES OF A HALF-INCH SODIUM-IODIDE GAMMA-CAMERA

Because of the interest in low-cost instrumentation for imaging positr on emitters and because of the low detection efficiency of conventiona l 3/8'' NaI(Tl) gamma cameras for 511 keV photons, basic imaging chara cteristics have been evaluated on a SPECT system with 1/2'' NaI(Tl) de tectors. Intrinsic spatial resolution was measured at 70, 140, and 511 keV to be 6.3 mm, 4.3 mm, and 3.2 mm FWHM, respectively. Counting eff iciency at 511 keV increased 55% over a similar 3/8'' system. Other pa rameters relevant to collimated and coincidence imaging were evaluated , including spatial linearity, spatial resolution vs. incidence angle, and energy resolution. Performance was considered to be acceptable fo r conventional applications, and significantly improved for 511 keV ap plications.