A SCANNING LINE SOURCE FOR SIMULTANEOUS EMISSION AND TRANSMISSION MEASUREMENTS IN SPECT

A scanning collimated line source for simultaneously acquiring emissio n and transmission data from a gamma camera has been developed. The li ne source is microprocessor-controlled and incorporates hardware to el ectronically window the spatial gamma camera signals in order to separ ate the emission signals of the subject from transmission signals from the line source. The device improves upon the previously described em ission-transmission scanning technique using a flood source in three w ays: (1) it overcomes the limitation that the transmission radionuclid e must have a lower energy than the emission radionuclide; (2) it prov ides narrow-beam (scatter free) attenuation measurements of the subjec t being examined; and (3) it reduces the radiation exposure to staff. Attenuation coefficients for an elliptical water-filled phantom were m easured to be mu = 0.15 +/- 0.01 cm-1. The technique has been validate d in phantom and human studies using a range of radionuclide combinati ons and imaging geometries and gives equivalent results using separate and simultaneous acquisitions.