Gamma camera radionuclide images: improved contrast with energy-weighted acquisition

An energy-weighted acquisition (EWA) technique has been developed that utilizes all scintillation events, weighting their contributions depending on their energy, to formulate a radionuclide image. Photopeak events from primary radiation contribute positively; scatter events contribute negatively, providing for scatter subtraction and improved image contrast. EWA is employed with an on-line weighted-acquisition module (WAM) as the data are acquired, rather than as a postprocessing technique. EWA was compared with normal window imaging in patients and in phantoms. For gallium-67 and thallium-201, contrast improved by as much as 40%. A much smaller improvement in contrast was observed with technetium-99m due to its ideal monoenergetic emissions. Single photon emission computed tomographic studies also showed improved contrast and were without artifact. EWA has great promise, and with further development quantitative scatter correction may be possible.