Attenuation effects in gamma-camera coincidence imaging

Images produced by gamma camera coincidence (GCC) techniques fall into a much lower count-density regime than those produced by PET. We examine the effects of attenuation and attenuation correction on GCC images using gamma-camera emission data and PET emission and transmission data from phantom and human studies. The effects studied include contrast, noise, and general image appearance. Results show that lung lesion contrast is improved but the signal to noise ratio is slightly degraded by the application of attenuation correction. Additionally the corrected images do not contain the distortions of the uncorrected images and they more accurately show the activity distribution of the imaged object. The net result is that lesions in the corrected images are more detectable and can be more accurately localized than in the uncorrected images.