An imaging controller comprising an electronic processor is programmed to perform a reduced radiation dose imaging method is described. The method includes: acquiring current emission imaging data from a subject using an emission imaging system； reconstructing the current emission imaging data without attenuation correction to generate a non-attenuation corrected current emission image of the subject； generating a spatial transform to spatially align a previous non attenuation corrected emission image of the subject to the current non attenuation corrected emission image of the subject； warping a previous CT image that is spatially aligned with the previous non-attenuation corrected emission image using the spatial transform to generate a warped CT image； and reconstructing the current emission imaging data with attenuation correction performed using the warped CT image to generate an attenuation-corrected current emission image. Reconstructing the current emission imaging data with attenuation correction includes computing a CT reusability metric.
