1. An imaging system comprising: a gantry having a bore extending therethrough; a plurality of image detectors attached to the gantry and radially spaced apart along a circumference of the bore at one or more predetermined intervals such that gaps exist between image detectors along the circumference of the bore; and an x-ray source attached to the gantry, wherein the x-ray source transmits x-rays across the bore towards at least two of the image detectors; wherein at least one image detector detects both emission radiation and x-ray radiation.