Variable-Resolution X-ray (VRX) techniques boost spatial resolution of a Computed Tomographic (CT) scanner in the scan plane by two or more orders of magnitude by reducing the angle of incidence of the x-ray beam with respect to the detector surface. A multi-arm multi-angle VRX detector for targeted CT scanning allows for "target imaging" in which an area of interest is scanned at higher resolution than the remainder of the subject, yielding even higher resolution for the target area than that obtained from prior VRX techniques. In one embodiment, the VRX-CT detector comprises four quasi-identical arms, each containing six 24-cell modules made of individual custom CdWO4 scintillators optically-coupled to custom photodiode arrays. The maximum scan field is 40 cm for a magnification of 1.4. A significant advantage of the four-arm geometry is that it can transform quickly to a two-arm or single-arm geometry for comparison studies and other applications.