X-ray screening is high priority for securing borders from the influx of firearms, narcotics, and contraband. The ability of an x-ray screening system to detect photons attenuated by dense cargo directly affects the radiographic image quality that an operator uses to identify such illicit material. When screening cargo and vehicles, high-energy high-dose pulsed linear accelerators are used to generate the x rays. The detection package integrates the signal over the duration of a single pulse and this forms the basis of each pixel value in the image. However, with no means to reject low-energy photons scattered into the detectors or electronic dark current, the signals include a large degree of noise that distorts the final radiographic images. The technological advances in recent years and the exploitation of spectroscopic techniques present an opportunity to utilise novel detector material and off-the-shelf fast electronic components to identify individual photons. This will vastly improve the performance of screening systems and increase image quality, particularly in areas of high attenuation. To this end, this project seeks to investigate new detector material, design, construct and test a prototype detection system capable of photon counting in such high x-ray flux environments. Detector characterisation and design will be carried out at the University of Manchester. Experimental investigations will require the use of the new Compact Linac facility at Daresbury laboratory, capable of producing low-dose x-ray pulses so that algorithms to control the detection package can be developed and the limitations obtained. The detection package will then be used at Rapiscan Systems facility at Stoke using a field-ready linac to prove its capabilities.