Final answer:
Cesium Iodide and Silicon are used in direct conversion flat panel image detectors, which convert incident radiation directly into an electrical current without a light conversion step.
Step-by-step explanation:
Cesium Iodide (CsI) and Silicon are utilized in direct conversion flat panel image detectors. These solid-state radiation detectors are semiconductors engineered to directly convert incident radiation into an electrical current. This process of direct conversion means that when ionizing radiation interacts with the semiconductor material, the energy is immediately converted into an electric signal, which is then used to construct an image.
Unlike scintillator systems that first convert radiation to light and then to an electrical signal, direct conversion detectors efficiently convert the energy deposition from radiation exposure into an electrical response without the intermediate light conversion step.