Final answer:
Direct detectors use a photoconductor to convert x-ray energy into an electrical signal. One type of direct detector is photographic film, which exposes when radiation interacts chemically with its emulsion. Another type is a solid-state radiation detector, where ionization produced in a semiconductor is converted directly into an electrical signal.
Step-by-step explanation:
Direct digital detectors use a photoconductor to convert x-ray energy, whereas indirect digital detectors use a scintillator (phosphor).
One kind of direct detector that is frequently used in dental and medical X-rays is photographic film. The way it operates is that a radioactive particle's quantum energy interacts with the film's emulsion, changing it chemically and exposing the film.
Solid-state radiation detectors are another kind of direct detectors, in which ionization generated in a semiconductor is directly translated into an electrical signal. Only when radiation produces ionization can semiconductors be built to conduct current, and the detector's current level is directly proportional to the energy deposited.