Autoradiography is the process of taking a type of picture, called an autoradiograph, which shows the relative concentration of radioactive material present within the subject. The subject is usually a biologic specimen or human body part. The photographic plate is exposed to radioactive emissions from the subject being studied, producing an image.
Radiography is the use of radioactive materials or x-rays to produce an image. Using x-rays to bombard a subject while exposing a photographic plate or film to the x-rays is the most common method for this type of imaging. Autoradiography produces a similar image but relies on emissions of alpha and beta particles and gamma rays released by the decay of radioactive substances within the subject, rather than an outside source. The resulting image will allow a a trained technician to determine the relative concentration of radioactive material and its distribution.
Sometimes scientists deliberately introduce radioactive substances into an object or tissue. The disciplines of cytology, which is the study of cells and their structure, and histology, the study of tissues and their structures, can both benefit from autoradiography. Autoradiographs can help scientists learn more about cellular and tissue structures and how radioactive materials are absorbed and distributed.
In digital autoradiography, computers and radiation detection instruments work together to provide the radiographic image. This type of autoradiography allows the study of tissues and objects over defined time periods. This technique can further enhance our knowledge of how radioactive materials disperse in tissues.
Research on chemical receptors, their distribution within tissues, and their function can also benefit from autoradiography. Biochemical agents infused with radioactive substances, called radioligands are injected into a tissue. These agents react with chemical receptors in the tissues, and when an autoradiograph is subsequently taken, it will allow the researcher to determine where these receptors are located, their relative frequency, and density of distribution. This technique is sometimes used to diagnose various medical problems.
Autoradiography may also be used to study RNA and DNA as well as the phases of cell development and function. It can also be used to isolate partial sequences of RNA and DNA for study, especially in viruses. Doctors may be able to use this technique to detect, diagnose, and devise treatment strategies for various types of radiation poisoning by determining which tissues may have absorbed radioactive materials.