Direct exposure films are highly sensitive to the direct effect of x-rays rather than in combination with an intensifying screen. However, a film is a relatively inefficient radiation detector and requires relatively high radiation exposure. The use of rectangular collimation and the highest speed films reduce radiation exposure.

See also Conventional Radiography.

A film consists of a thin, transparent sheet of polyester or similar material. Films are coated on one or both sides with an emulsion sensitive to radiation, light or heat. Films are relatively radiolucent due to their relatively low atomic number (that of silver halide).

See also X-Ray Film, Direct Exposure Film and Intensifying Screen.

When invented, a fluoroscopic system consisted of x-ray tube, fluorescent screen and x-ray table. In 1950's, the development of the image intensifier revolutionized fluoroscopes. The basic components are extended by a gantry, image intensifier, camera, film and monitor system. The x-ray tube is usually located under the patient table, in opposition to the image intensifier and film cassette or display unit. The patient table can be rotated to an upright position for certain examinations and can be lowered to horizontal position for other imaging procedures. In some instances, the unit can be operated from outside the room.
Today, the transition from conventional to digital fluoroscopy replaces the image intensifier. A flat-panel detector in combination with sensitive image sensors and digital image processing improves the diagnostic ability of a modern system.

Fluoroscopy is used to study moving body structures in real time. A fluoroscope is used to produce a continuous (advanced fluoroscopy machines provide pulsed techniques to lower the amount of radiation) x-ray beam, passing through the body part being examined and transmitted to a monitor so that dynamic images of deep tissue structures can be visualized. Fluoroscopy is primarily used for gastrointestinal exams, genitourinary studies, cardiovascular imaging and for invasive procedures performed by interventional radiologists and angiographers under fluoroscopic guidance. Fluoroscopy can also produce a static record of an image formed on the output phosphor of an image intensifier. The image intensifier is an x-ray image receptor that increases the brightness of a fluoroscopic image by electronic amplification and image minification. Modern fluoroscopy systems combine less radiation with better image quality due to digital image processing and flat-panel technology.
Roentgen's discovery of x-rays related directly to fluoroscopy, because fluorescence on the material in the room draws his attention to the x-ray's properties. In 1896, Thomas A. Edison created the first fluoroscope, consisting of a zinc-cadmium sulfide screen that was placed above the patient's body in the x-ray beam and provides a faint fluorescent image. In first-generation units, the exam room required complete darkness. The users wear red goggles for up to 30 minutes prior to the examination, to adapt the eyes to darkness. After this, the radiologist stared directly at a yellow-green fluorescent image through a sheet of lead to prevent the x-ray beam from striking the eyes.

Scintigraphic imaging of the lungs is a sensitive diagnostic imaging tool to detect certain kinds of pulmonary abnormalities in correlation with clinical data and chest radiographs. Pulmonary scintigraphy is particularly useful in diagnosing medical conditions such as pulmonary embolism, bronchial carcinoma and chronic obstructive pulmonary disease.
Lung scintigraphy can be performed with radioaerosols, gaseous radiopharmaceuticals and technetium-99m-labeled perfusion agents that are localized by temporary capillary blockade.

Different types of lung scintigraphy include:
The choice of the radioactive tracer varies and depends on the pulmonary function to be imaged. The radioactive tracer distribution within the lungs can be displayed on a computer screen via a gamma camera, a scanner or some other similarly suitable detector that records the radioactive disintegrations emitted by the patient. The images obtained present chromatic variations proportional to the regional radioactivity.