A cassette is a thin, low x-ray absorption plastic case, for holding the x-ray film. Inside the cassette are intensifying screens for the conversion of x-rays to visible light photons. The intensifying screens are mounted in close contact with the film. Mammography cassettes are equipped with single screens.

The Compton effect describes the interaction of x-ray photons with electrons, in Compton's experiment in 1922/23 the electrons of graphite atoms. The x-ray photons scatter (Compton scattering) off the electrons in different directions. The remaining energy (lower frequency) of the scattered x-ray photons depends on the scattering angle. From an energy based point of view, these 'new or old' photons are a part of the original energy, represented by the incident x-ray photon before the interaction. The photons loss of energy (reduced frequency) is gained by an electron. Depending on this energy the electron could leave the atom. Depending on the remaining energy of the photon the interaction can repeat with a more to more decreasing energy level in the form of further Compton Scattering or by photo-electric absorption. Usually the Compton effect involves atom-bound electrons.
The Compton effect is responsible for most scattering effects in radiography.

Contrast is the relative difference of intensities in two adjacent regions of an image. When referring to computed tomography (CT), contrast is defined as a difference in Hounsfield units between structures. The measurement of contrast resolution in CT imaging involves determining how easy it is to differentiate tissues whose CT density is similar to that of their surroundings. An image lacks contrast when there are no sharp differences between black and white. Brightness refers to the overall lightness or darkness of an image.
The contrast between air, soft tissue, and bones in x-ray and CT images is based on their different absorption of x-rays. Differences in tissue density, thickness and changes of the x-ray spectrum have consequences for image contrast, image noise as well as patient dose.
Optimized tube current, collimation, pitch and image reconstruction improves the contrast. Higher image contrast is produced by increased slice thickness, smaller matrix, and large field of view which results in large voxel size; high mAs to reduce noise; low pass filter.

See also Contrast Enhanced Computed Tomography.

Conventional (also called analog, plain-film or projectional) radiography is a fundamental diagnostic imaging tool in the detection and diagnosis of diseases. X-rays reveal differences in tissue structures using attenuation or absorption of x-ray photons by materials with high density (like calcium-rich bones).
Basically, a projection or conventional radiograph shows differences between bones, air and sometimes fat, which makes it particularly useful to asses bone conditions and chest pathologies. Low natural contrast between adjacent structures of similar radiographic density requires the use of contrast media to enhance the contrast.
In conventional radiography, the patient is placed between an x-ray tube and a film or detector, sensitive for x-rays. The choice of film and intensifying screen (which indirectly exposes the film) influence the contrast resolution and spatial resolution. Chemicals are needed to process the film and are often the source of errors and retakes. The result is a fixed image that is difficult to manipulate after radiation exposure. The images may be also visualized on fluoroscopic screens, movies or computer monitors.
X-rays emerge as a diverging conical beam from the focal spot of the x-ray tube. For this reason, the radiographic projection produces a variable degree of distortion. This effect decreases with increased source to object distance relative to the object to film distance, and by using a collimator, which let through parallel x-rays only.
Conventional radiography has the disadvantage of a lower contrast resolution. Compared with computed tomography (CT) and magnetic resonance imaging (MRI), it has the advantage of a higher spatial resolution, is inexpensive, easy to use, and widely available. Conventional radiography can give high quality results if the technique selected is proper and adequate. X-ray systems and radioactive isotopes such as Iridium-192 and Cobalt-60 for generating penetrating radiation, are also used in non-destructive testing.

See also Computed Radiography and Digital Radiography.

Gastrografin® is a water-soluble iodinated radiopaque contrast agent for x-ray examinations of the esophagus, stomach, proximal small intestine, colon and is also used for bowel visualization in abdominal computer tomograms.
The high opacification and delineation after oral or rectal administration is caused by a low absorption of the intact gastrointestinal tract. However, visualization of the distal small bowel is generally unsatisfactory, since the hypertonicity of the medium causes intraluminal diffusion of water with subsequent dilution.