Dosimetrists calculate the dose of radiation. To secure sufficient tumor destruction while sparing the normal tissues, a number of (often) complex treatment plans are developed.
The Medical Dosimetrist Certification Board certifies dosimetrists. Dosimetrists work with the physician and the medical physicist to choose the treatment plan that is best for each patient. A dosimetrist may start as a radiation therapist and become with intensive training a dosimetrist. Others are graduates of dosimetry programs.

Dosimetry is the science or technique of determining a radiation dose.

Patents can unintended respond with an idiosyncratic reaction to the application of contrast media. Idiosyncratic reactions to contrast agents start usually within 20 minutes after injection and occur more frequently in patients 20 to 40 years old.
Idiosyncratic reactions may or may not be dependent on the amount of dose injected, the speed of injection, the mode of injection and the radiographic procedure.


See also Adverse Reaction and Anaphylactoid Reaction.

Image quality is an important value of all radiographic imaging procedures. Accurate measures of both image quality and patient radiation risk are needed for effective optimization of diagnostic imaging. Images are acquired for specific purposes, and the result depends on how well this task is performed. The imaging performance is mainly influenced by the imaging procedure, examined object, contrast agents, imaging system, electronic data processing, display, maintenance and the operator. Spatial resolution (sharpness), contrast resolution and sensitivity, artifacts and noise are indicators of image quality.
A high image contrast provides the discrimination between tissues of different densities.
The image resolution states the distinct visibility of linear structures, masses and calcifications.
Noise and artifacts degrade the image quality. In computed tomography (CT), high spatial resolution improves the visibility of small details, but results in increased noise. Increased noise reduces the low contrast detectability. Noise can be reduced by the use of large voxels, increased radiation dose, or an additional smoothing filter, but this type of filter increases blurring.
An image acquisition technique taking these facts into account maximizes the received information content and minimizes the radiation risk or keeps it at a low level.

See also As Low As Reasonably Achievable.

An intensifying screen is used to intensify the x-ray effect during radiation exposure of the x-ray film. Approximately 5% of the x-ray photons will be absorbed by the film only. Intensifying screens consist of a sheet of inorganic salts that emits fluorescent light when stroked by x-rays. The fluorescent input and output screens of the image intensifier are very similar to intensifying screens.
Calcium tungstate and rare earths are two common salts (also called phosphors) used for intensifying screens. For example, a calcium tungstate (CaWo4) screen can absorb around 40% of the x-ray photons and convert the radiation into light photons. A basic feature of this screen types is related to the position of the k-edge on the energy axis. Tungsten (W) is a heavy element has a k-edge at 69.5 keV, while that for rare earth elements is in around 50 keV.
The fraction of x-rays absorbed by a screen is depending on the speed. Factors affecting the speed of a screen: Mammography cassettes contain usually one intensifying screen, but most others use two screens per film cassette. The intensifying screen as part of a film screen system has been an important component in radiology to reduce the radiation dose of the patient. Today, the conventional film cassette is being replaced by an imaging plate used in digital systems.

See also Actinides, Cinefluorography and Added Filtration.