Radiation Protection, Equipment Shielding, and Exposure Factors

Vocabulary flashcards covering X-ray tube shielding, secondary barriers, console controls, collimation, filtration, and radiation protection principles.

Leakage Radiation

Any X-rays that escape through the protective tube housing rather than the collimator port when operating at maximum voltage.

Primary Shielding

Radiation shielding positioned anywhere the X-ray tube can aim directly, engineered to withstand the full potential beam energy (maximum kVp).

Secondary Barrier

Protective barriers designed to attenuate scatter radiation rather than the primary beam, such as control booth windows or non-primary walls.

Radiolucent

The property of a material (such as a wood and carbon fiber composite examination table) that allows X-rays to pass through without appearing on the finished image or altering exposure.

Source-to-Image Distance (SID)

The distance from the X-ray tube target to the image receptor; standard practice requires maintaining at least $40\,\text{inches}$ (or $36\,\text{inches}$ where calibrated) to reduce patient entrance dose caused by beam divergence.

Detents

Mechanical stops that align the X-ray tube at fixed distances (such as $72\,\text{inches}$), which regulatory standards often require to be calibrated within an error margin of $1\%$ to $2\%$.

Aperture

The opening and closing mechanism of the collimator light field, which is round in a C-arm fluoroscopy unit and square in standard radiography systems.

Tight Collimation

The restriction of the exposed X-ray field size strictly to the anatomical area of clinical interest, primarily functioning to decrease undesirable scatter radiation and patient dose.

Inherent Filtration

Filtration naturally present in the construction of the X-ray tube assembly, consisting of the glass envelope and the surrounding insulating oil.

Added Filtration

Absorbing materials intentionally placed into the primary beam path (such as aluminum sheets mounted in the collimator box) to remove low-energy photons below $40\,\text{kVp}$.

Aluminum Filter

A lightweight, low-density metallic filter whose molecular structure allows diagnostic photons to penetrate while selectively absorbing non-diagnostic photons under $40\,\text{kVp}$.

Underexposure

An exposure error that compromises image quality and is considered as hazardous to cumulative patient dose as overexposure because it necessitates repeating the projection.