Quality Control VOCAB

quality assurance

on-going performance improvement activities that provide confidence that high quality images and services are provided

quality control

monitors technical equipment to insure it is operating within establishes tolerances

linearity is AKA

reciprocity

linearity

the changes in mA should produce proportional changes in exposure, when all other factors remain equal

law of reciprocity

any combination of mA and time that equals the same mAs should produce the same exposure

exposure reproducibility

the same set of exposure factors should always produce the same exposure intensity without varying more than 5%

half value layer (HVL)

a direct indication of the penetration power of the xr beam

higher hvl = more penetration

back up timer

should terminate exposure within 6 seconds or 600 mAs

acceptance testing

done at the time of equipment installation to confirm it is operating within set parameters and establish a baseline for follow-up QA testing

luminance

emission of light

ability to display different shades of brightness

measured in lumens (Lm)

lumen

power of light flow through space

illuminance

rate of light striking the surface

ambient light

light already present in the area before additional lighting is added

natural light from windows or artificial room lighting

primary monitor

the high-resolution monitor used by the radiologist for diagnostic purposes

used for interpretation

minimum of 2048 × 2560

secondary monitor

used by technologists which does not offer the same high resolution as the radiologist’s reading station

NOT used for interpretation

must be at least 1024 × 1280

dark noise

term used to describe noise seen on a digital image receptor that is processed without first making an exposure

degrades images

ghost images (DR)

residual image occurs when the DEL value does not return to 0 after an exposure

can occur after an excessively high exposure or from off-focus/STEM radiation

veiling glare

caused by light that scatters within the monitor

brightness uniformity

should not vary more than 10% between monitors in the same reading area

brightness between center and 4 corners of monitor should not vary more than 20% or 30% of their average

blooming

occurs when there is an unwanted change in the actual focal spot size during a change in exposure

low tube current = less expansion

high tube current = more expansion