Digital Imaging Display Processing and Artifacts

Vocabulary flashcards covering digital imaging histogram analysis, post-processing tools, exposure indicators, and equipment artifacts.

Positron Emission Tomography (PET)

An imaging modality utilizing a radioactive isotope that loses protons, creating higher energy that requires specific patient radiation precautions.

Histogram

A graphical representation of the collimated field of view and exposed pixels that illustrates the photon energy levels striking the detector.

Value of Interest (VOI)

The specific region of data located within the histogram that represents only the pertinent anatomical structure being imaged.

Lookup Table (LUT)

A pre-established setting configured by the radiologist that assigns standard brightness and contrast levels to the display monitor for a given exam type.

Exposure Index (EI) Number

A numerical indicator showing whether an exposure was optimal, overexposed, or underexposed compared to the required radiation amount.

Deviation Index

A value indicating how far the actual exposure falls outside of the targeted EI number, such as greater than or less than $3$.

Contrast Enhancement

A post-processing adjustment performed by the computer to alter image contrast independently of the exposure technique used.

Edge Enhancement

A post-processing tool that sharpens anatomical borders to make details crisper, aiding in visualizing subtle cortical rib fractures or tube placements.

Inversion

A processing feature that reverses pixel values by converting blacks to white and whites to black, standardly applied in fluoroscopy.

Smoothing

A post-processing technique that mathematically averages out quantum noise caused by insufficient exposure technique, which sacrifices spatial resolution.

Moiré Pattern

An artifact presenting as visible lines across an image, typically caused by improper grid function or processing errors.

Ghosted Image

An artifact occurring when residual signal from a previous high-technique exposure is not fully cleared during the detector plate's automatic erasure cycle.

Electronic Masking

Cropping or collimating the field of view after exposure has occurred to electronically cover unneeded anatomy on the display image.