Digital Radiography and PACS Flashcards

Image processing in digital radiography uses lookup tables (LUTs) to:

Answer: Map raw detector pixel values to displayed gray levels, controlling image brightness and contrast

LUTs (lookup tables) are mathematical functions that map raw detector pixel values to gray-level output values on the display, controlling image brightness, contrast, and tone mapping.

In PACS workflow, the term 'hanging protocol' refers to:

Answer: Pre-configured display settings that automatically arrange and display images in a specific layout for a particular exam type

Hanging protocols are pre-configured display configurations that automatically organize and display images in a consistent layout (window/level, orientation, comparison series) when a specific exam type is opened.

The quantum sink in a digital imaging chain refers to:

Answer: The step in the imaging process where the fewest number of information carriers (photons, electrons) are present, limiting the SNR of the final image

The quantum sink is the point in the imaging chain where signal quanta are fewest — this step limits the ultimate signal-to-noise ratio (SNR) of the entire system regardless of other improvements.

Spatial resolution in digital radiography is limited primarily by:

Answer: Detector pixel size (sampling frequency) and the detector's modulation transfer function (MTF)

Spatial resolution in digital radiography is limited by the physical pixel size (which sets the Nyquist sampling limit) and the MTF of the detector (which describes signal fidelity across spatial frequencies).

The IHE (Integrating the Healthcare Enterprise) initiative in radiology is designed to:

Answer: Define implementation profiles that specify how DICOM and HL7 standards should be used to enable seamless system integration and workflow

IHE creates implementation profiles (integration profiles) that specify how existing standards like DICOM and HL7 should be implemented to achieve specific clinical workflow goals across different vendors' systems.

When a digital radiograph shows a 'grid line' artifact (Moiré pattern), the most likely cause is:

Answer: Misalignment between the spatial frequency of the grid and the sampling frequency of the DR detector

Moiré patterns in digital radiography occur when the frequency of the antiscatter grid lines is close to the sampling frequency of the DR detector pixels, causing a beat frequency interference pattern.