1302 - module 9 - Image Quality Factors and Digital Imaging in Radiography

Flashcards covering key concepts in image quality factors and digital imaging in radiography.

What are the two types of image quality factors?

Subjective (personal perception, visual acuity) and Objective (exposure, dose, noise, resolution).

What is the technologist's role in image quality?

To apply knowledge of image quality factors to produce diagnostic images and balance dose with image clarity.

What is the Goldilocks Principle in radiography?

The ideal exposure is not too little, not too much—just right.

What does the Exposure Index (EI) assess?

Exposure adequacy, along with noise, contrast resolution, and spatial resolution.

What is contrast resolution?

The ability to display subtle differences between similar adjacent tissues.

What does high contrast resolution show well?

Sharp differences between very different tissues like bone and air.

What type of contrast is better for showing similar tissues like muscle and fat?

Low contrast resolution with many gray shades (high dynamic range).

Which tissues show high visual contrast and why?

Bone, fat, and air—due to large differences in attenuation.

How can you improve contrast resolution in underexposed images?

Increase mAs to boost signal and reduce noise.

What is bit depth and why is it important?

Number of grayscale shades a system can display; higher bit depth = better grayscale contrast.

What is spatial resolution?

Ability to display small, distinct objects clearly.

What determines spatial resolution in digital imaging?

Size and arrangement of detector elements (similar to pixels).

What does the Line Pair Test Tool measure?

Spatial resolution in line pairs per millimeter (lp/mm).

What is Modulation Transfer Function (MTF)?

A measure of how well a system reproduces the details of the object; ideal = 1.

What is image noise?

Unwanted data in an image, including electronic noise and quantum mottle.

What causes quantum mottle?

Insufficient exposure leading to noisy images.

What is Signal-to-Noise Ratio (SNR)?

Ratio of useful signal to noise; higher SNR = better image quality.

What does Detective Quantum Efficiency (DQE) measure?

Efficiency of a detector in converting x-rays to image signal; ideal = 1 (100%).

How does kV affect DQE?

DQE typically decreases as kV increases.

Which detector material offers the highest DQE?

Amorphous selenium (a-Se) in direct DR systems.

What is dynamic range in digital imaging?

Total number of gray shades a system can display.

How many gray shades can DR systems manage?

Over 16,000 shades due to high bit depth and processing.

What does window level (WL) control?

Image brightness.

What does window width (WW) control?

Image contrast.

Why must post-processed images revert to original grayscale before storage?

To ensure integrity of the original data when saved to PACS.