cch 9

Signal to Noise Ratio (SNR)

A measure that compares the level of a desired signal to the level of background noise. A higher BLANK indicates better image quality.

Contrast to Noise Ratio (CNR)

A measure that compares the contrast of an image to the noise level within it. A higher BLANK indicates clearer differentiation between structures in an image.

Image Artifact

An unwanted distortion or artifact in an image that can affect its quality and interpretation.

Phosphor in CR Plate

A material that stores and re-emits X-ray energy in a computed radiography BLANK system.

Conductive Layer

A layer in CR plates that helps dissipate static electricity and assists in the reading of the latent image.

Photodetector in CR Systems

The component that converts light emitted from the CR plate into an electrical signal.

Two Methods of Indirect Capture Material

Scintillation and photodetection.

Scintillator

A material that emits light when it absorbs X-rays, used in indirect digital radiography (DR) systems.

Scintillator Materials in Indirect DR System

Common materials include cesium iodide (CsI) and gadolinium oxyorthosilicate (GOS).

Photodetector Material in Indirect DR System

Usually consists of amorphous silicon or similar materials.

Photoconductor in Direct Capture DR Systems

Typically made of materials like amorphous selenium.

Histogram

A graphical representation of the distribution of pixel values in an image, used for image processing and analysis.

Relationship among Display Field of View, Matrix, and Pixel Size

A larger display field of view requires a larger matrix size or smaller pixel size to maintain image resolution.

Modulation Transfer Function (MTF)

A measure of an imaging system's ability to preserve the contrast of an object at different spatial frequencies.

Detective Quantum Efficiency (DQE)

A measure of the effectiveness of an imaging system in converting the incoming X-ray signal to a useful image.

Quantum Noise

Random variations in image signal caused by the discrete nature of photon detection, which can affect image quality.

Contrast to Noise Ratio (CNR)

Similar to CNR defined above, it measures the visibility of structures against the noise background.

Size Distortion vs Shape Distortion

Size distortion involves changes in image size, while shape distortion involves changes in proportions and angles of objects within the image.

Effects of Image Artifacts on Radiographic Quality

Artifacts can obscure or alter important diagnostic information, leading to potential misinterpretations or missed diagnoses.