The Medical Image - Digital Radiography Overview

A collection of flashcards covering the key concepts, definitions, and processes related to Digital Radiography, as discussed in the lecture.

What are the two main types of Digital Radiography (DR) systems?

Direct conversion and indirect conversion.

What does the direct conversion in Digital Radiography utilize to create a digital image?

A photoconductor made of Amorphous Selenium and a Thin Film Transistor (TFT) array.

How does indirect conversion in Digital Radiography work?

It converts X-rays to visible light using a scintillator layer, then a detector converts the light into an electrical signal.

What materials are commonly used in the scintillation layer for indirect DR systems?

Cesium iodide or gadolinium.

What does the Charge-Coupled Device (CCD) do in the indirect DR process?

The CCD converts light from the scintillator into an electrical signal.

What is the Fill Factor in Digital Radiography?

The percentage of the pixel face that is sensitive to X-rays.

What is the primary controlling factor of X-ray beam energy?

Kilovolt Peak (kVp).

What is the relationship between exposure time and milliampere-seconds (mAs)?

Exposure time is inversely proportional to mA; if exposure time is reduced, mA must be increased to maintain x-ray quantity.

What is the purpose of the Modulation Transfer Function (MTF)?

It measures the ability of an imaging system to render anatomic objects onto an image.

What should be done to prevent dose creep in Digital Radiography?

Techniques should be adjusted to maintain good contrast resolution, spatial resolution, and reduce patient dose.

What is the significance of detecting Quantum Noise in an image?

Quantum noise limits the contrast resolution of the image.

What is Automatic Exposure Control (AEC) in Digital Radiography?

AEC refers to systems that automatically adjust exposure to reduce patient motion blur but require proper operation by the technologist.

What effect does increasing the object-to-image distance (OID) have in magnification radiography?

It enhances visualization of small structures but can slightly increase patient dose.

What is a major benefit of high DQE in Digital Radiography?

It results in lower patient doses due to the higher efficiency of the image receptor.

What is the primary disadvantage of increasing kilovolt peak (kVp)?

Higher kVp can lead to more scatter radiation.

What does dynamic range in Digital Radiography signify?

The number of gray shades an imaging system can reproduce.