Digital Radiography

Question 1

What is digital radiography?

Answer 1

Digital radiography converts X-ray patterns detected by a digital receptor into an electrical signal that is processed into a radiographic image.

Question 2

Main components of a digital radiography system

Answer 2

Digital image receptor

Digital image processing unit

Image management system

Image and data storage devices

Interface to a patient information system

Communication network

Display device

Question 3

Role of the digital image receptor

Answer 3

Detects X-rays and converts them into an electrical signal.

Question 4

Role of image processing and storage systems

Answer 4

Processes, stores, manages, and displays digital radiographic images and patient data.

Question 5

what are the stages of Computed Radiography (CR)

Answer 5

1) A stimulated (photostimulable) phosphor screen is exposed to X-rays; changes occur in the phosphor crystals but are not visible.

2 )The receptor is processed through a CR reader and processing unit, where the screen is scanned by a small laser beam.

3) When the laser hits areas exposed to X-rays, light is produced, in proportion to the X-ray exposure at that site.

4 ) A light detector measures the light and sends the data to produce a digitised image.

Question 6

What is computed radiography (CR)?

Answer 6

Computed radiography uses a cassette similar to a film cassette, but instead of film it contains an imaging plate (IP) made of photostimulable phosphor.

Question 7

What does the computed radiography (CR) cassette contain?

Answer 7

An imaging plate (IP) made from photostimulable phosphor.

Question 8

How can a computed radiography (CR) cassette be used?

Answer 8

It can be used with or without a grid and on or under a tabletop.

Question 9

How does the imaging plate work in computed radiography (CR)?

Answer 9

The imaging plate stores X-ray energy proportional to the intensity it receives.

Question 10

How is stored energy released in computed radiography (CR)?

Answer 10

The stored energy is released as visible light when a laser scans the imaging plate in the CR reader.

Question 11

First stage of the computed radiography (CR) process

Answer 11

The photostimulable phosphor screen is exposed to X-rays; changes occur but are not visible.

Question 12

What happens in the CR reader?

Answer 12

A laser scans the imaging plate, causing exposed areas to emit light.

Question 13

What determines the amount of light produced in computed radiography (CR)?

Answer 13

The amount of light is proportional to the X-ray exposure at that site.

Question 14

How is the digital image created in computed radiography (CR)?

Answer 14

A light detector measures the emitted light and converts it into a digital image.

Question 15

One disadvantage of computed radiography (CR)

Answer 15

Computed radiography (CR) is slower than direct digital radiography because it requires a CR reader.
Also depends on crystals producing light, less sensitive than DDR .

advantage - cheaper than DDR

Question 16

What is Direct Digital Radiography (DDR / DR)?

Answer 16

Direct digital radiography (DDR / DR) is a system where X-rays are converted directly into a digital image without using a cassette or reader.

Question 17

Types of DDR / DR systems

Answer 17

1) Flat panel systems
-Indirect conversion
-Direct conversion

2) Charge-coupled device (CCD) systems

Question 18

Flat panel system – indirect conversion

Answer 18

X-rays → light → electrical signal → digital image

Question 19

Flat panel system – direct conversion

Answer 19

X-rays → electrical signal → digital image

Question 20

Charge-coupled device (CCD) system

Answer 20

X-rays → light → electrical signal → digital image
CCD systems are small and often used for dental radiography.

Question 21

Image quality of CCD systems

Answer 21

CCD systems usually produce lower image quality compared to flat panel systems.

Question 22

How DDR / DR is similar to a digital camera?

Answer 22

The receptor is a matrix of pixel elements, similar to a digital camera sensor.

Question 23

How is the image formed in DDR / DR?

Answer 23

X-rays interact with pixels, the energy is absorbed, producing an electrical signal that is converted directly into a digital image and stored on a computer.

Question 24

Speed and sensitivity of DDR / DR

Answer 24

Image produced very quickly (about 2–10 seconds)

Very sensitive system

Expensive compared to CR

Question 25

Effect of pixel number on image quality

Answer 25

More pixels = more detailed image More pixels require more memory to store the image

Question 26

What are processing algorithms in digital radiography?

Answer 26

they are software processes that handle the data received during digital radiography before the image can be viewed, ensuring optimal image quality.

Question 27

What is the purpose of processing algorithms?

Answer 27

Maximise image contrast Maximise image sharpness Optimise the image for the specific anatomical area being radiographed

Question 28

How is the area of interest handled during processing?

Answer 28

The area of collimation is detected, and only the area within the collimation boundary is processed.

Question 29

How are shades of grey assigned in digital radiography?

Answer 29

Pixels in the collimated area are assigned shades of grey using a look-up table (LUT), based on the amount of phosphor excitation.

Question 31

Memory trick - Algorithms adjust greys and sharpness for the best anatomical image.

Answer 31

Algorithms adjust greys and sharpness for the best anatomical image.

Question 32

Comparison of the 3 avabilable systems

Answer 32

Tradtional - slow - physical stroage - chemical ecposure -paitent under GA for longer as can not see image - unable to send to second op

Question 33

What is an Image Management System in digital radiography?

Answer 33

Software and computer interfaces that link the digital image with other parts of the system, allowing storage, retrieval, and communication.

Question 34

Other names for Image Management Systems

Answer 34

DIMS – Digital Image Management System PACS – Picture Archiving and Communication System (older term)

Question 35

How are digital radiographic images stored?

Answer 35

All images are stored as digital data.

Question 36

Advantages of digital image storage

Answer 36

Rapid storage and retrieval Minimal physical storage space required Images can be duplicated without loss of quality

Question 37

What is a Patient Information System?

Answer 37

A system of computer records including patient ID, medical history, blood results, and other records for each animal.

Question 38

Advantages of digital communication networks

Answer 38

Images can be transferred easily within a practice or to external specialists Enables teleradiography: transmission of radiological images (X-ray, CT, MRI) for remote consultation or study

Question 39

Advantages of digital image display over conventional film

Answer 39

Image optimisation after production (contrast, density – window leveling) Zoom control for detailed examination Multiple images can be viewed side by side for comparison

Question 40

Key advantages of digital radiography systems

Answer 40

Fast image production Improved safety – no chemicals needed Adjustable image quality without repeat exposure Efficient management of images in practice

Question 41

Considerations / disadvantages

Answer 41

High initial cost, especially for DDR/DR systems Servicing and repair costs Risk of computer crashes – regular backups required