IAEA Training Material on
Radiation Protection in Digital Radiology
Lecture
Topic
Educational objectives
No.
1
Contents
At the end of the programme, the participants
should know these
Fundamentals of
Digital
radiography

Explain how ordinary radiographic images can Details on digital radiographic image with information on discrete
be captured in digital form
physical pixel dimensions and grey-levels.

Discuss the advantages and limitations of The discrete nature of the DR image as a source of its advantages and
digital images
limitations

Explain how the dissociation of acquisition and Methods of acquiring digital radiographs: Digitisation of screen-film
display in DR can contribute to unnecessary radiographs; Non-photographic capture and digitisation; Direct
radiation exposure to patients
capture with or without conversion to light
Advantages of DR with respect to availability, flexibility, and
convenience over conventional screen-film.
The utilities of DR image with respect to patient demographics, type
of examination, and processing information from the DICOM header
Potential for unnecessary patient radiation exposure using DR systems
except for digitised film i.e., exposure factor creep
2
Exposure
indicators and
patient dose
estimation in CR
and DR

Explain why exposure indicators are necessary Importance of exposure indicators in digital radiography due to
in digital radiography.
adjustability of density and potentials for over exposure.

Explain why exposure factor control is Understanding the basis for exposure indicator; subjective and
complicated in digital projection radiography.
objective assessment of patient exposure.

Show the relationship between derived Interpreting exposure indicators and its subject to interferences
exposure indicators and radiation dose.

List other factors that influence image quality
even when appropriate values of exposure are
reported.
3
Optimisation in
CR & DR

Differentiate between
indicators and KAP

Provide rationale for optimisation in Computed
Radiography (CR) and Digital Radiography
(DR)

Describe components of optimisation and
specific methods to detect, correct, and avert
errors in CR and DR

receptor
Identify standards and
optimisation in CR and DR
exposure
references
for
Discuss basic principles of Quality Control (QC) applied to computed
radiography and digital radiography
Compare QC for CR and DR to accepted practices in conventional
radiography.
Explore opportunities for error prevention, detection and correction in
context of process map for creating, distributing and displaying CR
and DR images.
Discuss optimisation of image quality versus patient dose.
Describe status of efforts to standardise QC for CR and DR by
manufacturers and professional organisations
Highlight references useful in establishing and maintaining a QC
program for CR and DR
4
5
Optimisation of
Digital
Fluoroscopy
Digital
Radiographic
Image
Processing


Distinguish between digital fluoroscopy using Types of digital fluoroscopy images, i.e video frame capture, digital
an Image Intensifier (II) and digital fluoroscopy spot film from II, flat panel detectors
using a flat panel detector
Image quality using flat panel versus II
Differentiate between Automatic Brightness Rotational angiography and tomographic reconstruction
Control (ABC) and Automatic Dose Rate
Patient dose parameters
Control (ADRC) and Automatic Exposure Rate
Control

Patient dose parameters

List three main purposes of digital image How raw digital image is modified by digital image processing to
processing
improve correct non-uniformities and to improve contrast

Explain the term “greyscale histogram”

Show how radiographic technique factors affect Edge restoration and noise limitation are two additional purposes of
the greyscale histogram
digital image processing.
A greyscale histogram is rescaled to adjust output and match latitude

Suggest how errors in digital image processing Contrast modification can be accomplished by applying a look-upcan contribute to unnecessary radiation table (LUT) or by more digital post processing methods
exposure to patients
Segmentation algorithms automatically determine the values of
interest (VOI) in the digital image
Noise imposes a practical limitation on digital image processing
6
Avoiding
Artefacts in
Computed
Radiography

Explain how the CR image is created

Explain how errors in the process can produce The CR image is subject to fading, fogging and physical and chemical
sub-standard images
phosphor defects

Artefacts in CR
CR is based on the principle of photostimulable luminescence
CR image must be corrected for non-uniformity in collection
efficiency across one dimension
Types of artefacts from imaging plate, CR reader and how these
artefacts can be avoided
Failure to follow collimation rules comprises algorithms for
determining VOI and can cause loss of contrast
7
8
Avoiding
Artefacts in
Digital
Radiography

Explain how the DR image is created.

Explain how errors in the process can produce DR systems are subject to lag and ghosting
sub-standard images
The composition of the DR image affects the outcome of digital
Explain about the artefacts in DR
image processing
Optimising DR
Displays

List three major differences between DR Active matrix liquid crystal (LCD) displays and cathode ray tube
displays and trans-illuminated films
display medical imaging monitors

Explain how CRTs and LCDs differ with Displays for medical imaging that requires special calibration
respect to the display of medical images
according to DICOM Part 14 GSDF

Appreciate the differences between medical and Increasing use of pseudo-colour in digital imaging imposes special
commercial grade flat panels
demands on displays.

Give an example of how differences between a Novel display technologies are likely to find use in specific limited
technologist’s display and a radiologist’s applications.
display can contribute to unnecessary radiation
exposure.

Correction of non-uniformity critical to DR image quality
9
Picture Archival 
and
Communication
System (PACS)


10
Practical
Exercises



Understand how digital radiology depends on General overview of PACS components. Examples of unnecessary
Picture Archiving and Communications radiation exposure from accommodation of incorrect exposure factor
Systems (PACS)
selection, incorrect association of examination and demographic
information with the image, lost images and inappropriate rendering
List the four components of PACS
of images for interpretation. Challenges for oversight of radiographer
Explain how errors in each of the four
practice by radiologist including exposure indicators, digital shutters,
components of PACS can contribute to
post-acquisition annotation, and deletion of rejected images.
unnecessary radiation exposure to patients
List reasonable expectations of CR and DR Simple QC tests for CR and DR which includes
systems
Visual inspection
Develop unexposed receptor
Consider how to test these expectations
Flat field test
Illustrate how poor quality images arise when
Gain verification
these expectations are violated
Step wedge
Bar pattern
Laser jitter
Commercial QC phantoms and automated analysis to accomplish
similar goals
For maximum value, QC tests should be performed routinely with
attention to longitudinal results.