INTRODUCTION TO
INTERPRETATION
Dr. Iesha Lapun
Facilitator
Dentistry Division, SMHS
Objectives
• By the end of this session, students should be able to;
• Define interpretation
• List objectives of interpretation
• Describe essential requirements for image interpretation
• Describe how to interpret radiograph
What is interpretation?
• Interpretation of radiographs can be regarded as uncovering all the information
contained within the black, white and grey radiographic images
• An explanation of what is viewed on a dental image; the ability to read what is
revealed by a dental image
The main objectives are:
• To identify the presence or absence of disease
• To provide information on the nature and extent of the disease
• To enable the formation of a differential diagnosis.
Draige and Whaites, 2013
Essential Requirement for Interpretation
• The essential requirements for interpreting dental radiographs can be
summarized as follows:
• Optimum viewing conditions
• Understanding the nature and limitations of the black, white and grey
radiographic image
• Knowledge of what the radiographs used in dentistry should look like, so a
critical assessment of individual image quality can be made
Draige and Whaites, 2013
cont
• Detailed knowledge of the range of radiographic appearances of normal
anatomical structures
• Detailed knowledge of the radiographic appearances of the pathological
conditions affecting the head and neck
• A systematic approach to viewing the entire radiograph and describing
specific lesions
• Access to previous images for comparison.
Draige and Whaites, 2013
Optimum Viewing Conditions
• An even, uniform, bright light viewing screen (preferably of variable intensity
to allow viewing of films of different densities)
• A quiet, darkened viewing room
• Use of a magnifying glass to allow fine detail to be seen more clearly on
intraoral film
• The radiographs should be dry
Draige and Whaites, 2013
Critical Assessment of Image Quality
• WHY each projection was taken
• HOW the projections were taken using different image receptors
• WHAT the resultant radiographic image should look like
• WHICH anatomical structures they showed
Draige and Whaites, 2013
Factors influencing film captured images
• The practical factors that can influence film quality include:
• The X-ray equipment
• The image receptor-film or film/screen combination
• Processing
• The patient
• The operator and radiographic technique.
Draige and Whaites, 2013
Radiographic Technique
• Which technique has been used?
• How were the patient, film and X-ray tube head positioned?
• Is this a good example of this particular radiographic projection?
• How much distortion is present?
• Is the image foreshortened or elongated?
• Is there any rotation or asymmetry?
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• How good are the image resolution and sharpness?
• Has the film been fogged?
• Which artefactual shadows are present?
• How do these technique variables alter the final radiographic image?
Draige and Whaites, 2013
Draige and Whaites, 2013
Exposure factors and film density
• Is the radiograph correctly exposed for the specific reason it was requested?
• Is it too dark and so possibly overexposed?
• Is it too light/pale and so possibly underexposed?
• How good is the contrast?
• What effect will exposure factor variation have on the zone under
investigation?
Draige and Whaites, 2013
Processing
• Is the radiograph correctly processed?
• Is it too dark and so possibly overdeveloped
• Is it too pale and so possibly underdeveloped?
• Is it dirty with emulsion still present and so under-fixed?
• Is the film wet or dry?
Draige and Whaites, 2013
Normal Anatomy
• The type of radiograph being interpreted (e.g. conventional radiograph or
tomograph)
• The position of the patient, image receptor and X-ray tubehead.
Draige and Whaites, 2013
Detailed knowledge of pathological conditions
• Radiological interpretation depends on recognition of the typical patterns
and appearances of different diseases.
Draige and Whaites, 2013
Systematic approach
• A systematic approach to viewing radiographs is necessary to ensure that no
relevant information is missed. This systematic approach should apply to:
• The entire radiograph
• Specific lesions
Draige and Whaites, 2013
Draige and Whaites, 2013
Specific Lesion
• A systematic description of a lesion should include its:
• Site or anatomical position
• Size
• Shape
• Outline/edge or periphery
• Relative radiodensity and internal structure
• Effect on adjacent surrounding structures
• Time present, if known.
Draige and Whaites, 2013
Comparison to previous radiograph
• The availability of previous images for comparative purposes is an invaluable
aid to radiographic interpretation
• The presence, extent and features of lesions can be compared to ascertain
the speed of development and growth, or the degree of healing
Draige and Whaites, 2013
Documentation
• All dental images must be reviewed and interpreted. The interpretation must be
documented in the patient record and include the following:
• Date of exposure
• Number and type of images
• Evaluation of diagnostic quality
• List of limiting factors, retakes, or additional images needed
• Description of teeth
• Description of bone and supporting structures of the teeth
• Description of artifacts
• Indication of any areas that require additional imaging or clinic evaluation/confirmation
Draige and Whaites, 2013
Summary
• Successful interpretation of radiographs, no matter what the quality, relies
ultimately on clinicians understanding the radiographic image, being able to
recognize the range of normal appearances as well as knowing the salient
features of relevant pathological conditions.
Draige and Whaites, 2013
References
• Draige Nicholas and Whaites Eric, 2013. Essentials of Dental Radiography
and Radiology. Churchhill Livingstone Elsevier, China.
• Iannucci M Joen and Howerton Laura Jansen, 2017. Dental Radiography
Principles and Techniques. 5th ed. Elsevier, Canada.
