Podcast
Questions and Answers
Which imaging technique generally offers the quickest availability of images after exposure?
Which option most accurately describes the patient comfort associated with different imaging methods?
Which film processing technique typically requires a lengthy wait before image availability?
In the context of radiography, which of the following is a potential downside of using photographic film?
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Which imaging technique is least flexible in terms of patient packages?
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What is a significant disadvantage of the bisecting angle technique in dental radiography?
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Which regulatory framework focuses on the protection of patients during radiographic procedures?
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Why might the cost of a chemical service contract be considered excessive in dental imaging?
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In the context of dental radiography, what is a unique characteristic of the focal plane in an OPG?
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What is a common misconception regarding single-use dental materials?
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Which statement reflects a critical quality criterion for bitewing radiographs?
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What issue may arise when objects are positioned further away from the OPG detector?
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Which of the following is a potential challenge during the positioning of a radiographic image?
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Which of the following statements is true regarding the resolution of intra-oral radiography compared to DPT?
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What aspect of DPT radiography results in a higher radiation dose compared to intra-oral techniques?
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Which technique has a greater dependence on the operator's expertise for accurate results?
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Which radiography technique provides a larger field of view when assessing dental conditions?
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In terms of patient comfort, which radiography technique is generally better tolerated?
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When considering distortion of anatomy, which radiographic technique tends to have the lowest distortion with correct application?
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What is a common misconception about the coverage of intra-oral radiography?
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Which imaging technique might be chosen for a cost-effective solution without compromising image quality?
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Study Notes
Bitewing, Periapical, and Panoramic Radiography
- Intraoral radiographs include periapicals, bitewings, and occlusals.
- Extraoral radiographs include DPT, OPT, OPG, panoramic, oblique lateral radiography, and skull radiography.
- Cone beam computed tomography is also a method.
Intraoral Radiography
- Resolution: High
- Dose: Low with correct technique
- Distortion of anatomy: Low with correct technique
- Operator dependence: Highly dependent on operator expertise
- Coverage: Small area, may be insufficient for large maxillary or mandibular pathology
- Patient comfort: May be difficult/painful to accommodate film+holder; gagging may occur.
DPT Radiography
- Resolution: Medium due to image capture technology and motion of the machine
- Dose: Higher dose than intraoral, but still low with correct technique
- Distortion of anatomy: Variable magnification depending on position in dental arch
- Operator dependence: Relatively straightforward to learn and execute reliably
- Coverage: Large field of view
- Patient comfort: Usually well tolerated
Image Capture Methods
- Film + chemical processing: Silver halide emulsion on polyester base
-
Digital radiography:
- Computed radiography (indirect): Phosphor plates (photostimulable phosphor)
- Digital (direct): Imaging array connected to computer processing station
Photographic Film vs. Computed Radiography vs. Direct Digital
| Feature | Photographic Film | Computed Radiography | Direct Digital Radiography |
|---|---|---|---|
| Time from exposure to image availability | Typically 5-8 minutes | Typically a few seconds | Virtually instant |
| Patient comfort | Flexible packages easily accommodated | No flexibility | No flexibility, bulky. Cable connected to detector |
Versatility, Cost, Safety, and Infection Control
- Versatility: No scope for image adjustment. Unique copy - must be physically present
- Cost: Relatively low but has consumables (film, processing chemicals); high initial outlay, but reusable, no consumables.
- Safety: Chemicals require careful handling and disposal, additional expense. Single-use, few issues
- Infection control: Reused - must be adequately sealed to prevent saliva ingress
Periapicals - Paralleling and Bisecting Angle Techniques
-
Paralleling:
- Quality criteria: Crown to root visible, 5mm surrounding bone, no overlap of adjacent teeth, no distortion, no collimator cut off, no movement unsharpness, adequate contrast, no artefacts, dot at the crown end.
- Advantages: Geometric accuracy, consistent magnification, periodontal bone levels and periapical tissues shown, more reproducible
- Disadvantages: Uncomfortable for the patient, may be difficult with certain anatomies, positioning in 3rd molar may be difficult.
-
Bisecting angle:
- Quality criteria: Crown to root visible, 5mm surrounding bone, no overlap of adjacent teeth, no distortion, no collimator cut off, no movement unsharpness, adequate contrast, no artefacts, dot at the crown end.
- Advantages: Comfortable for the patient, no sterilisation of film holders needed
- Disadvantages: Operator dependent, not easily reproducible.
Bitewings
- Indications: Detection and monitoring of caries, assessment of restorations, assessment of periodontal status
- Quality criteria: Crowns visible from mesial edge of 4 to distal edge of 7, all interproximal shown with no overlap, crowns centered with buccal and lingual cusps superimposed, bone levels visible
- Technique advantages: Simple, cheap, easier for children, disposable
- Technique disadvantages: Collimator cuts as no beam aiming guide
OPG (Panoramic)
- Details: Only structures within the focal plane (focal trough) are projected sharply onto film; everything else is blurred.
- Focal plane: Narrower at the front than the sides. Objects further away from the detector appear bigger and wider, while those closer appear smaller and narrower.
- Positioning lines (e.g., median sagittal plane, Frankfort plane): Used to position the patient for accurate panoramic images.
- Slit beam radiography: Detector moves in same direction as tubehead for images.
- Indications: Grossly neglected mouth, assessment of third molars, mandibular fractures, implant assessment, etc.
TMJ (Temporomandibular Joint)
- Justification of OPG radiographs: History is taken, and the area is clinically examined. Ideally, intraoral radiographs for better detail and lower radiation; no justification for review panoramic exams.
- Field limitation: Full field, dentition only, maxilla only, etc. Additional subdivisions (e.g., right/left side, specific quadrants); child setting.
- Positioning: Tongue must be pressed against palate.
- Radiation dose: Ranges from equivalent few hours for bitewings or periapicals (as small as 0.002 mSv) to 1.5 days or 3 days (for teeth panoramic, chest PA)
Regulations
- IRR 2018 - worker and public protection, preliminary for radiation protection services, regulated areas and dose limits for workers.
- IR(ME)R 2018 (for patient protection): Referrer, practitioner, operator, justification, benefit risk, optimisation.
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Description
Explore the fundamentals of intraoral and extraoral radiography, including bitewing, periapical, and panoramic techniques. Understand the resolution, dose, and operator dependence for different types of radiographs. This quiz will help reinforce essential concepts in dental radiography.
