Abstract
This chapter focusses on the very basic concepts in dental radiology that a general dental practitioner should be aware of, including radiation safety and protection, current ADA imaging guidelines, radiographic exposure from common radiographic exams, normal radiographic anatomy, radiographic interpretation, radiographic features of common disease categories, and advanced imaging techniques.
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Keywords
- Articular Disk
- General Dental Practitioner
- Dental Radiology
- Inferior Alveolar Canal
- Radiographic Interpretation
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
1 Radiation Safety and Protection
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Check with local state board of dentistry for rules and regulations regarding use of radiation.
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Register all new x-ray equipment with the local state agency for radiation control.
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Do clinical examination and justify the need for each radiograph before ordering it. Refer to ADA/FDA selection criteria for prescribing radiographs (http://www.fda.gov/RadiationEmittingProducts/RadiationEmittingProductsandProcedures/MedicalImaging/MedicalX-Rays/ucm116503.htm).
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Follow ‘ALARA’ principle (As Low As Reasonably Achievable) for optimizing radiation dose based on specific diagnostic tasks.
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Use fastest speed films (F-speed)/photostimulable phosphor (PSP) plates/digital receptors.
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Rectangular collimation reduces patient dose by five times compared to round collimation.
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Use protective aprons and thyroid collars when appropriate.
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Develop a radiographic quality assurance program and document the steps taken to follow it. For digital radiography, periodically check the sensors for any physical damage, resolution, contrast, and density by comparing to good reference radiographs. Calibrate monitors periodically.
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See table 2.1 for effective radiation dose from common radiographic procedures and equivalent background radiation.
2 Normal Radiographic Anatomy (Fig. 2.1)
3 Radiographic Interpretation (Fig. 2.2)
Considerations when a lesion is noted on a radiograph:
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Location: in relation to teeth, inferior alveolar canal; localized vs. generalized, unilateral vs. bilateral, single vs. multifocal
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Shape: regular vs. irregular, hydraulic
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Size: extension
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Periphery: well-defined, moderately well-defined or poorly defined
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Corticated vs. noncorticated
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Internal structure: radiolucent, mixed, radiopaque, unilocular vs. multilocular
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See table 2.2 for characteristic radiographic features of common disease categories effect on surrounding structures: root resorption/displacement, cortical bone expansion/resorption, inferior alveolar nerve (IAN) canal, maxillary sinus floor
Radiographs showing a variety of radiolucent, mixed and radiopaque lesions. (Figs. 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 2.10, 2.11, 2.12, 2.13, 2.14, 2.15, 2.16, 2.17, 2.18, 2.19, 2.20, 2.21, 2.22, 2.23, 2.24, 2.25, 2.26, 2.27, and 2.28)
For more examples, refer to chapter “Oral Pathology” on section “Radiopaque and Radiolucent Lesions.”
4 Advanced Imaging
When three-dimensional information is necessary to provide direct benefit in patient’s diagnosis and treatment, advanced imaging procedures may be used. This should be considered on a case by case basis. When a lesion is detected on conventional radiographs, an oral and maxillofacial radiologist may be consulted to seek advice on further investigations and management of the lesion.
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Cone-beam computed tomography (CBCT)
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Can be used in implant planning, TMJ disorders, dental anomalies, fractures, extent of disease, and craniofacial relationships.
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Available in small, medium, and large fields of view.
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Small field of view usually gives better resolution, less noise, and less radiation dose to the patient as compared to large field of view. It also reduces the liability for any incidental findings by reducing the scan volume.
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All CBCT scans must be accompanied by a formal interpretation report. The referring dentist has liability for all the findings in the scan, including areas not in the region of interest. Oral and maxillofacial radiology interpretation services may be utilized if the dentist does not want to take the liability for radiographic findings.
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Multidetector/medical computed tomography (MDCT)
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Gives better soft tissue contrast than CBCT.
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Radiation dose is usually higher than CBCT.
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Used when both soft tissue and bone details are needed, e.g., extent of craniofacial disease, malignancies, aggressive benign lesions, and fractures.
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Magnetic resonance imaging (MRI)
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Best for soft tissue detail.
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Used to determine soft tissue extent of lesions, malignant involvement of lymph nodes, perineural spread of malignant neoplasms, salivary gland lesions, articular disk derangement in TMJ, articular disk, and surrounding soft tissue disorders in TMJ.
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Ultrasonography
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Can be used for evaluation of neoplasms in thyroid, parathyroid, salivary glands, lymph nodes, sialoliths, and atherosclerotic plaques in carotid arteries.
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Nuclear medicine
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Used to assess physiological change such as functions of the brain, thyroid, heart, and lungs and for diagnosis and follow-up of metastatic disease, bone tumors, and infection.
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Involves use of radionuclides with gamma camera or advanced imaging such as SPECT, PET, PET/CT, and PET/MRI.
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References
ISSN FDA US Food and Drug Administration. The ISSN register. http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/MedicalImaging/MedicalX-Rays/ucm116503.htm (2015). Accessed 30 Oct 2015.
ISSN American Dental Association. The ISSN register. http://www.ada.org/~/media/ADA/Member%20Center/FIles/Dental_Radiographic_Examinations_2012.ashx (2012). Accessed 30 Oct 2015.
White SC, Pharoah M. Oral radiology: principles and interpretation. 7th ed. Mosby: St. Louis; 2014.
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Katkar, R. (2017). Dental Radiology. In: Weinstein, G., Zientz, M. (eds) The Dental Reference Manual. Springer, Cham. https://doi.org/10.1007/978-3-319-39730-6_2
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DOI: https://doi.org/10.1007/978-3-319-39730-6_2
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