ABOMR flashcards
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33 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Gray (Gy)
- The SI unit of absorbed radiation dose, equal to one joule per kilogram of tissue; 1 Gy equals 100 rad.
- Effective dose
- A tissue-weighted sum of equivalent doses across organs, expressed in sieverts, used to compare stochastic risk from different imaging procedures.
- Half-value layer
- The thickness of a specified absorber that reduces the intensity of an x-ray beam by half; a measure of beam quality and filtration.
- Photoelectric effect
- Interaction in which an incident photon is completely absorbed and ejects an inner-shell electron; dominant at low energies and high atomic number, producing high contrast.
- Focal trough
- The curved three-dimensional zone of sharpness in panoramic imaging within which structures are imaged with acceptable resolution; objects outside appear blurred.
- Rectangular collimation
- A beam-restricting device that shapes the x-ray field to the receptor area, reducing patient absorbed dose compared with round collimation.
- kVp
- Peak kilovoltage, which determines the maximum photon energy and thus the penetrating power and contrast of the x-ray beam.
- Voxel
- A three-dimensional volume element in CBCT or CT; its size determines spatial resolution, with smaller voxels giving finer detail.
- ALARA
- As Low As Reasonably Achievable; the radiation protection principle of minimizing exposure while achieving the diagnostic objective.
- Occupational dose limit
- The recommended annual effective dose limit for radiation workers, typically 50 mSv per year under ICRP guidance.
- Quantum mottle
- Image noise caused by statistical fluctuation in the number of x-ray photons reaching the receptor; reduced by increasing exposure.
- Window and level
- Digital display adjustments that change the mapping of gray-scale values, altering apparent contrast (window) and brightness (level) without changing acquired data.
- Stafne defect
- A well-defined radiolucency near the mandibular angle below the inferior alveolar canal, representing a developmental lingual bone depression.
- Dens invaginatus
- A developmental anomaly in which enamel and dentin invaginate into the pulp chamber, appearing as a teardrop radiopacity within the tooth.
- Nasopalatine canal
- A midline radiolucency between maxillary central incisors representing the incisive canal; may appear heart-shaped and mimic a cyst.
- Taurodontism
- A developmental anomaly with an elongated pulp chamber and apically displaced furcation, giving a rectangular tooth shape.
- Radicular cyst
- The most common odontogenic cyst, arising from epithelial rests of Malassez at the apex of a nonvital tooth.
- Dentigerous cyst
- A developmental odontogenic cyst enclosing the crown of an unerupted tooth and attaching at the cementoenamel junction.
- Odontogenic keratocyst
- A cyst with a scalloped border, minimal expansion, and high recurrence rate, associated with nevoid basal cell carcinoma syndrome.
- Ameloblastoma
- A locally aggressive odontogenic tumor, often multilocular in the posterior mandible with a soap-bubble appearance.
- Odontoma
- The most common odontogenic tumor; compound type contains tooth-like denticles and complex type an irregular calcified mass.
- Osteomyelitis
- Bone inflammation often showing ill-defined radiolucency with radiopaque sequestra and, in chronic stages, sclerosis and involucrum.
- Le Fort III fracture
- A craniofacial disjunction separating the maxilla and zygomas from the cranial base, passing through the nasofrontal and zygomatic sutures.
- Paget disease
- A metabolic bone disorder showing cotton-wool radiopacities, bone expansion, and hypercementosis, with elevated alkaline phosphatase.
- Brown tumor
- A localized osteolytic lesion of hyperparathyroidism, appearing as a well-defined radiolucency and resolving after correction of the metabolic disorder.
- Anterior disc displacement
- TMJ derangement in which the articular disc lies anterior to the condyle; MRI shows the hypointense disc position in closed and open mouth.
- Sialolith
- A calcified salivary duct stone, radiopaque on plain film or CT, commonly in the submandibular gland and presenting with obstructive symptoms.
- Pleomorphic adenoma
- The most common benign salivary gland tumor, typically a well-defined parotid mass with mixed solid and cystic components on imaging.
- Hounsfield unit
- A CT attenuation scale where water is zero, air about minus 1000, and dense bone above 400, used to characterize tissue density.
- T2-weighted MRI
- An MRI sequence in which fluid and edema appear bright, useful for detecting cysts, inflammation, and salivary gland pathology.
- Bone scintigraphy
- A nuclear medicine technique using technetium-99m to show areas of increased bone turnover, sensitive for metastasis and active bone disease.
- Informed consent
- The process of explaining the purpose, benefits, and risks of a radiographic examination and obtaining the patient's agreement before exposure.
- Justification principle
- The radiation protection rule that a radiographic examination should be performed only when the expected benefit outweighs the risk.