Module 5 Rad

Indirect theory of radiation injury

Involves the absorption of an x-ray photon by water which can form toxins and free radicals that damage cells.

Direct theory of radiation injury

Involves a direct hit to and absorption of an x-ray photon within critical areas of a cell.

Non-threshold dose-response curve

Suggests that no matter how small the amount of radiation received, some biologic damage occurs.

Stochastic effects examples

Genetic effects, leukemia, cancer.

Non-stochastic (deterministic) effects examples

Skin erythema, loss of hair, cataract formation, decreased fertility, radiation sickness, fetal death.

Most radiosensitive cells

Cells that divide rapidly, immature cells that are not highly specialized, and cells with a higher metabolism, such as blood cells and young bone cells.

Most radioresistant cells

Bone cells, muscle cells, and nerve cells.

Sequence of radiation injury

Latent period, period of injury, recovery period.

Signs of acute radiation syndrome

Hair loss, nausea, vomiting, diarrhea, and hemorrhage.

Genetic cells affected in mutation

Genetic cells have been affected if offspring exhibit a mutation due to radiation exposure.

Gray to rad conversion

One gray is equivalent to 100 rads.

Sievert to rem conversion

One sievert is equal to 100 rem.

Ways to decrease patient radiation exposure

Receptor choice, collimation, technique, shielding.

Occlusal exam purpose

Used to examine large areas of the upper and lower jaw.

Size 4 receptor

Required for an occlusal exam for an adult.

Size 2 receptor

Required for an occlusal image taken on a 3-year-old patient.

Cross-sectional projection technique

Used to capture the location of salivary stones in the floor of the mouth.

Receptor holder necessity for occlusal images

A receptor holder is not necessary when taking occlusal images.

Topographic occlusal projection

Used to image the maxilla and the palate.

Pediatric projection recommendation

Recommended for use in children 5 years old or younger.

Dental image definition

A 2-dimensional picture of a 3-dimensional object.

Depth capture in dental images

A dental image captures the length and width but fails to capture depth.

Buccal object rule

Depends on horizontal shift in the second image to identify object location.

Mnemonic SLOB meaning

Same-Lingual, Opposite-Buccal.

Panoramic image uses

Evaluation of large areas of the maxilla or mandible, impactions, growth and development, diseases.

Limitations of panoramic images

Should not be used to diagnose decay or periapical lesions.

Focal trough definition

The 3-dimensional curved zone where anatomic structures are clearly demonstrated.

Thyroid collar use in panoramic imaging

Should not be used as it may obscure information.

Frankfort plane definition

Imaginary plane passing through top of ear canal and bottom of eye socket.

Collimator function in panoramic unit

A lead plate with a narrow vertical slit opening.

Midsagittal plane positioning

Must be positioned perpendicular to the floor.

Panoramic imaging advantages

Field size, simplicity, easy patient cooperation, minimal radiation exposure.

Panoramic imaging disadvantages

Quality limitations, image distortion, high equipment cost.

Panoramic image frown error

Chin tipped up too high causes an exaggerated frown.

Panoramic image smile error

Chin tipped down too far causes an exaggerated smile.

Magnified anterior teeth error

Patient too far back on the bite block.

Narrow anterior teeth error

Patient too far forward on the bite block.

Unequal magnification error

Patient's head not centered, turned slightly to one side.

Cortical bone synonym

Another name for compact bone.

Cancellous bone description

Bone containing trabeculae, located between two layers of cortical bone.

Bone ridge definition

Linear protrusion of bone identified as a ridge.

Bone spine definition

A pointed, spiked protrusion of bone.

Sinus radiolucency definition

Large radiolucent spaces seen on maxillary posterior images.

Foramen definition

An opening or hole permitting passage of nerves and blood vessels.

Suture definition

An immovable joint between two bones.

Septum definition

A bony partition dividing two spaces.

Incisive foramen appearance

Almond-shaped foramen seen between maxillary central incisors.

Median palatal suture characteristics

Found between palatine processes, appears radiolucent.

Nasal septum superimposition

Nasal septum may superimpose over median palatal suture on imaging.

Anterior nasal spine visual on PA

Appears as a V-shaped radiopacity.

Inverted Y definition

Radiopaque line above maxillary canine created by sinus and nasal cavity intersection.

Maxillary tuberosity appearance

Rounded radiopaque prominence posterior to maxillary third molar region.

Hamulus description

Extends from medial pterygoid plate of sphenoid bone.

Genial tubercles appearance

Ring-shaped radiopacities below apices of mandibular incisors.

Lingual foramen definition

Radiolucent finding at center of genial tubercles.

Nutrient canals appearance

Radiolucent lines on a PA image.

Mental ridge appearance

Superimposed over mandibular anterior teeth on imaging.

Mental foramen location

Located in area of mandibular premolars.

Mandibular canal description

Extends from just below the ramus to the premolar region.

Mylohyoid ridge definition

Ridge extending from the molar region to the premolar area.

External oblique ridge description

Radiopaque ridge extending from anterior border of the ramus.

Coronoid process visibility

Can be viewed on a maxillary molar PA.

Periodontal ligament space definition

Radiolucent space between alveolar bone and root of tooth.

Crest of alveolar bone position

Located 1.5-2.0 mm below the CEJ in a healthy mouth.

Most radiopaque part of a tooth

The enamel.

Best image for maxilla and mandible visualization

A panoramic image.

Maxillary sinus location

Above the apices of maxillary molars and premolars.

Mastoid process description

A sizable curved radiopacity not visualized on a PA.

Lateral pterygoid plate

Part of the sphenoid bone.

Styloid process description

Long, thin, pointed process below the external auditory meatus.

Mandibular condyle articulation

Articulates with the glenoid fossa to form the TMJ.

Articular eminence location

Radiopaque projection of bone located anterior to the glenoid fossa.

Infraorbital foramen visibility

May be superimposed over the maxillary sinus on panoramic imaging.

Panoramic image border visibility

Only inferior border of the orbit is seen.

Nasal cavity synonym

Also known as the nasal fossa.

Mental foramen on imaging

Seen on both PA and panoramic images.

Nasopharyngeal air space appearance

Diagonal radiolucency on panoramic images.

Ear superimposition on panoramic image

Ear may appear superimposed over the styloid process.

Tongue position effect on panoramic exam

Tongue not placed at roof creates a radiolucent artifact obstructing maxillary anterior teeth.

Zygomatic process appearance

J or U-shaped radiopacity located superior to maxillary 1st molars.