Radiology Flashcards
What is the best way to produce a radiographic image with low contrast, hence longer gray scales?
Increasing the kilovoltage peak (kVp)
What is measured by the half value layer?
Filtration
What is the half-value layer?
The thickness of a material (usually aluminum) that decreases the intensity of the x-ray beam by 1/2
the higher the half-value layer, the thicker the piece of aluminum needed to block the x-ray beam
A quarter-value layer is the amount of a material that reduces the beam intensity to 1/4 of the value obtained without any test filters
A dose of 4 grays of X-radiation administered locally to a patient’s hand would most likely result in ___
Erythema
The exposure to x-radiation beyond the allowable limit causes the top layer of the skin to experience tissue damage that is almost comparable with the damage of a sunburn
Energy generated from carrying electrons from the cathode to the anode in a Crookes tube is converted into ___ at the target.
Heat
As the electrons travel in a rapid motion to hit the target, the heat is created an photons are also formed
Approximately 99% of these electrons are converted to heat as it hits the target.
Only <1% of the electrons that hit the target are converted to photons
gamma rays are not part of the electromagnetic spectrum. they are used in the filed of medicine to…
Used in positron emission tomography (PET) scans and cancer therapy
When making a radiograph, the number of electrons produced determines the ___
Quantity of the X-rays produced
Crookes tubes are able to create free electrons through the ionization of the air present within the tube with the use of a high voltage direct current. The high voltage current excites and accelerates the electrons that originated from the cathode. The excitation of the electrons causes them to move rapidly, hit the anode, and produce X-rays.
The control over the X rays produced (quality) is based on the ____ and ___ of the X-ray machine
Peak kilovoltage (kVp)
Milliamperage (mA)
Excessive exposure to X-radiation may cause ___ that may ___, ___, and ___.
The creation of free radicals
Damage DNA
Causing genetic mutations
And cancer growth
True or false.. ionizing radiation directly affects DNA
False… it affects it through free radical formation
What is affected by the change in peak kilovoltage (kVp)?
Quantity and quality of X-ray photons
How does increasing kVp alter the quality of X-rays
Increases the intensity and energy thus degree of penetration
What does an increase in milliamperage do?
Increases the quantity of x-ray photons produced. (Quantity only)
What does increasing filtration do?
Increases quality while decreasing quantity
The amount of penetration by x-ray beams is most likely associated with ____
Peak kilovoltage (kVp)
How does Fixing solution interact with silver?
It removes underdeveloped silver salts
What does fixing solution do?
Ensures that the image on the film is fixed permanently by removing the silver halide crystals which were unexposed or undeveloped and by preserving the emulsion.
What does fixer solution contain? (5 things) what do they do?
Clearing agent - removes undeveloped silver halide crystals (ammonium thiosulfate)
Tanning agent - hardens and preserves the emulsion (aluminum salts)
Activator - maintains the fixer’s level of acidity and also neutralizes the developer (acetic acid)
Preservative - prolongs the shelf life of the solution (sodium sulfite)
Solvent - dissolves the other substance and ingredients (water)
The mean energy (wavelength) of an x-ray beam is affected by what factors?
Filtration
Peak kilovoltage (kVp)
Voltage
True or false… mA has NO affect on the mean energy of the beam
True
What type of radiation poses the greatest danger to clinicians during radiography procedures?
Secondary radiation and scatter
___ cells are most likely to be damaged first by radiation
Hematopoietic
Because they are actively dividing and undergoing several cellular processes to form many different cell types like red and white blood cells.
Overexposure to radiation may result in what 3 negative outcomes?
Xerostomia
Mucositis
Osteoreadionecrosis
True or false… X-rays are considered low energy waves
False.. they are high energy waves (higher than visible light)
Alpha particles, beta particles, and neutrons are considered ___ radiation.
Particulate
What material is responsible for making gutta-percha radiopaque?
Barium salts
What type of radiograph provides the best visualization of the maxillary sinus for detection of pathology? Why?
Water’s (occipitomental view) - because it provides a larger image, better angle, and exposure of both the frontal and maxillary sinus
Panos provide a wide view of teeth and other structures of the head but CANNOT be used to completely evaluate the location and position of lesions within the maxillary sinus because of the image overlap
Towne’s view is best in evaluating the…
Condyles, mastoid air cells, orbital floor, and the structures of the middle ear
A reduction in the size of the focal spot of the X-ray tube leads to an increase in ___
Definition
The definition and detail of the radiographic image are influenced by the focal spot through what three things?
The smaller the size of the focal spot, the better the detail, definition, or sharpness of the radiographic image created
The larger the size of the focal spot, the wider the coverage of the dam and more penumbra is created in the radiograph. This results in an unclear demarcation of the image outline and an increase in the blurriness of the image
The proper angulation of the beam and the size of the cone of an x-ray machine affects the size of the focal spot.
The mucosa of the soft palate is innervated by what three nerves?
Lesser palatine nerve
Pharyngeal branch of vagus nerve
Medial pterygoid nerve
True or false… the PSA nerve innervates the maxillary sinus mucosa
True
The classification of third-molar impaction is based on what two things?
Spatial positioning relative to the long axis of the adjacent second molar
Amount of tooth structure covered by bone or soft tissue
____ classification of tooth impaction is based on the position of the long axis of the third molar in relation to the long axis of the second molar
Winter’s
____ classification of tooth impaction deals with the position of the lower third molar impaction within the ramus in relation to the second molar
Pell and Gregory’s
What is indicated for a patient presenting with a persistent fascial plane infection following incision and drainage with adjunctive antibiotic therapy?
Repeat the culture and sensitivity assays
Elliptical incisions should be made ___ to the dermatological skin tension lines to reduce scar visibility after wound healing
Parallel
Which of the following interactions is responsible for the creating of Bremsstrahlung/Braking radiation?
Bremsstrahlung radiation is created when high-speed electrons interact with the Tungsten nuclei at the target.
The fast-moving electron loses kinetic energy when it interacts with the nuclei, converting the lost kinetic energy into a photon.
A dentist’s radiograph of a patient’s 3rd molar at 0° vertical angulation looks like the superior border of the mandibular canal contacts the apices of the tooth. The dentist then makes another radiograph at a -2° vertical angulation that suggests that the mandibular canal is separated from the apices of the 3rd molar by several millimeters. Using the information provided by these two radiographs, which of the following is true about the relation of the mandibular canal to the root apices of the 3rd molar? The mandibular canal is…
Inferior and lingual