Radiology Flashcards
Who discovered the x-ray in 1895
Wilhelm Roentgen
The production of ions
Ionization
When an electron is removed from an atom in the ionization process what is the results
Ion pair
The propagation of wave-like energy (without mass; without particles) through space or matter
Electromagnetic radiation
The speed of a wave
Velocity
The distance between the crest of one wave to the crest of the next wave
Wavelength
The number of wavelengths that pass a point in a certain amount of time
Frequency
What kind of wavelengths do we want
Very short wavelength with high velocity
what is made of a tungsten filament and molybdenum cup; Negative charge
Cathode
What supplies the electrons necessary to generate x-rays
Cathode
what is made up of a copper arm and focal spot; positive charge
Anode
what converts bombarding electrons into x-ray photons
Anode
What is the focal spot made out of
tungsten (target = tungsten)
Electron stream travel from
negative cathode to positive anode
kVp determines the ____ of the x-ray beam
Quality
Refers to the penetrating power of the beam
Quality
With low kVp (65 to 70), a high contrast the image results demonstrating what?
many black and white areas and a few shades of gray, short-scales of contrast
High kVp (>90), a low contrast image results demonstrating what?
many shades of gray instead of black and white, long scale contrast
Both milliamperage (mA) and exposure time have a direct influence on the number of electrons produced, when combined, they form a factor termed
milliampere-seconds (mAs)
in humans water comprises __% of cell
80%
What is the most common mechanism of damage
ionization of water
What is the time that elapses between exposure to raditation and the appearance of observable clinical signs
Latent Period
many cellular injuries may result including cell death, changes in cell function, abnormal mitotic activity
A period of injury
What effects are seen on the person irradiated, these changes are not transmitted to future generations
Somatic effects
What effects are not seen in the person irradiated but are passed on to future generations
genetic effects
Cell sensitivity to Radiation, What is highly sensitivity to radiation
reproductive tissue lymphoid system bone marrow intestines mucous membranes
Cell sensitivity of radiation, What has low sensitivity
nerve tissue skeletal muscle heart optic lens mature done
Dental x-ray machines operating at or below 70 kVp require a minimum of
1.5mm aluminum filtration
dental x-ray machines operating above 70kVp require a minimum of
2.5 mm aluminum filtration
What is the PID
Position indicating device (cone)
Less volume of tissue is irradiated and less scatter produced with king what type of PID (cone)
Long cone
What reduces the surface area exposed by the use of a lead diaphragm, it shapes the X-ray beam into a more restricted area and reduces scatter, reduction in size or beam of radiation
Collimation
Beam size at the patients face can be no longer than
2.75 inches
What type of collimation reduces the skin surface area by 60%
Rectangular
What is the most effective method of radiation protection
Fast film
What is ALARA
As little as reasonably achievable
What is the capability of the dental image to reproduce the distinct outlines of an object, or how the smallest details of an object are reproduced on a dental radiograph
Sharpness
The smaller the focal spot size, the image will appear
sharper
The composition of the film emulsion influences sharpness, the smaller the silver halide crystals, the image will appear
sharper
why does a image lose sharpness
if the film or patient moves during exposure
refers to an image that appears larger than the actual size of the object it represents
Magnification
A variation in the true size and shape of the object being rediographed
Distortion
To minimize distortion, the object and film must be
parallel to each other
To minimize distortion, the x-ray beam must be
directed perpendicular to the tooth and film
What is the process of Manual Film
Developer/wash/fixer/wash/dry
What is the time and temp. that the film stays in developer
5 minutes at 68 degrees
what softens the film emulsion in developer
hydroquinone and elon
How long does film stay in the fixer
10 minutes (twice the development time)
Where does the thermometer go at in a manual film processer
Developer
What is Automatic film processing basics
developer/fixer/wash/dry
This provides sufficient illumination in the darkroom to carry out processing activities without exposing or damaging the film
safelighting
What is the wattage of the safelight
7 1/2 or 15 watts and placed a minimum of 4 feet away from the film and working area
What type of filter can be used for extraoral and intraoral films
GBX-2
What type of film error cause overlapping of teeth contacts
incorrect horizontal angulation
What type of error of a film causes foreshortened images, short teeth with blunted roots
to much vertical angulation
what type of error causes elongated images, long distorted teeth
too little vertical angulation
over angulate causes
foreshorten
under angulate causes
elongated
What is the SLOB rule
same lingual; opposite buccal
What is the standard film size
size 2
What is the only mandibular landmark to appear on maxillary films
Coronoid process
What air space on a panoramic radiograph is seen between the palate and tongue horizontal radiolucent band
Palatoglossal air space
What air space on a pano refers to the portion of the pharynx posterior to the nasal cavity, diagonal radiolucency
Nasopharyngeal air space
What air space seen on a pano refers to the portion of the pharynx posterior to the tongue, vertical radiolucent band
Glossopharyngeal air space
Three-dimensional curved zone in which structures are clearly demonstrated on a panoramic radiograph
Focal trough
This passes through the floor of the orbit and the external auditory meatus on a pano
Frankfort plane
this plane divides the body into right and left sides
Midsagittal plane
Do you need a thyroid collars with panoramic radiography
NO
In a pano what type of image is found on the opposite side of the image, higher than its actual counterpart.
Ghost images
Your patient historically presents with new decay on an annual basis. To view the caries more precisely, you decide to change the contrast of the radiographic images. Which adjustment is recommended to increase contrast?
Decrease kVp
Thermionic emission occurs at which area of the x-ray tube?
negative cathode
When the electrons strike the tungsten target, the energy of motion is converted to x-ray energy and heat. How much of the energy is lost as heat?
99%
Which length of PID is most preferred for intraoral radiography?
12inch
Movement of the patient during radiographic exposures will effect which image characteristic?
Sharpness
In manual film processing procedures, the thermometer should be kept in which solution?
Developer
Which anatomical landmark is found in the mandible
lingual foramen
Which ridge of bone continues downward from the ramus as the “mylohyoid ridge”
internal oblique ridge
Which dental material has the radiographic appearance most similar to enamel?
porcelain
Which anatomical landmark is radiolucent on dental images?
median palatal suture
