Final Flashcards
Cone cut
A clear, unexposed area on the dental radiograph from misalignement.
Alara
As Low As Reasonably Achievable
Millamperage
The quantity of x-rays emitted from the tube head (measurement).
Kilovoltage peak
The maximum/peak voltage that is used during x-ray exposure.
Exposure time
The interval during which x-rays are produced.
Contrast
How sharply dark and light areas are differentiate or separated in an image; difference in the degrees of blackness between adjacent areas.
Short scale contrast
An image with only two densities (black and white) from using lower kilovoltage range.
Long scale contrast
Image with many densities (shades of grey) from using higher kilovoltage range.
Low contrast
An image with many shades of grey and few area of black and white.
High contrast
An image with many very dark and light areas, few shades of grey.
Focal spot
The tungsten target of the anode; converts bombarding electrons into x-ray photons.
Penumbra
The fuzzy, unclear are that surround the radiograph.
Image magnification
The ability to ‘zoom’ in on an image.
Identification dot/bubble
A feature on a film which must face up when mounting.
Polychromatic x-ray beam
An x-ray beam containg many different wavelengths of varying intensities.
Radiolucent
The portion of the image that is dark or black; its structure readily permits the passage of x-ray beam and allows more x-rays that reach the receptor.
Radiopaque
The portion of the image that is light or white; its structure resists the passage of x-ray beam and limits the amount of x-rays that reach the receptor.
Latent image
The pattern of stored energy on the exposed film.
Photons
A bundle of energy with no mass or weight that travels as a wave at the speed of light and moved through space in a straight line.
Long wave length = ____ frequency
Low frequency
High wave length = ____ frequency
High frequency
What is vertical angulation?
Refers to positioning of PID up and down.
What is horizontal angulation?
Refers to positioning of PID side-to-side
Basics of paralleling technique
Used to expose periapicle and bite wing image receptors.
Receptor is placed parallel to long axis of tooth.
Central ray of the x-ray beam is directed at a right angle to receptor.
What results from incorrect horizontal angulation?
Results in overlapped contact areas.
What results from incorrect vertical angulation?
Results in image not the same length as the tooth.
Where is ‘a’ located on periapicles, why?
A crown of a tooth so it does not interfere with the diagnosis portion of the radiograph.
What is overlap, how do you correct it?
When horizontal angulation is incorrect, correct angulation.
What is the purpose of the lead foil in the film packet?
to protect film from back scattered radiation
Distortion
A geometric characteristic that refers to variation in the true size and shape of the object being radiographed.
Collimation
The restriction of the size and shape of the x-ray beam in order to reduce patient exposure.
H.A.R.P
Healing Art Radiation Protection
Film focal distance
is the distance between the X-ray source and the film.
Object film distance
the measure of space intervening between two objects.
What is the KeV binding energy of the tungsten K shell electron?
69KeV
What should appear on periabicle
All of tooth root.
What should appear in premolar bitewings?
all of the 4 and 5
- mesial of the 6
- distal of the 3
What should appear on molar bitewings?
- all of the 8, 7, and 6
- distal of the 5
What is the difference between short and long wavelengths as it relates to energy and penetration…
a long wavelength has less energy and less power
a short wavelength has more energy…
Why is a filter inserted in the path of the direct x-ray beam
minamize the amount of x-radiation.
What happens when the funsten filament of the cathode in an x-ray machine is heated?
when heated the tungsten filament produces electrons
How should the client’s head be positioned during the taking of radiographs?
the patient’s head must positioned such that the maxillary arch is paralle to the floor.
Describe the basics of the paralleling technique
a method that can be used to expose periapical and bitewing image receptors
How do you align the central beam when using the paralleling technique?
a beam alignment device must be used to keep the receptor parellel with the long axis of the tooth
According to the H.A.R.P. act, who is permitted to take x-rays in a dental office? Prescribe
dentist, hygienist, dental assistant
-if the receptionist has taken a H.A.R.P arroved
What is the primary reason for using fast speed film or sensors?
the minamize the exposure time (ALARA)
Where should the radiographer position themselves in relation to the primary beam when exposing
2 meters away from tube head (6 feet )
The electromagnetic radiation with the most penetrating power will have what type of wavelength
short wavelength, high frequency and high penetration powe
What is differential absorption?
Radiographic opacity refers to the actual penetrative ability of x-rays to pass through an object and reach the film.
Identify the tissues that are radiolucent and radiopaque.
radiopaque-thick dense
radiolucent- soft and thin
Which tissues absorbs more x-rays ?
soft and thin
What is the purpose of contrast on a radiograph?
the difference of degess of blackness of adjacent areas on a dental radiograph
The exposure time for dental radiographs will depend upon what factors?
The type of emulsion.
What contributes to produce the best detail in sharpness of a dental radiograph.
Smaller focal spot
How do you decrease the density in a dental radiograph?
Decrease in object-film distance.
What is the purpose of the lead foil in a film packet?
To stop radiation (ALARA)
If you increase the kilovoltage of the x-ray machine, what do you have to do with the exposure time?
Has to be increased.
Quantity
refers to # of x-rays emitted from tube head
Quality
refers to energy of penatrating ability of x-ray
Intensity
product of quantity and quality.
Which radiology innovator is known as the father of the science of radiation protection?
Willhelm Roentgen
What percentage of energy is converted to x-radiation when electrons collide from the cathode
1%?
What is the ideal temperature of the automatic processor for developing dental radiographs?
68 degrees F
Should the developer and fixer be mixed together? Why?
no because it will make a toxic mixter that must be disposed of as dangerous waste
What is the binding energy of the tungsten K shell electron?
the energy that it would take to knock an electron out of its shell.
Who is the Bavarian physicist who discovered x-rays and won a Nobel Prize?
willham conrad rontgen
Why is the filter placed in the path of x-ray beam?
Aluminum filters
What could result if there are light leaks around the dark room door?
an effect of fog
How do you increase the sharpness of a radiographic image?
As the size of the focal spot decreases, the image sharpness increases because penumbra…
What is the principle of the paralleling technique?
The paralleling technique is accomplished by placing the receptor parallel to the long axis of the tooth
The length of the PID is changed from 16 to 8in. The resultant intensity of the beam will be?
four times as intense
