Intraoral film is non-screen film. It does not use an intensifying screen. True or False
True
Overlapping in the interpromixal spaces is to incorrect _____.
horizontal angulation
X-rays are regulated on a federal, state, and local level. True or False
True
Extraoral film is screen film. It is placed inside an intensifying screen. True or False
True
To view large areas on film such as the whole maxillary arch, you use _____.
Occlusal film
With extra oral film, it is exposed by light. True or False
True
What is the purpose of the lead foil in the film packet?
To absorb backscatter radiation from reaching the film which causes fogging of the film
Absorbs some radiation that would otherwise exit the film and be absorbed by the patient's face
With intraoral film, it is light that primarily exposes the film. True or False
False
Cone Cutting on a radiograph is caused by ____.
Failure to cover the film with the field of radiation (cone)
The fuzziness (lack of detail or sharpness) of the outline of an image is ______.
Penumbra
Interproximal caries can best be detected with _____.
Bitewings
All of the following are intraoral films used except.
Panorex, Periapical, Bitewings, Occlusal
Panorex
Periapical radiographs are mainly used to view, what?
Apices of the teeth and surrounding structures
Occlusal x-rays are used to view, what?
A large area such as an entire arch on one film
The efficiency with which a film responds to x-ray exposure is known as film sensitivity or film speed. Which speed is best for reducingradiation to the patient?
Speed "F"
Which of the following is screen film.
1, 2, 3, 4, panorex
panorex
Incorrect vertical angulation will result in an image that is _____ and _______.
Elongation and Foreshortening
Foreshortening of the image on a maxillary radiograph may be caused by ________.
vertical angulation being too high (excessives)
Positive vertical is accomplished by pointing the head position indicating device (PID) of the x-ray unit _____.
Downward
Conditions that radiographs can demonstrate include:
Periodontal diseases
Calculus
Unerupted or supranumerary teeth
Caries
What is the purpose of the intensifying screen?
Increase radiation, to allow a decrease in exposure time
Negative vertical is accomplish by pointing the PID or cone of the x-ray unit ____.
Upward
Periapicals show one arch and the entire tooth and root and bitewings show crowns of teeth. True or False
True
What is the term for when radiation is not able to pass freely through and appears white to light gray on an x-ray?
radiopaque
What are crystals (grains) composed of that cover film?
Silver Halide
What is the purpose of the dot on a piece of film?
To help in mounting
On what mounted radiographs is the dot convex (raised)?
Labial Mounting
When radiation is able to pass freely through and object that appears black to dark gray on film is what?
Radiolucent
A lead apron with a throid collar should be used for all intraoral films. True or False
True
All removeable appliances in the patients mouth must be removed before taking x-rays. True or False
True
Which of the following does not have to be documented in the patients record.
Total # of takes and retakes, type of x-ray taken, date of exposure, All above must be documented
All must be documented
What is the most important use of radiographs in the dental practice?
Diagnosis
What side of the film should be facing the source of radiation?
White side
Who has the responsibilty to diagnosis and x-ray?
The Dentist
What is a latent image?
invisible image produced after exposure and becomes visible
Contrast is the different densities that make up our image. True or False
True
Elongation of an image on a maxillary radiograph is caused by, What?
Vertical angulation being too low (insufficient)
Which film is placed in the mouth long Vertically?
Anterior films
Which film is placed in the mouth long horizontally?
posterior films
When mounting radiographs, which one is best to aid in mounting?
Right and left bitewings
What is functioning of the outer portion (covering) of the film packet?
To protect from moisture and light
What effect does crystal (grain) size have on speed or sensitivity of the film?
The larger the crystal, the faster the film
When changing from "D" speed film to "E" speed film what happens to exposure time?
Decreases 50%
Density on a radiograph refers to:
The overall degree of blackness of a single film
Extra oral screen film uses an intensifying screen and is exposed by light. True or False.
True
Overlapping in the interporximal spaces is due to what?
horizontal angulation
In the bisecting technique, what is the only principle of shadowcasting.
close film to object distance
In the paralleling technique, the central ray is directed at what angle?
90 degree to the film and tooth
Which film is also called the long cone technique?
Paralleling
Who is the father of the science of radiation protection?
Rollins
Interproximal caries are best detected by what type of radiograph?
Bitewings
X-rays were discovered in 1895 by who?
Roentgen
Why is the paralleling technique recommended over the bisecting technique?
It gives a less distorted image
The ability of x-rays to penetrate some objects better than others is known as what?
Differential Absorption
Properties of X-rays
Can cause fluorescent screen to glow
Can affect a photographic plate
Invisible
Travel long distances at 186,000 mi/sec
Has no mass or weight
Principles of Shadow casting
Source- small as possible
Long distance b/w source and object
Short distance b/w object and film
film and object parallel
90 degree angle of x-ray beam
X-rays are now known to belong to the ____spectrum.
electromagnetic
True or False. In Bisecting the film and tooth should be close.
True
What is the best way to reduce unnecessary radiation to the patient?
Fast speed film
Properties of a Cathode Ray
Causes fluoscence in certain cases
Travels short distances
Has Negative charged particles
Have Mass or weight
What anatomical structure is used to locate the molars?
Outer canthus of the eye
What anatomical structure is used to locate the premolars?
inner canthus of the eye
What angle is the central ray directed in the bisecting technique?
90 degrees to the imaginary line dividing the long axis of the tooth.
What effect does the film sensitivity (spped) have on the radiograph image?
The faster the film, the poorer the image
What material is the filament wire and target made of?
Tungsten
What is the function of the diaphragm or collimator?
To restrict the size of the beam
The mA is a measurement of the _____ and the kVp measures the _____ of an electrical current.
Quantity, Quality
In the step up transformer, which coil has more turns?
Secondary
The number of electrons produced are controlled by what?
mA and time
Define Self-rectification
X-rays are produced only when the electrical cycle is going from (-) cathode to (+) anode
What term means the boiling off of electrons?
Thermionic emission
When electrons are converted to x-ray energy and heat, what percentage is heat and what percentage is x-ray?
99% Heat
1% x-ray
The speed or force of electrons and penetrating power of the x-ray beam is controlled by what?
kVp
What is attenuation of x-rays by absoption?
Photoelectric effect
What is Attenuation by scatter?
Compton effect
To get more penetrating x-ray, you would increase the what?
kVp
What is the source of the x-ray in the dental tube?
Target
What is the source of the electrons in the dental tube?
filament wire
How many impulses of x-rays are produced in 1/2 a second?
30
What controls the contrast of the radiograph?
kVp
What is the filter thickness required for a machine operating at and above 70 kVp?
2.5mm aluminum
What is the purpose of the aluminum filter?
To remove weak, less penetrating x-rays from the beam
What should the diameter of the beam not exceed at the patient's face?
2.75 inches
When a electron is stopped or slowed by the nucleus of a target atom is what?
Bremstrahlung
When an electron is stopped or slowed by the outer shell electron of a target atom is what?
Characteristic
The mA sends a current through the what?
step down transformer to the filament wire
What happens when the electric current is allowed to flow through the low voltage circuit?
The filament wire heats up
Adjustments in exposure time are made in order to control what?
Density of film
What is the collimator made of?
Lead
How are x-rays generated?
Electrons striking the target
High scale (short-scale) contrast exhibits what?
pretty much black and white tones
Approximately, how much does a rectangular PID reduce radiation exposure compared to the circular one?
50%
3 Protective Devices
Collimator, filter, and PID
Conditions for x-rays to be produced
Source of free electrons
High voltage to give them speed
And a target to stop them
What happens when a high voltage circuit is activated?
Potential difference b/w cathode and anode
Electrons are propelled toward the target
X-rays are produced
Heat is produced
If an operator wishes to change from 15 mAs with a 2 second exposure time to 10 mAs and maintain the same density, what would be the exposure time?
3 seconds
Short scale (high) contrast is achieved by what?
decreasing kVp
If the operator wants to change from a short scale contrast to a long scale contrat and maintain the same density, what should be done?
Increase the kVp and Decrease the mA or time
Attenuation
The removal of x-ray photons from the beam by absoption or scatter.
