Radiology Flashcards
Who discovered x-rays?
Willhelm Conrad Roentgen in 1895
What is energy?
the ability to do work; energy cannot be created or destroyed, it can change form
What are the 2 parts of an atom?
a central nucleus
orbiting electrons
What is the primary kind of radiation produced in the dental x-ray tubehead?
bremsstrahlung radiation
What is ionization?
electrons are removed from orbital shells of stable atoms through collision with x-raWy photons
What is a photon?
a tiny bundle of pure energy that has no weight or rmass
What is the lead collimator
a metal disc with a small opening in the center that limits the x-ray beam to a circular 2-inch opening
located in the position indicator device
What does the position indicator device (PID) do?
used to aim the x-ray beam at the film in the patient’s mouth
What is the selector button used for?
select the exposure time, milliamperage, and kilovoltage
What is exposure time measured in? Examples?
fractions of a second called impulses
60 impulses = 1 second
What does the mA amount control?
the number of electrons produced
What does the kilovoltage (kVo) control? What is the general amount?
control the penetrating power
70/90 kVp
What is a thermionic emission?
the release of electrons from the tungsten filament when the electrical current passes through and heats up
What is primary radiation?
made of x-rays that come from the target of the x-ray tube
What is secondary radiation?
x-radiation that is created when primary radiation interacts with matter
What is scatter radiation?
a form of secondary radiation that occurs when an z-ray beam has been deflected from its path
DANGEROUS
What does “density” mean in x-rays?
the overall blackness or darkness of a film
What is Penumbra?
the fuzzy/blurred area that surrounds and image
What is distortion?
the disproportionate change in size of images that is caused by too much or too little vertical angulation
“exposure to radiation doesn’t become evident for many years after the time the rays were absorbed” this time lag is known as?
the latent period
What are examples of critical organs?
skin
thyroid
lens of eye
bone marrow
How much radiation do occupationally exposed persons experience?
5000 millirem
How much radiation do non-occupationally exposed persons experience?
0.1 rem/year
What is a dosimeter?
used to measure the amount of occupational exposure to ionizing radiation
What concept states all exposure to radiation must be kept to a minimum?
ALARA
In direct imaging, what is the image receptor?
a solid state sensor
In indirect imaging, what is the image receptor?
a thin, flexible plate, the size of a conventional x-ray film that has been coated in phosphor crystals
What is intraoral film?
a semiflexible acetate film that is coated on both side with an emulsion of silver bromide, silver halide, and silver iodide
When an image is not visible before processing it is called the?
latent image
What does film speed refer to? What classifications?
the amount of radiation required to produce a radiograph of standard density
Classified from letters A through F
What is the tube side of the outer packet?
solid white and when placed in mouth it faces towards the teeth
What is the label side of the outer packet?
has a flap used to open the packet before processing
What are the five basic sizes of intraoral film packets?
Child (#0)
Narrow anterior 9#1)
Adult (#2)
Performed bitewing (#3)
Occlusal (#4)
What extraoral film is used to show a panoramic view of the upper and lower jaws on a single radiograph?
panoramic film
What extraoral film is used to show the bony and soft tissue areas of the facial profile?
Cephalometric
What is a cassette?
a plastic/metal case that is used to hold the film a protect it from light exposure
What a re the two types of screen film used in extraoral radiography?
green-sensitive film - rare earth intensifying screen
blue-sensitive film - calcium tungstate
When an expired film is used it may produce a foggy image, this is known as?
age fog
What is a stepwedge?
a device constructed of layered aluminum steps
