Card Set Information
How many cycles of electricity occur in a second, 1/2 second?
60 cycles, 1/2 second 30
How many impulses of x-rays are generated per second, 1/2 second?
What does the mA measure?
Quantity or amount
What 2 factors determine quantity of electrons thus x-rays?
mA and time
What control factor determines the speed of electrons thus the penetrating power of x-rays?
What does kVp measure?
Quality or speed
What control panel setting controls contrast?
A radiograph with mostly black and white is called a ______ contrast.
High scale or short scale
What produces a short scale (high scale contrast)?
What produces a long scale (low scale contrast)?
A radiograph with lots of grays is called a _____contast.
low scale or long scale
What is the step-down transformer controlled by?
What is the step-down transformer connected to and heats up?
Filament wire (low voltage filament circuit)
What is the step-up transformer connected to?
mA and kVp
What is the step-up transformer controlled by?
Which transformer has more turns in the secondary coil?
Which transformer has more turns in the primary coil?
Which is the negatively charged terminal?
Which is the positively charged terminal?
What two structures are made of Tungsten?
Target and filament wire
What is the source of electrons?
What is the source of x-rays?
What parts are inherent filtration?
Glass (aperature), Oil bath, and Metal barrier
What part is added filtration?
Which 3 structures are protective devices?
filter, PID, and collimator
What does the filter do, what is it made of, and how thick does it have to be?
Removes weak, less penetrating x-rays from the beam
70 kVp and 2.5
70 and above
What does the collimator do, and what is it made of?
Restricts the size of the beam to 2.75 inches
Which PID reduces the radiation exposure the most and how much?
long, lead lined, rectangular
What two control panel factors settings control density?
mA and time
High density film is obtained by increasing the ___or ___.
mA or time
Low denstiy film is obtained by decreasing the ____or____.
mA or time
What must be present to produce x-rays?
A source of free electrons
A high voltage to give them speed
A target to stop them
What happens when the low voltage circuit is activated?
The filament wire heats up and thermionic emission occurs
What happens when the high voltage circuit is activated?
There is a potential difference between the cathode and anode
Electrons are propelled towards the target
X-rays and heat are produced
When are x-rays produced?
When electrons strike the tungsten target
How much is heat and how much is x-ray that is produced?
X-rays are only produced when the cathode is negative and the anode is positive
The removal of x-rays from the beam by absorption or scatter
Radiopaque structures are a result of more or less attenuation of x-rays?
Radiolucent structures are a result of more or less attenuation of x-rays?
Attenuation by absorption is?
Attenuation by scatter is?
Define Bremstrallen radiation
When electrons interact with the nucleus of a target atom
Define Characteristic radiation
When electrons interact with an electron of a target atom
Define Thermionic emission
The boiling off of electrons into a cloud at the filament wire
Too much vertical angulation
Error in horizontal angulation
Not enough vertical angulation
#00 and 0 film
children PA and BW
Adult anterior PA
Adult posterior PA and BW
Long adult posterior BW
Occlusal, whole arches
Characteristics or Properties of X-rays?
Can cause a fluorecent screen to glow
Can affect a photographic plate
Travel long distances at the speed of light (186,000 mi/sec)
Have no mass
Advantages of paralleling and bisecting?
Paralleling- less distortion
Bisecting- good for shadow palates
Define Density and Contrast
Density- overall blackness of the film
Contrast- difference in densities within a film
Purpose of intensifying screen
To intensify the radiation to allow a reduction in radiation exposure time
Why use fast speed film?
To reduce exposure time
What is the fastest speed film and how much does it reduce exposure time?
To change from 10 mA and 6 seconds to 15 mA exposure time and maintain density?
10 X 6=60 mAs
15x = 60 mAs
x = 4 seconds