IP
what type of anode angle provides the best spatial resoltution?
small anode angle
What is the anode made out of?
tungsten with rhenium.
why is a rotating anode used?
1. increases surface area
2. increases heat capacity
3. improves efficiency of radiation production.
what does AEC stand for?
automatic exposure control
why do AEC images vary?
due to changes in subject contrast within the patient population
what is the key advantage of having a large anode angle?
can handle a higher heat capacity
why is tungsten with rhenium used for the anode target material?
1. high atomic number
2. high melting point
3. ability to dissipate heat.
X-rays are produced ________, which means they are produced with ___________?
1. Isotropically
2. produced with equal intensity in all directions.
what type of device is an AEC?
ionization chamber
how does AEC reduce the number of repeat exposures?
by preventing overexposure andunderexposure
which anode angle would provide the best spatial resolution:
a. 7 degrees
b. 11 degrees
c. 15 degrees
d. 20 degrees
a. 7 degrees
what does the induction motor operate?
operates the rotor that spins the anode during a radiographic procedure
what is the name of the motor that powers the anode?
the induction motor
what is the purpose of AEC?
designed to reproduce a desired amount of receptor exposure on images taken of selected body parts regardless of changes within the patients being examined.
what does AEC rely heavily on for accuracy?
accurate patient positioning and phototimer cell selection
what is the relationship between anode angle and focal spot size?
1. small anode angle- small focal spot (better detail)
2. large anode angle- large focal spot (more heat capacity)
what two components make up the induction motor?
rotors and stators.
radiation that is emitted through the metal protective housing is called ________?
leakage radiation
why is AEC important in a mixed population?
it keeps radiographs within in acceptable diagnostic range.
what components are commonly involved in positioning with AEC?
tube, patient, table, grid, IR/bucky
Which anode angle is larger, 10 degrees or 17 degrees.
10 degrees, the angle is more steep.
what happens when the rotor switch is engaged?
fires the stator, comprised of paired sets of electromagnets, in a circular direction around the outside of the x-ray tube, resulting in a circular movement of the rotor within the tube
leakage radiation should not exceed _______?
1 mGya /hr at 1 meter
will images produced using AEC always look identical?
no, they will not necessarily be identical
what is the purpose of a backup timer with AEC?
patient protection