IP
on the lateral edges.
what type of grid typically cause moire pattern?
short dimensional grids
what is the best way to minimize magnification?
use a short OID, long SID will result in greater entrance exposure to the patient.
what is the purpose of the Glass envelope?
1. protects internal components of x-ray tube
2. maintains a vacuum environment within x-ray tube.
what is the function of the focusing cup?
provides an electrostatic field designed to control the path of electron from the cathode to the anode at the time of exposure (flow - to +)
a wave like or watery appearance of an image is referred to as ________?
moire pattern
When can a moire patterns occur in CR systems?
when the laser light in the CR reader runs paralell with the area of grid lines and are projected onto the PSP plate.
what causes shape distortion?
1. tube angulation
2. part angulation
3. image receptor angulation
4. motion
what does the thinner section of the glass envelope do?
designed to reduce the amount of inherent filtration of the envelope.
what principle does the focusing up help maintain?
the line focus principle.
when two linear grids are placed on top of one another to make up a crosshatched grid, but the lead lines are not aligned at right angles to one another.
how can you prevent moire pattern?
use a grid frequency of at least 60 lines per centimeter
what causes elongation?
(longer/skinnier) results from improper tube or receptor angulation.
X-rays directed through the window port (exit window) of the glass envelope will comprise the ________?
primary x-ray beam
what is the line focus principle?
size of the focal spot directed toward the IR (effective focal spot) is smaller than the size of the focal spot (actual focal spot) measured on the surface of the anode.
what causes moire pattern in digital imaging?
misalignment of pixels between the digital mask and a second digitized image.
what is magnification?
size distortion.
what causes foreshortening?
(shorter/fatter) occurs when the object is angled
what is the location of the stators?
external, all other components are internal.
why is a smaller effective focal spot important to have in radiography?
it produces better spatial resolution.
what is another name for moire pattern?
aliasing artifact.
what increases magnification?
long OID and short SID
What is a Ghost image?
1. only occurs in CR.
2. cause from insufficient erasure of a previous image and ghost image is seen on the new image.
what type of charge does the focusing cup have?
a negative charge.
What are the typical sizes for focal spots?
1.) 0.5-0.6= small focal spot
2.) 1.0-1.2= large focal spot