Resolution + Contrast
Type of focal spot size that improves definition
smaller
Improper tube, object, and IR alignment with no change in the SID will result in what type of distortion?
shape
The unsharpness of the outer edge of the radiographic image is called?
penumbra
What are the two categories of motion?
Involuntary and Voluntary
The focal spot projected onto the patient and the IR is known as what?
APEU Focal Spot
Apparent
Projected
Effective
Useful
Which type of IR would produce the worst recorded detail?
Par speed
Cardboard holder (non-screen)
Fast speed
Medium speed
Fast speed
True or False: A change in FSS (Focal Spot Size) will effect the magnification of the radiograpic image.
False
The factors which govern unsharpness include:
A. EFSS
B. Grid Ratio
C. OID
D. SID
A, C, D
The best factor to adjust for the elimination of motion is?
decrease exposure time
The APEU Focal Spot is _____________ and ___________ compared to the actual FS.
smaller and squarer
The loss of recorded detail due to the materials used to produce a radiograph is called?
Intrinsic unsharpness
If SID and SOD are given, what is formula for magnification?
MAG = SID/SOD
Geometric principles of radiography include:
A. contrast
B. definition
C. distortion
D. density
B and C
When motion is a problem, exposure time can be reduced by 1/2 if the kVp is increased by what?
15%
Which IR type gives the most latitude for an exposure?
non-screen exposure
What governs which focal spot size can be used for radiographic procedure?
the tube rating chart
What is the affect to shape distortion when the tube angle is decreased?
What is the Unsharpness formula?
FSS x OID/SOD
What type of focal spot size, SID, and OID will result in the worst unsharpness?
Large FSS, Shortest SID, Longest OID
There is the liklihood of more quantum mottle with what type of screen?
high speed rare earth
Which of the following is NOT a factor affecting recorded detail?
motion
size of the film (IR)
geometry
screens
size of the film (IR)
What percentage increase is usually used for magnification radiography?
100%
Which of the following measurements will produce the highest resolution?
A. 8 lp/mm
B. 18 lp/mm
C. 15 lp/mm
D. 10 lp/mm
B
As motion increases, recorded detail ___________
Decreases
The graphic representation of the resolution characteristics of an x-ray imaging system is referred to as?
modulation transfer function
High quality images is characterized by a _____________ in densities.
variation
What factor in the 15% rule is increased in order to double the density?
kVp
What SID is typically used for a chest procedure?
72" SID
Why are higher kVp levels needed? Two answers
1. lower patient radiation dose
2. to obtain a broader range of densities in the image
1000 volts = _____ kV
1 kV
Two categories of radiographic contrast?
film and subject
In order to have more high-energy x-rays produced, what type of kVp is needed?
higher kVp
A small focal spot _____________ unsharpness and requires ____________ mAs settings.
reduces; lower
What OID is needed to reduce magnification?
as low as possible
Which factor has the greatest effect on image contrast?
kVp
A grid can absorb up to how much scatter radiation?
90%
With a variable kVp technique chart, what is constant?
mAs
In order to obtain 1/4 of the original radiation intensity, what should be done to the SID?
doubled
Reason to use technique charts?
to obtain the best image the first time; reduces repeats
Piece of equipment that is placed between the IR and the patient
grid