26-29 Flashcards
Photographic properties make the _____ of an image.
Detail
What are the 2 photographic properties?
IR exposure
Contrast
Without IR exposure and contrast
We would never be able to see am X-ray
How light or how dark we make our final image is known as
Brightness
Which post processing function controls brightness
Window Level
Where does contrast come from?
LUTS
Is contrast a post processing feature or pre processsing?
Pre-processing
The best way to evaluate an image to see if it contains good IR exposure is by
Checking EI/DI values
Where does IR exposure come from?
mAs and Contrast
Too many photons striking the IR results in
Overexposure
A _______ image will appear too dark
Overexposed
It is better to ________ than to _______ because we can post process.
Overexpose
Underexpose
A _____ image will appear too light.
Underexposed
When the IR did not receive enough photons, it has been _______.
Underexposed
mAs is ________ proportional to IR exposure.
Directly
If mAs is increased, what will happen to the IR exposure
An increase
In order to see a visible difference between 2 images, the mAs factor must have a minimum ______ change.
25%-35%
When adjusting mAs, adjustments should be made in increments of
Doubles or halves
An increase in kV will cause the IR exposure to
Increase
____ alters the intensity of the beam reaching the IR.
kVp
The target of the tube is the
Anode
A 15% increase in kVp will _____ the IR exposure.
Double
Single phase = _____% ripple
100
Three phase = ______% ripple
4-14
High frequency = ______ ripple
1%
The generator type we want to use is
High frequency
FSS does what to IR exposure?
No effect
Which side of the tube does the anode heel effect alter the beam?
Cathode side
An increase in SID causes IR exposure to
Decrease
If SID is increased, what should we do to maintain IR exposure
Increase mAs (double)
A decrease in SID causes IR exposure to
Increase
If SID is decreased, what needs to be done to maintain IR exposure?
Decrease mAs (half it)
When dealing with intensity and distance, you’re dealing with the
Inverse square law
If kVp increases, scatter_______
Increases
An increase in OID, causes IR exposure to
Decrease
Where is filtration located?
In the tube
An increase to filtration cause IR exposure to
Decrease
What does beam restriction do?
Reduces the total number of photons available, which reduces scatter.
What does beam restrictions do to IR exposure?
Decreases it
An increase in Gris ratio causes IR exposure to
Decrease
_______ gives us anatomical detail
Contrast
Contrast ranges from
Black to white
The post processing function that controls contrast is
Window width
______ contrast has few shades of gray.
High
____ contrast is long scaled and has _____ shades of gray.
Low
Many
_____ is the primary controller of subject contrast,.
kVp
Range of differences in the intensity of the X-ray beam after it has been attenuated by the subject
Subject contrast
A _____ in field size means you’re opening up the collimators and will ____ IR exposure, causing a _____ in subject contrast.
Increase
Increase
Decrease
Can subject contrast be improved by post processing?
No
A decrease in IR exposure will cause a ____ to subject contrast
Increase
Does kVp effect subject contrast?
Yes
An increase in mAs causes contrast to
Increase
If filtration increases, contrast will
Decrease
A decrease in collimation is the same as saying
Opening collimation
An increase in collimation is the same as
Closing collimation
A decrease in collimation causes contrast to
Decrease
An increase in part size will cause contrast to
Decrease
Which of the following can impact the remnant signal?
1. Tissue density
2.pathology
3.beam restriction
1,2, and 3
Which of the following devices is used to overcome severe variation in patient anatomy or tissue density, providing more uniform receptor exposure?
Compensating filter
In digital imaging, kilovoltage selection has an effect on
1. Photon energy
2. Penetration
3. Image contrast
1 and 2
Increasing the technique factor kVp will have what effect on scatter production
Increase production
Scatter _______ IR exposure
Increases
Increasing IR exposure means to make the image
Darker
Subject contrast comes from the
Patient
If anatomic details are not recorded on the image, then the IR has been
Underexposed
Range of brightness levels and how they are displayed on the monitor is called
Dynamic range
The use of filtration devices will cause an/a __________ in IR exposure.
Decrease
True or false: Subject contrast that is underexposed can be improved by post-processing algorithms.
False
The filament and focusing cup are found on the __________ side of the x-ray tube.
Cathode
Post-processing can make an image that is __________ acceptable for interpretation.
Overexposed
LUT’s is what determines image
Contrast
Which focal spot is projected out of the tube toward the object being radiographed.
Effective
The primary function of x-ray beam filtration is to
Reduce patient skin dose
What are the 2 geometric properties?
Spatial resolution
Distortion
How do we measure spatial resolution?
Line pairs per mm on the test tool
Degree of geometric sharpness or accuracy of the structural lines actually recorded in the image
Spatial resolution
Geometric properties control
Detail
Photographic properties control
Visibility of detail
We want a ______ matrix with ____ pixels to get good spatial resolution
Large
Small
High frequency spatial resolution has ____ wavelengths and _____ contrast
Shorter
High
QC testing are types of _____ test tools to make sure we’re getting good detail on our images
Resolution
What are the types of QC testing
Point spread
Line spread
Edge spread
We want an MTF of
1
Low signal and high noise gives us
Bad detail
CNR stands for
Contrast to noise ratio
Where does Nyquist Criterion happen
Within the system
Takes the data from the pixels and samples the signals twice from each cycle to make sure nothing was missed
Nyquist Criterion
When the Nyquist Criterion doesn’t get sampled twice
Aliasing
Detail is affected by
SID
OID
SOD
If SID increases, spatial resolution _______
Increases
We want a ____ OID to increase spatial resolution
Short
An increase to SOD will cause a _____ to spatial resolution
Increase
The main controller of detail is
FSS
What controls penumbra
FSS
The _____ penumbra, the better the resolution
Less
A smaller FSS will give us _____ penumbra
Less
What surrounds the Umbra
Penumbra
A long SID gives us _____ penumbra
Less
Less penumbra gives us _____ detail.
Greater
The smaller the pixels the _____ the detail
Better
Misrepresentation of the size of shape of the structure being examined
Distortion
Magnification is controlled by
SID/OID
The greater the SID the ____ the magnification
Smaller
Objects _____ from the IR will be magnified
Further
Magnification factor is
SID divided by SOD
What are the 2 types of shape distortion
Elongation
Foreshortening
Elongation makes the object look
Longer than what it is
Foreshortening makes the object look
Shorter than what it is
Poor alignment of the part causes
Foreshortening
Poor alignment of the tube and/or IR causes
Elongation
Angulation of the tube will always change
SID
An increased SID will cause magnification ton
Decrease
__________ will occur with central ray and IR alignment issues.
Elongation
In digital imaging, thin film transistor (TFT) and detector element (DEL) size is related to
Spatial resolution
An increase in patient thickness __________ spatial resolution
Decreases
Sharpness/resolution is ________ related to OID.
Inversely
An MTF of 1.0 represents a signal of extremely ______ fidelity
High
Misalignment of the tube-part-IR relationship results in
Shape distortion
The best method to reduce patient motion
Communication
The electronic term used to describe anything that interferes with visualization of the x-ray image is
Noise
Which focal spot size will create a larger penumbra?
Large FSS
Magnification is considered __________ distortion.
Size
For the same field of view (FOV), spatial resolution will be improved using
A larger matrix
The line focus principle expresses the relationship between
the actual and the effective focal spot.
