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Term 3 IP2-Unit 2

Prime & Geometric Factors

QuestionAnswer
What are the 4 prime factors of the x-ray beam? Contrast, Density, Detail, Distortion
This is the sharpness of structural lines or minute details on the radiograph: Detail
What are the 2 categories of radiographic detail? 1) Visibility of detail 2) Geometric Detail
These are factors that can be seen but not necessarily measured: Visibility of detail
These are factors that can be measured: Geometric Detail
In digital radiography, the term is __________ when referring to radiographic detail. Resolution
Anything that deviates from optimum technique will have what effect on visibility of detail? Reduce visibility of detail
Increasing motion will have what effect on the visibility of detail? Reduce
Increasing speed screen will have what effect on the visibility of detail? Reduce
kVp or mA that is too high or too low will have what effect on the visibility of detail? Reduce
What has the greatest effect on the reduction of detail? Motion
Decreasing collimation is making the field size _____________, and __________ detail. Larger; Reduces
What are 4 ways to reduce motion: 1) Short exposure technique 2) Immobilization 3) Suspension of respiration 4) Communication
What is the MOST important way to reduce motion? Communication
Geometric detail refers to what 2 radiographic properties? Umbra & Penumbra
Image proper or true image is called: Umbra
The light hazy area surrounding the true image is called: Penumbra
Anything that increases penumbra does what to detail? Reduces detail
What factors affect Geometric Detail? SID, OID, FSS
Regarding Geometric Detail and the factors that affect it, what is the best factor settings to produce the greatest geometric detail? Small FSS Long SID Short OID
Of the 3 factors that affect Geometric Detail, which factor affects Geometric Detail the most? OID
What would increasing FSS do to penumbra? Increase penumbra
Shorter SID's do what to penumbra? Increase Penumbra
Extremities would tend to require a small or large FSS? Small FSS
Typically, anytime the mAs is above 100 would require what type of focal spot size? Large FSS
When mAs is 50 or below the focal spot size will be __________. Small FSS
Certain situations may cause for an increase in OID, in these cases what can be done to reduce the negative effects of a larger OID? Increase the SID
As mA is increased, what happens to the focal spot? Blooming (bulging) of the focal spot
What is used to measure the focal spot size on focal spots larger than 0.3mm? Pinhole Camera
What is used to measure the focal spot size on focal spots smaller than 0.3mm? Star Pattern
What is the projection of an inclined line into a surface resulting in a smaller area? Line Focus Principle
The advantage of the line focus principle gives the heat capacity of a _________ focal spot and the geometric _____________ of a _______ focal spot. Large; Sharpness; Small
Which is larger, the effective focal spot or the actual focal spot? Actual focal spot
This is the area projected onto the patient and the image receptor: Effective focal spot
This is the area bombarded by electrons: Actual focal spot
What is the average target angle? 5 to 15 degrees
The smaller the angle, the ________ the effective focal spot. Smaller
Small angle = _________ effective focal spot Small Effective Focal Spot
What tool is used to measure the radiographic detail? Line Pair Test Tool
SOD: _______ _______ ________ Source to Object Distance
How can you calculate the SOD? SOD = SID - OID
What is the calculation for penumbra? FSS(width) X OID ÷ SOD
In calculating for penumbra, the smaller the number would equal what? Greater detail
This is the misrepresentation of the true size and or shape of the object: Distortion
What are the 2 types of distortion? Size & Shape
True distortion is _________ distortion. Size
False distortion is _________ distortion. Shape
This is the misrepresentation of the true size of an object: Size distortion
The width of the image is to (÷) the width of the object as the (=) distance of the image from the light source is to the distance of the object from the light source: Law of magnification
Formula for Law of Magnification: Image width ÷ Object width = SID ÷ SOD (I/O=I/O)
Decreasing _______ = increase in magnification SID
This is the misrepresentation of the shape of an object: Shape Distortion
Shape distortion is caused by misalignment of _________, _________, or __________. Tube; Object; Film
The greater the distortion, the poorer the _______________. Definition
Ideally, what should be parallel and what should be perpendicular? Object and film parallel; Tube perpendicular to both object & film
What are the 2 types of shape distortion? Foreshortening and Elongation
What is caused when the object is not parallel with the film? Foreshortening
What causes elongation? Tube Angulation
Increases in magnification results in increasing what? OID
Distortion primarily occurs because subject anatomy is __________. Inclined
How can distortion be corrected? Proper patient positioning
To reduce magnification, reduce _____. OID
Distortion of an x-ray image results from unequal ____________. Magnification
How much larger will an image be if placed midway between the image receptor and the light source? 2 times larger
A foreshortened image results from an __________ object. Inclined
What effect does focal spot size have on the magnification factor? None
What effect does collimation have on geometric factors? None
What is MOST responsible for radiographic spacial resolution? Focal Spot Size
To increase image sharpness use a _______ focal spot size. Small
A relative lack of FSB would be ________ in detail. Sharp
An IVP is routinely conducted with an anteroposterior projection to ________ the FSB of the kidneys. Minimize
What principally controls geometric blur? FSS
Best way to minimize FSB without affecting optical density is to use a very _______ focal spot. Small
Another term for FSB is _________. Penumbra
Imaging an object lateral to the central axis of the beam will cause FSB to be __________ on the __________ side. Larger; Cathode
What can be increased to reduce FSB? SID
When the focal spot is switched from large to small, penumbra will be _________. Reduced
Image contrast is the product of image receptor contrast and ___________ contrast. Subject
Spatial resolution is principally affected by what? FSS
Ensuring good screen film contact will also ensure reduced __________. Blur
Use of contrast media principally affects ____________ resolution. Contrast
Increasing collimation results in improved ___________ resolution and patient dose. Contrast
Geometric blur is most influenced by _____________ _______ _______. Focal Spot Size
kVp does what to image blur? Nothing
Direct exposure radiography is used for better ______________ resolution. Spatial
Increasing grid ratio will have what affect on radiographic contrast? Increase
When the mAs is adjusted to provide constant optical density after an increase in kVp, motion blur is reduced if the same _____ is used. Why? mA; mAs is adjusted by reducing time (shorter exposure) which reduces blur (motion)
the ability of an imaging system to discriminate between two adjacent high-contrast objects. Spatial resolution
When an object is present to one side of the central axis of the x-ray beam what will happen to subject contrast? Nothing
When an object is to one side of the central axis of the x-ray beam, what will happen to magnification? Nothing
What does kVp do for the visibility of detail? Nothing
What will increasing mAs do for the visibility of detail? Nothing
Created by: foster1317