Ch. 3 TEST MATERIAL Flashcards
The atomic number of iodine is:
53
The atomic number of barium is:
56
Place the following tissue densities in order of easiest to hardest to penetrate by x-ray:
Lung
Muscle
Fat
Bone
Lung
Fat
Muscle
Bone
The total reduction in the number of x rays remaining in an x ray beam after penetration through a given thickness of tissue is called:
attenuation
Place the following tissue densities in order of hardest to easiest to penetrate by X-ray:
Lung
Muscle
Fat
Bone
Bone
Muscle
Fat
Lung
Coherent scattering is an interaction between low energy x rays and _____
Whole atoms
An x ray image results from the difference between those x rays absorbed photoelectrically in the patient and those transmitted to the image receptor.
This difference in x ray interaction is called ____
Differential absorption
air is considered a negative contrast agent
True or False
True because it appears dark on an image due to low-density
X rays throughout the diagnostic range can undergo an interaction with outer-shell electrons that not only scatters the x ray but reduces its energy and ionizes the atoms as well.
This interaction is called:
Compton Scatter
What type of x-ray interaction with matter is the source of most of the occupational radiation exposure that radiographers receive?
Compton Scattering
How could you decrease quantum noise in a digital image?
(fill in the bank on the test)
Increase mAs
The principal source of radiographic fog is _______.
scatter
How can a technologist compensate for the involuntary motion of the patient?
Short exposure time
Which factor has the greatest effect on size distortion?
OID
Which factor would cause an increase in spatial resolution?
long SID
The two types of shape distortion are:
Elongation and Foreshortening
High contrast; short scale or long scale?
Short scale ( few shades of gray)
long low lots of gray
What is considered to be the most detrimental to spatial resolution and the number one cause of repeat X-rays?
Motion blur
Fat tissue absorbs less radiation than muscle because fat tissue has a lower:
density
As compared to the patient with a 24 cm thick abdomen, imaging a patient with a 30 cm thick abdomen will result in ___________ scatter being produced and ________ image contrast
more, lower
Due to the anode heel effect, radiation intensity can vary by as much as:
(fill in the blank on the test)
45 Percent
What is defined as the range of exposure intensity that an IR can accurately detect?
Dynamic Range
An increase in kVp will have what effect on digital imaging?
- More Scatter?
- Higher Exposure Rate?
- Lower Contrast?
ALL THREE
- More Scatter
- More Exposure
- Less Contrast
What controls contrast on an image?
(fill in the blank on the test)
kVp
What controls the density or brightness on an image?
(fill in the blank on the test)
mAs
What would be an example of a low-contrast image?
(fill in the blank on the test)
Abdomen
What interaction is only dependent on the energy of the photon?
Compton
Unwanted exposure to the IR due to scatter radiation is called:
Fog
What is another name for the invisible image on the image receptor before processing?
Latent Image
What is another name for the invisible image after processing?
Manifest image or visible image
What kind of radiation has passed through the patient and on the way to the IR?
Remnant Radiation
Digital radiography has better or worse contrast when compared to conventional?
Better
What kind of radiography has the highest spatial resolution?
(fill in the blank on test)
Film or Digitial Mammo
Digital radiography has a shorter or wider dynamic range when compared to conventional radiography
Wider
When the x-ray photon travels completely through the patient or through the part without an interaction is it called:
Transmission
The photoelectric effect involves the removal (ejection) of an electron. This process of removing an electron from an atom is known as:
Ionization
Visibility of the image is dependent on what two factors?
Contrast and Spatial Resolution
As tissue thickness increases, what happens to scatter attenuation?
scatter attenuation also increases
What reduces image contrast?
Compton Scattering
What interaction with matter acts independently of the atomic number of tissue?
Compton
the photoelectric absorption of x-rays produces the ____ areas in a radiograph.
White
Compton scatter X-rays can be deflected in any direction, including 180 degrees from the incident x-ray?
true or false
True
A photoelectric interaction can not occur unless the incident x-ray has equal to or greater energy than the electron binding energy?
True or False
True
The result of coherent scatter is the change in the direction of the x-ray without a change in its energy.
True or False
True
X-rays scattered back in the direction of the incident X-ray beam is called ________.
Backscatter radiation
X rays in the diagnostic range undergo ionizing interactions with inner shell electrons. The x-ray is not scattered but is totally absorbed. This process is called:
Photoelectric Effect
The x ray image is a product of absorption and transmission. True or False
True
High-contrast images display…
fewer shades of gray but greater difference among them
Low-contrast images display….
a greater number of gray shades but smaller differences among them
____ is the loss of some energy from the x ray beam as it passes through the imaged tissue.
attenuation
