Ch. 3 Flashcards
The device that receives the radiation leaving the patient is the
Image receptor
_____ results in the process of image formation, whereby the X-ray beam interacts with the anatomic tissue, and a portion of the beam passes through the part and strikes the image receptor.
Differential absorption
______ is the loss of some of the energy from the X-ray beam as it passes through the imaged tissue:
Attenuation
The photoelectric effect involves the removal (ejection) of an electron. This process of removing an electron from an atom is known as:
Ionization
When the X-ray photon travels completely through the part without any interaction, it is called:
Transmission
When the X-ray photon strikes an atom within the tissue being imaged and loses all of its energy to an
inner shell electron of that atom, the photon is said to have been
Absorbed
When the x-ray photon strikes an atom within the tissue being imaged and loses only part of its energy to an outer shell electron of that atom, the photon is said to have been
Scattered
The interaction between x-ray photons and tissue that results in the production of a secondary x-ray photon is the:
Photoelectric interaction
When the entering x-ray photon loses energy and changes its path of travel as a result of interacting with an atom, the interaction is known as the:
Compton effect
The probability of total photon absorption by the photoelectric effect depends on the:
the energy of the incoming X-ray photon and atomic number of the anatomic tissue
The outer shell electron that is ejected during the Compton interaction is also known as a:
secondary electron and Compton electron
The x-ray photon that is scattered as a result of the Compton effect CANNOT:
strike the image receptor and provide useful anatomic information.
Interactions of high-energy x-rays (energies beyond the diagnostic range) with tissue include:
pair production and photodisintegration
Interactions of low-energy x-rays (energies below the diagnostic range) with tissue include:
Coherent scattering
The x-ray beam that leaves the patient in the direction of the image receptor is often referred to as:
Remnant radiation (useful)
If scattered photons are absorbed within the anatomic tissue, they:
contribute to the radiation exposure of the patient and do not contribute any useful
information about the anatomic part of interest
The amount of x-ray beam attenuation is affected by the:
-thickness of the body part and anatomic number of the atoms in the tissue
-thickness of the body part and energy of the X-ray beam
-atomic number of the atoms in the tissue and energy of the x-ray beam
-All options are correct.
-thickness of the body part and anatomic number of the atoms in the tissue
-thickness of the body part and energy of the X-ray beam
-atomic number of the atoms in the tissue and energy of the x-ray beam
- ALL OPTIONS ARE CORRECT
A body tissue with an increased tissue density results in:
increased beam attenuation
An increased part thickness results in:
increased beam attenuation
Unwanted exposure to the IR due to scatter radiation is called:
fog
Following exposure, the ________
image occurs first on the image receptor.
latent (not yet processed)
What occurs at higher kilovoltage?
fewer photon interactions and more photons transmitted
Beam attenuation ______ with a higher energy x-ray beam.
decreases
Image qualities for the visibility of anatomic structures include.
brightness (mAs) and contrast (kVp)
Image qualities for the accuracy of structure lines include.
spatial resolution and distortion
Muscle tissue absorbs more radiation than fat tissue because muscle tissue has a:
higher tissue density
The amount of luminance of a display monitor is:
brightness
Increased brightness means:
lighter
The difference in the brightness levels is:
image contrast
An image that has excessive brightness is considered:
unacceptable
________ refers to the absorption characteristics of the anatomic tissue imaged and the quality of the x-ray beam.
Subject contrast
The number of shades of gray that can be displayed by a computer system is:
Grayscale
A radiographic image with a greater number of similar brightness levels with small differences between them is said to have
low contrast (hard to see)
The ability of an image receptor to distinguish between objects with similar subject contrast is:
Contrast resolution
The smallest object that can be detected in an image is the
Spatial resolution
The accuracy of the anatomic structural lines in the radiographic image displayed is determined by the:
spatial resolution
Radiographic misrepresentation of the size or shape of the anatomic structure being imaged is:
-magnification and elongation
-magnification and foreshortening
-elongation and foreshortening
All options are correct.
-magnification and elongation
-magnification and foreshortening
-elongation and foreshortening
All options are correct.
Size distortion is affected by:
SID and OID
As seen on the radiographic image, scatter radiation:
decreases the visibility of anatomic structures
What occurs when too few photons reach the IR?
-The visibility of quantum noise is increased.
-image brightness is insufficient
-Image quality may be poor.
-All options are correct.
-The visibility of quantum noise is increased.
-image brightness is insufficient
-Image quality may be poor.
-All options are correct.
An unwanted brightness level in an area of interest on a radiographic image is:
An artifact
Which of the following are common artifacts?
-Jewelry covering part of the anatomy being imaged and fog because of scatter
-Jewelry covering part of the anatomy being imaged and quantum noise
-Fog because of scatter and quantum noise
-All options are correct
-Jewelry covering part of the anatomy being imaged and fog because of scatter
-Jewelry covering part of the anatomy being imaged and quantum noise
-Fog because of scatter and quantum noise
-All options are correct.
As compared to digital imaging, film-screen imaging has:
a narrower dynamic range
Disadvantages of film-screen imaging include:
-Susceptible to over- and under-exposure and limited contrast resolution
-Susceptible to over- and under-exposure and cannot alter the permanent image
-Limited contrast resolution and cannot alter the permanent resolution
-All options are correct.
-Susceptible to over- and under-exposure and limited contrast resolution
-Susceptible to over- and under-exposure and cannot alter the permanent image
-Limited contrast resolution and cannot alter the permanent resolution
-All options are correct.
With radiographic imaging, anatomic tissues, such as bone, that absorb most of the radiation result in that area of the image being:
lighter
During attenuation of the x-ray beam, the photoelectric effect is responsible for the total absorption of the incoming x-ray photon.
True or False
True
The photoelectric effect is dependent on both the energy of the X-ray photon and the composition of the anatomic tissue
True or False
True
The Compton interaction can occur within all diagnostic x-ray energies
True or False
True
Compton interactions are more likely to occur in soft tissue as compared to bone.
True or False
False, bone has a higher electron density
Approximately 20% of the primary X-ray beam reaches the image receptor.
True or False
False: Usually around 1%
X-ray absorption is more likely in tissues with a lower atomic number.
True or False
False (higher)
Beam attenuation is increased with a higher-energy x-ray beam
True or false
False (decreases)
The process of differential absorption for image formation remains the same for digital, film, and fluoroscopy.
True or False
True
An area of increased brightness on a display monitor indicates more tissue absorption.
True or False
True
The abdomen has low subject contrast.
True or False
True
The highest quality radiographic image has no unsharpness.
True or False
False
Flat panel detector fluoroscopy is rapidly being replaced with image-intensified fluoroscopy.
True or False
False (image-intensified is taking over flat panel)
Radiographic images of structures are always magnified when compared to the actual structure.
True or False
True
Magnification always results in reduced spatial resolution.
True or False
False (not always, only true in x ray)
When an image is distorted, spatial resolution is increased.
True or False
False (decreased)
Shape distortion can be useful in radiographic imaging.
True or False
True
Dynamic imaging provides imaging of the movement of internal structures.
True or false
True
The density and contrast of film-screen images can be adjusted
True or False
False (Cannot)
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
The atomic number of barium is:
56
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
air is considered a negative contrast agent
True or False
True because it appears dark on an image due to low density
The atomic number of iodine is:
53
Place the following tissue densities in order of easiest to hardest to penetrate by x-ray:
Lung
Soft Tissue
Muscle
Fat
Bone
Lung
Fat
Soft Tissue
Muscle
Bone
What type of x-ray interaction with matter is the source of most of the occupational radiation exposure that radiographers receive?
Compton Scattering
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
Compton scattered x rays can be deflected in any direction, including 180 degrees from the incident x ray.
True or Flase
True
The photoelectric absorption of x rays produces the _____ areas in a radiograph.
White
What is the atomic number of bone?
13.8
What is the atomic number of fat?
6.3
What is the atomic number of muscle?
7.4
What type interaction with matter acts independently of the atomic number of tissue?
Compton Scattering
______ reduces image contrast.
Compton Scattering
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
A photoelectric interaction cannot occur unless the incident x ray has energy equal to or greater than the electron binding energy. True or False?
True (70 KVP needed to occur)
To image small differences in soft tissue, one must use a high kVp to get maximum differential absorption
True or False
False (low)
X-rays scattered back in the direction of the incident X-ray beam is called ________.
Backscatter radiation
The result of coherent scattering is a change in the direction of the X-ray without a change in its energy
True or False
True
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
Fat tissue absorbs less radiation than muscle tissue because fat tissue has a
Lower tissue density
A digital image with decreased distortion may be due to
Decreased OID
Increased SID
What would result in decreased quantum noise in the digital image?
Increasing MAS
imaging a thinner patient
What is considered to be the most detrimental to spatial resolution and the number one cause of repeat X-rays?
Motion Blur
What is defined as “ill-defined edges”?
penumbra
How can a technologist compensate for the involuntary motion of the patient?
Short exposure time
The principal source of radiographic fog is _______.
Scatter
Which factor would cause an increase in spatial resolution?
Long SID
Which factor has the greatest effect on size distortion?
OID
The two types of shape distortion are elongation and magnification
True or False
False (Elongation and Foreshortening)
As part thickness increases…
Scatter increases and
contrast decreases
An increase in kVp will have which of the following effects in digital imaging?
More scatter radiation will be produced and
the exposure rate will increase
Subject contrast (kVp) is related to
Differential tissue absorption and
the atomic number of tissues being traversed
What is the range of exposure intensities that an image receptor accurately detect?
Dynamic range
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
