final review prep Flashcards
When an X-ray beam is filtered, photon quantity in the primary beam would be
decreased
The formula for magnification factor is
SID/SOD (SID divided by SOD)
A measurement between the source of the X-rays ( in the primary beam) and the image or IR is known as:
SID
To obtain minimum magnification, a technologist should:
position the object close to the image receptor
A foreshortened image:
results from an inclined object
Any misrepresentation of an anatomic structure that alters its size and / or shape defines:
distortion
smaller focal spot sizes cause
less blur (less geometric/inherent blur)
The greatest enemy of the sharpness of detail is
motion
To avoid shape distortion, which of the following must be paid close attention to?
Part angulation
What radiographic quality factor would be most affected by an excessive amount of geometric blur (focal spot blur)?
recorded detail
When proper radiographic detail cannot be obtained because of excessive OID, what change in technique may be use to improve the detail?
increase SID
Which of the following directly affects the degree of shape distortion in an image
- object thickness and shape
- angle of the object in relation to the film
- OID
- angle of the beam in relation to the object
- centering of the x-ray beam to the object
1,2, 4, and 5 only
Which of the following would not be included in the principal geometric factors affecting radiographic quality?
collimation
Which set of conditions will produce an image with the greatest magnification?
A. 20 inches SID, 1 inch OID
B. 40 inches SID, 3 inches OID
C. 50 inches SID, 5 inches OID
D. 72 inches SID, 5 inches OID
C. 50 inches SID, 5 inches OID
Which would provide the greatest detail in an x-ray image?
(1) Small focal spot
(2) Longer SID
1 and 2
With all other factors unchanged, if focal spot size is decreased, image magnification will
increase/decrease/not change at all
not change at all
With all other factors unchanged, if mAs is decreased, image magnification will:
increase/decrease/not change at all
not change at all
If the CR is off-centered to an object but there is still alignment with the anatomy/IR and CR, magnification will
increase/decrease/not change at all
not change at all
With all other factors unchanged, if the anatomy of interest is tilted in relation to the IR (and the IR remains parallel with the table/Bucky), image distortion will:
increase/decrease/not change at all
increase
T/F:
Foreshortening and elongation are examples of shape distortion
true
T/F: Recorded detail is a degree of sharpness on the radiograph.
true
T/F: to acquire greater detail you should use a small focal spot
true
T/F: typically there is always slight magnification on radiographic images
true
T/F: You can increase detail by increasing OID.
false
The smaller the effective focal spot the _______ the recorded detail.
greater
radiation is defined as _______________
energy in form of waves sent out over a distance
When a neutral atom gains or loses an electron, the atom is said to be:
ionized
What is defined as a charged particle?
an ion
Which of the following is an ionizing radiation
microwave
radiowave
x-ray
ultrasound wave
x-ray
X-rays are what form of ionizing radiation?
electromagnetic
X-ray wavelength is _________ to frequency
inversely proportional
X-ray energies are ______ related to their wavelength.
inversely
X-rays are considered ____________
heterogeneous
Which of the following is a characteristic of x-rays?
capable of producing harmful effects
capable of penetrating matter
electrically neutral
have no mass
all of the above
all of the above
The property of x-rays that accounts for their effect on biological systems is that they
cause ionization in matter
No useful input/ undiagnostic information on the image that will interfere with the visibility of the anatomy is called
noise
The ability to demonstrate/distinguish a small object in a high contrast image, its accuracy and clarity, is the definition of which of the following?
Spatial resolution
Contrast resolution
spatial resolution
The _________ the SID the _________ the magnification.
greater, smaller
Spatial resolution is affected by which of the following
focal spot size
kVp
none of the above
focal spot size
Sharply recorded details are demonstrated when:
- motion is controlled
- a large focal spot is used
- a large OID is used
1 only
Shape distortion is controlled by
alignment
Examinations of body parts with large inherent OID use _________ whenever possible.
large SID
Any unwanted marks on a film are classified as
artifacts
An increase in OID will cause an increase in:
magnification
A radiograph showing a relative lack of focal spot blur would be called:
sharp in detail
T/F:
In radiography, optical density is a visible representation of the quantity of X-ray photons reaching the IR.
true
T/F: increasing mAs increases optical density
true
T/F:
Increasing mAs increases optical density.
true
T/F: increasing mAs increases brightness
false
what controls the scale of contrast in a radiographic image?
kVp
what controls optical density in the radiographic image?
mAs
A radiograph that has sharp differences in optical density is called:
high contrast
A radiograph with a small number of widely varying optical density values is said to possess:
short scale contrast
which scale of contrast has a short gray scale and used a low kVp
high scale of contrast
which scale of contrast has a long gray scale and used a high kVp?
low scale of contrast
scale of contrast increases as ___________
kVp is decreased
scale of contrast decreases as __________
kVp is increased
gray scale increases as ___________
as kVp is increased
gray scale decreases as ___________
kVp is decreased
Doubling the mAs will result in:
- increased patient dose
- twice as many photons in the x-ray beam
- increased radiographic density
1, 2, and 3
If all other factors are unchanged and mA is decreased, image optical density will
directly decrease
If all other factors are unchanged and time is decreased, image optical density will
directly decrease
Which of the following is the best to obtain 20 mAs
100 mA @ 1/5 sec
200 mA @ .1 sec
300 ma @ 1/15 sec
400 mA @ .05 sec
400 mA @ .05 seconds
According to the reciprocity law, a technique of 200 mA, .5 second and 68 kVp can be changed to 400 mA, _______ second and 68 kVp.
0.25
For the 1st exposure, 10 mA @ .5 seconds were used. There was considerable motion on the finished image. For the repeat, the time was decreased to .05 seconds. What mA would need to be used in order to maintain density?
100
Which of the following would result in the shortest scale of contrast?
300 mA
1/30 sec
70 kVp
300 mA
1/60 sec
80 kVp
200 mA
1/20 sec
70 kVp
100 mA
2/10 sec
60 kVp
100 mA
2/10 sec
60 kVp
In the term kVp, the ‘p’ actually stands for
highest voltage (peak)
Long wavelength radiation will produce a radiograph with
short scale contrast
If an image (if the anatomical anatomy) is under-penetrated, the cause would be
not enough kVp
If an image (if the anatomical anatomy) is under-exposed, the cause would be
not enough mAs
T/F: Radiographic contrast and optical density of the manifest image in a digital image is primarily affected by predetermined algorithms in the computer.
true
T/F: Differential absorption results in the process of image formation, whereby the x-ray beam interacts with the anatomic tissue and a portion of the beam strikes the image receptor.
true
________ defines the range of colors of gray (the differences) in a radiograph including the dark areas and the bright (or clear areas)
contrast scale
_________ defines a color of gray in the image
density
differences in the brightness levels on the radiographic image is called
image contrast
a longer scale of contrast (many shades of gray) within the part can be obtained by
increasing the kVp
An image with a brief range of widely different densities possesses
- short scale contrast
- long scale contrast
- high contrast
- low contrast
1 and 3 only
In order to maintain the same density level and the mA is doubled, you should
1/2 the time
an additive disease requires a(n) (increase/decrease) in (mAs/kVp)
increase, kVp
Select the factors that affect subject contrast
- physique
- age
- development (muscle vs. soft tissue)
- pathology
all of the above
, the thorax represents high subject contrast. Therefore, which of the following is most appropriate?
High kVp
Low kVp
high kVp
Which of the following is not a primary factor in the production of a radiograph?
intensification factor
mA
seconds
kVp
intensification factor
Which of the following does not belong in this group
wavelength
penetration
kV
intensity
intensity
The use of 15% kilovoltage rule in the maintenance of OD as mAs is halved offers the advantage of:
lower patient dose
shorter exposure times
both
What does the 15% rule state?
That a change of 15% in kVp will result in approximately the the same change in density as doubling, or halving the mAs.
At 30 inch SID, 200 mR of radiation reaches the IR changing the distance to 72 inches, the new intensity of radiation will be
To solve this problem, we would use…
Inverse Square Law
An exposure is made at 40 inches using 100 mAs. At 60 inches, what is the new mAs to maintain density?
To solve this problem, use the….
Direct Square Law
A technique of 160 mAs and 60 kV has been employed in producing a satisfactory image. In order to reduce patient exposure and to maintain density, _______ mAs and ______ kVp should be used.
To solve this problem, use the
15% rule
“The intensity or exposure rate of radiation at a given distance from a point source is inversely proportional to the square of the distance” defines
Inverse Square Law
Which affect the quality of a radiographic image?
(1) Patient positioning
(2) Selection of technique factors
1 and 2
The amount of energy absorbed by an irradiated object is primarily controlled by:
- Energy of incident photon
- Atomic number of the tissue
- Speed of the incident photon
1 and 2 only
“…the ability of the imaging system to distinguish between small objects that attenuate the x-ray beam similarly…” defines
contrast resolution
The function of radiographic contrast in a radiograph is to
make detail visible
According to the textbook, the number of different shades of gray that can be stored and displayed by a computer system is termed
scale of contrast/gray scale
Which of the body tissues has the highest absorption when exposed to diagnostic x-rays?
soft tissue
bone
muscle
gas
bone
Which of the primary exposure factors has the greatest effect on beam quality, attenuation, and exposure latitude?
kVp
Which term might be used to describe an x-ray image that has a few shades of gray with marked visible differences between the ODs?
short scale contrast
kVp is the controlling factor for which of the following?
quantity of x-rays
size of the focal spot
OID
none of the above
none of the above
The ability of an IR to display different definition shades of gray from light to dark.
exposure latitude
The range of exposure intensities an IR can accurately detect.
dynamic range
T/F: As the energy of an x-ray beam is increased, the penetrability is increased.
true
T/F: In the diagnostic range, characteristic radiation constitutes most of the x-ray beam.
false
T/F:
Penetrability is an expression of x-ray quality and conveys the ability of x-rays to pass through tissues.
true
T/F:
Transmission is the term used to describe what happens when the x-ray photon travels through the part completely.
true
____________ is the reduction of intensity of the X-ray beam as it passes through the tissue being imaged.
attenuation
With the Compton effect an ______ shell electron is ejected.
outer shell
Which x-ray interactions with tissue occur in the diagnostic imaging x-ray energy range?
Compton
Photoelectric
both of the above
none of the above
both of the above
Which x-ray interactions with tissue involve the removal of an orbital electron?
(1) Compton
(2) Characteristic
(3) Photoelectric
1 and 3 only
When the kVp selected is equal to or slightly greater than the inner shell binding energy of a tissue atom, which interaction predominates?
Compton
Classical
Photoelectric
Pair production
photoeletric
What is the ejected electron called in a photoelectric event?
photoelectron
What is the effect of increasing kVp on the x-ray beam?
increased quality and penetrability
The x-ray beam that leaves the patient in the direction of the image receptor is often referred to as:
exit radiation
The photoelectric interaction most commonly occurs when the incident photon strikes an (inner/outer) shell electron
inner
The opposite of radiolucent is:
opacity
The amount of energy absorbed by an irradiated object is primarily controlled by:
- Energy of incident photon
- Atomic number of the tissue
- Speed of the incident photon
1 and 2 only
Primary radiation can be defined as
radiation that exits the tube port
During a photoelectric interaction, the incident photon is ____________ by the electron of the target atom.
totally absorbed
Attenuation is
- affected by absorption only
- affected by scattering only
- the product of both absorption and scattering
- the product of both absorption and scattering
_______ refers to x-rays leaving the patient that did not interact with atoms as it passed through the patient.
Absorption
Attenuation
Scattering
Transmission
Transmission
Changing the mA controls which of the following?
- Penetrating power of the x-ray beam
- Quality of the x-ray beam
- Quantity of the x-ray beam
- Average photon energy of the x-ray beam
- Quantity of the x-ray beam
The number of x-rays in the useful (primary beam) is called
x-ray quantity
radiation exposure
all of the above
all of the above
X-rays were discovered by ________
Roentgen
X-rays were discovered on __________ and the 1st x-ray was of a ____
November 8 1895; hand
Which factors if changed, change x-ray quantity?
(1) mAs
(2) kVp
1 and 2
Which factors if changed, change x-ray quality?
(1) mAs
(2) kVp
kVp
At higher kilovoltage (kVp) the percentage of photoelectric interactions:
decreases
Which tissue interaction is responsible for patient dose of ionizing radiation?
photoelectric
The shift of the characteristic x-ray spectrum to higher energy occurs because of ____________ in kVp
increase
The probability of the incident photon having a Compton scattering interaction is influenced principally by ______________
energy of the incident photon
The photoelectric effect is principally associated with the _________ of an x-ray photon.
absorption
The percentage of Compton interaction _________ with increasing energy (higher kVp) of the incident x-ray photon.
increases
The Compton interaction involves outer shell electrons due to their (high/low) binding energy.
low
In reference to target interactions, only kVp settings of _____ or greater will produce K characteristic photons.
70
A change in mA (does/does not) change the number of electrons flowing from the cathode to the anode.
does
A change in mA (does/does not) change the kinetic energy of electrons flowing from cathode to anode.
does not
Anatomic structures that readily transmit x-rays have a _____ atomic number.
low
Decreasing tissue atomic number _________ beam attenuation.
decreases
Increasing kVp _________ transmission
increases
The attenuation of x-rays occurs:
exponentially
