exposure exam 4: technical factors, contrast & spatial resolution, magnification & distortion

-the actual test questions and answers -doesnt include the math

the brightness of the image on a viewing monitor is…

a) the result of receptor exposure

b) the result of the tissue density

c) the result of tissue thickness

d) a function of the monitor

d) a function of the monitor

the principal controlling factor of radiographic receptor exposure is…

a) kVp

b) mAs

c) focal spot size

d) filtration thickness

b) mAs

which factor influences the number of photons reaching the IR?

a) kVp

b) mAs

c) focal spot selection

d) exposure time

b) mAs

spatial resolution is…

a) the degree of geometric sharpness

b) recorded detail

c) the accuracy of the structural lines actually recorded in the radiographic image

d) all of the above

d) all of the above

factors affecting recorded detail include…

a) kVp and filtration

b) radiographic grids and collimation

c) mAs and grid ratio

d) focal spot size and patient thickness

d) focal spot size and patient thickness

spatial resolution is improved when…

a) OID increases

b) OID decreases

c) SID decreases

d) the x-ray tube is angled

b) OID decreases

spatial resolution in digital imaging is determined by the…

a) bit depth

b) matrix size

c) pixel size

d) all of the above

d) all of the above

which radiograph below exhibits the best recorded detail?

a) a PA chest radiograph for evaluation of the heart at 40 in

b) a PA chest radiograph for evaluation of the heart at 72 in

c) a lordotic projection of the chest at 72”

d) an AP chest radiograph for evaluation of the heart at 72 in

b) a PA chest radiograph for evaluation of the heart at 72 in

the best method for controlling motion when the patient is unable to cooperate is to…

a) decrease the focal spot size

b) maintain mAs, while decreasing time

c) maintain mAs, while decreasing mA

d) decrease kVp

b) maintain mAs, while decreasing time

the composite measure of image accuracy compared to the original object, on a scale of 0 to 1 is referred to as?

a) line spread function

b) modulation transfer function

c) point spread function

d) noise reduction function

b) modulation transfer function

all of the following affect visibility of detail EXCEPT…

a) 15% rule

b) filtration

c) radiographic grids

d) SID

d) SID

for general radiography, an MTF value of 1 is…

a) average

b) suboptimum

c) theoretically impossible

d) a function of mAs

c) theoretically impossible

the Nyquist frequency is…

a) important in analog imaging

b) sampling a minimum of twice per cycle

c) unique to radiography

d) related to involuntary motion

b) sampling a minimum of twice per cycle

when the sampling frequency is less than the Nyquist value,

a) aliasing is eliminated

b) the Moire effect/aliasing can occur

c) patient dose must increased

d) the Nyquist value must be altered

b) the Moire effect/aliasing can occur

quantum noise impacts radiographic image quality by…

a) decreasing geometric unsharpness

b) increasing temporal resolution

c) diminishing the visibility of recorded detail

d) adding artifacts to the image

c) diminishing the visibility of recorded detail

the recorded detail of a digital radiographic image is primarily visible because of…

a) insufficient contrast

b) sufficient receptor exposure

c) low signal to noise ratios (SNR)

d) all answers are correct

b) sufficient receptor exposure

the difference between two adjacent gray shades on a radiographic image is…

a) recorded detail

b) quantum mottle

c) radiographic contrast

d) distortion

c) radiographic contrast

a radiograph with few shades of gray exhibits…

a) low contrast

b) high contrast

c) medium contrast

d) long scale contrast

b) high contrast

a radiograph that demonstrates considerable differences between gray shades is said to have…

a) short scale

b) high contrast

c) increased contrast

d) all of the answers are correct

d) all of the answers are correct

a radiograph that demonstrates minimal differences between gray shades is said to have…

a) long scale

b) low contrast

c) decreased contrast

d) all of the answers are correct

d) all of the answers are correct

with digital imaging technologies, the final contrast appearance of an image is due to…

a) kVp

b) window and level controls

c) look-up table (LUT) application

d) image rescaling

c) look-up table (LUT) application

varying tissue thicknesses and densities is referred to as…

a) differential absorption

b) attenuation

c) subject contrast

d) image contrast

c) subject contrast

radiographic image contrast is a combination of..

a) grid ratio and field size

b) receptor contrast and subject contrast

c) filtration thickness and field size

d) data rescaling and look-up tables

b) receptor contrast and subject contrast

with digital imaging systems, the primary factors affecting final image contrast are the…

a) window level and brightness

b) histogram and look-up table (LUT)

c) EI numbers and S numbers

d) kVp and mAs

b) histogram and look-up table (LUT)

distortion is a misrepresentation of…

a) size only

b) shape only

c) size and shape

d) detail

c) size and shape

size distortion in radiography can be ___ only.

a) foreshortening

b) magnification

c) elongation

d) minimization

b) magnification

size distortion is controlled by…

a) SID

b) OID

c) radiographic distances

d) all of the above

d) all of the above

the ____ the SID, the ___ the degree of magnification.

a) greater, larger

b) greater, smaller

d) lesser, smaller

d) SID has no effect on magnification

b) greater, smaller

examination of body parts with a large inherent OID warrant a ____ whenever possible.

a) small SID

b) large SID

c) small SOD

d) large focal spot

b) large SID

which of the following occurs when the tube or the image receptor are not properly aligned?

a) elongation

b) magnification

c) foreshortening

d) minification

a) elongation

proper alignment is achieved when the central ray is ___ to the part and ___ to the image receptor.

a) perpendicular; parallel

b) parallel; perpendicular

c) perpendicular; perpendicular

d) parallel; parallel

c) perpendicular; perpendicular

shape distortion is calculated…

a) as the ratio of SID and SOD

b) using the tube angle and OID

c) automatically in the computer postprocessing

d) none of the above

d) none of the above

the type of kVp chart that establishes an optimal kVp for each body part is known as a _____ chart.

a) variable

b) fixed

c) programmable

d) deviating

b) fixed

the type of kVp chart that uses a base kVp of 30-50 and adds additional kVp based on the body part being imaged is known as a ___ chart.

a) variable

b) fixed

c) programmable

d) deviating

a) variable

a number that represents technical factors that achieve a perfect exposure is known as the:

a) deviation index

b) exposure index

c) target index

d) dynamic range

c) target index

the range of exposures that produce quality images at an appropriate dose is known as the…

a) dynamic range

b) exposure latitude

c) deviation index

d) exposure index

b) exposure latitude

what affect does mA have on IR exposure?

+

what affect does time have on IR exposure?

+

what affect does mAs have on IR exposure?

+

what affect does kVp have on IR exposure?

+

what affect does SID have on IR exposure?

-

what affect does OID have on IR exposure?

-

what affect does FSS have on IR exposure?

0

what affect does grid ratio have on IR exposure?

-

what affect does field size have on IR exposure?

+

what affect does filtration have on IR exposure?

-

how tightly the atoms of a given structure are packed together is known as…

a) differential absorption

b) attenuation

c) absorption

d) tissue density

d) tissue density

what impact does mA have on contrast?

0

what impact does time have on contrast?

0

what impact does mAs have on contrast?

0

what impact does kVp have on contrast?

-

what impact does SID have on contrast?

0

what impact does OID have on contrast?

+

what impact does FSS have on contrast?

0

what impact does grid ratio have on contrast?

+

what impact does field size have on contrast?

-

what impact does filtration have on contrast?

-

what impact does mA have on spatial resolution?

0

what impact does time have on spatial resolution?

0

what impact does mAs have on spatial resolution?

0

what impact does kVp have on spatial resolution?

0

what impact does SID have on spatial resolution?

+

what impact does OID have on spatial resolution?

-

what impact does FSS have on spatial resolution?

-

what impact does IR pixel size have on spatial resolution?

-

what impact does motion have on spatial resolution?

-

what impact does grid ratio have on spatial resolution?

0

what impact does field size have on spatial resolution?

0

what impact does filtration have on spatial resolution?

0

the best way to prevent voluntary motion from a patient who is compliant is by:

a) communicating with your patient

b) reducing exposure time

c) increasing kVp

d) immobilization

a) communicating with your patient

if an object measures 2 cm and the image measures 3 cm, what is the percent of magnification?

a) 50%

b) 100%

c) 150%

d) 25%

a) 50%

a deviation index of +3 would indicate that the exposure factors are…

a) 100% too high

b) 50% too high

c) 100% too low

d) 50% too low

a) 100% too high

when a detector element becomes overwhelmed with energy that it loses the information completely, it is termed…

a) quantum mottle

b) data drop

c) aliasing

d) moire effect

b) data drop

the dose response curve for DR is ___.

a) inverse

b) linear

c) d log e

d) flat

b) linear

as spatial frequency increases, modulation transfer function…

a) decreases

b) increases

c) remains the same

d) doubles

a) decreases

modulation transfer function is measured on a scale of…

a) 1 to 10

b) -3 to +3

c) 0 to 1

d) .01 to .1

c) 0 to 1