Chapter 10 concepts of radioGraphic quality

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what are the radiographic quality rules

1. fast IRs have high noise and low spatial resolution and low contrast 2. high spatial resolution and high contrast resolution require low noise and slow IRs 3. low noise accompanies slow IRs with high spatial resolution and high contrast resolution

what are some principles to be considered when planning a particular examination

1. use of intensifying screens decreases patient dose by a factor of at least 20 2. as the speed of the IR increases radiographic noise increases and spatial resolution is reduced 3. low contrast imaging procedures have wider latitude or margin of error in producing an acceptable radiograph

Accuracy in positioning the patient is most critical with which of the following ?

APR/ Automatic exposure

Magnification

All images on the radiograph are larger than objects they represent

Foreshortened

An example of gross distortion shows that the image of an inclined object can be smaller than the object itself

Before a radiographic technique chart is prepared which if the following would be most important

Calibrating the xray imaging system

Which of the following is necessary to construct a characteristic curve?

Densitometer

Subject contrast

Determined by the size shape and xray attenuating characteristics of the anatomy that is being examined and the kVp of the xray beam

Which of the following technique charts requires accurate measurement

Fixed , high, and variable kilovoltage ,

Which of the following technique charts provides the least amt of patient radiation exposure?

High kilovoltage

Which of the following will increase exposure latitude ?

High kilovoltage chart

A longer grayscale on a radiograph can be obtained by doing which of the following ?

Increasing kVp

Image receptor contrast

Inherent in the screen film combo and is influenced somewhat by processing of the film

Penetration of the anatomic part by the xray beam can best be controlled by which of the following ?

Kvp

Which of the following anatomic structures should exhibit the greatest subject contrast with muscle ?

LUNG

The optical density present on the radiograph can be best controlled by which of the following ?

MAs

When fixed kVp tech is used for various anatomic thickness, a change will be required in which of the following ?

MAs

A radiograph that exhibits a long grayscale contrast has which if the following features ?

Many shades of gray that have minimal diff

image magnification increases with increasing ?

OID

the magnification factor increases with increasing ?

OID

Which of the following procedures would make best use if high kilovoltage chart

Pelvis

increasing which of the following is effective in reducing FSB

SID

the magnification factor is dependent on what?

SID

which of the following geometric factors affect radiographic quality ?

SID

Which of the following is a basic characteristic of variable kilovoltage chart

Short scale of contrast

Structure mottle

Similar to film graininess but refers to the phosphor of the radiographic intensifying screen

Quantum mottle

Somewhat under the control of the radiologic tech and is a principal contributor to radiographic noise in many radiographic imaging procedures

Base density

The OD that is inherent in the base of the film

Contrast resolution

The ability to distinguish anatomical structures of similar subject contrast such as liver-spleen and gray matter-white matter

Resolution

The ability to image 2 separate objects and visually distinguish one from the other

Spatial resolution

The ability to image small objects that have high subject contrast such as bone -soft tissue interface a breast microcalcification

Visibility of detail

The ability to visualize recorded detail when image contrast and OD are optimized

Radiographic contrast

The contrast of a radiograph viewed on an illuminator

Fog density

The development of silver grains that contain no useful information

Film graininess

The distribution in size and space of silver halide grains in the emulsion

Radiographic Noise

The random fluctuation in the OD of the image

Straight line portion

The region in which a properly exposed radiograph appears

Characteristic curve

The relationship btw OD and radiation exposure

The anatomic part to be examined must be measured bc

The selected radiograph tech depends on anatomy thickness

Sensitometry

The study of the relationship btw the intensity of exposure of the film and the blackness after processing

Which of the following is the function of optimizing contrast

To make detail visible

Distortion

Unequal magnification of different portions of the same object

Which of the following technique charts requires higher patient radiation dose

Variable kilovoltage

a foreshortened image results from what?

an inclined object

When radiographic technique factors are adjusted to provide an acceptable image and then filtration is added to the xray tube which of the following will increase ?

avg energy of the xray beam

unexposed but processed film may appear cloudy and dull bc of which of the following ?

base density

Distortion primarily occurs ?

bc subject anatomy is inclined

which of the following is the principal reason for using direct-exposure radiography

better spatial resolution

ensuring good screen film contact also ensures reduced

blur

How can distortion be corrected ?

by proper patient positioning

what factors may affect the finished radiograph

concentration of processing chems, degree of chemistry agitation during development , development time and temp

use of contrast media principally affects which of the following

contrast resolution

reducing field size through proper collimation usually results in improved

contrast resolution ; patient dose

spatial resolution improves as screen blur

decreases , motion blur decreases and geometric blur decreases

if the object plane and the image plane are not parallel

distortion occurs

geometric blur is controlled principally by which imaging system characteristic?

focal spot size

spatial resolution is principally affected by which of the follwoing

focal spot size

which of the following is most responsible for radiographic spatial resolution ?

focal-spot size

as the time of film development is increased beyond the manufactures recommendations what happens ?

fog increases

which of the following is most often influenced by focal spot size ?

geometric blur

Which of the following radiographic techniques should result in the widest exposure latitude?

high kvp ,latitude film,low grid ratio

focal spot blur is the most

important factor for determining spatial resolution

When proper radiographic detail cant be obtained bc of a large OID what change in technique may be used to improve the detail ?

increase SID

magnification is reduced by which of the following

increasing SID and reducing OID

latitude and contrast are

inversely proportional

the primary control of radiographic contrast is

kvp

which of the following does not affect image blur?

kvp

when one images an object lateral to the central axis of the xray beam the FSB will be

larger on the cathode side

the primary control of OD is

mAs

Distortion of an xray image results from unequal?

magnification

what are the 3 geometric factors

magnification , distortion , focal-spot blur

patient motion is usually the cause of

motion blur

Abortion blur is most clearly related to which of the following?

object shape

which factor most often reduces the visualization of low contrast structures on a properly exposed radiograph ?

patient motion

another term for FSB is

penumbra

When the focal spot is switched from large to small

penumbra will be reduced

Subject contrast is enhanced with the use of contrast media bc

photoelectric interaction is increased

focal spot blur occurs bc the focal spot is not a

point

to obtain minimum magnification one should of which of the following ?

position the anatomy close to the IR

to minimize magnification one should do which of the following ?

position the object as close to the ir as practical

in mammo which of the following conditions would be most effective in improving the sharpness of detail of microcalcifications near the chest wall?

positioning the anode on the same side as the chest wall

which of the following will reduce motion blur?

proper patient instructions

The use of high-mas , low kvp and of slower IRs reduces

quantum mottle

which of the following is the main component of radiographic noise?

quantum mottle

to reduce magnification one should do which of the following?

reduce OID

FSB can be reduced by

reducing OID

sharpness of detail on a radiograph is principally improved by which of the following ?

reducing patient motion

film contrast is

related to the slope of the straight line portion of the characteristic curve

a radiograph that shows a relative lack of FSB would be ?

sharp in detail

we need to exposure time as

short as possible

extremity xray exam results in which of the following

short scale contrast

the focal spot blur is small on the anode side and large on the cathode

side of the image

radiographic spatial resolution is improved by the use of which of the following ?

slower radiographic intensifying screens

the best way to minimize FSB w/out affecting optical density is to use a very what?

small focal spot

the sharpness of detail in a radiographic is best increased by the use of which of the following ?

small focal spot

image contrast is the product of IR contrast and

subject contrast

kvp is the most important influence on

subject contrast

when an object is present to one side of the central axis of the xray beam what remains unchanged?

subject contrast and magnification factor

higher fog density reduces

the contrast of the radiographic image

base density refers to which of the following ?

the optical density of the base

the principal cause of motion blur mvmt of which of the following ?

the patient

The diagnostically useful portion of a characteristic curve most often includes which of the following ?

the straight- line portion

thick objects are more distorted than

thin objects

to improve bony detail in a radiograph , the radiologic technologist could do which of the following ?

use a smaller focal spot

Focal spot blur can be reduced by which of the following

using the small focal spot


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