RAD 205 resolution

The degree of geometric sharpness or accuracy of the structural lines actually recorded in the radiographic image

Spatial resolution

Factors that affect resolution

Motion

Distance (SID/OID)

Focal spot size

what are different types of motion

voluntary

involuntary

equipment

How is voluntary motion best reduced

effective communication

what’s the best way to reduce involuntary motion

reduce exposure time

immobilization

what the best way to reduce equipment motion

secure equipment

How does Distance affect resolution

increasing SID betters resolution

decreasing OID betters resolution

Which has more impact on resolution SID or OID

OID (penumbra)

How does focal spot size affect resolution

it can make an image more sharp or blurred depending on the focal spot size used

which focal spot size give better image sharpeness

small focal spot size

Positive characteristics of phosphors

High atomic number

emitting the proper wavelength

emitting a large number of light per interaction w/ x-ray

minimal afterglow

The ability to emit visible light immediately on the absorption of x-rays

Fluorescence

Emitting light or glowing after the source of radiation is removed

Phosphorescence (afterglow)

Is the term given to a nonuniform or nonhomogenous appearance
of the recorded image commonly associated with high speed recording systems

Radiographic Mottle

Background information received by the image receptor

Radiographic Noise

Is attributed to random absorption of the x-ray quanta absorbed by the image receptor

Quantum mottle

Measures accuracy of image to actual object, the capabilities and
limitations of radiographic imaging systems, the loss of imaging
capability between the image forming radiation emerging from the
body part and the recorded image of the imaging system used

MTF

increase mA/mAs

N/A

increase seconds

decrease resolution

increase SID/SOD

increase resolution

increase OID

decrease resolution

increase grid ratio or tube angulation

N/A

increase in part density/atomic #, destructive or additive pathology

N/A

increase part thickness or collimation

depends

increase focal spot

decrease resolution

increase motion

decrease resolution

As focal sport size increases, mA…

remains the same

When the radiograph image appears grainy due to quantum mottle, what is the best method of obtaining an acceptable radiograph image?

Increase mAs

Resolution is …. SID/SOD

directly proportional

As kVp increase, resolution…

remains the same

how much must the mAs be increased when changing from 5:1 grid to a 8:1 grid?

increase 2x

If the SID is halved, what charge must be made in order to maintain exposure

decrease 4x

In Digital Radiography, resolution is also determined by:

Matrix size

Pixel size

Gray scale bit depth

3D measure of volume in an image

voxel

Measurement of recorded detail, sharpness, and resolution; the ability of a film/screen system to accurately measure the boundaries of an image

line spread function (LSF)

Expression of the boundaries of an image; determined by a mathematical measurement of an image produced at a single point

point spread function (PSF)

Expression of the boundaries of an image

edge spread function (ESF)

Means Frequency signal must be sampled twice per cycle

Digital Sampling (Nyquist Criterion)

When does Aliasing occur

when Nyquist is not met

describes the relationship between the actual focal and the spot effective focal spot

Line focus principle

Expressed in line pairs per millimeter ( lp /mm) or cycles per mm

Unit of resolution

The measure of Spatial Resolution in a radiographic image in terms of line pairs per millimeters

Spatial Frequency