Radiographic Quality pt2

What is wrong with this xray images

1. This image shows scatter and fog and how little contrast there in the image

What is affecting this image

This image shows motion on sharpness The image looks out of focus not sharp and blurry

Lateral chest xray is the image

What does the left image and right image show

Voluntary and involuntary motion

What does this image show

1. This image shows SID being increased reduces distortion (magnification) better spatial resolution 

What does this image show

1. This image shows Decrease in OID reduces distortion (magnication) better spatial resolution 

What does this iamge show

1. These images shows that not having the anatomy parallel will give you distortion reducing spatial resolution

What does this image show

The left image is not parrell to IR and the right is Parallel its needs to be completely flat noo finger should be raised ]

What is happening with these bones

1. Left is the correct

2. Middle is foreshortened

3. Right is elongated

What does this image show

This image shoes quantum noise on the right image it looks very grainy like sandpaper reduces the details

What does this image show

Quantum noise is seen more in thicker areas this image shows it on the left size

What does this image show

This image shows over exposure but can still be used because the digital imaging will adjust the brightness and contrast over saturation of contrast would mean repeat tho

What does this image show

This shows SNR with high on left and right low SNR

Scatter definition

Unwanted exposure to the image receptor resulting in fog

Cause of scatter

Scatter is a result of Compton interactions

Scatter provides

No useful information

Effect of scatter on contrast

Scatter decreases image contrast

How scatter affects the image

Scatter masks desired brightness and alters adjacent brightness levels

Digital IR and scatter

Digital receptors are more sensitive to scatter because they detect lower radiation levels

Spatial resolution definition

The smallest object that can be detected in a digital image

High spatial resolution

Able to see small anatomical structures clearly (good)

Low spatial resolution

Unable to distinguish small structures (bad)

Unsharpness

All radiographic images have some unsharpness; no image is perfect

Effect of contrast on small structures

Small structures are easier to see with high contrast

Effect of decreased sharpness

Decreases brightness differences between structure and background making structures hard to see

Temporal resolution definition

Ability to accurately image an object over time without motion blur

Long exposure effect

Longer exposure time decreases temporal resolution (more motion)

Motion effect

Motion decreases temporal resolution and sharpness

Temporal resolution decrease

Undesirable in imaging

Distortion definition

Misrepresentation of object size or shape; impacts spatial resolution (undesirable)

Two types of distortion

Size distortion (magnification) and shape distortion

Size distortion definition

Increase in object's displayed size compared to its true size

To reduce magnification

Increase SID and decrease OID

Shape distortion definition

Image appears elongated or foreshortened due to improper alignment

Cause of shape distortion

Misalignment of x-ray tube, part, or IR

Effect of distortion

Reduces spatial resolution

CR alignment importance

Incorrect CR alignment causes beam divergence and distortion

Distortion controlling factors

SID, OID, object alignment, IR alignment, and CR alignment

Effect of SID on resolution

Increased SID increases spatial resolution

Effect of OID on resolution

Increased OID decreases spatial resolution

Beam divergence

If CR is not aligned properly, divergent rays cause distortion

Brightness control in digital imaging

Brightness is NOT determined by technical factors in digital systems (computer-controlled)

Contrast control in digital imaging

Contrast is NOT controlled by tech factors; adjusted by computer processing

High contrast image

More black & white, fewer grays

Low contrast image

More shades of gray

Subject contrast definition

Tissue absorption characteristics: thickness, density, atomic number, and beam quality

Displayed image contrast

Image adjustments after exposure (windowing & leveling)

Quantum noise definition

Too few photons reaching IR causing grainy, noisy, static-like appearance

Appearance of quantum noise

Grainy, blotchy, mottled, poor image clarity

Quantum noise and underexposure

Digital systems cannot fix severe underexposure → quantum noise appears

How to fix quantum noise

Increase mAs on repeat image

Where quantum noise appears most

Thicker anatomy (requires more photons)

Quantum noise detailed definition

Disturbances from insufficient photons that obscure image clarity

Signal-to-noise ratio (SNR)

Comparison of useful signal (photons) to noise

High SNR

Desirable; means lots of signal and minimal noise

Low SNR

Undesirable; occurs when not enough photons reach the IR

How to increase SNR

Increase technical factors (mAs)