Geometrical Qualities of the Image

These flashcards cover key principles concerning the geometrical qualities of images in radiography, focusing on sharpness, magnification, shape distortion, and related formulas.

What are the three primary geometrical qualities of an image?

Sharpness, Magnification, and Shape Distortion.

What is spatial resolution in radiography?

Spatial resolution is defined as the sharpness of the structural edges recorded in the image.

What does resolution refer to in imaging?

Resolution refers to the total amount of useful information in an image.

What is blurriness in imaging known as?

Blur is referred to as penumbra.

Define the term 'magnification' in radiography.

Magnification is the difference between the size of the real object and the size of the projected image.

What should be minimized to ensure accurate representation of object sizes?

Magnification should be kept to a minimum.

What causes shape distortion in radiographs?

Shape distortion occurs when the shape of the real object differs from the shape of its projected image.

What are the two forms shape distortion may take?

Foreshortening or elongation.

How is unsharpness measured in radiography?

Unsharpness is controlled by Source to Object Distance (SOD), Object Image Receptor Distance (OID), and the size of the focal spot.

What is the formula to calculate unsharpness/penumbra?

Unsharpness = (focal spot x OID) / SOD.

What is the Radiographic Sharpness Formula?

The ratio of SOD to OID indicates relative sharpness.

What should not be confused with reduced sharpness?

Low contrast should not be confused with reduced sharpness.

What device can be used to measure sharpness?

A line pair tool can be utilized to gauge sharpness/spatial resolution.

What factors affect the sharpness of a radiograph?

Motion, Geometry (SID, SOD, OID), Focal Spot size, Size of detector elements, Size of monitor pixels.

How does motion affect image resolution?

Controlling motion can lead to increased image resolution.

What happens to the dimensions of an object in a magnified image?

Both the length and width of the image will measure larger than the actual object.

What inherent factor contributes to magnification in radiographs of bones?

Soft tissue contributes to inherent magnification in bone radiographs.

How can magnification be calculated using distances?

Magnification can be calculated by the ratio of SID to SOD.

Define 'Geometrical Integrity.'

Geometrical integrity consists of sharpness, magnification, and shape distortion.

What is unsharpness in the context of imaging?

Unsharpness refers to the lack of clarity in the image due to blur.

What is the inner area without shadows known in imaging?

The inner area without shadows is known as umbra.

What does a higher number in the Radiographic Sharpness Formula indicate?

A higher number indicates higher relative sharpness.

What can motion during imaging lead to?

Motion can lead to a blurry image, reducing image quality.

What is the relation between size distortion and shape distortion?

If only one dimension changes, it is shape distortion; if all parts change uniformly, it is size distortion.

What does image quality hierarchy include?

Hierarchy includes Brightness, Visibility, Resolution, Recognizability, Contrast, Sharpness, Magnification, Shape, Noise, and Distortion.

What does 'grey scale' refer to in image analysis?

Grey scale refers to noise in the image.

What impact does SID have on magnification?

Increased SID can reduce magnification.

What does OID stand for in imaging terminologies?

OID stands for Object Image Receptor Distance.

What is the significance of the focal spot size in imaging?

Focal spot size affects the sharpness of the image.

How do technical factors influence image distortion?

Technical factors like SOD, OID, and SID can significantly influence image distortion.

What must be carefully managed to prevent distortion caused by motion?

Patient movement must be carefully managed.

What does a lower SOD result in regarding unsharpness?

A lower SOD increases unsharpness.

What is the maximum influence of focal spot size on sharpness?

Larger focal spot sizes decrease sharpness.

What effects do correctly calibrated distances have on imaging?

Correctly calibrated distances help minimize magnification and distortion.

What is the effect of increased time in exposure on image clarity?

Increased exposure time can cause blurriness due to patient motion.

Explain the term 'noise' in the context of imaging.

Noise refers to random variations in brightness or color information in an image.

What can shape distortion lead to in practical applications?

Shape distortion can affect the accuracy of diagnoses based on radiographs.

What should be avoided to maintain effective radiographic quality?

Excessive magnification and distortion should be avoided.

What types of variables influence radiographic sharpness?

Motion, geometry, focal spot size, detector element size, and monitor pixel size.

How is the hierarchy of image qualities structured?

It is structured from basic attributes like brightness and resolution to more complex qualities like recognizability and contrast.

What are the two types of shape distortion mentioned?

Elongation and foreshortening.

What principle underlies the calculation of magnification?

Magnification equals SID divided by SOD.

What is an essential consideration for physicians interpreting images?

Accurate assessment of object sizes is essential for diagnosis.

In image sharpness assessment, what does the term 'line pair' refer to?

Line pairs refer to the narrow lines used to measure sharpness and resolution.