Anatomic Distortion in Radiography Image: Quiz and Flashcards

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What is the term used to describe the shape distortion that occurs when the object is not parallel to the image receptor?

Foreshortening

What is the result of the x-ray beam being oriented at right angles to the object but not to the image receptor?

Elongation of the image

Why is it important to position the image receptor parallel to the long axis of the object?

To minimize shape distortion

What is the result of the central ray not being directed at right angles to the object and image receptor?

Image shape distortion Signup and view all the answers

What is the optimal orientation of the x-ray beam to the object and image receptor?

Perpendicular to both the object and image receptor Signup and view all the answers

What type of views are most prone to image shape distortion?

Maxillary molar views Signup and view all the answers

What is the result of the object being parallel to the image receptor, but the central ray not being directed at right angles to each?

Image shape distortion Signup and view all the answers

What is the reason for the distortion of the resultant image?

Unequal distances of the object parts from the focal spot Signup and view all the answers

What is the purpose of orienting the central ray perpendicular to the object and image receptor?

To minimize image shape distortion Signup and view all the answers

Which roots appear disproportionately longer in the image due to angulation?

Palatal roots Signup and view all the answers

What is the effect of increasing the distance between the focal spot and the object?

Decreased magnification and increased sharpness Signup and view all the answers

What is the result of decreasing the distance between the object and the image receptor?

Decreased magnification and increased sharpness Signup and view all the answers

What is the relationship between the distance of the object from the focal spot and the image sharpness?

Increased distance results in increased sharpness Signup and view all the answers

What is the effect of angulation on the image of the roots?

Palatal roots appear longer Signup and view all the answers

Which of the following statements is true about the image formation?

All of the above Signup and view all the answers

What is the purpose of adjusting the distance between the focal spot and the object?

To improve the image sharpness Signup and view all the answers

What is the primary benefit of the paralleling technique in intraoral radiography?

Minimized image distortion and increased image sharpness Signup and view all the answers

Why is it necessary to position the image receptor away from the teeth in the paralleling technique?

To achieve parallel orientation with the long axis of the tooth Signup and view all the answers

What is the purpose of using image receptor holders in the paralleling technique?

To support the image receptor in the patient's mouth Signup and view all the answers

What is the main challenge in deriving three-dimensional information from radiographs in clinical practice?

Deriving three-dimensional information from a two-dimensional image Signup and view all the answers

What type of radiograph is commonly used to determine the mediolateral position of an object or feature?

Mandibular occlusal view Signup and view all the answers

Why is it important to use multiple radiographic views to determine the location of an object or feature?

To derive three-dimensional information from a two-dimensional image Signup and view all the answers

What is the main advantage of using the paralleling technique in intraoral radiography?

It produces images with minimal distortion and increased sharpness Signup and view all the answers

What is the purpose of using radiographs in clinical practice?

To determine the location of a foreign object or an impacted tooth Signup and view all the answers

What happens when the object in question appears to move in the same direction with respect to the reference structures as does the x-ray tube?

It lies on the lingual aspect of the reference object. Signup and view all the answers

What is the significance of the object in question moving distally when the tube is shifted mesially?

It is on the buccal aspect of the reference object. Signup and view all the answers

What does the acronym SLOB stand for?

same lingual, opposite buccal Signup and view all the answers

What happens when the object in question does not move with respect to the reference object?

It lies at the same depth as the reference object. Signup and view all the answers

What is the relationship between the object in question and the reference object when the tube is shifted mesially and the object appears to move distally?

The object is on the buccal aspect of the reference object. Signup and view all the answers

What is the significance of the x-ray tube's movement in determining the location of the object in question?

It helps in determining the buccal or lingual aspect of the object. Signup and view all the answers

What can be concluded if the object in question appears to move in the opposite direction as the x-ray tube?

It is on the buccal aspect of the reference object. Signup and view all the answers

What is the purpose of the SLOB rule?

To determine the buccal or lingual aspect of the object. Signup and view all the answers

What can be inferred about the position of the palatal root in images A and B?

It lies behind the distobuccal root in image A, but between the two buccal roots in image B. Signup and view all the answers

What is the significance of the inferior border of the zygomatic process of the maxilla?

It lies buccal to the teeth and appears to move mesially as the x-ray beam is oriented more from the distal. Signup and view all the answers

What is the characteristic feature of an expansile lesion on the buccal surface of the mandible?

The periphery of the expanded cortex is more opaque than the region inside the expanded border. Signup and view all the answers

What is the reason for the eggshell effect on plain images?

The x-ray beam is more attenuated in the region of the bony cortex. Signup and view all the answers

What is the orientation of the x-ray beam when the zygomatic process is projected occlusally over the teeth?

The x-ray beam is oriented vertically. Signup and view all the answers

What is the effect of increasing the angulation of the x-ray beam vertically?

The zygomatic process is projected occlusally over the teeth. Signup and view all the answers

What is the significance of osseous landmarks with respect to the teeth?

They help identify changes in horizontal or vertical angulation. Signup and view all the answers

What can be inferred about the attenuation of the x-ray beam in the region of the expanded bony cortex?

It is more attenuated due to the longer path length of photons. Signup and view all the answers

Study Notes

Focal Spot and Image Receptor

The physical shape of the object may prevent its optimal orientation, resulting in shape distortion.
To minimize shape distortion, the practitioner should align the tube, object, and image receptor carefully.
The image receptor should be parallel to the long axis of the object.
The central ray of the x-ray beam should be perpendicular to the object and image receptor.

Image Shape Distortion

Image shape distortion occurs when the object and image receptor are not parallel, or the central ray is not directed at right angles to each.
Distortion is most evident on maxillary molar views, where the palatal roots appear disproportionately longer than the buccal roots.

Paralleling Technique

This technique is the preferred method for making intraoral radiographs.
The image receptor is placed parallel to the long axis of the tooth, minimizing image distortion.
Image receptor holders should be used to support the image receptor in the patient’s mouth.

Factors Affecting Image Sharpness and Magnification

Increasing the distance between the focal spot and the object results in an image with increased sharpness and less magnification.
Decreasing the distance between the object and the image receptor increases the sharpness and results in less magnification.

Object Localization

Three methods are used to obtain three-dimensional information from radiographs:
The SLOB rule (same lingual, opposite buccal) helps identify the location of an object.
Comparing the anatomy displayed on the images helps distinguish changes in horizontal or vertical angulation.
The relative positions of osseous landmarks with respect to the teeth help identify changes in horizontal or vertical angulation.

Eggshell Effect

Plain images may produce an eggshell effect, where the periphery of an expanded cortex appears more opaque than the region inside.
The cortical bone is not thicker on the cortex, but rather the x-ray beam is more attenuated in this region due to the longer path length of photons through the bony cortex on the periphery.

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