5- Radiographic Interpretation

How should a lateral view radiograph be oriented for proper interpretation?

Cranial should be to the left and dorsal at the top of the image.

What does the 'L' indicator on a lateral view radiograph signify?

It indicates that the view is a left lateral view.

What does the 'R' indicator on a lateral view radiograph signify?

The "R" indicator tells the reader this is a right lateral abdomen. Notice that it is also positioned with cranial to the reader's left

Extremity Views

extremities in the Medial-Lateral projection should be oriented with cranial or dorsal to the readers left.

In a ventrodorsal (VD) view, where is cranial positioned?

Cranial is positioned at the top of the image and the patients right on the readers left.

How to Appropriately Read a Radiograph

• 1. Systematically and Repetitive

• Read radiographs in the same manner every time.

• Develop your own system so you do not miss anything!

• 2. Optional Approaches

• Top to Bottom?

• Outside in? Inside out?

• Organ system?

• Compartments?

What are the five opacities that help differentiate structures on a radiograph?

Bone/Mineral, Soft Tissue, Fat, Gas/Air, and Radiolucent/Radiopaque.

What are the six roentgen signs used in radiographic interpretation?

Size, Shape, Location, Number, Margination, and Opacity.

What is the recommended approach for reading radiographs?

Read radiographs systematically and repetitively, developing a consistent method.

What does taking a 2D picture of a 3D structure?

Causes- Magnification and Distortion, Motion, Summation, and Border Effacement or Silhouette Sign

What is magnification in radiographic images?

Magnification is the enlargement of a structure due to the distance between the structure and the receiver. This can reduce detail as the image is spread over a larger area. Setting patients up in a standard manner every time reduces the effect on our own

vision.

What causes distortion in radiographic images?

Distortion occurs when the object and receiver are not parallel. Will always have some degree of distortion but minimize as much as possible with standard positioning!

What is summation in the context of radiography?

Summation is a special case of superimposition that creates an opacity not representing a structure within the patient. Common in kidneys on lateral radiograph where the intersection of the caudal pole of the right kidney with the cranial pole of left kidney. Could be misinterpreted as a mass.

What is border effacement or silhouette sign?

It occurs when two structures in contact have the same opacity, resulting in a loss of margin distinction.

What are the effects of underexposure in radiographs?

Underexposed images appear too bright, usually due to low kVp or mAs, resulting in more noise and lack of detail.

What are the effects of overexposure in radiographs?

Overexposed images appear too dark, typically due to high kVp or mAs, resulting in too many x-rays.

What is contrast in x-rays?

It links directly to the differing of opacities discussed earlier based on varying degrees of x-ray beam absorption. The ability of an x-ray beam to penetrate tissue depends on its energy. The x-ray beams energy directly ties to a varying kVp with a stable mAs.

- Higher kVp gives less contrast because more x-rays are transmitted through the patient to the plate.

- Lower kVp allows a varying absorption so

higher contrast

- Varying degrees of kVp and mAs can get you a visible image but a contrast adequate for interpretation

will depend on a specific kVp to mAs combo.

What does detail refer to in x-ray?

Spatial Resolution or Sharpness

What does spatial resolution in x-ray indicate?

How close can lines be together and still be distinguished?

Can software improve spatial resolution in x-ray?

Yes, but it is not a shortcut and requires proper settings.

What can detail be influenced by?

Exposure factors, Matrix of IP (Pixels), Software, Monitor, Reader's visual acuity

Pixel in X-Rays

PICTURE ELEMENT

• High number = better image but larger file

• Check out numbers when purchasing machines

DICOM

DIGITAL IMAGING AND COMMUNICATIONS IN MEDICINE - Standardized format

PACS

PICTURE ARCHIVING AND COMMUNICATING SYSTEM

Labeling X-Rays

• Patient name

• Patient number?

• Species

• Date

• Area radiographed?

• Right or left

• Legality