Lecture 3: Radiographic Interpretation

What is the proper orientation for a Lateral View?

Cranial to the Left

Dorsal at the Top

What is unique about the way this indicator was placed?

“R” indicator tells this is a R lateral abdomen with the cranial to the reader’s left

How should extremities be oriented in the medial-lateral projection?

Cranial or Dorsal to the readers left

How should a patient be oriented for ventrodorsal (VD)/dorsoventral (DV) views?

Cranial at the top of the image with the patient’s Right to the readers left

How is Ventrodorsal (VD) and D

What is the appropriate way to read radiographs?

• What does that mean? (2)

Systematically & Repetitive

• Read radiographs in the same manner every time

• Develop your own system so you don't miss anything

T/F - Different materials interact with x-rays differently

True

What are the 2 types of opacities?

1. Radiolucent

2. Radiopaque

Match:

• Radiopaque

• Radiolucent

• Black

• White

Radiopaque = white

Radiolucent = black

What is an example of radiopaque and radiolucent?

Radiopaque: Urinary Stones

Radiolucent: Air

What is #1?

Gas/Air

What is #2?

Soft Tissue

What is #3?

Fat

What is #4?

Bone/Mineral

What are the 6 Roentgen signs?

1. Size

2. Shape

3. Number

4. Location

5. Margination (smooth vs. rigid)

6. Opacity

*ALL these should be in a report

With an x-ray, a 3D structure becomes a 2D image. What 4 things can this cause?

1. Magnification and Distortion

2. Motion

3. Summation

4. Border Effacement or Silhouette Sign

_____ occurs due to the distance between the structure and the receiver

Magnification (enlargement of a structure)

What does magnification do to an image since it’s spread over a larger area?

Reduces detail (of the image)

When does Distortion occur?

When the object and the receiver are NOT parallel

• Need everything to be aligned together

Radiographs will always have some degree of what? How do you minimize it?

Distortion

• Minimize distortion using standard positioning

What is Summation?

What term defines: “opacity created that does NOT represent a structure that is present within the patient”?

Superimposition

What organ is Summation/Superimposition common in? Where?

Kidneys (on lateral views)

• Caudal Pole of R kidney with Cranial Pole of L kidney

What can the summation of the kidneys be misinterpreted as?

A mass

What term defines: “Two structures in contact with each other that has the SAME opacity”?

• Causes a loss of margin distinction

Boarder Effacement/Silhouette Sign

Why can’t the heart be seen in this picture?

• (where arrow is pointing)

Boarder Effacement: fluid is sitting on top with the same opacity

What term is used to describe when an image is too bright?

Underexposed

• Undercooked cookies are lighter

What term is used to describe when an image is too dark?

Overexposed

• Overcooked cookies are darker

What things may cause an image to be underexposed?

kVp or mAs is too LOW

What things may cause an image to be overexposed?

kVp or mAs is too HIGH

If an image is underexposed, do you need more/less x-rays?

• What about if the image was overexposed?

• Underexposed = need MORE x-rays

• Overexposed = need LESS x-rays (too many x-rays)

Underexposure has more “_____”

“Noise”

Contrast or Detail?

• 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

Contrast

What term defines: “links directly to the differing of opacities based on varying degrees of x-ray beam absorption”

• Degree of x-ray beam absorption = differing of opacities

Contrast

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

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

Higher/Lower kVp allows a varying absorption so higher/lower contrast

Lower kVp allows a varying absorption so higher contrast

What term defines: “spatial resolution or sharpness”?

Detail

Contrast or Detail?

“How close can lines be together and still be distinguished?”

Detail

What 5 things can influence detail?

1. Exposure factors

2. Matrix of IP (Pixels)

3. Software

4. Monitor

5. Readers visual acuity

What radiograph technology is being described?

1. High number better image but larger file

2. Check out numbers when purchasing machines

Pixel: Picture Element

What radiograph technology is being described?

1. Digital Imaging and Communications in Medicine

2. Standardized format

DICOM

What does PACS stand for?

Picture Archiving and Communicating System

What 6 things should be labeled on a radiograph (document)?

1. Patient name

2. Patient number

3. Species

4. Date

5. Area radiographed

6. Right or left