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Flashcards in Week 4 - Notes Deck (32)
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1
Q

Radiographic positioning

Femur & Humerus

A

If leg is fractured, make sure affected leg is down

Medial-lateral is the usual projection

Always collimate to joint above and below

Center on pathology

Might add kVp to compensate for Fx hematoma

2
Q

Medial Lateral of Scapulo Humeral Joint

A

This position and view is important in cases of osteochondrosis dissecans (OCD - mainly a large dog breed issue)

3
Q

Shoulder

A

Diagnostic image of OCD

4
Q

Medial Lateral of RIGHT humerus

A
5
Q

Caudal Cranial of Humerus

A

May need anesthesia, as this position may be painful

Place animal in dorsal recumbency with front legs stretched out (especially the one to be radiographed)

Center beam about midshaft on humerus

May be difficult to position long axis of bone parallel to cassette

6
Q

Cranial Caudal of Shoulder

A

Place dog in ventral recumbency

Stretch out front leg to be radiographed

May be difficult to position long axis of bone parallel to cassette

(Same goes for cranial caudal of humerus)

7
Q

What is geometric distortion?

A

When the image is distorted from anatomic accuracy due to improper positioning.

e.g. elongation, foreshortening, magnification

8
Q

How does magnification of scale occur?

A

The bone is positioned off the cassette

9
Q

How does foreshortening occur?

A

The bone is not parallel to the plane of the film/sensor.

10
Q

Stifle

A
11
Q

Medial Lateral of Elbow

A

Affected area in center

1/3 of bone above and below as well

May need flexed, unflexed and oblique projections as well

Extreme flexion is needed to expose anconeal process (GSDs older than 7 mos commonly have ununited anconeal process)

12
Q

Cranial Caudal of Elbow

A
13
Q

Flexed Lateral of Elbow

A
14
Q

Forearm (Antebrachium)

A
15
Q

DorsoPalmar of Carpus

A

Control angulation of leg from elbow w/gloved hand

16
Q

Can soft tissue injuries be seen on x-rays?

A

No, maybe on an MRI!

17
Q

Lateral projection of Carpus

A
18
Q

DorsoPalmar Metacarpus/Phalanges

A
19
Q

VD Pelvis/Coxofemoral Joints

A

For a diagnostic image:

Need to be perfectly symmetrical

Obturator foramina have to be identical

Stifle on both legs need to be symmetrical

20
Q

Directional terms

A

Projections are named by a two-part term relating to beam orientation as it enters and exits the targeted area

First part of term is incoming direction of beam

Second part of term is direction of beam exiting from target

Third part of projection term is naming the targeted body part

Examples:

  • VD of abdomen
  • DV of thorax
  • Dorsopalmar of L Metacarpus
  • Lateral-Medial of R Carpus (Flexed)
  • DorsoPalmar L P3/Navicular 45 degree oblique
21
Q

Exposure Rules: Centering

A

Restrict the area imaged to the area of clinical interest

Center anatomy to center of cassette

Center cassette to center of beam

Critically important for joints in spine and extremities

Whole body studies not done unless no other option (e.g. small pets, birds, reptiles, pocket pets)

22
Q

Exposure Rules: Collimate

A

Tightly restrict beam geometry to only what’s needed

Improves film quality by reducing scatter & fog (less scattered radiation plus better film)

23
Q

Collimation & Aids

A

Collimate and use proper aids to achieve proper positioning of targeted anatomy

e.g. heavy sedation, sandbags to keep desired position

24
Q

Exposure Rules: Two Views

A

Two views of same area

Taken at right angles to each other (to get 3 dimensional pic)

Example: VD and Lateral

Exceptions:

  • can’t position for exposure
  • no practical info to be gained
  • dental x-rays are usually just a lateral
25
Q

Define orthogonal

A

2 views taken at right angles to each other to achieve a diagnostic all-around image

With one view, you may not know exact pathology

26
Q

Anode Heel Effect

A

Place thickest part of anatomy towards cathode

(at CAVT Cathode is to the left)

27
Q

Exposure Rules: Affected Side Down

A

Clinically affected side down = closest to cassette

Sharpens the image

Helps keep anatomy as parallel to cassette as possible to reduce geometric distortion

Reduces enlargement (a projection artifact)

  • some radiologists like enlargement and will create a bigger buffer between cassette and PT on purpose
28
Q

Exposure Rules: Work Clean

A

Always examine hair coat for being wet, dirty, or caked with manure

Spilled contrast agts on hair are the worst and need to be dealt with carefully or they may compromise exposure

Positioning accessories are friends

29
Q

Positioning Checks: Lateral View

A

Rib heads are superimposed

Intervertebral foramina are the same size

Transverse processes are superimposed at the origin from the vertebral bodies

Coxofemoral joints are superimposed

30
Q

Positioning Checks: Ventrodorsal View

A

Spinous processes are aligned in the center of the vertebral bodies

Rib and abdominal symmetry

Wings of the ilium are symmetrical

Obturator foramina are symmetrical

31
Q

Hanging your Films - Lateral

A

Head is to the left

Spine is up (toward viewbox clips)

32
Q

Hanging your Films - VD/DV

A

Head is toward viewbox clips (up)

Animal’s right side is mounted to viewer’s left side