Contributors: Justin Goggin, Patsy Whelehan
Species: Canine | Classification: Techniques
- A high detail film-screen combination is required.
- A grid is required if patient thickness is >10 cm.
- In UK, kV should not exceed about 60.
- Both joints should always be included.
- Soft tissues should be included.
- General anesthesia or sedation is required.
- The film should be correctly exposed and developed, and free from movement blur and artefact.
- The anatomical marker must be clearly visible, along with the patient's identification, the date, and the name of the hospital or practice.
- → Fracture .
- → Panosteitis Panosteitis .
- → Neoplastic bone disease Bone: neoplasia .
- → Soft tissue neoplasia invading bone.
- → Osteomyelitis Osteomyelitis.
- → Metabolic bone diseases.
- Equipment available in general practice.
- Dependent upon the method of chemical restraint (GA or sedation).
- 10 - 15 min or longer, dependent upon skill of radiographer.
Criteria for choosing test
Is the examination appropriate?
- Can you make the diagnosis without it?
- Can it tell you what you need to know?
- Will your management be affected by the radiological findings?
- Always take at least two orthogonal views.
- Standard projection.
- Standard projection.
- Alternative to caudocranial.
- Enables distal humerus to lie flatter against film, thus minimizing distortion and magnification.
- Radiographer, or veterinary nurse/technician to carry out radiography.
- X-ray machine.
- Cassettes with high detail screens.
- Film ID system.
- Processing facilities.
- Immobilization and positioning aids: sandbags, foam wedges, 1" white tape or roll gauze.
- Protective clothing (lead-rubber aprons, gloves, thyroid shields).
- High output X-ray machine.
- Rare earth high detail screens.
- Automatic processing facilities.
- Film ID camera.
- Film ID card or tape.
- X-ray film.
- Pharmaceuticals for chemical restraint.
- One to two competent people.
- Foam wedges.
- 1" tape and roll gauze.
- Positioning troughs.
Step 1 - Lateral
- Position the patient in lateral recumbency on the side to be examined and immobilize.
- Use a sandbag or tie to hold the contralateral limb caudally and dorsally away from the field.
- Secure the affected limb in a cranial position but without undue distraction.
- Use padding under the scapula and elbow as necessary to achieve a true lateral position of the humerus, parallel to the film.
- Center the vertical beam at mid-shaft .
- Collimate to include the elbow and the shoulder, as well as the soft tissues cranial and caudal to the shaft .
Step 2 - Caudocranial
- Position the patient in dorsal recumbency in a trough and immobilize.
- Extend the affected limb cranially and secure with a tie.
- Rotate the thorax to ensure that the humerus is in a true caudocranial position .
- In the likely event that the humerus is not horizontal, angle the beam until it is perpendicular to the shaft and elevate the cranial edge of the cassette to bring it as near perpendicular to the beam as possible, if using a table-top technique.
If an undistorted view of the elbow is important, opt for a craniocaudal projection.
- Center the beam at mid-shaft.
- Collimate to include both joints, and the lateral and medial skin surfaces.
Step 3 - Craniocaudal
- Place the patient in dorsal recumbency, with a positioning trough at hip level, and immobilize.
- Draw the affected limb caudally and secure with a tie.
- Rotate the thorax to achieve a true craniocaudal position of the humerus.
- Separate the limb from the thoracic wall with foam padding if necessary .
The humerus will not lie horizontal in close apposition to the film. Obtain the position closest to horizontal and compensate for the increased object film distance by increasing the focal film distance.
- Center mid-shaft.
'Off-center' medially to project the humerus clear of the thoracic wall.
- Collimate to include both joints and the lateral and medial skin surfaces.
Reasons for Treatment Failure
- Incomplete studies (one view only) lead to misdiagnosis.
- Inadequate sedation.
- Failure to label film properly.
- Poor technique: inaccurate positioning or centring, wrong exposure factors, inadequate collimation.
- Poor processing.
- Equipment failure.