CAMRT Radiographic Procedures: Skeletal System Questions and Answers 2 — Questions and Answers
Question 1: For an AP shoulder, how should the arm be positioned to show the greater tuberosity in profile?
- Internal rotation with hand on hip
- External rotation with hand supinated and epicondyles parallel to detector (Correct answer)
- Neutral position at side
- Full 90-degree abduction
Correct answer: External rotation with hand supinated and epicondyles parallel to detector
External rotation places the greater tuberosity in lateral profile.
External rotation is the standard AP shoulder. Internal rotation superimposes the greater tuberosity on the humeral head. In trauma, do not force rotation.
Question 2: What is the Mortise view of the ankle and how is it positioned?
- Demonstrates tibial plateau; external rotation
- Demonstrates ankle mortise joint uniformly open; internally rotate 15-20 degrees (Correct answer)
- Demonstrates calcaneus; maximum dorsiflexion
- Demonstrates subtalar joint; lateral position
Correct answer: Demonstrates ankle mortise joint uniformly open; internally rotate 15-20 degrees
Internal rotation 15-20 degrees places the intermalleolar line parallel to the detector.
Widened medial clear space (over 4 mm) suggests deltoid ligament injury. Critical for Weber fracture classification. Standard series: AP, lateral, mortise.
Question 3: What are the key positioning elements for an AP pelvis radiograph?
- Centre at umbilicus; no special positioning
- Centre between ASIS and symphysis pubis; feet internally rotated 15-20 degrees; verify symmetric ASIS positioning (Correct answer)
- Centre at symphysis; external rotation
- Centre at iliac crest; hips flexed
Correct answer: Centre between ASIS and symphysis pubis; feet internally rotated 15-20 degrees; verify symmetric ASIS positioning
Internal foot rotation compensates for femoral neck anteversion, showing necks in full length.
Pelvis symmetry verified by equal ASIS-to-midline distances. Obturator foramina should appear symmetric. Lesser trochanters minimally visible.
Question 4: What are the Ottawa Ankle Rules?
- Positioning guidelines for ankle X-rays
- Clinical decision rules determining whether ankle radiographs are needed based on physical findings (Correct answer)
- Image quality evaluation criteria
- Radiation dose limits for ankles
Correct answer: Clinical decision rules determining whether ankle radiographs are needed based on physical findings
Validated rules that reduce unnecessary ankle imaging by 30-40%.
Developed in Ottawa, Canada. Radiographs indicated if bone tenderness along posterior malleolus edge or tip, or inability to bear weight for 4 steps.
Question 5: What projections constitute a standard knee series?
- Only AP
- AP, lateral, and obliques showing joint space, patella, and tibial plateaus respectively (Correct answer)
- Only lateral
- AP and sunrise only
Correct answer: AP, lateral, and obliques showing joint space, patella, and tibial plateaus respectively
Multiple projections demonstrate different structures without superimposition.
AP with 5-7 degree cephalad angle. Lateral at 20-30 degree flexion. Obliques demonstrate tibial plateaus and proximal fibula. Weight-bearing AP increasingly requested for osteoarthritis.
Question 6: What is proper positioning for a lateral cervical spine, and what must be demonstrated?
- Prone with chin elevated; C1-C5
- Erect true lateral, shoulders depressed, 72-inch SID; all 7 cervical vertebrae including C7-T1 (Correct answer)
- Supine with lateral beam; C3-C7
- Erect facing detector; C1-C4
Correct answer: Erect true lateral, shoulders depressed, 72-inch SID; all 7 cervical vertebrae including C7-T1
All 7 vertebrae including the C7-T1 junction must be demonstrated.
Shoulders depressed to prevent overlap. Swimmer lateral if C7-T1 not visible. In trauma, cross-table lateral without moving the patient. Centre at C4.
CAMRT Radiographic Procedures: Skeletal System Questions and Answers 2
For an AP shoulder, how should the arm be positioned to show the greater tuberosity in profile?