Lecture Notes: Sacrum and Coccyx Imaging

Patient Positioning

• Position: Patient laying on the table, supine
• SID: 40 inches
• Cassette Size/Collimation: 10x12 since a 14x17 cassette is being used
• Tube: Ensure it's in transverse content

Angulation for Imaging

• Sacrum: Angle 15 degrees towards the nose (AP view)
• Coccyx: Angle 10 degrees towards the toes (AP view)

Finding the Central Ray Breakpoint

• Typically 2 inches superior to the symphysis pubis
• Alternative method: Find ASIS, go about 2 inches (or 3 fingers) inferior to that
• Ensure patient is centered at the mid-sagittal plane

Checking Centering

• Confirm by finding the top of the iliac crest; ensure light reaches the top
• Have patient bend knees slightly to confirm location of symphysis pubis

Adding Markers and Breath Instructions

• Right marker in the anterior corner of the cassette
• Breath instruction: Patient takes a breath, blows it out, and holds it out

Coccyx Imaging

• Angle tube 10 degrees towards the toes
• Realign tube and bucky
• Center at the same spot due to angle change
• Collimate down (Coccyx is small, size of a quarter or stamp)
• Double-check centering at mid-sagittal plane
• Confirm 2 inches superior to the symphysis pubis
• Breath instruction: Same as for sacrum

Lateral View

• Positioning: Patient rolls onto left side, feet and hips aligned, hands together in front of face
• Remove angle, realign tube and bucky
• Open collimation to 10x12 lengthwise
• Ensure patient is not rotated
• Centering: Find ASIS, center 4 inches posterior, and ensure at least 1 inch posterior to mid-coronal plane
• Confirm top of the sacrum is in the view
• Breath instruction: Same as previous views

Final Checks

• Ensure proper collimation and centering
• Confirm with breath instructions