At a source-to-image distance (SID) of 60 inches (152 cm), the central ray must align to the central ray indicator within:

At a source-to-image distance (SID) of 60 inches (152 cm), the central ray must align to the central ray indicator within:

• A. 1.2 inches (3.0 cm)
• B. 0.6 inches (1.5 cm)
• C. 3.0 inches (7.6 cm)
• D. 6.0 inches ( 15.2 cm)

Answer: (B)

Centering accuracy is essential: the beam’s central ray must pass through the center of the image receptor, aligning with the central ray indicator so the anatomy is projected onto the midportion of the plate. For a SID of 60 inches, this tolerance is about 1.5 cm (0.6 inches). Keeping the CR within this range helps ensure the exposure is centered, minimizes geometric distortion, and prevents cropping or uneven density. Larger deviations would push the anatomy toward the edge of the IR and increase distortion and exposure nonuniformity.

Centering accuracy is essential: the beam’s central ray must pass through the center of the image receptor, aligning with the central ray indicator so the anatomy is projected onto the midportion of the plate. For a SID of 60 inches, this tolerance is about 1.5 cm (0.6 inches). Keeping the CR within this range helps ensure the exposure is centered, minimizes geometric distortion, and prevents cropping or uneven density. Larger deviations would push the anatomy toward the edge of the IR and increase distortion and exposure nonuniformity.