To balance density along a lower leg radiograph with uneven joint exposures, which joint should be placed toward the cathode end of the beam?

To balance density along a lower leg radiograph with uneven joint exposures, which joint should be placed toward the cathode end of the beam?

• A. Distal joint
• B. Proximal joint
• C. Center
• D. Both joints

Answer: (B)

Because the X-ray beam is more intense on the cathode side due to the heel effect, placing thicker anatomy toward the cathode end helps compensate for greater attenuation. In a lower leg, the knee region near the proximal joint is the thicker part, so positioning that area toward the cathode end increases exposure where absorption is highest. This helps achieve more uniform density along the leg. If the distal joint were toward the cathode, the knee would be underexposed and density would be uneven.

Because the X-ray beam is more intense on the cathode side due to the heel effect, placing thicker anatomy toward the cathode end helps compensate for greater attenuation. In a lower leg, the knee region near the proximal joint is the thicker part, so positioning that area toward the cathode end increases exposure where absorption is highest. This helps achieve more uniform density along the leg. If the distal joint were toward the cathode, the knee would be underexposed and density would be uneven.