Which central ray location is used for the AP projection of the fifth digit?

Which central ray location is used for the AP projection of the fifth digit?

• A. Fifth MTP joint
• B. Proximal interphalangeal joint
• C. Distal interphalangeal joint
• D. Base of fifth metatarsal

Answer: (A)

Centering the central ray at the fifth metatarsophalangeal joint places the beam right through the joint between the head of the fifth metatarsal and the proximal phalanx. This is the proper location for an AP view of the fifth toe because it centers the projection on the main articulation of the toe and ensures the entire toe length is captured with consistent magnification and minimal distortion. If the ray were aimed at the proximal or distal interphalangeal joints, the beam would pass through joints within the toe rather than at the metatarsophalangeal articulation, which can compromise alignment and image quality. Centering at the base of the fifth metatarsal would miss the toe’s proximal phalanx region and reduce the usefulness of the image for evaluating the toe and its joint spaces.

Centering the central ray at the fifth metatarsophalangeal joint places the beam right through the joint between the head of the fifth metatarsal and the proximal phalanx. This is the proper location for an AP view of the fifth toe because it centers the projection on the main articulation of the toe and ensures the entire toe length is captured with consistent magnification and minimal distortion. If the ray were aimed at the proximal or distal interphalangeal joints, the beam would pass through joints within the toe rather than at the metatarsophalangeal articulation, which can compromise alignment and image quality. Centering at the base of the fifth metatarsal would miss the toe’s proximal phalanx region and reduce the usefulness of the image for evaluating the toe and its joint spaces.