Anatomy and Positioning Principles Questions and Answers Flashcards

What is the purpose of using a 15-degree internal rotation for AP hip radiography?

Answer: To profile the femoral neck without foreshortening

15 degrees of internal rotation of the foot aligns the femoral neck parallel to the IR, preventing foreshortening of the neck in the AP projection.

The Waters method (modified Waters) is used to demonstrate which facial structures?

Answer: Maxillary sinuses and orbits

The Waters (parietoacanthial) projection is the standard view for demonstrating the maxillary sinuses, orbits, and zygomatic arches.

Which positioning error causes the intervertebral disk spaces to appear narrowed or closed on a lateral lumbar spine radiograph?

Answer: The spine not being parallel to the IR

If the lumbar spine is not parallel to the IR (often due to hip width differences), the diverging beam causes disk spaces to appear narrowed; a foam wedge under the waist corrects this.

What does the term 'SID' (source-to-image-receptor distance) most directly affect in radiography?

Answer: Image magnification and recorded detail

SID directly affects image magnification (shorter SID = more magnification) and geometric sharpness (longer SID = less penumbra, better recorded detail).

For a PA wrist radiograph, the central ray is directed to which carpal bone?

Answer: Midcarpal area (capitate)

The central ray is directed to the midcarpal area at the level of the capitate bone for a PA wrist projection.

Which positioning method is used to demonstrate the scaphoid without foreshortening?

Answer: PA with ulnar deviation

PA projection with ulnar deviation (ulnar flexion) extends the scaphoid and aligns it parallel to the IR, reducing foreshortening.