Which skull projection would result in elongation of the anatomy being imaged?

Which skull projection would result in elongation of the anatomy being imaged?

• A. Posteroanterior (PA) skull
• B. Lateral skull
• C. Parietoacanthial ( Waters ) sinuses
• D. Anteroposterior (AP) axial (Towne) skull with a 37 degree tube angle

Answer: (D)

Elongation on a radiograph occurs when the beam geometry causes structures to be projected along their long axis, making them appear longer than they actually are. The Anteroposterior axial Towne skull projection uses a significant caudal tube angle (about 37 degrees) to place the dorsum sellae and occipital region through the foramen magnum. That axial tilt aligns the central ray more with the skull’s axis, stretching the posterior structures in the image and producing an elongated appearance of the anatomy. The other views are typically true or near-true projections when properly performed: a PA skull and a lateral skull give relatively undistorted dimensions of the skull when correctly aligned, and the parietoacanthial (Waters) view is angled specifically to visualize the sinuses in a way that doesn’t elongate the entire skull in the same manner.

Elongation on a radiograph occurs when the beam geometry causes structures to be projected along their long axis, making them appear longer than they actually are. The Anteroposterior axial Towne skull projection uses a significant caudal tube angle (about 37 degrees) to place the dorsum sellae and occipital region through the foramen magnum. That axial tilt aligns the central ray more with the skull’s axis, stretching the posterior structures in the image and producing an elongated appearance of the anatomy.

The other views are typically true or near-true projections when properly performed: a PA skull and a lateral skull give relatively undistorted dimensions of the skull when correctly aligned, and the parietoacanthial (Waters) view is angled specifically to visualize the sinuses in a way that doesn’t elongate the entire skull in the same manner.