CAMRT Radiography Practice Exam

To obtain a reverse Caldwell (AP axial) image in a patient with a cervical collar, which position should be used?

1. AP projection, OML perpendicular to the IR, central ray perpendicular to the IR

2. AP projection, IOML perpendicular to the IR, central ray angled 15 degrees cephalad

3. AP projection, IOML perpendicular to the IR, central ray angled 15 degrees caudad

4. AP projection, IOML perpendicular to the IR, central ray approximately 8 degrees cephalad

The correct answer is: AP projection, IOML perpendicular to the IR, central ray approximately 8 degrees cephalad

To obtain a reverse Caldwell (AP axial) image effectively, it is essential to position the patient's skull in a specific way to ensure that the appropriate structures are visualized. When the IOML (Infraorbital Meatal Line) is perpendicular to the image receptor (IR), a central ray angled approximately 8 degrees cephalad targets the orbits and the cranial structures effectively. In a reverse Caldwell projection, the primary goal is to visualize the occipital area of the skull with the central ray directed toward the nasion. The alignment of the IOML to be perpendicular to the IR minimizes distortion and ensures that the cranial anatomy is correctly represented in the image. The angling of the central ray is also critical—but in this case, with a lesser angle (8 degrees cephalad), it is appropriate given the positioning of the cervical collar, which may prevent a more elevated angle typically required in other configurations. So, the use of IOML perpendicular to the IR in conjunction with a slight cephalad angle allows for a satisfactory reverse Caldwell projection while accommodating patients who cannot move their neck, such as those wearing a cervical collar. This combination achieves optimal image quality and visualization of critical anatomical details, making it the correct choice