ARRT - American Registry of Radiologic Technologists Head and Neck Procedures Questions and Answers — Questions and Answers
Question 1: For a parietoacanthial projection (Waters method) of the facial bones, what is the correct relationship between the positioning lines and the image receptor (IR) to best demonstrate the maxillary sinuses?
- Orbitomeatal line (OML) is perpendicular to the IR.
- Midsagittal plane (MSP) is parallel to the IR.
- Acanthomeatal line (AML) forms a 37-degree angle with the IR.
- Mentomeatal line (MML) is perpendicular to the IR, placing the OML at a 37-degree angle to the IR. (Correct answer)
Correct answer: Mentomeatal line (MML) is perpendicular to the IR, placing the OML at a 37-degree angle to the IR.
In the parietoacanthial (Waters method) projection, the patient's head is tilted back so the chin touches the IR. This positioning makes the mentomeatal line (MML) perpendicular to the image receptor. As a result, the orbitomeatal line (OML) forms an approximately 37-degree angle with the IR. This specific angulation projects the dense petrous ridges just below the floor of the maxillary sinuses, providing an unobstructed view.
Question 2: A patient arrives in the emergency department with potential facial trauma. The physician suspects a depressed fracture of the right zygomatic arch. Which of the following projections would best demonstrate this specific injury with minimal superimposition?
- PA axial (Caldwell method) with a 15-degree caudal angle.
- Lateral projection of the facial bones.
- Submentovertical (SMV) projection. (Correct answer)
- Parietoacanthial (Waters method).
Correct answer: Submentovertical (SMV) projection.
The submentovertical (SMV) projection is ideal for demonstrating the zygomatic arches. By directing the central ray from beneath the chin (submento) to the top of the head (vertex), the arches are projected bilaterally with minimal superimposition from other cranial structures. A modified Towne (AP axial) view can also be used, but the SMV provides a classic, unobstructed tangential view of the arches.
Question 3: When performing a cross-table lateral projection of the cervical spine on a trauma patient, what is the most critical anatomical landmark to ensure is included on the image for it to be considered diagnostically complete?
- The sella turcica.
- The spinous process of C2 (axis).
- The top of the T1 vertebral body. (Correct answer)
- The mastoid tips.
Correct answer: The top of the T1 vertebral body.
For a trauma cross-table lateral cervical spine radiograph to be considered complete and adequate for diagnosis, it must visualize all seven cervical vertebrae (C1-C7) and the C7-T1 junction. Failure to include the top of the T1 vertebral body is a common error and can lead to missed fractures or dislocations at this critical junction.
Question 4: Which of the following radiographic projections of the skull is specifically designed to demonstrate the petrous pyramids, internal auditory canals, and mastoid air cells of the temporal bone?
- AP Axial (Towne method)
- PA (Caldwell method)
- Axioanterior oblique posterior (Stenvers method) (Correct answer)
- Parietoacanthial (Waters method)
Correct answer: Axioanterior oblique posterior (Stenvers method)
The Stenvers method, an axioanterior oblique posterior projection, is specifically designed to visualize the structures within the temporal bone. By rotating the head 45 degrees and angling the central ray 12-14 degrees cephalad, this view projects the petrous pyramid, internal auditory canal, and mastoid process in profile, free from superimposition.
Question 5: A patient is scheduled for a sialography procedure to evaluate the submandibular gland. Which of the following is a primary clinical indication for this examination?
- To assess for sinusitis.
- To diagnose a fracture of the mandible.
- To rule out temporomandibular joint (TMJ) dysfunction.
- To investigate suspected calculi or strictures in the salivary duct. (Correct answer)
Correct answer: To investigate suspected calculi or strictures in the salivary duct.
Sialography is a specialized contrast-enhanced radiographic examination of the salivary glands and their ducts. Its primary indications include the evaluation of suspected obstructions, such as calculi (stones) or strictures (narrowing), as well as fistulas and other ductal pathologies.
Question 6: In a lateral projection of the paranasal sinuses, the central ray should be directed to a point:
- At the nasion.
- 2 inches superior to the EAM.
- Midway between the outer canthus and the EAM. (Correct answer)
- At the acanthion.
Correct answer: Midway between the outer canthus and the EAM.
For a true lateral projection of the paranasal sinuses, the central ray is centered to a point midway between the outer canthus (the outer corner of the eye) and the external auditory meatus (EAM). This centering ensures that all four sinus groups (frontal, ethmoid, sphenoid, and maxillary) are included and properly demonstrated in the image.
ARRT - American Registry of Radiologic Technologists Head and Neck Procedures Questions and Answers
For a parietoacanthial projection (Waters method) of the facial bones, what is the correct relationship between the positioning lines and the image receptor (IR) to best demonstrate the maxillary sinuses?