ARRT Study Guide 2026

The modified barium swallow (videofluoroscopic swallow study) is performed with a speech-language pathologist to assess oropharyngeal swallowing function and detect aspiration.

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.

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.

Quantum mottle is caused by insufficient photons reaching the detector; increasing mAs increases photon fluence and reduces this noise.

The Deviation Index (DI) indicates how much the actual exposure to the receptor deviates from a pre-set target exposure. A DI of 0 is ideal. A positive DI indicates overexposure, while a negative DI indicates underexposure. A DI of +1 represents about 25% overexposure, and a DI of +3 represents a 100% (doubling) of the intended exposure. Therefore, a DI of +2.5 signifies significant overexposure, and the technologist should reduce the exposure technique (typically mAs) to adhere to the ALARA principle for subsequent examinations.

A falling load generator starts the exposure with the highest possible mA and then drops the mA to lower levels as the tube's heat loading capacity is reached. This process is designed to deliver the desired mAs in the shortest time possible, which is crucial for minimizing motion artifacts.