Diagnostic Imaging Equipment Flashcards

What does the term 'spatial resolution' describe in diagnostic imaging?

Answer: The ability to distinguish two closely spaced objects as separate

Spatial resolution quantifies how small a detail the imaging system can distinguish, typically measured in line pairs per millimeter (lp/mm).

A fluoroscopy unit's automatic exposure control (AEC) is not functioning. What is the main risk?

Answer: Patient may receive excessive radiation dose

AEC modulates dose to maintain adequate image quality; without it, fixed high technique settings can significantly over-irradiate the patient.

What does 'acoustic coupling gel' accomplish in ultrasound imaging?

Answer: It eliminates air gaps between the transducer and skin to prevent signal reflection loss

Air has very different acoustic impedance from tissue; gel fills the gap so ultrasound energy transmits into the body instead of reflecting at the skin surface.

Which test verifies that an MRI RF transmitter is delivering accurate flip angles?

Answer: RF power calibration / transmitter gain verification

RF transmitter calibration ensures the pulse power produces the intended flip angle, which directly affects image contrast and SAR calculations.

In a nuclear medicine gamma camera, what crystal converts gamma photons to light?

Answer: Sodium iodide (NaI) scintillator crystal

Gamma cameras use a large NaI(Tl) crystal that scintillates (emits light flashes) when struck by gamma photons, which are then detected by photomultiplier tubes.

What is the ALARA principle as applied to diagnostic imaging in US healthcare?

Answer: Keep radiation exposure As Low As Reasonably Achievable while maintaining diagnostic quality

ALARA mandates minimizing radiation dose through technique optimization, collimation, shielding, and appropriate protocol selection without compromising diagnostic value.