Diagnostic Imaging & Radiology Flashcards
7 cards from real DHA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Diagnostic Imaging & Radiology flashcards as text
Which unit is used to measure radiation absorbed dose in tissue?
Answer: Gray (Gy)
The Gray (Gy) is the SI unit of absorbed dose, defined as one joule of radiation energy absorbed per kilogram of tissue.
What does the acronym ALARA stand for in radiation protection?
Answer: As Low As Reasonably Achievable
ALARA (As Low As Reasonably Achievable) is the guiding principle of radiation protection, aiming to minimize exposure while maintaining diagnostic quality.
Which imaging modality uses magnetic fields and radiofrequency waves to produce images?
Answer: MRI
MRI (Magnetic Resonance Imaging) uses strong magnetic fields and radiofrequency pulses to align and then perturb hydrogen nuclei, generating detailed soft-tissue images.
The standard diagnostic chest radiograph is taken in which projection?
Answer: Posteroanterior (PA)
The standard chest X-ray is taken in the posteroanterior (PA) projection with the patient standing and the X-ray beam passing from back to front, minimizing cardiac magnification.
Which contrast agent is most commonly used to enhance MRI images?
Answer: Gadolinium
Gadolinium-based contrast agents (GBCAs) are the standard MRI contrast agents, shortening T1 relaxation times and improving tissue differentiation.
Which type of ionizing radiation has the greatest penetrating power?
Answer: Gamma rays
Gamma rays are high-energy photons with the greatest penetrating power, requiring dense materials like lead or thick concrete for adequate shielding.
In nuclear medicine, the 'half-life' of a radiopharmaceutical refers to:
Answer: The time for half the radioactive atoms to decay
Physical half-life is the time required for half of the radioactive atoms in a sample to undergo decay, a fixed property of each radionuclide.