Practice Test Geeks(CABT) Certified Associate in Biomedical Technology Practice Test
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Imaging Systems Flashcards

7 cards from real CABT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Imaging Systems flashcards as text

  1. Which artifact in MRI is caused by the difference in resonant frequencies between water and fat protons?

    Answer: Chemical shift artifact

    Chemical shift artifact occurs because water and fat protons precess at slightly different frequencies, causing a spatial misregistration at tissue interfaces.

  2. In computed tomography, the Hounsfield unit (HU) value for air is approximately:

    Answer: -1000

    Air is assigned a Hounsfield unit value of -1000 on the CT attenuation scale, while water is defined as 0 HU.

  3. A biomedical technologist notices that an ultrasound image shows a bright echo directly behind a highly reflective structure. This is best described as:

    Answer: Reverberation artifact

    Reverberation artifact appears as multiple equally spaced bright lines behind a strongly reflective interface due to sound bouncing back and forth.

  4. What is the primary purpose of a grid in diagnostic radiography?

    Answer: To reduce scattered radiation reaching the detector

    A radiographic grid is placed between the patient and detector to absorb scattered radiation, improving image contrast.

  5. In fluoroscopy, the automatic brightness control (ABC) system primarily adjusts which parameters to maintain image quality?

    Answer: kVp, mA, and pulse width

    ABC systems dynamically adjust kVp, mA, and pulse width to maintain consistent image brightness as the beam passes through varying tissue thicknesses.

  6. Which MRI sequence is most sensitive for detecting acute cerebral ischemia within the first few hours?

    Answer: Diffusion-weighted imaging (DWI)

    DWI detects restricted diffusion of water molecules in acutely infarcted tissue, making it the most sensitive sequence for hyperacute stroke within hours of onset.

  7. The spatial resolution of a digital radiographic system is most directly limited by which factor?

    Answer: Detector pixel pitch

    In digital radiography, the pixel pitch (size of individual detector elements) sets the fundamental limit on spatial resolution through the Nyquist sampling theorem.