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. A patient with a pacemaker is referred for imaging. Which modality poses the greatest safety risk?

    Answer: MRI

    The strong static and time-varying magnetic fields in MRI can cause pacemaker malfunction, lead displacement, or device heating, making it the highest-risk modality for most pacemaker patients.

  2. In digital subtraction angiography (DSA), the 'mask' image is:

    Answer: A pre-contrast image used to subtract background structures

    In DSA, the mask is a pre-contrast fluoroscopic image; subtracting it from post-contrast images eliminates overlying bone and soft tissue, revealing only the contrast-filled vessels.

  3. The modulation transfer function (MTF) of an imaging system describes:

    Answer: How spatial frequencies (detail) are preserved from object to image

    The MTF quantifies what fraction of the true contrast is preserved for each spatial frequency, characterizing the system's spatial resolution performance.

  4. Which parameter most directly controls image noise in a CT acquisition?

    Answer: Tube current-time product (mAs)

    mAs (milliampere-seconds) determines the number of X-ray photons reaching the detector; higher mAs reduces quantum noise while increasing patient dose.

  5. In echocardiography, the Doppler technique used to measure high-velocity blood flow across a stenotic valve is:

    Answer: Continuous-wave (CW) Doppler

    Continuous-wave Doppler has no aliasing limit and can accurately measure the high velocities (>2 m/s) encountered across stenotic cardiac valves, unlike pulsed-wave Doppler.

  6. A biomedical technologist is performing a daily quality control check on a diagnostic ultrasound system using a tissue-equivalent phantom. Which parameter is being tested when measuring the depth of the last resolvable reflector?

    Answer: Penetration depth (sensitivity)

    Penetration depth (maximum depth of visualization) is assessed by identifying the deepest reflector that can be consistently resolved, indicating the system's overall sensitivity.

  7. The half-value layer (HVL) of an X-ray beam is defined as the thickness of material that reduces beam intensity by:

    Answer: 50%

    The HVL is the thickness of a specified attenuator (typically aluminum) that reduces the X-ray beam intensity to exactly half (50%) of its original value.