Lesson 6.5.3
6.5.3 Using ultrasound Quiz: OCR Physics, Unit 5
20 questions
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Lesson 6.5.3, Using ultrasound: 20 multiple choice questions for the OCR Physics (H156), Unit 5: Particles and medical physics, written with Revision Ninja.
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The 20 questions
-
What type of wave is an ultrasound wave used in medical imaging?
- Transverse wave
- Electromagnetic wave
- Torsional wave
- Longitudinal wave
-
What is the minimum frequency threshold for a sound wave to be classified as ultrasound?
- 2 MHz
- 20 Hz
- 20 kHz
- 200 Hz
-
Which effect converts electrical signals into ultrasound vibrations within a transducer?
- Thermionic effect
- Photoelectric effect
- Piezoelectric effect
- Compton effect
-
Which component in an ultrasound scanner both emits and detects ultrasound waves?
- Transducer
- Collimator
- Photomultiplier
- Scintillator
-
What parameter does an ultrasound A-scan display on its vertical oscilloscope axis?
- Organ density
- Blood velocity
- Echo amplitude
- Echo wavelength
-
What visual output is produced by combining multiple A-scans in a B-scan?
- Frequency spectrum
- One-dimensional graph
- Two-dimensional image
- Three-dimensional video
-
What is the formula for the acoustic impedance Z of a tissue medium?
- Z = speed / density
- Z = density x speed
- Z = density / speed
- Z = density x frequency
-
What unit is used to measure the acoustic impedance of a material?
- kg m^-3
- N m^-1 s
- kg m^-2 s^-1
- J m^-2
-
Why is coupling gel applied to a patient's skin during an ultrasound scan?
- To absorb radiation
- To cool skin
- To match impedance
- To reduce friction
-
What proportion of ultrasound intensity is reflected when two media have identical acoustic impedances?
- 50%
- 25%
- 100%
- Zero
-
What change occurs to ultrasound frequency when reflected from blood flowing towards the transducer?
- Frequency decreases
- Velocity decreases
- Frequency increases
- Wavelength increases
-
In Doppler ultrasound, what variable does theta represent in the doppler shift equation?
- Refraction angle
- Critical angle
- Phase angle
- Probe angle
-
What is calculated using the Doppler ultrasound frequency shift in medical diagnostics?
- Blood flow speed
- Bone thickness
- Tissue density
- Heart volume
-
If acoustic impedances are 1 and 3 units, what fraction of ultrasound intensity reflects?
- 0.25
- 0.10
- 0.50
- 0.75
-
What material is commonly used as the crystal element inside an ultrasound transducer?
- Sodium iodide
- Copper sulphate
- Barium sulphate
- Lead zirconate titanate
-
What happens to ultrasound energy as it travels deeper through body tissues?
- It polarises
- It amplifies
- It accelerates
- It attenuates
-
In a PET scan, what event produces the pair of gamma photons used for imaging?
- Positron-electron annihilation
- Alpha decay
- Nuclear fission
- Photoelectric ejection
-
What economic issue is associated with installing PET and MRI scanners in hospitals?
- Zero running cost
- Short lifespan
- Low maintenance
- High capital cost
-
What relative acoustic impedance difference causes almost total reflection of ultrasound at a boundary?
- Small difference
- Large difference
- Negative difference
- Zero difference
-
Why is ultrasound imaging preferred over X-ray CT scans for monitoring fetal development?
- Non-ionising radiation
- Deeper penetration
- Higher resolution
- Faster scanning speed
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