Biomedical Instrumentation Questions and Answers – PACS (Picture Archiving and Communication System)

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This set of Biomedical Instrumentation Multiple Choice Questions & Answers (MCQs) focuses on “PACS (Picture Archiving and Communication System)”.

1. Which of the following instrument is used to measure blood flow in the skin?
a) NMR Blood Flowmeter
b) Ultrasonic Blood Flowmeter
c) Electromagnetic Blood Flowmeter
d) Laser Doppler Blood Flowmeter
View Answer

Answer: d
Explanation: A system utilizing the Doppler-shift of monochromatic laser light to measure blood flow in the skin is described by Watkins and Holloway (1978). When a laser beam is directed towards the tissue under study, absorption and scattering take place. Radiation scattered in movable structures, such as red cells, is shifted in frequency due to the Doppler effect, while radiation scattered in nonmoving soft tissue is unshifted in frequency.
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2. What is the effective radiation penetration depth in soft tissue?
a) 1 mm
b) 2 mm
c) 3 mm
d) 4 mm
View Answer

Answer: a
Explanation: The effective radiation penetration depth is approximately 1 mm in soft tissue and scattering and absorption take place mostly in the papilla region and the underlying corium—two dermal layers containing the capillary network of the skin.

3. What is the power of laser light used in Laser Doppler Blood flowmeter?
a) 2 mW
b) 3 mW
c) 4 mW
d) 5 mW
View Answer

Answer: d
Explanation: In principle, light from a low power (5 mW) He–Ne laser is coupled into a quartz fibre and transmitted to the skin. The light is reflected from both the non-moving tissues (reference beam) and moving red blood cells (Doppler-shifted beam). The two beams are received by a plastic fibre and transmitted back to a photo-diode where optical heterodyning takes place.
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4. Which laser is used in Laser doppler blood flowmeter?
a) Nd-YAG
b) Argon
c) He-Ne
d) CO2
View Answer

Answer: c
Explanation: In principle, light from a low power (5 mW) He–Ne laser is coupled into a quartz fibre and transmitted to the skin. The light is reflected from both the non-moving tissues (reference beam) and moving red blood cells (Doppler-shifted beam). The two beams are received by a plastic fibre and transmitted back to a photo-diode where optical heterodyning takes place.

5. What is used to receive beams of light?
a) Plastic fibre
b) Photo diode
c) He-Ne Laser
d) CO2 Laser
View Answer

Answer: a
Explanation: In principle, light from a low power (5 mW) He–Ne laser is coupled into a quartz fibre and transmitted to the skin. The light is reflected from both the non-moving tissues (reference beam) and moving red blood cells (Doppler-shifted beam). The two beams are received by a plastic fibre and transmitted back to a photo-diode where optical heterodyning takes place.
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6. Where optical heterodyning takes place in Laser Doppler Blood Flowmeter?
a) Plastic fibre
b) Photo diode
c) He-Ne Laser
d) CO2 Laser
View Answer

Answer: b
Explanation: In principle, light from a low power (5 mW) He–Ne laser is coupled into a quartz fibre and transmitted to the skin. The light is reflected from both the non-moving tissues (reference beam) and moving red blood cells (Doppler-shifted beam). The two beams are received by a plastic fibre and transmitted back to a photo-diode where optical heterodyning takes place.

7. The laser output is coupled into the fibre using a converging lens.
a) True
b) False
View Answer

Answer: a
Explanation: True, The He–Ne laser operating at 632.8 nm wavelength is used. The laser output is coupled into the fibre using a converging lens, which results in an increased power density at the skin surface and thus enables the detection of flow in the more deeply seated veins and arteries.
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8. What is the operating wavelength of He-Ne laser?
a) 610.8 nm
b) 622.6 nm
c) 632.8 nm
d) 650 nm
View Answer

Answer: c
Explanation: The He–Ne laser operating at 632.8 nm wavelength is used. The laser output is coupled into the fibre using a converging lens, which results in an increased power density at the skin surface and thus enables the detection of flow in the more deeply seated veins and arteries.

9. What functions as a square law device and gives out current?
a) Plastic fibre
b) Photodetector
c) He-Ne Laser
d) CO2 Laser
View Answer

Answer: b
Explanation: The photodetector functions as a square law device and gives out current, which is proportional to the intensity of the incident light and, therefore, to the frequency of beating of the shifted and unshifted signals. The light falling on the photodetector is an optically mixed signal involving a Doppler-shifted signal back scattered from the moving red blood cells with the ‘reference’ signal reflected from the non-moving skin surface.
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10. Which technique seems to offer several advantages like light reproducibility and sensitivity?
a) NMR
b) Laser Doppler
c) Electromagnetic
d) Ultrasonic
View Answer

Answer: b
Explanation: Laser Doppler flowmetry is a non-invasive technique and seems to offer several advantages like light reproducibility and sensitivity. However, its disadvantages like poor selectivity, baseline instability and restriction in a site of measurement are still limiting factors in its successful clinical utilization.

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn | Youtube | Instagram | Facebook | Twitter