Biomedical Instrumentation Questions and Answers – Cyber Medicine

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This set of Biomedical Instrumentation Multiple Choice Questions & Answers (MCQs) focuses on “Cyber Medicine”.

1. In which type of electromagnetic flowmeter, the probe magnet is energized with sine wave?
a) Sine wave electromagnetic flowmeter
b) Square wave electromagnetic flowmeter
c) Sawtooth wave electromagnetic flowmeter
d) Impulse wave electromagnetic flowmeter

Explanation: In a sine wave flowmeter, the probe magnet is energized with a sine wave and consequently the induced voltage will also be sinusoidal in nature. The major problem encountered with the sinusoidal type of magnetic field is that the blood vessel and the fluid contained in it act as the secondary coil of a transformer when the probe magnet is excited.

2. In which type of electromagnetic blood flowmeter, the energizing voltage is given to magnet is a square wave?
a) Sine wave electromagnetic flowmeter
b) Square wave electromagnetic flowmeter
c) Sawtooth wave electromagnetic flowmeter
d) Impulse wave electromagnetic flowmeter

Explanation: This differs from a sine wave flowmeter in that the energizing voltage given to the magnet is a square wave and therefore, the induced voltage is also a square wave. The square wave flowmeter has less stringent requirements of phase stability than the sine wave type as it can suppress the quadrature voltages relatively easily.

3. The preamplifier used in square wave blood flowmeter has a CMRR of _______ dB.
a) 96
b) 100
c) 106
d) 110

Explanation: The preamplifier used by Goodman (1969(a)) has a CMRR of 106 dB (200,000 : 1) with a common mode input impedance of 150 MW. The preamplifier gain is of the order of 1000. The preamplifier also must incorporate the facility for ‘probe balance’ by which signals in phase with the magnet current can be selected to balance background voltages in phase with flow voltages.
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4. What is the common mode input impedance of preamplifier used in square wave blood flowmeter?
a) 110 MW
b) 130 MW
c) 150 MW
d) 180 MW

Explanation: The preamplifier used by Goodman (1969(a)) has a CMRR of 106 dB (200,000 : 1) with a common mode input impedance of 150 MW. The preamplifier gain is of the order of 1000. The preamplifier also must incorporate the facility for ‘probe balance’ by which signals in phase with the magnet current can be selected to balance background voltages in phase with flow voltages. A calibrating signal of 30 mV amplitude can be connected to the preamplifier with an input selector switch.

5. A calibrating signal of _____ mV amplitude can be connected to preamplifier with an input selector switch.
a) 10
b) 20
c) 30
d) 40

Explanation: The preamplifier used by Goodman (1969(a)) has a CMRR of 106 dB (200,000 : 1) with a common mode input impedance of 150 MW. The preamplifier gain is of the order of 1000. The preamplifier also must incorporate the facility for ‘probe balance’ by which signals in phase with the magnet current can be selected to balance background voltages in phase with flow voltages. A calibrating signal of 30 mV amplitude can be connected to the preamplifier with an input selector switch.
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6. What is used to recover the signal, which is analogue of the flow rate being measured?
a) Low-pass filter
b) Phase sensitive detector
c) Gating Circuit
d) Bandpass filter

Explanation: A phase sensitive detector is used to recover the signal, which is an analogue of the flow rate being measured. This type of demodulator not only offers maximum signal-to-noise ratio but also helps in the rejection of interfering voltages at frequencies well below the carrier frequency.

7. The major problem encountered with the sinusoidal type of magnetic field is that the blood vessel and the fluid contained in it act as the primary coil of a transformer when the probe magnet is excited.
a) True
b) False

Explanation: False, the major problem encountered with the sinusoidal type of magnetic field is that the blood vessel and the fluid contained in it act as the secondary coil of a transformer when the probe magnet is excited. As a result, in addition to the induced flow voltage, there is an induced artefact voltage generally referred to as ‘transformer voltage’.

8. _______ instruments are now available for the measurement of blood velocity, volume flow, flow direction, flow profile and to visualize the internal lumen of blood vessel.
a) Transit-time
b) Doppler-shift
c) Square wave
d) Sine wave

Explanation: For routine clinical measurements, the transcutaneous Doppler instrument has, by far, superseded the transit-time type. Therefore, most of the recent efforts have been concentrated on the development of Doppler-shift instruments, which are now available for the measurement of blood velocity, volume flow, flow direction, flow profile and to visualize the internal lumen of a blood vessel.

9. Which of the following is a non-invasive technique to measure blood velocity in a particular vessel from surface of the body?
a) Electromagnetic
b) Ultrasonic
c) NMR
d) Laser Doppler

Explanation: Ultrasonic is a non-invasive technique to measure blood velocity in a particular vessel from the surface of the body. It is based on the analysis of echo signals from the erythrocytes in the vascular structures. Because of the Doppler effect, the frequency of these echo signals changes relative to the frequency which the probe transmits.

10. Which of the following is a non invasive method for measurement of peripheral blood flow or blood flow in various organs?
a) Electromagnetic
b) Ultrasonic
c) NMR
d) Laser Doppler

Explanation: Nuclear magnetic resonance principle offers yet another non-invasive method for the measurement of peripheral blood flow or blood flow in various organs. The method pertains to a quantum mechanical phenomenon related to the magnetic energy levels of the nucleus of some elements and their isotopes.

11. The Angular frequency of precession is given by W=2pv=rBo,where Bo is _______
a) ratio of magnetic moment to angular momentum
b) density of steady magnetic field
d) length of coil

Explanation: The angular frequency (Larmor frequency) of this precession is given by:
W = 2p v = r Bo
Where r is the ratio of the magnetic moment to the angular momentum (the magnetic gyro ratio) and Bo is the density of the steady magnetic field and v is the frequency of radiation.

12. For blood flow measurement work, the behavior of the two hydrogen atoms of water is studied.
a) True
b) False

Explanation: True, for blood flow measurement work, behaviour of the two hydrogen atoms of water is studied, since blood is approximately 83% water. Due to the magnetic moment of the hydrogen atom, the nucleus behaves as a microminiature magnet which can be affected by externally applied magnetic fields.

13. The Angular frequency of precession is given by W=2pv=rBo, where r is ____________
a) ratio of magnetic moment to angular momentum
b) density of steady magnetic field
d) length of coil

Explanation: The angular frequency (Larmor frequency) of this precession is given by:
W = 2p v = r Bo
Where r is the ratio of the magnetic moment to the angular momentum (the magnetic gyro ratio) and Bo is the density of the steady magnetic field and v is the frequency of radiation.

14. The Angular frequency of precession is given by W=2pv=rBo, where v is _____________
a) ratio of magnetic moment to angular momentum
b) density of steady magnetic field
d) length of coil

Explanation: The angular frequency (Larmor frequency) of this precession is given by:
W = 2p v = r Bo
Where r is the ratio of the magnetic moment to the angular momentum (the magnetic gyro ratio) and Bo is the density of the steady magnetic field and v is the frequency of radiation.

Sanfoundry Global Education & Learning Series – Biomedical Instrumentation.

To practice all areas of Biomedical Instrumentation, here is complete set of 1000+ Multiple Choice Questions and Answers.