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Generators of high frequency electromagnetic waves. Frequency ranges used in physiotherapy. Inductive and capacitive methods. Determination of the power of electromagnetic wave sources. Safety technique - Medical Physics -MCQs

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Medical Physics Quiz on Generators of high frequency electromagnetic waves. Frequency ranges used in physiotherapy. Inductive and capacitive methods. Determination of the power of electromagnetic wave sources. Safety technique - Medical Physics -MCQs, created by Hussain Basheer on 23/11/2018.
Hussain Basheer
Quiz by Hussain Basheer, updated more than 1 year ago
Hussain Basheer
Created by Hussain Basheer over 5 years ago
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Resource summary

Question 1

Question
Which of the following human organs and tissues have the least thermal conductivity?
Answer
  • Muscles
  • Brain
  • Skin and fat

Question 2

Question
Which of the following diagnostic/therapeutic methods cause deep tissue heating?
Answer
  • Thermography
  • High frequency electric current therapy
  • Deep x-ray therapy

Question 3

Question
Faradization is a method for:
Answer
  • Electro-stimulation with low frequency pulsed current
  • High frequency electromagnetic therapy
  • Interferential current therapy of deep-seated tissue

Question 4

Question
The most common frequency used in high-frequency electro-stimulation is:
Answer
  • 20 Hz
  • 20 kHz
  • 2 MHz

Question 5

Question
Modern electromyography methods rely on the following parameter (chose one):
Answer
  • Rheobase
  • Chronaxie
  • Accommodation coefficient

Question 6

Question
Thermography is a medical imaging method that:
Answer
  • Is harmless
  • Has high resolution
  • With diagnostic significance similar to MRI

Question 7

Question
Which of the following body fluids and tissues has the least electrical conductivity?
Answer
  • Blood
  • Bones
  • Bone marrow

Question 8

Question
Electric resistance (R) is inversely proportional to:
Answer
  • Electric conductance (G)
  • Frequency (f)
  • Period (T)

Question 9

Question
What is the main effect that causes heating in microwave diathermy, and also in the microwave oven (f = 2.45 GHz)?
Answer
  • Resonance: water molecules oscillate with the same frequency
  • Dielectric heating: electric dipoles of water are made to rotate
  • Refraction: bending of waves inside the substance

Question 10

Question
Electric potential difference is measured in units of volts (V) that represent the ratio of:
Answer
  • Charge per time, Q/t
  • Energy per charge, E/Q
  • Energy per distance, E/x

Question 11

Question
Which of following electric currents is the most dangerous for the human body?
Answer
  • High frequency AC
  • Low frequency AC
  • Pulsed current

Question 12

Question
Which of the following currents will cause stimulation in excitable tissue (nerves or muscles)?
Answer
  • Low frequency, pulsed, above threshold
  • Low frequency, alternating, below threshold
  • High frequency, alternating, above threshold

Question 13

Question
High-frequency generators produce electromagnetic waves with:
Answer
  • Aperiodic behavior
  • Constant amplitude
  • Gradually damping amplitude

Question 14

Question
Which of the following currents causes differential heating in tissues?
Answer
  • Pulsed current
  • High frequency current
  • DC current

Question 15

Question
Which of the following features are common forelectrosurgery and electrostimulation?
Answer
  • The frequency
  • The shape of the electrodes
  • The use of alternating current

Question 16

Question
Specific heat capacity is defined as:
Answer
  • The amount of heat needed to raise the temperature of 1 kg of substance by 1 degree Kelvin (or Celsius)
  • The heat released during the controlled burn of 1 kg of substance
  • The heat gain in a substance when Gibbs free energy increases by 1 joule

Question 17

Question
Electrosurgical procedures apply alternating current in the radio frequency (RF) range (100 kHz - 5 MHz) directly to the tissue. Why during electrosurgery there is no nerve and muscular stimulations?
Answer
  • High frequencies currents do not penetrate deep enough
  • Oscillations are much faster than membrane depolarization time
  • The power is below stimulation threshold

Question 18

Question
What is the heating mechanism of high frequency alternating current (2MHz)?
Answer
  • Brief polarization of tissue
  • Oscillations of ionized molecules, rotation of dipoles and associated collisions
  • Absorption of energy from the electromagnetic waves

Question 19

Question
When an inductor (L) and a capacitor (C) are connected in series, the resulting (L-C) electric circuit is called:
Answer
  • Operational amplifier (compares and amplifies signal)
  • Current rectifier (converts AC into DC)
  • Harmonic oscillator (used to emit radio waves)

Question 20

Question
The Earth surface is (reasonably) constant potential reference, and for that reason taken to be the :
Answer
  • Infinite potential
  • Negative potential
  • Zero potential
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