Hussain Basheer
Quiz von , erstellt am more than 1 year ago

Medical Physics Quiz am 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, erstellt von Hussain Basheer am 23/11/2018.

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Hussain Basheer
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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

Frage 1 von 20

1

Which of the following human organs and tissues have the least thermal conductivity?

Wähle eine der folgenden:

  • Muscles

  • Brain

  • Skin and fat

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Frage 2 von 20

1

Which of the following diagnostic/therapeutic methods cause deep tissue heating?

Wähle eine der folgenden:

  • Thermography

  • High frequency electric current therapy

  • Deep x-ray therapy

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Frage 3 von 20

1

Faradization is a method for:

Wähle eine der folgenden:

  • Electro-stimulation with low frequency pulsed current

  • High frequency electromagnetic therapy

  • Interferential current therapy of deep-seated tissue

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Frage 4 von 20

1

The most common frequency used in high-frequency electro-stimulation is:

Wähle eine der folgenden:

  • 20 Hz

  • 20 kHz

  • 2 MHz

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Frage 5 von 20

1

Modern electromyography methods rely on the following parameter (chose one):

Wähle eine der folgenden:

  • Rheobase

  • Chronaxie

  • Accommodation coefficient

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Frage 6 von 20

1

Thermography is a medical imaging method that:

Wähle eine der folgenden:

  • Is harmless

  • Has high resolution

  • With diagnostic significance similar to MRI

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Frage 7 von 20

1

Which of the following body fluids and tissues has the least electrical conductivity?

Wähle eine der folgenden:

  • Blood

  • Bones

  • Bone marrow

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Frage 8 von 20

1

Electric resistance (R) is inversely proportional to:

Wähle eine der folgenden:

  • Electric conductance (G)

  • Frequency (f)

  • Period (T)

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Frage 9 von 20

1

What is the main effect that causes heating in microwave diathermy, and also in the microwave oven (f = 2.45 GHz)?

Wähle eine der folgenden:

  • 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

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Frage 10 von 20

1

Electric potential difference is measured in units of volts (V) that represent the ratio of:

Wähle eine der folgenden:

  • Charge per time, Q/t

  • Energy per charge, E/Q

  • Energy per distance, E/x

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Frage 11 von 20

1

Which of following electric currents is the most dangerous for the human body?

Wähle eine der folgenden:

  • High frequency AC

  • Low frequency AC

  • Pulsed current

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Frage 12 von 20

1

Which of the following currents will cause stimulation in excitable tissue (nerves or muscles)?

Wähle eine der folgenden:

  • Low frequency, pulsed, above threshold

  • Low frequency, alternating, below threshold

  • High frequency, alternating, above threshold

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Frage 13 von 20

1

High-frequency generators produce electromagnetic waves with:

Wähle eine der folgenden:

  • Aperiodic behavior

  • Constant amplitude

  • Gradually damping amplitude

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Frage 14 von 20

1

Which of the following currents causes differential heating in tissues?

Wähle eine der folgenden:

  • Pulsed current

  • High frequency current

  • DC current

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Frage 15 von 20

1

Which of the following features are common forelectrosurgery and electrostimulation?

Wähle eine der folgenden:

  • The frequency

  • The shape of the electrodes

  • The use of alternating current

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Frage 16 von 20

1

Specific heat capacity is defined as:

Wähle eine der folgenden:

  • 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

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Frage 17 von 20

1

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?

Wähle eine der folgenden:

  • High frequencies currents do not penetrate deep enough

  • Oscillations are much faster than membrane depolarization time

  • The power is below stimulation threshold

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Frage 18 von 20

1

What is the heating mechanism of high frequency alternating current (2MHz)?

Wähle eine der folgenden:

  • Brief polarization of tissue

  • Oscillations of ionized molecules, rotation of dipoles and associated collisions

  • Absorption of energy from the electromagnetic waves

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Frage 19 von 20

1

When an inductor (L) and a capacitor (C) are connected in series, the resulting (L-C) electric circuit is called:

Wähle eine der folgenden:

  • Operational amplifier (compares and amplifies signal)

  • Current rectifier (converts AC into DC)

  • Harmonic oscillator (used to emit radio waves)

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Frage 20 von 20

1

The Earth surface is (reasonably) constant potential reference, and for that reason taken to be the :

Wähle eine der folgenden:

  • Infinite potential

  • Negative potential

  • Zero potential

Erklärung

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