Ultrasound and Radiation Physics Quiz

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Questions and Answers

What causes the piezoelectric effect?

The interaction of light waves with piezoelectric materials.

The presence of a temperature gradient in a solid, leading to the formation of an electric polarization.

The movement of objects under the influence of gravity, as seen in the Tower of Pisa.

The application of a mechanical stress to certain solids, causing them to become electrically polarized. (correct)

Which of the following is NOT a property of human tissue related to ultrasound?

Ultrasound waves can be reflected by human tissue.

Human tissue exhibits piezoelectric properties. (correct)

Human tissue can be imaged using ultrasound.

Ultrasound waves can be absorbed by human tissue.

Which of the following statements about ultrasonic imaging is correct?

The size of the ultrasonic equipment directly influences the acoustic density of the imaged tissue.

The precision of the ultrasonic instrument has no effect on the quality of the received images.

The ultrasonic image displayed on the monitor directly represents the acoustic density of the studied tissues.

Ultrasonic imaging relies on differences in acoustic impedance between tissues, resulting in variations in reflected signals. (correct)

Which of the following is a characteristic of infrasound?

Infrasound is a type of mechanical wave with frequencies below 20 Hz. (D) Signup and view all the answers

What is the principle behind Doppler ultrasound?

The change in frequency of ultrasound waves is proportional to the speed of the reflecting object, allowing for the measurement of blood flow. (C) Signup and view all the answers

Which of these natural sciences studies infrasound?

Seismology (B) Signup and view all the answers

Which of the following describes the way ultrasound waves propagate through human tissue?

Ultrasound waves propagate exclusively as longitudinal waves through human tissue. (D) Signup and view all the answers

Why does lithotripsy, the use of ultrasound waves to break kidney stones, cause minimal damage to surrounding tissue?

The acoustic pressure within the kidney stones is significantly higher than in surrounding tissue. (A) Signup and view all the answers

What is the primary mode of interaction between radiation and tissue, primarily water, in the energy range of 0.5 MeV to 5 MeV?

Compton scattering (C) Signup and view all the answers

What is the correct unit for the absorbed dose of ionizing radiation, measured in Gray (Gy)?

Joules per kilogram (J/kg) (D) Signup and view all the answers

Which property of gamma rays makes them suitable for treating deep-seated tumors?

Gamma rays deposit their maximum dose deep within the body, minimizing surface dose. (A) Signup and view all the answers

Why are electron beams produced by medical accelerators well-suited for treating surface and skin tumors?

Electron beams have a lower maximum energy than photon beams, making them more effective at shallower depths. (D) Signup and view all the answers

The unit Sievert (Sv) measures what quantity related to ionizing radiation?

Equivalent dose (B) Signup and view all the answers

What type of ionizing radiation consists of charged particles?

Charged particles (C) Signup and view all the answers

Which of the following processes involves the scattering of photons by electrons?

Compton scattering (D) Signup and view all the answers

What property primarily determines the probability of Compton scattering (linear attentuation coefficient)?

Electron density per unit mass (A) Signup and view all the answers

What does a positive Doppler shift ( a. ∆f > 0) indicate about the movement of erythrocytes?

Erythrocytes move towards the transducer. (D) Signup and view all the answers

Which frequency is most suitable for deep tissue and organ imaging due to better penetration?

3 MHz (A) Signup and view all the answers

How is the Doppler shift defined?

The frequency difference between emitted and received signals for observers at relative motion. (A) Signup and view all the answers

At which frequency range is the human ear most sensitive?

From 2000 Hz to 5000 Hz (B) Signup and view all the answers

What does 0 dB represent?

The sound is at threshold reference level (D) Signup and view all the answers

At what angle should the ultrasonic probe be applied for maximum Doppler shift?

Θ = 45° (A) Signup and view all the answers

Which factor does NOT affect the speed of ultrasound in human tissue?

The speed of the apparatus. (B) Signup and view all the answers

What is timbre related to?

Harmonic overtones (A) Signup and view all the answers

Which factor does NOT affect the reflection/transmission of sound waves?

The colors of substances near the boundary area (B) Signup and view all the answers

What is the primary application of the reverse piezoelectric effect?

Ultrasound generation. (B) Signup and view all the answers

Phonophoresis refers to what application of ultrasound?

Therapeutic application of ultrasound. (C) Signup and view all the answers

What does the Weber-Fechner law describe?

A logarithmic relationship between sound intensity and perception of loudness (B) Signup and view all the answers

How is the acoustic impedance Z of a substance defined?

The density and the speed of sound (B) Signup and view all the answers

Which medium does infrasound NOT propagate through?

Vacuum. (D) Signup and view all the answers

Which property of sound is quantified in decibels (dB)?

Intensity level (C) Signup and view all the answers

If the period of a wave is 0.02 s, what is its frequency?

200 Hz (C) Signup and view all the answers

What is necessary to prevent backflow of substances from dialysate solution into the blood?

A semipermeable membrane (B) Signup and view all the answers

What is the effect of having a hypertonic dialysate solution during hemodialysis?

It can have negative effects on the dialysis (A) Signup and view all the answers

Which of the following best describes osmosis?

Movement of solvent into a region of higher solute concentration (D) Signup and view all the answers

Which is absolutely necessary for osmosis to occur?

Water (B) Signup and view all the answers

What happens to a semiconductor at absolute zero temperature?

It exhibits superconductivity (C) Signup and view all the answers

According to Band Theory of Solids, what relationship exists between band-gap width and conductivity?

Greater band-gap width results in lower conductivity (D) Signup and view all the answers

In terms of conductivity, where do P-type and N-type conductivities exist?

P-type in the valence band, N-type in the conduction band (A) Signup and view all the answers

What are the respective charge carriers in N-type and P-type conductivity?

P-type carriers are holes, N-type are electrons (C) Signup and view all the answers

What fraction of its period (T) does an alternating current take to reach from zero to half of its amplitude?

1/12 T (D) Signup and view all the answers

What are the electric current carriers in metals?

Electrons (A) Signup and view all the answers

To satisfy the photoelectric effect, which inequality must the wavelength (λ) of the incident light meet?

λ ≤ hc/ɸ (C) Signup and view all the answers

Electric current is measured in units of amps (A), which represent what rate of change?

Charge per time, Q/t (B) Signup and view all the answers

What characteristic does alternating current (AC) have?

Changes direction with time (B) Signup and view all the answers

Which pair correctly represents the axes measured by an oscilloscope?

Voltage (input) vs Time (reference) (B) Signup and view all the answers

What happens to the current (DC) in a metallic conductor if the voltage is doubled?

It will double (A) Signup and view all the answers

Ohm's Law states how the electric current relates to applied voltage and resistance. What is the correct formula?

I = V/R (D) Signup and view all the answers

Study Notes

Audiogram and Sound

An audiogram is a diagnostic tool for the hearing apparatus
Sound amplification in the outer ear (auditory canal) is affected by sound speed, sound pressure, and sound amplitude
Prolonged exposure to loud noise can damage the air conductivity, eardrum (tympanic membrane), and inner ear.
Stiffening of the tympanic membrane leads to a decrease in hearing threshold and reduced binaural effect.
Sound intensity level (dB) and loudness (phones) are equal at 1000 Hz (refer to equal-loudness graph)
A perceived louder sound at 4000Hz than at 1000Hz, according to the equal loudness curve

Sound Intensity Level

Sound Intensity Level (SIL) is proportional to the logarithm of the ratio of incoming to threshold intensity
An increase in intensity by a factor of 100 results in a 20 dB increase in SIL

Sound Properties

Frequency is a physical property of sound, measured in Hertz (Hz)
Intensity is a physical property of sound, measured in decibels (dB), which represents the loudness
The fundamental harmonic (fo) in a complex sound is characterized by the lowest frequency and highest amplitude.
The speed of sound is calculated using the Newton-Laplace formula.

Speed of Sound in Air

The speed of sound in air is approximately 330 m/s

Sound Absorption

Sound absorption depends on the wavelength. Longer wavelengths are absorbed less, and penetrate deeper.

Sound in Internal Organs

Internal organs can generate sounds audible at the skin.

Noise

Noise is characterized as superposition of random, constantly changing frequency and amplitude sounds.

Damping Oscillations

Damping oscillations involve decreasing amplitude.

Sound Intensity in a Room

If the sound intensity level in a room is 20 dB, and a TV produces an additional intensity level of 60 dB, the total intensity in the room is 80 dB.

Psychophysical Properties of Sound

Frequency corresponds to pitch
Intensity corresponds to loudness
Acoustic spectrum corresponds to timbre.

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Description

Test your knowledge on the properties of ultrasound and radiation as they relate to medical technology. This quiz covers topics such as the piezoelectric effect, Doppler ultrasound, and the interaction of radiation with human tissue. Explore your understanding of these critical concepts in medical physics.