Ultrasound (Part 1)

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You got 18 of 30 possible points.

Your score: 60%

Question

With regards to ultrasound waves: Wave properties predominate.

These include properties such as diffraction and interference.

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These include properties such as diffraction and interference.

Question

With regards to ultrasound waves: Velocity in a given material is dependent on the wave frequency.

Velocity is a constant in a given material and is independent of frequency and wavelength

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Velocity is a constant in a given material and is independent of frequency and wavelength

Question

With regards to ultrasound waves: Increased material density results in reduced ultrasound wave velocity.

(For a detailed explanation, please refer to Farr's Physics for Medical Imaging, 2nd Edition)

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(For a detailed explanation, please refer to Farr's Physics for Medical Imaging, 2nd Edition)

Question

With regards to ultrasound waves: Increased material compressibility results in increased velocity.

Increasing compressibility of a material results in reducing velocity

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Increasing compressibility of a material results in reducing velocity

Question

With regards to ultrasound waves: Velocity is independent of temperature.

As temperature affects compressibility

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As temperature affects compressibility

Question

With regards to ultrasound: The intensity is measured in MHz.

Watts per square mm

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Watts per square mm

Question

With regards to ultrasound: Intensity of ultrasound is proportional to the square of the wave amplitude.

(For a detailed explanation, please refer to Farr's Physics for Medical Imaging, 2nd Edition)

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(For a detailed explanation, please refer to Farr's Physics for Medical Imaging, 2nd Edition)

Question

With regards to ultrasound: Transducers lose their piezoelectric properties when heated above to its Curie temperature.

This is about 350 degrees for lead zirconate titanate (PZT)

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This is about 350 degrees for lead zirconate titanate (PZT)

Question

With regards to ultrasound: If 2 sounds waves travelling in the same direction are slightly out of step they form a wave with partially increased amplitude.

This will result in a wave of reduced intensity (destructive interference)

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This will result in a wave of reduced intensity (destructive interference)

Question

With regards to ultrasound: The highest transducer output is produced when it vibrates to produce a wavelength twice the thickness of the piezoelectric disc.

This is the resonant frequency. Waves reflect off the back face and combine (constructive interference)

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This is the resonant frequency. Waves reflect off the back face and combine (constructive interference)

Question

With regards to ultrasound: A low mechanical coefficient (Q) means that ultrasound waves continue for a relatively short time period.

A larger Q means there is longer ringing. This can be remembered by the fact that a capital Q looks a bit like a ring and the larger the Q the longer the ring.

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A larger Q means there is longer ringing. This can be remembered by the fact that a capital Q looks a bit like a ring and the larger the Q the longer the ring.

Question

When using a single transducer probe: Continuous mode produces a single frequency.

(For a detailed explanation, please refer to Farr's Physics for Medical Imaging, 2nd Edition)

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(For a detailed explanation, please refer to Farr's Physics for Medical Imaging, 2nd Edition)

Question

When using a single transducer probe: Short pulses have a narrower bandwidth of frequencies compared with longer pulses.

Short pulses have a wider bandwidth of frequencies

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Short pulses have a wider bandwidth of frequencies

Question

When using a single transducer probe: Greater mechanical coefficient (Q) results in narrower bandwidth.

As larger Q means longer ringing, a longer Q can almost be thought of as a longer pulse which as we have already seen produces a purer not and a narrower bandwidth

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As larger Q means longer ringing, a longer Q can almost be thought of as a longer pulse which as we have already seen produces a purer not and a narrower bandwidth

Question

When using a single transducer probe: A transducer with a low mechanical coefficient (Q) responds to a greater range of frequencies than a transducer with a high Q.

See (c)

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See (c)

Question

When using a single transducer probe: A transducer with a low Q produces a purer note than a transducer with a high Q.

A transducer with a high Q produces a purer note

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A transducer with a high Q produces a purer note

Question

With a single transducer probe: A transducer diameter of less than one wavelength will produce ultrasound waves in all directions.

(For a detailed explanation, please refer to Farr's Physics for Medical Imaging, 2nd Edition)

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(For a detailed explanation, please refer to Farr's Physics for Medical Imaging, 2nd Edition)

Question

With a single transducer probe: A transducer with a diameter greater than one wavelength produces a directional beam roughly the same diameter as the transducer .

(For a detailed explanation, please refer to Farr's Physics for Medical Imaging, 2nd Edition)

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(For a detailed explanation, please refer to Farr's Physics for Medical Imaging, 2nd Edition)

Question

With a single transducer probe: The Fresnel region describes the far field.

The Fresnel region refers to the near field

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The Fresnel region refers to the near field

Question

With a single transducer probe: The length of the near field is proportional to the cube of the transducer diameter.

The near field is proportional to the frequency X diameter2 (or diameter2/4 X wavelength)

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The near field is proportional to the frequency X diameter2 (or diameter2/4 X wavelength)

Question

With a single transducer probe: The Fraunhofer region refers to the far field.

(For a detailed explanation, please refer to Farr's Physics for Medical Imaging, 2nd Edition)

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(For a detailed explanation, please refer to Farr's Physics for Medical Imaging, 2nd Edition)

Question

In Ultrasound with a single transducer probe: Using a higher frequency increases the far field divergence angle.

Using a high frequency reduces the far field divergence angle.

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Using a high frequency reduces the far field divergence angle.

Question

In Ultrasound with a single transducer probe: Using a higher frequency increases the length of the near zone.

(For a detailed explanation, please refer to Farr's Physics for Medical Imaging, 2nd Edition)

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(For a detailed explanation, please refer to Farr's Physics for Medical Imaging, 2nd Edition)

Question

In Ultrasound with a single transducer probe: Side lobes are a result of divergence of the main beam.

Side lobes are a result of vibration of the transducer edges which produce low intensity beams outside the main beam

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Side lobes are a result of vibration of the transducer edges which produce low intensity beams outside the main beam

Question

In Ultrasound with a single transducer probe: Focusing of the beam improves lateral resolution in the focussed region.

To due stronger echoes. Lateral resolution is the ability to distinguish between two structure side by side at the same depth

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To due stronger echoes. Lateral resolution is the ability to distinguish between two structure side by side at the same depth

Question

In Ultrasound with a single transducer probe: The greater concave curvature of the transducer the longer the focal length.

The focal length being the distance from the transducer to the region of strongest focus. Greater curvature results in a shorter focal length. You can imagine that the edges of a steeply curved transducer point to a focus that is close to the probe whereas the edges of a mildly concave transducer point to a focus further in the distance.

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The focal length being the distance from the transducer to the region of strongest focus. Greater curvature results in a shorter focal length. You can imagine that the edges of a steeply curved transducer point to a focus that is close to the probe whereas the edges of a mildly concave transducer point to a focus further in the distance.

Question

In ultrasound: When using an annular array for electronic focussing, a greater time delay between energising annular rings results in shorter focal length.

Taken to its extreme, for a focal length of just greater than 0, the time delay would need to be long enough for the ultrasound wave produced on the outer element to reach a point just in front of the centre of the transducer. This would mean that ultrasound waves produced from inner element rings would reinforce the initial wave almost immediately after they leave the probe.

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Taken to its extreme, for a focal length of just greater than 0, the time delay would need to be long enough for the ultrasound wave produced on the outer element to reach a point just in front of the centre of the transducer. This would mean that ultrasound waves produced from inner element rings would reinforce the initial wave almost immediately after they leave the probe.

Question

In ultrasound: A shorter focal length means there will be less divergence in the far field.

A shorter focal length means there will be more divergence in the far field.

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A shorter focal length means there will be more divergence in the far field.

Question

In ultrasound: A shorter focal length results in a shorter focal region.

(For a detailed explanation, please refer to Farr's Physics for Medical Imaging, 2nd Edition)

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(For a detailed explanation, please refer to Farr's Physics for Medical Imaging, 2nd Edition)

Question

In ultrasound: The velocity of ultrasound in average soft tissue is 1540 cm/s.

It is 1540 m/s

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It is 1540 m/s

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