Chapter 5

Question 1

As the transducer emits pulses, it causes _

Answer 1

large fluctuations of intensity in the region through which the pulses move.

Question 2

Each pulse consists of multiple cycles that produce _

Answer 2

intensity variations within the pulse itself.

Question 3

Intensity is the ultrasound beam’s _

Answer 3

power divided by area

Question 4

Five key words are related to the intensities of pulsed waves:

Answer 4

• Spatial
• Peak
• Average
• Temporal
• Pulsed

Question 5

Spatial refers to

Answer 5

Distance or space

Question 6

Does an ultrasound beam have the same intensity at different locations within the beam?

Answer 6

No

Question 7

Temporal refers to

Answer 7

all time, transmit and receive.

Question 8

Does a pulsed ultrasound beam have to same intensity at different time?

Answer 8

No

Question 9

Peak refers to

Answer 9

The maximum value

Question 10

Average refers to

Answer 10

The mathematical middle value

Question 11

Pulsed refers to

Answer 11

only to the transmit time (pulse duration)

Question 12

Does a pulsed ultrasound beam have the same intensity at different times during the pulse.

Answer 12

No

Question 13

Pulsed average is the _

Answer 13

average intensity for the pulse duration only (ignoring listening time)

Question 14

MEASURING AND REPORTING SOUND BEAM INTENSITY:

The strength of a sound beam varies depending on _

Answer 14

the measurement point within the beam.

Question 15

MEASURING AND REPORTING SOUND BEAM INTENSITY: Intensity also varies over time in pulsed ultrasound depending on

Answer 15

whether the system is transmitting or receiving.

Question 16

SPATIAL CONSIDERATIONS: The intensity of a sound beam varies depending on

Answer 16

the location of the measurement

Question 17

The beam’s intensity at the location where it is maximum.

Answer 17

Spatial peak intensity (Isp)

Question 18

the average intensity across the beam’s entire cross-sectional area.

Answer 18

Spatial average intensity (Isa)

Question 19

TEMPORAL CONSIDERATIONS: In addition to location within the beam, sound wave intensities also vary

Answer 19

Over time

Question 20

There are _ different methods of measuring intensity in pulsed ultrasound.

Answer 20

4

Question 21

The intensity of the beam at the instant in time of its maximal value.

Answer 21

Temporal peak intensity (Itp)

Question 22

The time-averaged intensity over the largest half-cycle in the pulse at the spatial peak.

Answer 22

Maximum Intensity (Imor Imax)

Question 23

The average intensity during the pulse duration (the transmit time).

Answer 23

Pulse average intensity (Ipa

Question 24

The average intensity during the entire pulse repetition period (both transmit and receive times).

Answer 24

Temporal average intensity (Ita)

Question 25

Temporal Intensities from largest to smallest:

Answer 25

* Temporal Peak Intensity * Maximum Intensity (Imax) * Pulse Average Intensity * Temporal Average Intensity

Question 26

COMBINING SPATIAL AND TEMPORAL FACTORS: For the study of bioeffects, the intensity characteristics of sound must be described accurately with regard to

Answer 26

Time and space

Question 27

COMBINING SPATIAL AND TEMPORAL FACTORS: Spatial Peak Temporal Peak (Isptp): measured at the location where _

Answer 27

ntensity is maximum and the instant in time when the most powerful part of the pulse passes

Question 28

COMBINING SPATIAL AND TEMPORAL FACTORS: Spatial Peak Pulse Average (Isppa): measured at the location where

Answer 28

ntensity is maximum, averaged over the transmit time (pulse duration)

Question 29

COMBINING SPATIAL AND TEMPORAL FACTORS: Spatial Peak Temporal Average (Ispta): measured at the location where

Answer 29

ntensity is maximum and averaged over all time, both the transmit and receive times.

Question 30

COMBINING SPATIAL AND TEMPORAL FACTORS: Spatial Average Temporal Average (Isata): measured

Answer 30

over the entire cross-sectional area of the sound beam, and over all time.

Question 31

SPTP

Answer 31

Highest peak value | Spatial peak, temopral peak

Question 32

SATP

Answer 32

Spatial average, temporal peak

Question 33

SPTA

Answer 33

Most important for thermal bioeffects | Spatial peak, temporal average

Question 34

SATA

Answer 34

Lowest value | Spatial average, temporal average

Question 35

SPPA

Answer 35

Spatial peak, pulse average

Question 36

SAPA

Answer 36

Spatial average, pulse average