Intensities Ch 5

Question 1

the beam’s power divided by it’s area

Answer 1

Intensity

Question 2

Five key words related to reporting intensities of pulsed waves

Answer 2

• SPATIAL
• PEAK
• AVERAGE
• TEMPORAL
• PULSED

Question 3

Refers to distance or space,

does not have the same intensity at different locations within the beam

Answer 3

Spatial Intensity

Question 4

Number of possibilities used to measure spatial intensity

Answer 4

Two possiblities, Isp and Isa

Question 5

The beams intensity at the location where it is maximum

Answer 5

Isp (spatial peak intensity)

Question 6

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

Answer 6

Isa (spatial average intensity)

Question 7

Refers to time
*with pulsed ultrasound, the transducer is usually receiving (listening), but for brief moments it is transmitting (talking)

Answer 7

Temporal

Question 8

Number of methods of measuring intensity, pulsed waves

Answer 8

Four methods,
Itp
Imax or Im
Ipa
Ita

Question 9

Intensity of the beam at the instant in time of it’s maximal value

Answer 9

Itp (temporal peak intensity)

Question 10

average intensity during the most intense half cycle

Answer 10

Imax or Im

Question 11

average intensity during -the transmit time — is called

Answer 11

Ipa (pulse average intensity)

Question 12

Averaging the intensity during the entire pulse repetition period—both the transmit and receive times— is called

Answer 12

Ita (temporal average intensity)

Question 13

Measured during transmit time only

Answer 13

Pulse average intensity

Question 14

Measured during both the transmit and receive times

Answer 14

Temporal average

Question 15

The highest temporal intensity is _______ and it is slightly higher than ___________

Answer 15

Itp and it is slightly higher than Imax

Question 16

Is lower than Imax, because it includes values over the entire pulse duration, and the tail end of the pulse is less intense than the beginning

Answer 16

Ipa (pulse average intensity)

Question 17

The lowest of all temporal intensities is ____________ because it is the only method that includes the receive and transmit time

Answer 17

Ita (temporal average intensity)

Question 18

Measured at the location where intensity is maximum, and at the instant in time that the most powerful fart of the pulse passes

Answer 18

Isptp (spatial peak/temporal peak)

Question 19

Measured at the location where intensity is maximum, averaged over the transmit time (pulse duration)

Answer 19

Isppa (spatial peak/pulse average)

Question 20

Measured at the location where intensity is maximum and averaged over all time, both the transmit and receive times

Answer 20

Ispta (spatial peak/temporal average)

Question 21

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

Answer 21

Isata (spatial average/temporal average)

Question 22

Temporal intensities From Largest to Smallest

Answer 22

Itp (temporal peak)
Imax (average of most intense half cycle)
Ipa (pulse average)
Ita (temporal average)

Question 23

All measurements have units of

Answer 23

W/cm^2

Question 24

Six different methods to measure and report intensities. Methods describe the same wave in a variety of ways

Answer 24

SPTP (spatial peak/temporal peak)
SATP (spatial average/temporal peak)
SPTA (spatial peak/ temporal average)
SATA (spatial average/temporal average)
SPPA (spatial peak/pulse average)
SAPA (spatial average/pulse average)

Question 25

No independently confirmed significant bioeffects have been confirmed in mammalian tissue below (medical usage)

Answer 25

100W/cm^2

Question 26

Two bioeffects of ultrasound

Answer 26

Heat and cavitation

Question 27

As sound energy is transmitted through tissue, some energy is reflected and some energy is absorbed as

Answer 27

Heat

Question 28

The formation, growth and dynamic behavior of gas bubbles

Answer 28

Cavitation

Question 29

The peak intensity at the point in space where the intensity is the highest, and that occurs when the ultrasonic emitting device is "on" * It is the highest of the measured intensities

Answer 29

SPTP (spatial peak/ temoporal peak

Question 30

The average power output of the device over the pulse repetition period, divided by a reference, usually that of the transducer face * yields the lowest, and more commonly used measures of intensity - most quickly determined & most frequently quited by manufacturers

Answer 30

SATA (spatial average/ temporal average)

Question 31

The peak intensity over a selected area, such as the transducer face, that occurs when the ultrasonic emitting device is "on"

Answer 31

SATP (spatial average/ temporal peak)

Question 32

The maximum spatial intensity when the sound beam is "on" average over the pulse reptition period

Answer 32

SPTA (spatial peak/ temporal average)

Question 33

The pulse averaged intensity measured at the point in space where the value is maximal

Answer 33

SPPA (spatial peak/ pulse average)

Question 34

The pulse average intensity averaged over the beam cross-sectional area of the sound beam, averaged over the transmit time ( pulse duration)

Answer 34

SAPA (spatial average/ pulse average)