Intensity Chapter 4

Question 1

What is intensity? Why is it important? What’s an important characteristic about it?

Answer 1

The concentration of the power in a beam. Key parameter for bioeffects. Intensity is not uniform across a sound beam (in space). With pulsed ultrasound, intensity is not uniform throughout time.

Question 2

What does spatial mean?

Answer 2

An ultrasound beam does not have the same intensity at different locations within the beam. More focus = more intense.

Question 3

What does temporal mean?

Answer 3

Pulsed ultrasound does not have the same intensity at different times.

Question 4

What are the 5 key words when it comes to intensity and what do they mean?

Answer 4

1. Peak - max value
2. Average - mean value
3. Spatial - refers to distance or space
4. Temporal - refers to all time (transmit and receive)
5. Pulsed - referring only to the time the pulse exists (transmit only)

Question 5

What are the units of the 6 intensity descriptions? What are these used for?

Answer 5

W/cm squared (intensity). Describe the same wave in different ways.

Question 6

What is SPTP?

Answer 6

Spatial peak, temporal peak HIGHEST VALUE

Question 7

SATP?

Answer 7

Spatial average, temporal peak

Question 8

SPTA?

Answer 8

Spatial peak, temporal average. Most relevant for thermal bioeffects. ***

Question 9

SATA?

Answer 9

Spatial average, temporal average. Lowest value

Question 10

SPPA?

Answer 10

Spatial peak, pulse average

Question 11

SAPA?

Answer 11

Spatial average, pulsed average

Question 12

What are the 3 commandments of intensity?

Answer 12

1. Intensities may be reported in various ways with respect to time and space.
2. Intensity is the key parameter with regard to bioeffects. The different intensities are important in the study of bioeffects. SPTA intensity is the most relevant with respect to tissue heating.
3. peak is greater than average. So, SPTP is the highest and SATA is the lowest.