Ultra Sound

Question 1

What are the Thermal Effects of US?

Answer 1

Pain relief with anything ending in “itis”, pain relief for neuromas, adhesive scars(loosens bonds, stretch after), affects nerve conduction velocity (helps decrease pain), improves extensibility of the connective tissues by loosening bonds

Question 2

What are the non-thermal effects of US? (less than 20% Duty Cycle)

Answer 2

Cavitation may break down calcium deposits and increase the rate of healing, affects nerve conduction velocity (could change pain perception), phonophoresis drives chemicals through skin via US beam.

Question 3

What are the contraindications of US?

Answer 3

Where heat is not indicated (when using thermal effects), severe cardiac disease, malignancy, sepsis, Hemophiliac pt, Over deep vein thrombosis, over neoplasm (Will grow faster if US), over pregnant belly, over the eyes, over the heart, near a pacemaker, over growth plates

Question 4

What are the precautions for using US?

Answer 4

over healing fracture (.1-.2 watt can improve healing), Over Spinal Cord, Over Metal Implants

Question 5

How far into the skin does 1MHz penetrate? 3MHz?

Answer 5

1MHz - 5cm (2in)

3MHz - 1cm (1/2in)

Question 6

What is a BNR?

Answer 6

BNR (bean nonconformity ratio)
rates the quality of the head, 1:1 is a perfect ratio, sound is equal all of the head. A BNR 6:1 is the minimum acceptable.

Question 7

What is the difference in practice when using an US with a good BNR, compared to using an US with a poor BNR?

Answer 7

The worse the BNR => the faster you must move the head. if BNR is 3 or slower, you can move really slow.

Question 8

What is the difference between continuous, and non continuous US? Why would they be used?

Answer 8

Continuous gives thermal and non-thermal effects. Pulsed US, especially below 10%, gives only non-thermal effects. Typically, if heat is not contraindicated, continuous is used. pulsed may be used to promote healing without heating the area.
10-20% - acute injuries
30-50% - subacute injuries
60-100% - chronic injuries

Question 9

What determines the intensity of the US?

Answer 9

Maximum intensity is typically determined by the pt. tolerance. Typical maximum intensity is 1.5 w/cm^2, but you have to take the BNR into consideration. (poor BNR, that intensity could hurt). Also, if a deep structure that is not near bone needs to be heated, the pt. may safely tolerate intensities above 1.5

Question 10

What should the intensity settings be for an acute injury? Subacute? Chronic?

Answer 10

Acute Injury - .1-.2 w/cm^2
Subacute Injury - .3-.8 w/cm^2
Chronic Injury - .9-1.5 w/cm^2

Question 11

What is the effective radiating area, and how is it applied when using US?

Answer 11

ERA - the area of the sound head which is producing an ultrasonic wave. As a rule of thumb, an 8-10min treatment of US can cover an area twice the area of the sound head. If a larger area is covered, treat in segments, each twice the sound head size.

Question 12

What should the head movement speed be?

Answer 12

1-4 cm/sec for BNR of 3 or less

4 cm/sec for BNR > 3

Question 13

What does the “intensity” of an US beam mean?

Answer 13

Strength of the US beam. It is the rate at which energy is delivered per unit area and is expressed in units of watts per cm squared (typically ranging from .5-3.0). The greater the intensity, the greater resulting temperature elevation.

Question 14

How do you measure intensity?

Answer 14

measuring the total power output (in watts) of the ultrasound applicator and dividing by the area (in cm2) of the applicator face.

Question 15

What is the Duty Cycle?

Answer 15

duration of pulse (time on) - continuous
pulse period (time on + time off) - pulsed wave

Question 16

What is the temporal average intensity of the duty cycle?

Answer 16

The average of the intensity of both the on and off periods. Amount of heating depends on the temporal average intensity.

Question 17

What is the temporal peak intensity of the duty cycle?

Answer 17

The maximum intensity.

Question 18

When would “pulsing” be of benefit?

Answer 18

when the desired effect is due to non-thermal mechanism and when heating is to be minimized (stasis ulcers, acute injury)

Question 19

Attenuation (as applied to US)

Answer 19

decrease of energy contained within a sound beam as it travels through a tissue

Question 20

What are the three processes that occur that effect attenuation?

Answer 20

Reflection, refraction, and absorption.

Question 21

Pt. is a 34 y/o male w/ the inability to flex mp joints of R hand due to a crush injury 6 weeks ago. Please treat with US underwater. BNR - 5:1. 4 ERA. Use Depth of penetration of .5cm, area to be treated as 3cm.

Answer 21

Is this indicated? - Yes
Frequency? 3MHz
Duty Cycle? - continuous
Ultrasound Headspeed, based on a BNR?
Area to be treated?
Treatment time? 
What should your intensity be?

Question 22

pt. is an 18 y/o who sprained her ankle 2 weeks ago. has continued pain and swelling. please treat with US. BNR - 5:1. ERA - 4. Depth of penetration wanted - 3cm. Area - 6cm.

Answer 22

Frequency - 1MHz
Ultrasound head speed? 4cm/s
Duty cycle - 30-50% 
Treatment time? 15min
Intensity?

Question 23

What is the calculation for depth?

Answer 23

Desired +(depth)(Ratio)(desired)

Question 24

What does a BNR of less than 3 indicate?

Answer 24

That the clinician must move the head at a speed of 1cm/s

Question 25

What does a BNR of > 3 indicate?

Answer 25

That the clinician must move the head at a speed of 4cm/s

Question 26

What is the ERA?

Answer 26

Effective Radiating Area. The area of the sound head which is producing the ultrasonic wave. as a rule of thumb, 8-10min can treat 2x the area of the sound head (always multiple the ERA by two!).

Question 27

What are the ratio #’s for the intensity calculations for 3MHz and 1MHz?

Answer 27

.4/cm for 3MHz

.25/cm for 1MHz

Question 28

What does Intensity refer to in regards to ultrasound?

Answer 28

the strength of an ultrasound beam. It is the rate at which energy is delivered per unit area and is expressed in W/cm2

Question 29

What are the non-thermal settings and effects of Ultrasound?

Answer 29

Cavitation (vibrational effect on gas bubbles, pulsation of bubbles cause changes in cellular activity and tissue damage). Causes stretching of cell wall, balloons out, collapses back in, causing nutrients to be absorbed.
Acoustical streaming (Mechanical pressure waves, movement of fluids along the boundries of the cell membranes) pulls on sound walls, opens membranes, allows for nutrients to be absorbed. 
Micro-Massage(increase cell membrane permiability, increase cell activity, increase capillary density, and increased protein synthesis).

Question 30

What is the Duty Cycle?

Answer 30

Produced as a continuous, or pulse wave. Thermal effects are found when the duty cycle is continuous (or at a high pulse). Nonthermal effects are found when pulsed (at a low duty cycle). less than 20% duty cycle provides nonthermal effects.

Question 31

pt is a 35 y/o player with “Tennis Elbow” please administer hydrocorisone with phono. BNR = 5:1 ERA = 4.

Answer 31

Frequency - 3MHz
Head Speed = 4cm/s
Duty Cycle = 30-50% pulsed

Question 32

Why is it important to use a pulsed duty cycle when treating with phonophoresis?

Answer 32

Because using a continuous stream causes the medication to spread into the body via blood. The non-thermal effect would propel the medication into the body via sound waves, and also allow it to pool in the spot specific area it is needed.

Question 33

Pt. is a 45 y/o laborer with cc of LBP (spasms). Treat with US. BNR - 5:1 ERA 4 Depth 3cm Area - 4cm

Answer 33

Frequency - 1MHz
Head Speed - 4cm/s
Duty Cycle - Continuous
intensity - calculation