Ultrasound

Question 1

Superficial ultrasound

Answer 1

Depth: 1-2 cm
Target tissue: skin and subcutaneous tissues

Modalities used: HP, paraffin, fluido, hydrotherapy.

Question 2

Deep ultrasound

Answer 2

Depth: 2-5cm
Target tissue: deeper subcutaneous tissues and superficial musculature

Modalities: US, diathermy

Question 3

Piezoelectric effect

Answer 3

The transducer converts the electrical current into a mechanical vibration via this effect. When alternating current is applied across a crystal, the shape of the crystal changes with each change in current direction.

Question 4

Absorption

Answer 4

To take something in like sponges take in water. Highest amount of absorption in tendons, ligaments, fascia, joint capsules and scar tissue.

Question 5

Penetration

Answer 5

Pass through, like a diver diving into water.

Question 6

Attenuation

Answer 6

A measure of the decrease in sound energy as a sound wave travels. Either by absorption,reflection or refraction.

Question 7

Reflection

Answer 7

Reflection of an incident beam away from a reflecting surface at an angle equal and opposite the angle of incidence.

Question 8

Standing wave

Answer 8

When a reflected wave travels back though it’s original path, both waves can become in phase. The energies from both waves are combined creating an area of more intense energy in that area producing tissue damage.
Keep the sound head moving over RX area!

Question 9

Refraction

Answer 9

Bending of waves as they pass from one medium to another.

Keep sound head perpendicular to RX area.

Question 10

Beam Non uniformity Ratio (BNR)

Answer 10

The ratio between spatial peak intensity of US output and spatial average intensity of an US beam.
good BNR: 1:1-5:1
Poor BNR : 6:1 and greater

Question 11

Effective radiating area ERA

Answer 11

Measure of the actual cross sectional area of the US beam as it exits the metal end plate of the transducer.
Do. It sound areas greater then 2x ERA

Question 12

Duty factor

Answer 12

It is the fraction of time during a single pulse period that the US is present.
Selected based on RX goal ( heating or healing tissues)

Question 13

Frequency

Answer 13

Frequency is the number of sound oscillations produced in one second.
Superficial: 3 MHz
Deep: 1 MHz

Question 14

Intensity

Answer 14

Intensity is the strength of the US wave acoustic energy at the point of application, expressed in W/cm2.
Selected based on RX goal.(thermal vs non thermal

Question 15

Duration

Answer 15

Duration is the actual time the US is being delivered.

Question 16

Phonophoresis

Answer 16

The use of US to enhance delivery of medication through the skin.
Commonly used medications:
Hydrocortisone, Dexamethasone, Lidocaine.

Parameters:
20% duty factor cycle, .5-.75 w/cm2, 5-10 mins