US Flashcards
1
Q
Ultrasound
A
Use of inaudible acoustic vibrations at high frequency to cause a physiological effect
2
Q
ERA
A
Effective radiating area
- area of transducer from which US energy radiates
- 2x size of the sound head, takes 5-10 minutes
- area should be 1.5 - 4x ERA
3
Q
BNR
A
Beam non-uniformity ratio
- rate of peak intensity to the average intensity (or output)
- usually 2:1 to 6:1
- the amount of energy produced by the sound head is not equal throughout the surface area so there are areas where US is applied that are receiving 5-6x the amount of energy so beacuas eof this, CONSTANT motion is required to prevent “hot spots”
4
Q
Sound head
A
Transducer
- a crystal inside the sound head converts electrical energy into sound by alternately contracting and expanding
- creates a mechanical vibration
- generates US
- requires a transmission medium
5
Q
Physiological effects: thermal
A
- phases of healing: subacute and chronic conditions, later part of proliferation and maturation phases Increases: 1. Tissue temp 2. Collagen extensibility 3. Circulation and nerve conduction 4. Cellular metabolism and enzymatic activity 5. Tissue perfusion 6. Pain threshold
6
Q
Physiological effects: non-thermal
A
- phases of healing: acute and early subacute conditions; inflammation and early proliferation phases
1. No measurable increase in tissue temperature
2. Increases cell permeability and promotes normal cellular funciton
3. Decreases inflammation
7
Q
Thermal US
A
Heats tissues with high collagen content
- ideal target tissues: tendons, ligaments, joint capsules, mm
- soft tissue shortening
- scar tissue
- pain control
- mm spasms and trigger points
- must be performed in conjunction with stretch/ROM program to be effective
8
Q
Non-thermal US
A
- acute and/or post-acute conditions
- inflammation
- delayed soft tissue healing
- dermal ulcers/wound care
- tissue regeneration
9
Q
Contras
A
- Cancer or over irradiated areas
- Pacemaker
- Blood clots
- Preganancy donut
- Active bleeding
- Decreased sensation
- Decreased circulation or vascular insufficiency
- Infection
- Fracture
- Metal
- Never over:
- epiphyseal plate in children
- implants (breast, booty, birth control)
- carotid sinus
- CNS tissue
- reproductive organs, eyes, or heart
10
Q
Questions to ask yourself
A
- tx goals?
- where is pt in healing process?
- specifici tissue issue identified?
- size of area?
- depth of area?
- contras?
11
Q
Frequency
A
Number of complete wave cycles per unit of time
- 1MHz absorption 3-5 cm
- 3MHz absorption 1-2 cm
12
Q
Duty cycle
A
Proportion of the total treatment time the US is on
- continuous: 100% (thermal)
- pulsed: 20% - 50% (non-thermal)
13
Q
Intensity
A
Power per unit area of the sound head; magnitude of force in a sound wave; quantity of energy delivered
- W/cm^2
- therapeutic treatment intensity = 0.5 - 2.5 W/cm^2
14
Q
Thermal intensity
A
- 1 MHz = 1.5 - 2.5 W/cm^2
- 3 MHz = 0.5 - 1.5 W/cm^2
15
Q
Non-thermal intensity
A
- 1 MHz = 0.5 - 1.0 W/cm^2
- 3 MHz = 0.5 - 1.0 W/cm^2
