UltraSound Flashcards
What is the typical therapeutic range utilized for Ultrasound?
1 or 3 MHZ
An alternating current is passed through a crystal causing it to vibrate and produce what?
High-Frequency sound waves
Effective Radiating Area (ERA) is what?
The area of the crystal that actually produces sound waves.
*It produces more than 5% of the energy at 5mm from the transducer face.
Beam Profile
Multiple waves emerge from the head.
*Energy diverges as it moves away from the source and is uniform close to the head called “Near Zone”
1 MHz output penetrates how deep?
5-7cm
3 MH Output penetrates how deep?
1-2cm
Heating rate and magnitude is based on what?
- Duty Cycle
- Output Frequency
- Intensity
- Target Tissue
- Size of Treatment area
What are the Thermal effects of Ultrasound?
Increased sensory nerve conduction velocity
-increased motor nerve conduction velocity
-increased extensibilityof collagen rich fibers
increased Blood flow, vascular permeability, increases macrophage activity, Reduces muscle spasm
For mild inflammation and to Accelerate metabolism, you should increase tissue by how many degrees?
1 degree celsius
To help decrease muscle spasms, what temperature should be acquired?
Mild temperature, increasing the tissue 2-3 degrees celsius
For nonthermal application, the pulsed output should be?
20-25% duty cycle
Continuos Output, a 100% duty cycle creates what effect?
A Thermal effect
Accustic Streaming is what?
It is ultrasound that causes interstitial fluids to flow, striking cell membranes, producing EDDY Currents, which displace ions and molecules. This altars cell membrane permeability and Cellular function.
The vibrating crystal is known as what effect?
Electropiezo Effect!
ERA (Effective Radiating Area) is always smaller than the what?
The transducer face
Is energy more concentrated on the outside or near the center for ultrasound?
Near the center.
Spatial Peak Intensity
The spatial peak intensity is the point in the sound field with maximum intensity. Becomes less consistent farther away from the head.
Spatial Average Intensity
Describes the energy per unit of area, AKA W/cm2
*15 watts over 10cm2 ERA = 1.5 W/cm2
This describes the amount of variation in the beam and is the ration between spatial Peak intensity (SPI) and spatial Average intensity?
Beam Nonuniformity Ratio *BNR = SPI / SAI *Perfect beam = 1:1 Minimally acceptable = 8:1 *most units are 5:1 or 6:1
What setting is needed to provide a thermal effect for ultrasound?
Continuous, based on output intensity and treatment duration.
*100% duty cycle
A patient has swelling in the ankle but Ultrasound is still administered, what setting is used?
A pulsed setting to produce Non-thermal effects!
*Usually 20-25% duty cycle
The following effects are due to what?
- increased cell membrane permeability
- Alters cell membrane diffusion rate
- increased histamine release
- Mast cell degranulation and increased rate of protein synthesis
Acoustical Streaming
Thermal effects on cellular response from US include?
Increased cell metabolism and rate of inflammation
The thermal effect from US may lead to an earlier onset of proliferation, increase macrophage activity, lead leukocytes to bind to damaged endothelial cells, and increase cell division, helping through which phase?
Inflammation
