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PA: Ultrasound

Does US have more proof with human or animal studies? Animal
What frequency is US? Anything above 20,000 Hz
Definition of frequency Number of oscillations a molecule undergoes during one second
Definition of hertz measurement of sound waves
What is 1 Hz? 1 cycle/second
What is the wavelength? Distance between two successive peaks in the pressure wave
What is US? Form of acoustic energy requiring a medium when treating human tissue
How does US work? Sound waves "bump" into adjacent molecules, transfer energy and continues
What is the positive pressure phase of US considered? Compression
What is the negative pressure phase of US considered? Dispersion
What is the piezoelectricity? Crystals generate electric voltage when mechanically compressed or expanded
What is the reverse piezoelectric effect? Voltage is applied and the crystal can compress and expand
What type of wave are US waves? Chemical pressure waves
How deep does 1 MHz go? >2cm below skin
How deep does 3 MHz go? 1-2cm
What is the duty cycle? Fraction of time during a single pulse period that the beam of sound is present
What is the intensity? Strength of power or quantity of energy produced by US transducer
What is power measured in? Watts
Is power uniform across an US transducer? No
Wat is the effective radiating area? Actual cross-sectional area of the US beam exiting metal end plate
What is the beam non-uniformity ratio? Ratio between spatial peak intensity and spatial average intensity
What is the lowest acceptable beam non-uniformity ratio? 6:1
What types of waves do gases and liquids have? Longitudinal waves
What direction are gases and liquids to the direction of energy flow? Parallel
What types of waves do solids have? Longitudinal and transverse waves
What direction are solids to the direction of the energy flow? Perpendicular
What are the majority of tissues in the body? Gases and liquids
What is the only tissue to get a transverse wave? Bone
What is acoustic impedence? Materials ability to transmit sound and density of structure of material
If a AI is low, what is the transmission, what does this mean, and what is an example? Low AI = High transmission = material absorbs little sound Ex: Blood
If a AI is high, what is the transmission, what does this mean, and what is an example? High AI = Low transmission = material absorbs more, not letting things through Ex: Bone
When does reflection and refraction occur? When energy is transmitted through materials of differing impedances
What happens with sound waves from subcutaneous tissue to muscle? Some reflection back to subcutaneous tissue
What happens with sound waves from muscle to bone? Way more reflected back to muscle
Which heats up faster, tendons and ligaments or muscle? Tendons and ligaments
Why do tendons and ligaments heat up faster? High collagen content Avascularity
What do animal studies show about wound healing with US? Increased wound healing
When energy strikes at a perpendicular angle the reflection is directly ____ to the tissue Perpendicular
When energy strikes a boundary at a non-perpendicular angle the reflection angle is the ______ as the strike angle Same
What is a standing wave and when does it occur? When reflected wave interacts with waves traveling away from the energy source Occurs when you don't move the head
Definition of attenuation Measure of the decrease in sound energy as the US travels, either by absorption, reflection, or refraction
Which types of tissues absorb US energy the best? Denser tissues with high protein content
How do thermal effects occur during US? Occur due to friction between molecules
Temp increase for metabolic rate 1 degree C
Temp increase to reduce spasm and pain and increase blood flow 2-3 degrees C
Temp increase to increase collagen extensibility 4 degrees C
What is cavitation? Small gas bubbles present in tissue
What part of the body actually have studies that show improvement due to US? Calcific tendonitis of the shoulder
What are deep heat indications for US? Joint contracture Scar tissue Pain Muscle spasm Subacute or chronic soft tissue inflammation
What are indications for US to facilitate healing? Acute injury/inflammation of soft tissue or peripheral nerve Open wounds Fracture
Contraindications of US Region of pacemaker During pregnancy (over area) Over eyes and testes Region of active bleeding or infection Region of a tumor or malignancy Region of DVT Over heart, stellate or cervical ganglia Over epiphyseal plates or growing bones Over spina
Precautions of US Sensation of area being treated Communication or cognitive deficits Poor circulation or vascularity Treatment over plastic or metal implants
What is direct contact coupling? Coupling medium required
What is indirect coupling? Water immersion (1-2cm away)
What is phonophoresis? Use of US to enhance delivery of medication through the skin
Mechanisms of phonophoresis Dilating points of entry (hair follicles, sweat glands) Increasing local circulation Increasing kinetic energy of local cells and the medication itself Increasing cell membrane permeability
Created by: 1185240090
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