Download - Ultrasound Flor
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ULTRASOUND
Prepared By: Floriza P. de Leon, PTRP
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PRODUCTION OF US
Piezoelectric effect
When crystals are subjected to pressure or
tension, they develop electric charges on
opposite crystal surfaces
Reverse piezoelectric effect
Conversion of high frequency alternating voltage
into a mechanical vibration
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CRYSTALS
Ex: quartz, tourmaline, seignettes salt, produceelectric current when they are alternatelycompressed and relaxed in certain directions
Conversely, these crystals will contract underthe influence of an electric current and expandwhen the current is switched off (reversedpiezoelectric effect)
With this continuous change in direction, thecrystal will be made to vibrate and the vibrationsproduce sound waves
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PHYSICAL PHENOMENON OF ULTRASOUND
Bone-periosteum interface
Tissue-air interface
Transducer head-skin interface with anairpocket
refraction
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TISSUE-AIR INTERFACE
Air acts as a reflector and the ultrasound beamis reflected back to the surface of the tissue arebeing treated. Excessive heating will occur,
causing a heating pain in the skin. This occurs if ultrasound is given to a thin area
such as the palm, where ultrasound will gothrough the tissues and then meet the air on the
opposite side Pain will be felt in the area of the skin opposite
the transducer head
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TRANSDUCER HEAD-SKIN INTERFACE WITH AN
AIRPOCKET
If the metal of the ultrasound head and the
tissues are not completely in contact with
one another, and there is a small air pocket,
reflection into the transducer head of themachine will occur, with no acoustic power
going into the patient. Head will be heated
rapidly and cause excessive heating of theskin. There is minimal transmission of
ultrasound and danger of burn
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REFRACTION
Refraction is deviation. It means that the
ultrasonic energy impinges the tissue at one
angle and continues at a different angle
(angle of refraction)(critical angle is 15degrees)
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TRANSMISSION OF US
US beam is homogenous
BNR ratio between peak intensity and
average intensity
Increase frequency
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ABSORPTION OF US
Increase Protein Content
Low-------------------------------------------------------------High
Blood-fat-nerve-,muscle-skin-tendon-cartilage-
bone
Low---------------------------------------------------------
-----High
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PHYSIOLOGICAL EFFECTS OF ULTRASOUND
Thermal effects
Non-thermal effects
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PHYSIOLOGICAL EFFECTS OF ULTRASOUND
1. Cavitation2 types
a. stable
b. transient/collapse
stationary 1-2 W/cm2
moving - >4 W/cm2
2. Acoustic streaming(+) acoustic streaming responsible for reduction of edema
3. Micromassage
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IMPORTANT THINGS TO REMEBER
B fibers most sensitive to US followed by
C. A gamma fibers least sensitive
Protein major absorbers of US
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PHONOPHORESIS VS IONTOPHORESIS
Phonophoresis Iontophoresis
US Direct Current
Substance Transported Whole Molecule IonDepth Penetration 50 mm Skin Deep
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INDICATIONS
Adhesions
Pain and mm spasm
Pain caused by sympathetic dysfunction
Neuralgia/neurons phonophoresis (drugs mostcommonly used: hydrocortisone lasonil andVitamin E)
Traumatic prepatellar neuralgia
Calcified tendinitis
swelling
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CONTRAINDICATIONS
Brain and spinal cord
Eyes
Reproductive organs/abdominal organs Pregnant uterus
Tumors
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DANGER
Burns
Shock
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COUPLING MEDIA
Characteristic of an ideal couplant
High transmissivity
Low absorption
Non-corrosive
Non-irritant to the tissue
Low susceptibility to bubbles
Hygienic dispenser
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DOSAGE
Frequency
1 MHz
3 MHz
Intensity 0.1 3 w/cm2
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ACUTE AND CHRONIC DOSIMETRY
Acute Chronic
Superficial andlocalized
.25 w/cm2 .5 w/cm2
Deep and Diffuse 1.5 w/cm2 2.5 w/cm2
mode pulsed Continuous
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TIME OF INSONATION
Continuous 10 mins
Pulsed 15 mins
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MODES OF APPLICATION
Moving
Stationary
Underwater
Water bag