ultrasound flor

7/31/2019 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

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