Flashcards in Ultrasound Deck (48)
Define Transducer (sound head)
A crystal/part of ultrasound unti that contains crystal that converts electrical energy into sound
Amount of acoustic energy per unit time. Expressed in Watts (W)
Power per unit area of the sound head. Expressed in Watts/centimeter squared (W/cm2)
Application of ultrasound with a topical drug to facilitate transdermal drug delivery
What are some clinical applications of ultrasound?
Soft tissue shortening, pain control, dermal ulcers, surgical skin incisions, tendon injuries, resorption of calcium deposits, bone fractures, carpal tunnel syndrome, phonophoresis, plantar warts, herpes zoster infection
List the contraindications for US
Malignant tumor, pregnancy, CNS tissue, joint cement, plastic components, pacemaker, thrombophlebitis, eyes, reproductive organs
What the precautions for US?
Acute inflammations, epiphyseal plates, fractures, breast implants
Conversion of the mechanical energy of ultrasound into heat
Number of compression-rarefaction cycles per unit of time
Increasing the frequency of the US causes a(n) (increase/decrease) in its depth of penetration & concentration of the US energy in the tissue
Define Duty Cycle
The proportion of the total treatment time that the US is on
What is the difference between 20% and 100% duty cycle?
20% duty cycle means the US is on 20% & off 80% for the treatment time
100% duty cycle is continuous & is on the entire treatment time (100%)
Sound with a frequency greater than 20,000 cycles per second that, when applied to the body, has thermal and non thermal effects. (pg 201)
Produced only non-thermal effects, has been shown to facilitate tissue healing, modify inflammation and enhance transdermal drug deliver (pg177)
A non-thermal effect of ultrasound. The stead, circular flow of cellular fluids induced by ultrasound. This flow is larger in scale than with micro streaming and is thought to alter cellular activity by transporting material from one part of the ultrasound field to another. (pg178 & 199)
A non-thermal effect of ultrasound. Microscope eddying (circular movement of water counter to that of the main current) that takes place near any small, vibrating object. Micro streaming occurs around the gas bubbles set into oscillation by cavitation.
A non-thermal effect of ultrasound. The formation, growth and pulsation of gas-filled bubbles caused by ultrasound. During the compression phase of an US wave, bubbles present in the tissue are made smaller, and during the rarefaction phase, they expand. Cavitation may be stable or unstable.
List some types of tissues that are heated by ultrasound?
Tendons, Ligaments, Joint Capsule, and Fasciae.
Therapeutic ultrasound has a frequency of?
Between 0.7 and 3.3 megahertz (MHz)
What is the depth in the soft tissue at which ultrasound is absorbed at?
2 to 5 cm
True or False? Ultrasound generally heats smaller, deeper areas than superficial heating agents.
What is considered the best frequency for heating tissues?
During an ultrasound what helps keep hot spots from forming?
Continuous movement of the sound head throughout application.
What was the first large scale application or ultrasound?
Sound navigation during World War II
The types of tissue heated by ultra sound have a high content of what?
What are the two types of ultrasound used clinically?
Attenuation is the combination of what three things?
Absorption, Reflection, and Refraction.
True or False? The effect of ultrasound on the healing of surgical skin incisions has been demonstrated to be beneficial?
It is recommended that ultrasound be applied in a pulse mode at a low or high intensity during the acute phase of tendon inflammation?