Ultrasound Flashcards
What is the most common DEEP heating modality
Ultrasound
What is the most common heating modality
Moist hot packs
How are sound waves generated in ultra sound
Current passes through a crystal causing it to vibrate and produce a sound
How is duty cycle calculated
Divide the time sound is delivered by the total treatment time
What is the duty cycle for continuous ultrasound
100% duty cycle
what are the common duty cycles for ultrasound
50% and 20%
What is the result of continuous ultrasound
Tissue healing
What type of effects does pulsed ultrasound have
Mechanical/ non-thermal
What is the piezoelectric effect
Mechanical deformation of a crystal causes an electrical current to form
What effect causes the high frequency sound waves produced in ultrasound
Reverse Piezoelectric effect
What two things determine the quality of an ultrasound machine
ERA (effective radiating area)
BNR (beam non uniformity ratio)
Since the Effective Radiating area (ERA) is always smaller than the size of the head, what is the ideal size
Only slightly smaller than the head
What determines BNR (Beam non uniformity ratio)
Amount of variability of the beam
What is the ideal BNR
1:1
What is the acceptable range for BNR
8:1
What does having a lower BNR do
Eliminate hot spots
Allows for higher dosages without discomfort
Allows for greater comfort and safety
What describes the area of the sound head covered by the peak intensity
PAMBNR (Peak area of the Maximum bean non-uniformity ratio)
What does a large PAMBNR indicate
less uniform heating
Other than using ultrasound gel or a pad what else can you use to conduct ultrasound waves
Place the head and the anatomy under water
How far should you keep the ultrasound head from the patient when using underwater ultrasound
0.5cm to 3.0cm
What frequency do you use for superficial tissues
3 MHz
What frequency do you use for deep tissue
1MHz
What tissues absorb ultrasound the most
Higher density (bone, ligament, Cartilage)
Higher protein concentration (muscles)
What causes scattering in ultrasound
When they encounter a boundary between tissues
Where are ultrasound waves reflected
Bone
Where is the highest point of refraction in ultrasound
The point of refraction (ex. where tendon joins bone)
An increase of how many degrees is associated with an increase of metabolic activity
1
An increase of how many degrees is associated with a reduction of muscle spasm, increase in blood flow, reduction of chronic inflammation
2-3
An increase of how many degrees alters viscoelastic properties of collagen
4
How long does it take to increase tissue to 4 degrees C at 3MHz
4-5 min
How long it take to increase tissue to 4 degrees C at 1MHZ
10 min
What should be done to tissues immediately after ultrasound treatment
Manipulation or stretching
What has pulsed ultrasound been shown to do to tissues
Increase cellular activity and tissue healing
What does pulsed ultrasound do at a cellular level
Stimulate fibroblast activity
Increase blood flow
Increase protein association
Unstable cavitation (cause tissue damage) is associated with what type of ultrasound
Low frequency, high intensity (not therapeutic)
What are risks associated with ultrasound
Bony prominence
Epiphyseal plate
How large should the treatment area be for ultrasound
2-3 times the size of the ERA
Never use ultrasound longer than how many minutes
15 min
What is the term used to describe the use of sound energy to drive medication into the tissue
Phonophoresis
What special instrument is used to stimulate fracture healing
Low intensity pulsed Ultrasound
What is noncontact Low-frequency ultrasound used for
(the ultrasound sprays)
Used for wound cleaning and debridment
