Lecture 5 - Ultrasound Continued Flashcards
List coupling agents
Gel Petroleum based creams Water based lotions Immersion in Water –¼ inch to ½ inch from treatment area Temperature of Coupling Agent Phonophoresis
What is phonophoresis?
Processes by which we administer topical medication directly to the lesion site
- sometimes people cant take pills orally due to contraindication, same for injection so this is an alternative
Why do you think phonophoresis gets medication to the area faster?
-the whole idea is to bypass the bodies digestive process
How do you think phonophoresis works?
Driving medication directly through the tissue
What is one thing that limits phonophoresis effectiveness?
- limited by the frequency of the sound head your using with regard to depth of penetration
What do you feel during each application to the quadriceps?
Continuous - Gentle warming
In general don’t feel a whole lot other then gentle heating
The patient will likely feel nothing and you will need to be able to explain why
What is Half –Value, Half Layer Rate
Frequency dependent
Always want to target 50% with regard to depth of lesion
why would you not want to target a lesion deeper then half value layer?
- Not very effective - when you calculate chosen intensity calculate it based upon depth you can reach with a particular frequency
the higher the frequency the less ____ of penetration
depth
What is the penetration depth according to Starkey for 1MHz and 3MHz
1.5cm to 2cm with a 3Mhz with a 1MHz head 5cm - that is the max or half value distance as referenced in starkey
What does ERA stand for?
Effective radiating area (The amount of head that actually emulates the sound wave
Recognize ERA and actual size of the head are not the same
Why is ERA important?
Dictates how large of a lesion you can treat - which is 2x the size of the ERA
What is BNR?
Mass produced crystals will always have microimperfections and these imperfections will cause random peaks in the sound waves
What ratio of BNR is the limit?
8:1
elsa personally wouldnt use it beyond a ratio of 6:1
What does a BNR of 8:1 mean?
8:1 means 8 times the normal intensity
EXAM Q: What is Elsa and Starkey’s limit for BNR?
6:1
Ultrasound is used as one part of the rehabilitation process before exercising because….
- Thermal effects: increase tissue temperature
- Allows tissue to stretch easier, gaining increase in rang of motion priming well for exercise - Mechanical effects: even non-thermal effects break up waste products increasing cell diffusion and easily dissipated with subsequent exercise
- The waste products is causing some of the limitation in ROM
- Increased ROM will prime the patient for exercise
What must you know prior to ultrasound application?
Physiological effects
Therapeutic effects
Needs of the injured tissue
Why must you know the needs of the injured tissue prior to ultrasound application?
Heat in general and ultrasound respond to different type of tissues in different ways so knowing the type of tissue that is injured will help you get to where you want to go
What must you find out to determine dosage for ultrasound?
- Establish stage of healing
- Depth of the lesion
- Damage to tissue
The goals of the treatment and the ____ of the ultrasound must align
Dosage
- first and foremost determine aims of treatment
Increased frequency = ____ wavelength
Decreased
Increased frequency = ____ in height of waves
Decreased
Increased frequency = ____ tissue depth of penetration
Decreased
Increased frequency means the beam is more ____
Collimating (Parallel in nature)
Increase frequency = _____ absorption
Increase
Most important point is thermal and mechanical effects occur with _____ and no thermal effects, mechanical only with _____
Continuous
Pulsed
Describe continuous ultrasound
Continuous waves
Thermal effects
- Pressure changes
- Amplitude
- Micromassage
- Acoustic streaming
Describe pulsed ultrasound
Interrupted waves (bursts)
1:5 = 1/5 on and 4/5 off
% = 20% duty cycle
Non-thermal effects only
- Pressure changes
- Amplitude
- Micromassage
- Acoustic streaming
How much heat will 20% duty cycle generate?
None
How much heat will 50% duty cycle generate
A little
T/F increased duty cycle means more heat Ex. 80% produces more heat then 30%
True
When would you use pulsed ultrasound?
If you still have inflammation, if heating the area causes pain, if all you want to do is generate mechanical effects - for examples in a post-op fracture… you can use to break up scar tissue
Why would you not want to ultrasound a 7 day old fracture?
You would not want to disrupt a fracture in the early stage of healing. Once the fracture is stable.
- new research that pulse ultrasound speeds up rate of healing
- you have to look at parameters of the modality. dosages in and around the 0.01 - 0.03 w/cm squared were used in study. our machines at sheridan only go as low as 0.1 w/cm squared.
What should you ensure before using ultrasound on a fracture?
you want to make sure there is no risk of shock and that the fracture is stable - so it could be used relatively quickly (such as day 3)
What is attenuation with regard to ultrasound?
Attenuation: decrease in the US energy as a result of: Reflection Refraction Absorption Transmission
As wave is transmitted through the various tissues, there will be a _______ (or an attenuation) in energy intensity.
decrease
Attenuation occurs due to absorption or dispersion and scattering of the sound waves as a result of _____ or _____
reflection or refraction
Attenuation results in reduction of one-half its previous intensity in a certain distance (called ______)
“half-value distance” or HVD
Capability of the energy to penetrate to deeper tissues is determined by the _____ of the ultrasound as well as the _______ of the tissue through which it is traveling
Frequency.
Characteristics
Attenuation is ____ and ____ dependent
Frequency and tissue dependent
Absorption takes place at a _____ level
molecular
The greater the collagen content the greater the ______
absorption
Inverse relationship between absorption and ______
penetration
There is an increase in absorption with an increase in _______ –less energy is transmitted to the deeper tissue
frequency
fat does not absorb as much as we work our way ______
deeper
______ in nerve tissue will absorb a fair amount of energy - so need to be cautious
proteins
You will get better absorption with a (higher/lower)______ frequency - so better with _mhz rather then _mhz
higher. so better with a 3mhz rather then 1mhz
Ultrasound: List 4 properties that have the greatest amount of absorption
Ligaments
Cell membranes
Joint capsules
Highly collagenous tendons
every substance every bit of tissue has within itself acoustic impedence - it is this impedence that is going to change the ultrasound and reduce the _____ it carries through
energy
everytime you go through a different ____ you will get some sort of attenuation
interface
Amount reflected and amount transmitted is determined by the ________ of the two materials on either side of the interface
acoustic impedances