Week 3- Ultrasound and Laser, Thermo/Cold Therapy and Short Wave Diathermy Flashcards
ULTRASOUND AND LASER
ULTRASOUND AND LASER
What is ultrasound?
- Therapeutic modality where high-frequency sound waves are transmitted through a wand or probe into the body.
- Sound waves lead to vibrations of the molecules in the body.
Sound waves can be either _______,__________, or ____________.
- reflected
- refracted
- absorbed
What are the 2 main equipment components for ultrasound?
- generator
- applicator
The generator is the “___ ____” of the US device that generates the high-frequency alternating current that is transmitted through the applicator.
“big box”
The applicator is composed of __________ and ___________ crystal in the soundhead.
- soundhead
- piezoelectric
What does the piezoelectric crystal do?
Expansion and compression of the crystal produces the sound waves.
What does the soundhead do?
Acoustic energy from the crystal is conducted to the sound head then through a conductive gel into the skin.
Is the crystal perfectly uniform? What does this lead to?
- No
- Leads to nonuniformity of the intensity of the beam (beam nonuniformity ratio (BNR))
What is spatial peak intensity?
Power of beam at highest point of effective radiating area.
What is spatial average intensity?
total power (watts) across the transducer head (cm²) usually what is recorded for intensity during treatment. (W/cm²)
What is beam non-uniformity ratio?
Ratio of spatial peak intensity and spatial average intensity.
What does a beam non-uniformity ratio of 1:1 mean?
Means the beam is close to uniform throughout.
- What is absorption?
- What is refraction?
- What is Reflection?
Absorption
-When the kinetic energy of movement is absorbed by tissue and transformed into thermal energy.
Refraction
-Ultrasound signal is deflected from a straight path and the angle of deflection is away from the transducer.
Reflection
-Ultrasound waves are deflected towards the transducer.
What are standing waves? What reduces them?
- Standing waves are when reflected waves interact with waves going in and creates more energy.
- This is reduced by keeping the sound head moving.
Intensity is the power of the ultrasonic energy and is expressed as __/____. There are no difinitive guidelines for intensity but continuous (thermal) is typically __-__ W/cm².
- W/cm²
- 0.5-3 W/cm²
What is attenuation in regards to US?
-Reduction of acoustical energy as it passes through soft tissue.
- Do absorption, reflection, and refraction affect attenuation?
- Absorption is highest in tissues of ________ density.
- Reflection of acoustic waves can create ________ waves and thus an increased intensity.
- Yes
- greater
- standing waves
Rate these in order from low attenuation to high attenuation:
- Muscle
- Skin/Tendon
- Bone
- Cartilage
- Blood/Fluids
LOW 1.) Blood/Fluids (3%) 2.) Muscle (24%) 3.) Skin (39%)/Tendon (59%) 4.) Cartilage (68%) 5.) Bone (96%) HIGH
- Frequency is the _______ of waves per second delivered.
- What are the 2 most common frequencies and how deep do they penetrate?
-number
- 3MHz (UP TO 2.5cm DEEP)
- 1MHz (UP TO 5cm DEEP)
3MHz leads to greater heat production in _________ layers due to increase in scatter (________) of sound waves in superficial tissue.
- superficial
- attenuation
1MHz heats _______ layers due to less scatter in superficial tissue, thus more energy able to penetrate deeper.
deep
What is duty cycle (mode) of US?
Fraction of time the US energy is on over one pulsed period (time on + time off)
What are the types of duty cycles (modes)?
- Continuous (thermal)- US is applied at a constant energy level; duty cycle 100%
- Pulsed (nonthermal)- duty cycle range usually 5%-50%.
What are the 3 most common duty cycle mode %’s seen?
20%, 50%, and 100%
Indications for Use of US:
- Modulate _____
- Increase ____________ extensibility
- Reduce muscle ______
- Increase tissue _________
- Increase blood ____
- Facilitate ________
- pain
- connective tissue (CT)
- spasm
- temperature
- flow
- healing
Contraindications for US:
- Impaired ________
- Impaired _________ function
- Absent _________
- Cancer
- Joint cement
- Directly over ________ components
- Over ______ areas (brain, eyes, heart, ear, reproductive organs)
- Pregnancy
- circulation
- cognitive
- sensation
- plastic
- vital
Precautions for US:
- Acute __________
- Open ________ Plates
- Healing ________
- Breast Implants
- inflammation
- epiphyseal
- fracture
What is the intention of thermal (continuous) US?
Increasing tissue temperature through friction (aka vibration) between molecules (1-5cm depth dependent on frequency)
Proposed impacts of thermal US:
- Increased pain _________
- Increased collagen extensibility
- Alteration of nerve conduction velocity
- Increased enzymatic activity
- Increased tissue _________
- threshold
- perfusion
Excessively high temperatures of thermal US may produce sudden strong ache caused by overheating of periosteal tissue (periosteal pain); if occurs reduce __________ or increase treatment ___________.
- intensity
- surface area
Insufficient coupling agent may produce discomfort due to a “hot spot” (periosteal pain) which is uneven distribution of the acoustic energy through the sound head; if occurs add more _________ and ensure ___________ movement.
- coupling
- soundhead
What are the 2 theories for the intention of non-thermal (pulsed) US?
Cavitation
-Alternating compression and expansion of small gas bubbles in tissue fluids due to the mechanical pressure waves of the acoustic waves.
Acoustic Streaming
-Forward movement of fluid and ions along boundaries of cell membranes.
What are the 2 types of cavitation?
Stable Cavitation
-Gas bubbles resonate without tissue damage; may be responsible for diffusional changes in cell membranes.
Unstable Cavitation
-Severe collapse of gas bubbles during compression phase of pulsed US which can results in local tissue damage due to high temperatures.
Application Techniques:
- ) Explain procedure and explain they must tell operator if discomfort or painful.
- ) Select soundhead; should be about __ treatment area; if area to be treated is greater than 2 times the size of the soundhead perform two separate treatments
- ) Cover area or sound head with generous amount of gel medium
- ) Turn on unit and set timer
- ) Set _________ and _______
- ) Place sound head firmly on patient and begin motion in overlapping circles or longitudinal strokes; each motion should cover ½ of previous circle or stroke
- ) Adjust intensity as desired
- ) Begin timer countdown
- ) Treatment ends with timer sounding and shut off unit
- ) Remove soundhead and clean gel from patient
- ½
- frequency and mode
- When is the Immersion Technique US indicated?
- Imemrsion technique is useful for ________ surfaces, _______ or broken integument.
- When criteria for direct contact can not be safely met.
- irregular, sensitive
How is the immersion technique performed?
-Patient area placed in water in plastic containter.
-Immersion of US head in basin and hover 1cm from treatment area.
-Perform same rhythmic movement over area as you would with direct contact.
Remove and dry patient and equipment.
What are some things you would document when performing US?
- Treatment area
- Patient position
- Parameters (frequency, mode, duty cycle, intensity, treatment time, transducer size)
- Outcome measures (pain, tenderness on palpation, tenderness with resisted motion, ROM)
What is phonophoresis?
- Using US sound waves to attempt to deliver medications through skin.
- Very limited/weak evidence of efficacy
