ultrasound
Download
Skip this Video
Download Presentation
Ultrasound

Loading in 2 Seconds...

play fullscreen
1 / 23

Ultrasound - PowerPoint PPT Presentation


  • 177 Views
  • Uploaded on

Ultrasound. HEAT 4100 Chapter 7-8 p. 156. Ultrasound - p. 158. Transmission of inaudible sound waves Thermal & non-thermal effects Frequency of US dictates effects (imaging, thermal,etc). Production of Ultrasound - p.159.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Ultrasound' - erek


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
ultrasound

Ultrasound

HEAT 4100

Chapter 7-8

p. 156

ultrasound p 158
Ultrasound -p. 158
  • Transmission of inaudible sound waves
  • Thermal & non-thermal effects
  • Frequency of US dictates effects (imaging, thermal,etc)
production of ultrasound p 159
Production of Ultrasound-p.159
  • AC current passing through a crystal -) vibration of the crystal (piezoelectric effect)
  • High frequencies produced & requires a medium for transmission
  • Figure 6-2, p.272
  • Transmitted acoustic energy
ultrasound transmission p 160
Ultrasound Transmission-p. 160
  • Reflection-Energy is not absorbed due to tissue density; partial vs. complete; i.e.-echo
  • Refraction-Energy is partially absorbed; speed changes dictated by density changes; i.e.-prism
  • Absorption-Acoustic energy converted to kinetic energy (heat); partial vs. complete
physics of ultrasound
Physics of Ultrasound-
  • Law of Grotthus-Draper-p. 101
    • An inverse relationship exists between energy absorbed & energy penetrating the next level
  • Arndt-Schultz Principle--p. 396
    • For energy to affect the tissues, it must be absorbed at a level which stimulates a physiological change; The amount of change is dictated by the level of phys. response
ultrasound parameters p 157 table 7 1
Ultrasound Parameters—p. 157; Table 7-1
  • BNR--Beam nonuniformity ratio—
    • consistency of the US output;
    • Greater than 8:1 is unsafe
    • FDA mandates that BNR be given on the US unit
    • 3:1 @ 2 W = US occasionally reaches 6W (keep sound head moving!)—Fig. 7-6, p. 171

Duty Cycle--on/off cycles

    • 100%= continuous output (thermal)
    • lower duty cycle= lower thermal effects
ultrasound parameters p 159
Ultrasound Parameters--p. 159
  • ERA--effective radiating area
    • amount of sound head which actually emits sound waves
    • Measured in square cm.
  • Frequency–number of waves occurring in 1 sec.
    • output which dictates tissue penetration
    • 1 MHz = 5 cm depth of penetration
    • 3MHz= 2cm penetration
    • Higher frequencies are absorbed more rapidly
power intensity p 162
Power & Intensity –p. 162
  • Measured in Watts or Watts/Cm2
  • Describes the amount of energy produced at the transducer
  • Half-layer value—depth at which 50% of the US energy has been absorbed
  • Total energy produced and passed into the tissues increases with ERA
  • W/cm2 used to indicated power as a product of ERA
treatment duration p 280
Treatment Duration—p. 280
  • Duration dictated by:
    • Desired effect (thermal vs. nonthermal)
    • Intensity (greater intensity = lower duration)
    • Size of area treated (greater area = longer duration)
  • Treatment area should only be 2x-3x the size of the US transducer head
    • Use multiple tx’s if area is too large
    • 10-12 min. tx’s are common with 1 MHz
  • Table 7-5, p. 167; Table 8-3, p. 179
effects of us on blood flow p 169
Effects of US on Blood Flow—p. 169
  • Continuous US may increase blood flow for 45 min.
  • US promotes vasodilation
  • Combine with thermal modalities?
effects of us on tissue healing p 169
Effects of US on Tissue Healing–p. 169
  • Accelerates the inflammatory stage
  • Promotes cell division in proliferation stage
  • Enhances fibroblast formation in high-collagen tissues (muscles/tendons)
  • Enhances collagen deposition in superficial wounds (1 MHz)
effects of us on tissue elasticity p 169
Effects of US on Tissue Elasticity—p. 169
  • Combine US with ROM exercises
  • Collagen becomes more elastic with US
  • Target temp = 5°C elevation
  • “Stretching Window” longer with 1 MHz
    • Place tissues on stretch during the tx
    • Stretch immediately after tx
    • Shorter window and shorter duration of effects with 3 MHz
effects of us on pain control p 169
Effects of US on Pain Control—p. 169
  • Nerve transmission altered through increased permeability of Na+ (elevates pain threshold)
  • Thermal US Counterirritant effect
  • Decreased spasm & Increased relaxation  decreased pain
phonophoresis p 170
Phonophoresis—p. 170
  • Introduction of medication into tissues
  • Transmission Factors: Table 6-8,p. 293
  • Thermal effects dilate points of entry
  • Nonthermal effects enhance diffusion rates
  • Preheating the area increases absorption
  • Greatest limitation: transmission medium
  • Cover remaining med with occlusive dressing to complete absorption
  • Common Meds:Table 7-7, p. 171
us and e stim combo p 180
US and E-stim (Combo)—p. 180
  • Concurrent US and ES treatment
  • US head becomes the active stim electrode
  • Benefits of both modalities with shorter tx duration
  • Commonly used to decrease spasm and trigger point sensitivity
modes of us application p 166
Modes of US Application—p. 166
  • Continuous—
    • Thermal effects
    • Penetration up to 5 cm
  • Pulsed—
    • Primarily Nonthermal effects
    • Decreased penetration of US
  • Table 7-4, p. 166
coupling agents p 175
Coupling Agents—p. 175
  • Direct Coupling—p. 175
  • Water Immersion—p. 176
  • Bladder Method—p. 177
direct coupling p 175
Direct Coupling—p. 175
  • Traditional method
  • Applied directly to skin
  • Blocks air and maintains contact of transducer with skin
  • Works best with broad flat surfaces
  • Maintain .44- 1.32 pounds of pressure
  • Faster speed decreases thermal effects
  • Table 8-1, p. 176
water immersion p 176
Water Immersion—p. 176
  • Most effective in treating irregularly shaped areas
  • Body part and transducer are immersed in water
  • Transducer does not touch skin (approx. 1” away)
  • Decreases thermal effects because of dispersion of sound waves
  • “Echo Chamber” effect
  • Fig. 8-4, p. 177
bladder method p 177
Bladder Method—p. 177
  • Water-filled balloon or plastic bag coated with US gel
  • Better transmission to irregularly shaped areas
  • Avoid air pockets in the bladder
  • Fig. 8-5, p. 178
biophysical effects of nonthermal us p 166
Biophysical Effects of Nonthermal US—p. 166
  • Table 7-46, p. 166
  • Reduces edema
    • Increases cell membrane permeability
    • Increases diffusion rates across the cell membrane
    • Stimulation of phagocytosis
  • Stimulates collagen synthesis
  • Stimulates protein synthesis
  • Forms stronger connective tissues
biophysical effects of thermal us p 166
Biophysical Effects of Thermal US—p. 166
  • Thermal effects dictated by tx duration, intensity, and duty cycle
  • Thermal of effects of 1MHz treatment are more superficial, but longer lasting
  • Maintain elevated tissue temp for 3-5 minutes
  • Thermal effects greatest in hydrated tissues
  • Nonvascular tissues warm faster
  • Reflection/refraction may lead to greater temperature increases
summary
Summary
  • Thermal & Nonthermal modality
  • Penetration dictated by frequency (1MHZ vs. 3 MHz)
  • Phonophoresis
  • Combo treatment
ad