Therapeutic Ultrasound Intensity and Frequency

Intensity = The power per unit area of the sound head, expressed in watts per centimeter squared Frequency = The number of compression-rarefaction cycles per unit of time, expressed in hertz Effective Radiating Area = The area of the transducer from which the US energy radiates Attenuation = The reduction of US energy as it enters the body due to absorption, reflection, and refraction

Increasing frequency of US = Decreases depth of penetration and concentrates energy in superficial tissues Beam nonuniformity ratio = Describes the uneven distribution of US energy from the transducer Absorption = Accounts for about half of the attenuation of US energy in tissues Attenuation coefficients = Tissue-specific and frequency-specific measures of US energy reduction

Continuous US = Generally used for thermal effects Pulsed US = Used for nonthermal effects and to accelerate treatment goals when applied appropriately

<p>Reflection = The redirection of an incident beam away from a surface at an angle equal and opposite to the angle of incidence ERA always smaller than treatment head area = Due to uneven crystal vibration, the Effective Radiating Area is smaller than the treatment head area</p> Signup and view all the answers

<p>Bone = Piezoelectric material Natural quartz = Piezoelectric material Synthetic pulmbium zirconate titanate (PZT) = Piezoelectric material Barium titanate = Piezoelectric material</p> Signup and view all the answers

<p>Fresnel zone = Convergent region Near Field = Fresnel zone Fraunhofer zone = Divergent region Far Field = Fraunhofer zone</p> Signup and view all the answers

<p>Acceleration of metabolic rate = Thermal effects of US Reduction or control of pain &amp; muscle spasm = Thermal effects of US Alteration of nerve conduction velocity = Thermal effects of US Increased circulation = Thermal effects of US</p> Signup and view all the answers

<p>Tissues with high collagen content = Heated by US more Tissues with high water content = Heated by US less Tendons, ligaments, joint capsules, &amp; fasciae* = Tissues with high collagen content Scar tissue in muscle (increased collagen content) = Tissues with high water content</p> Signup and view all the answers

<p>Frequency = Directly proportional to temperature increase Average intensity = Higher intensity leads to increased temperature Duration of US application = Proportional to the absorption coefficient of tissues being applied to Speed of US transducer = Does not affect temperature increase on tissues</p> Signup and view all the answers