Ultrasound Effects and Thermal Index

As ultrasound frequency increases, the absorption of ultrasound energy by tissues also increases, leading to a greater rise in tissue temperature.

Thermal and mechanical effects.

The extent of temperature increase is influenced by intensity, frequency, exposure duration, and tissue properties like absorption and attenuation.

<p>Fetal and neonatal tissues are less tolerant to temperature increases compared to adult tissues.</p> Signup and view all the answers

<p>The Thermal Index provides an estimate of the maximum temperature increase in tissue during ultrasound exposure.</p> Signup and view all the answers

<p>The three subdivisions are Soft Tissue Thermal Index (TIS), Bone Thermal Index (TIB), and Adult Cranial Exposure Thermal Index (TIC).</p> Signup and view all the answers

<p>Stable cavitation involves bubbles that oscillate in diameter with the sound wave's pressure variations. Transient cavitation involves bubbles that collapse after undergoing large oscillations.</p> Signup and view all the answers

<p>Cavitation, both stable and transient.</p> Signup and view all the answers

<p>TIS is recommended for the first 8 weeks of pregnancy, while TIB should be monitored thereafter.</p> Signup and view all the answers

<p>The estimated maximum temperature increase is 2 degrees Celsius (∆Tmax ≤ 2°C).</p> Signup and view all the answers

<p>Contrast agents are used to increase echogenicity, allowing for better visualization of structures and improved diagnostic accuracy.</p> Signup and view all the answers

<p>A higher MI indicates a greater likelihood of cavitation, which can potentially lead to adverse biological effects.</p> Signup and view all the answers

<p>A focused ultrasound beam concentrates energy within the focal zone, potentially increasing tissue heating in that specific region.</p> Signup and view all the answers

<p>Deeper penetration requires ultrasound waves to travel through more tissue, potentially leading to increased energy absorption and higher tissue heating.</p> Signup and view all the answers

<p>The two main parameters are the pressure amplitude of the ultrasound wave and the duration of the ultrasound pulse.</p> Signup and view all the answers

<p>Higher frequency ultrasound waves are absorbed more readily by tissues, leading to increased local heating.</p> Signup and view all the answers

<p>Spectral Doppler ultrasound uses high-frequency pulses to measure blood flow velocity, which requires a higher output intensity compared to other imaging modes.</p> Signup and view all the answers

<p>If the FOV includes areas with gas-filled structures (such as the gastrointestinal tract), there may be an increased risk of cavitation, potentially increasing the MI.</p> Signup and view all the answers

<p>Cavitation occurs when tiny bubbles form and collapse in fluids due to ultrasound energy. This process can generate localized pressure changes and heat, which can potentially damage tissues.</p> Signup and view all the answers

<p>ALARA stands for 'As Low As Reasonably Achievable'. It's a principle to minimize the risk of ultrasound exposure while still obtaining the necessary diagnostic information.</p> Signup and view all the answers

<p>Contrast agents are composed of microbubbles or particles with a different acoustic impedance compared to the surrounding medium. This difference in impedance causes stronger reflections of ultrasound waves, leading to enhanced echogenicity.</p> Signup and view all the answers

<p>SCE is a process where parts of duplicated chromosomes exchange genetic material. In cell studies, SCE is used as an indicator of potential DNA damage and chromosomal instability after ultrasound exposure.</p> Signup and view all the answers

<p>Plants contain gas-filled channels between cell walls, which are prone to cavitation caused by ultrasound waves.</p> Signup and view all the answers

<p>Two in vivo effects observed in animals exposed to ultrasound are fetal weight reduction and fetal abnormalities.</p> Signup and view all the answers

<p>The study aimed to compare the health outcomes, including Apgar scores, birth weight, and congenital abnormalities, between children exposed to diagnostic ultrasound in utero and those who were not.</p> Signup and view all the answers

<p>Cells studied in suspension or culture environments differ from those in the complex environments of an intact patient.</p> Signup and view all the answers

<p>The phases refer to cycles of low pressure (A and B) and high pressure (C and D) created by ultrasound waves, which cause microscopic bubbles in liquids to expand and contract until they implode (cavitation).</p> Signup and view all the answers

<p>SCE formation is considered an early indicator of chromosomal instability. It suggests that there might be errors in DNA replication or that the process is being inhibited, leading to potential mutations and chromosomal abnormalities.</p> Signup and view all the answers

<p>Plants studies offer insights into the effects of cavitation, a bioeffect of ultrasound, due to the presence of gas-filled channels in plant tissues.</p> Signup and view all the answers

<p>The conclusion stems from the fact that cells studied in vitro (in the lab) are different from those in vivo (in a living organism). The results may not accurately represent the effects of ultrasound on human tissues</p> Signup and view all the answers

A mechanical form of energy that propagates through tissues.

Conversion of ultrasound to heat in tissue through absorption.

Increased intensity or frequency leads to greater tissue heating.

The potential biological effects caused by ultrasound.

As Low As Reasonably Achievable; minimizes risk during ultrasound use.

Ratio of acoustic power to power needed to raise tissue temp by 1°C.

Absorption of ultrasound is higher in bone than in soft tissue.

An early indicator of chromosome instability due to DNA replication errors.

Microscopic bubble expansions and implosions caused by sound waves.

The biological effect depends on the duration of exposure to ultrasound.

Bubbles oscillate in size with sound wave pressure variations.

Experiments using plants to understand ultrasound effects on cavitations.

Research involving animals to assess in vivo ultrasound effects.

Cavitation where bubbles collapse due to large oscillations.

Research analyzing health data of populations, often focusing on ultrasound exposure.

Adult tissue tolerates temperature increases better than fetal tissue.

TIS, TIB, and TIC indicate thermal exposure in different tissues.

Outcomes in children who were exposed to ultrasound in utero.

Types of ultrasound bioeffects; one raises tissue temperature, the other does not.

Estimated max temperature increase during ultrasound exposure.

A value to evaluate cavitation risk, calculated as MI = Pr / √f.

The maximum negative pressure in ultrasound that leads to cavitation.

The frequency of the ultrasound waves during transmission, impacting cavitation potential.

The area where ultrasound energy is most concentrated for effective imaging.

A measure of the potential for tissue heating from ultrasound energy.

How deep ultrasound waves can go, affecting energy absorption.

Suspensions injected into blood to enhance echogenicity, containing microbubbles.

The ability of a substance to reflect ultrasound waves, creating an image.

No known risks, but subtle bioeffects may occur during use.