Unit 24: Patient Saefty & Bioeffects Sononerds Physics
TLDRThis educational video from Sono Nerds covers Unit 24 on patient safety and bio effects in ultrasound imaging. It explains the importance of understanding bio effects—thermal and mechanical—to ensure patient safety during ultrasound exams. The video discusses the role of various studies and tools like hydrophones and calorimeters in measuring ultrasound energy, and highlights the significance of the ALARA principle, thermal and mechanical indices in minimizing risks. It also touches on regulatory guidelines from the AIUM and FDA, emphasizing the safety of diagnostic ultrasound when used appropriately.
Takeaways
- 📚 The video discusses Unit 24 on patient safety and bio effects in ultrasound, emphasizing the importance of understanding how sound energy can impact the body.
- 🔍 Bio effects in ultrasound are categorized into two mechanisms: thermal, which involves heating of tissue, and mechanical, which can affect bubbles in tissue and potentially cause damage.
- 🧬 Studies on bio effects aim to determine safe levels of ultrasound energy and ensure patient safety during diagnostic imaging exams.
- 🛡️ When used within diagnostic imaging intensities, there are no known adverse effects of ultrasound; however, higher intensities can have therapeutic effects and potential bio effects.
- 🔬 Research methods for studying bio effects include mechanistic and empirical studies, as well as in vivo and in vitro models to simulate and observe ultrasound impacts.
- 📉 The American Institute of Ultrasound in Medicine (AIUM) and the FDA regulate ultrasound equipment to ensure safety, recommending intensity limits to prevent adverse effects.
- 🔄 The ALARA principle (As Low As Reasonably Achievable) guides sonographers to minimize patient exposure to ultrasound energy and to use the correct settings for each exam.
- 🛠️ Tools for measuring ultrasound output include hydrophones, radiation force balances, acousto-optic devices, calorimeters, thermocouples, and liquid crystals to assess the potential for bio effects.
- ⚠️ Thermal indices (TIS, TIB, TIC) and Mechanical Index (MI) are displayed on ultrasound machines to inform users of the potential for temperature increases and cavitation, respectively.
- 🌡️ Temperature increases from ultrasound should be kept under 2 degrees Celsius to avoid cellular impairment, with special considerations for sensitive areas like fetal bones and testicles.
- 💥 Mechanical bio effects are related to the potential for cavitation, where gas bubbles can expand and potentially rupture, causing localized damage to cells.
Q & A
What is the primary focus of Unit 24 in the video?
-Unit 24 focuses on patient safety and bio effects in the context of ultrasound imaging, discussing the study of bio effects, the tools used for measurement, and the risks associated with thermal and mechanical effects.
What are the two main mechanisms by which bio effects occur in ultrasound?
-The two main mechanisms by which bio effects occur in ultrasound are thermal effects, which involve the heating of biological tissue, and mechanical effects, which involve the impact on small bubbles that can potentially destroy biological tissue.
What is the significance of the SPI test's section on safety, quality assurance, and new technology in relation to bio effects?
-The section on safety, quality assurance, and new technology in the SPI test, which covers about 10% of the test, is significant because it includes a broad category of information pertaining to the bio effects of ultrasound, ensuring that practitioners are aware of safety guidelines and best practices.
How are bio effects studied in relation to ultrasound?
-Bio effects are studied through mechanistic and empirical studies. Mechanistic studies involve hypothesizing about potential bio effects and testing these hypotheses, while empirical studies review outcomes of patients who have already undergone ultrasound exams.
What challenges are faced when studying bio effects in vivo?
-Studying bio effects in vivo, or in a live specimen, presents challenges such as maintaining a controlled environment and obtaining consent from patients, especially obstetric patients, to push the limits of safety.
What is the role of the American Institute of Ultrasound in Medicine (AIUM) and the FDA in ultrasound safety?
-The AIUM contributes to the scientific understanding of ultrasound bio effects, and the FDA considers this science to make recommendations and regulate the output power or intensity of ultrasound machines in the U.S.
What does the term 'ALARA' stand for in the context of ultrasound safety?
-ALARA stands for 'As Low As Reasonably Achievable,' which means that sonographers should minimize patient exposure to ultrasound energy by performing only ordered exams, choosing correct settings, and not prolonging the use of ultrasound unnecessarily.
What is the purpose of using tools like hydrophones, calorimeters, and thermocouples in measuring ultrasound output?
-These tools are used to measure the sound energy produced by ultrasound machines to ensure that the output does not exceed FDA limits, providing a way to calculate the dose of ultrasound that a patient receives and ensuring patient safety.
How does the thermal index (TI) on an ultrasound machine provide safety information?
-The thermal index indicates the potential temperature increase in tissues during an ultrasound exam. It helps sonographers assess the risk of thermal bio effects and adjust machine settings to minimize the risk of cellular impairment due to overheating.
What is the difference between stable and transient cavitation in the context of mechanical bio effects?
-Stable cavitation involves gas bubbles oscillating without bursting, creating pressure waves that can cause microstreaming and shear stresses in surrounding cells. Transient cavitation, also known as inertial cavitation, occurs when bubbles rupture, releasing energy that can damage or destroy adjacent cells.
Why is the mechanical index (MI) important for patient safety in ultrasound imaging?
-The mechanical index informs the likelihood of harmful bio effects due to cavitation. An MI value less than 1.9 is considered generally safe for humans, but higher values increase the risk of cavitation and potential cell damage.
Outlines
🚑 Patient Safety and Bio Effects in Ultrasound
This paragraph introduces the topic of patient safety and bio effects in ultrasound imaging. It discusses the importance of recognizing the potential lasting consequences of sound energy on the body, including thermal and mechanical bio effects. The paragraph outlines the goal of studying bio effects to ensure patient safety during ultrasound exams, noting that while diagnostic ultrasound is considered safe, higher intensities can lead to bio effects. It also touches on the challenges of studying bio effects in vivo and the use of in vitro studies to predict and regulate these effects. Professional organizations like the American Institute of Ultrasound in Medicine (AIUM) and the FDA are highlighted for their role in creating safety guidelines and regulating ultrasound equipment.
🔍 Measuring Ultrasound Output and Bio Effects
This section delves into the measurement of ultrasound output power and the tools used to assess bio effects. It explains the importance of adhering to FDA limits and the various methods and tools for measuring ultrasound energy, including hydrophones, radiation force, acoustical optics, calorimeters, thermocouples, and liquid crystals. The paragraph also introduces the concept of dosimetry, which is the study of dosing and measurement of radiation absorbed by a substance or living organism. The focus is on understanding the spatial peak temporal average (SPTA) intensity and the spatial peak temporal peak (SPTP) intensity, which are crucial for evaluating thermal and mechanical bio effects, respectively.
🌡️ Thermal and Mechanical Bio Effects Mechanisms
This paragraph explores the two primary mechanisms of bio effects caused by ultrasound: thermal and mechanical. Thermal effects result from the heating of biological tissue, which can impair cellular functions if the temperature exceeds the body's normal range. The paragraph emphasizes the importance of monitoring thermal indices during ultrasound exams, especially in sensitive cases like fetal imaging. Mechanical effects, on the other hand, involve the interaction of ultrasound with small gas bubbles in the body, potentially leading to bubble rupture and cell damage. The thermal and mechanical indices displayed on ultrasound machines provide an estimate of the risk associated with these effects.
🛑 Understanding Thermal Indices and Mechanical Index (MI)
The focus of this paragraph is on the thermal indices and the mechanical index (MI), which are critical parameters for assessing the safety of ultrasound procedures. It explains how different types of thermal indices (TIS, TIB, TIC) are sensitive to changes in tissue interaction with sound and why they are particularly important in exams involving soft tissue, bony structures, and cranial bones. The paragraph also discusses the mechanical index, which indicates the likelihood of harmful bio effects due to cavitation. It highlights the significance of using the lowest possible ultrasound intensity to minimize the risk of cavitation and potential cell damage.
📉 Cavitation and Its Impact on Bio Effects
This section provides a detailed explanation of cavitation, a mechanical bio effect that occurs when gas bubbles in the body respond to ultrasound pressure. It differentiates between stable and transient cavitation, explaining that while stable cavitation involves bubbles expanding and contracting without bursting, transient cavitation results in bubble rupture, which can cause localized cell damage. The paragraph emphasizes the importance of being cautious with ultrasound power to avoid the risk of transient cavitation, especially in sensitive areas or populations such as embryos.
🏥 Clinical Relevance of Bio Effects in Ultrasound
The final paragraph concludes the unit by discussing the clinical implications of bio effects in ultrasound. It addresses common patient concerns about the safety of ultrasound and the potential 'radiation' from the procedure. The paragraph reassures that ultrasound is a safe and beneficial imaging method, provided that it is used correctly and prudently. It underscores the sonographer's role in patient care, the importance of following professional guidelines, and the application of the ALARA (As Low As Reasonably Achievable) principle to minimize patient risk.
Mindmap
Keywords
💡Bio effects
💡Ultrasound
💡Thermal effects
💡Mechanical effects
💡Safety
💡ALARA principle
💡Mechanistic studies
💡In vitro studies
💡Dosimetry
💡Hydrophone
💡Thermal index (TI)
Highlights
The video discusses Unit 24 on patient safety and bio effects in ultrasound imaging, emphasizing the importance of understanding bio effects to ensure patient safety.
Bio effects in ultrasound can occur through two mechanisms: thermal effects, which involve heating of tissues, and mechanical effects, which involve pressure changes affecting gas bubbles in tissues.
Studies on bio effects aim to determine safe levels of ultrasound energy for diagnostic imaging, with no known adverse effects when used within these levels.
Therapeutic ultrasound intentionally uses higher intensities to heat tissues, but this is distinct from diagnostic imaging intensities, which prioritize safety.
Mechanistic and empirical studies are used to investigate bio effects, with the former hypothesizing effects and the latter reviewing outcomes from existing ultrasound exams.
In vivo studies of bio effects are challenging due to the difficulty of controlling environments and obtaining patient consent to push safety limits.
In vitro studies using computer models are a substitute for in vivo studies, helping to regulate diagnostic imaging equipment for safety.
Prospective and randomized studies are preferred for investigating ultrasound bio effects, despite the challenges of controlling variables and requiring large participant numbers.
Ultrasound safety is regulated by groups like the American Institute of Ultrasound in Medicine (AIUM) and the Food and Drug Administration (FDA), which set guidelines and regulate equipment output power.
The AIUM contributes to the science behind ultrasound bio effects, while the FDA uses this science to regulate the intensity of ultrasound machines in the U.S.
The Spatial Peak Temporal Average (SPATA) intensity is recommended to be limited to ensure patient safety during ultrasound exams.
The ALARA principle (As Low As Reasonably Achievable) guides sonographers to minimize patient exposure to ultrasound energy and avoid unnecessary prolongation of exams.
Sonographers should select appropriate ultrasound settings and presets for each exam to minimize thermal and mechanical indices, which indicate potential bio effects.
Pulsed wave Doppler ultrasound uses higher power and can create high intensities, whereas 2D Doppler requires much lower intensity due to the good reflection of sound by soft tissues.
M-mode, being a single line of 2D, is generally safe for first-trimester ultrasounds due to its lower intensity requirements.
Quality assurance is crucial for ultrasound equipment to prevent electrical and mechanical hazards, including maintaining transducer integrity to avoid electrical shock.
Various tools like hydrophones, calorimeters, and thermocouples are used to measure ultrasound output and ensure it does not exceed FDA limits.
Hydrophones are the gold standard for measuring acoustics in ultrasound, detecting amplitude, period, pulse durations, and beam shape.
Dosimetry studies the dosing and measurement of radiation absorbed by a substance or living organism, with applications in monitoring ultrasound exposure.
Thermal bio effects are a concern due to the potential for temperature increases to impair cellular functions, particularly in tissues near bones or in fetuses.
The Thermal Index (TI) on ultrasound machines indicates the possible temperature increase, helping to monitor and control thermal effects during exams.
Different types of Thermal Indices (TIS, TIB, TIC) are used to express the potential for temperature changes based on the interaction of ultrasound with different tissues.
Mechanical bio effects, or non-thermal effects, are related to pressure changes in the ultrasound beam that can cause cavitation in gas bubbles, potentially damaging cells.
The Mechanical Index (MI) informs users of the likelihood of harmful bio effects due to cavitation, with values less than 1.9 considered safe for humans.
Cavitation involves the oscillation and potential rupture of gas bubbles in the ultrasound beam, with stable cavitation causing microstreaming and transient cavitation causing cell damage.
Contrast agents in ultrasound are designed to withstand pressure and are less likely to be affected by cavitation compared to naturally occurring gas bubbles.
Clinical discussions about ultrasound safety should reassure patients of its benefits and risks, emphasizing the safety of ultrasound when used correctly and the role of sonographers in minimizing patient risk.
Transcripts
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