Tag Archives: bioeffects

Safely Using Diagnostic Ultrasound

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The clinical applications for diagnostic ultrasound have expanded tremendously since its introduction in the late 1950s thanks to technological advancements in both hardware and software, enabling rapid diagnoses at the patient bedside. With this expansion, the medical specialties employing ultrasound as a diagnostic tool have also increased substantially, resulting in a consistently growing group of new users across all levels of medical training and practice.

Ultrasound has long been understood as a low-cost, portable, and ionizing radiation-free imaging method, which has, in part, fueled this rapid expansion. However, ultrasound is ultimately a type of mechanical energy that is able to penetrate tissue, yielding the potential for bioeffects. Practically, the potential for bioeffects is measured through the thermal index (TI) and mechanical index (MI), which provide indicators of the temperature elevation and likelihood of cavitation, respectively, at a particular scan setting. While there have been no independently confirmed adverse effects in humans caused by current diagnostic instruments without contrast agents, biological effects have been reported in pre-clinical mammalian systems, emphasizing the importance of proper clinical use. As diagnostic ultrasound expands to new users and clinical applications, it is imperative that we continue to understand and assess these potential bioeffects and educate new ultrasound users to continue to use ultrasound safely.

The AIUM bioeffects committee has long undertaken this task, examining emerging technologies and making recommendations based on findings. Recently, the bioeffects committee updated its statement on the “Prudent Clinical Use and Safety of Diagnostic Ultrasound”. This statement reaffirms the promise of ultrasound as a safe and effective tool for diagnostic imaging when used properly by qualified health professionals.

Specifically, we emphasize three main ways to ensure diagnostic ultrasound is used safely:

  1. Monitor acoustic outputs—The likelihood of bioeffects can increase by increasing acoustic outputs, indicated by the thermal and mechanical indices. Exposure time should also be monitored, as increased exposure time can also increase the likelihood of bioeffects.
  2. Follow the ALARA principle—The as low as reasonably achievable (ALARA) principle maintains that users employ the lowest acoustic output and shortest scanning time to reasonably achieve diagnostic-quality images.
  3. Only allow qualified professionals to use ultrasound—Ultrasound should be used only by qualified health professionals to provide medical benefit to the patient.

As new diagnostic ultrasound technologies are developed and evaluated, it will continue to be critical to ensure new users understand the proper use of diagnostic ultrasound and the potential for bioeffects, particularly as the use of ultrasound expands beyond traditional use cases and into the future—perhaps even one day into the home!

Alycen Wiacek, PhD, is an engineer, ultrasound researcher, and educator, working to develop new ultrasound-based imaging technologies and improve the quality and diagnostic accuracy of ultrasound. She is a member of the AIUM Bioeffects Committee and is passionate about developing technology to increase access to high quality ultrasound.

Ultrasound: The Therapy of the Future Coming to a Clinic Near You!

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Ultrasound is most commonly known for diagnostic imaging and image-guided interventions, but there is also the potential to harness its power for therapeutic benefits. The use of ultrasound as a therapy is growing, with more than 1,900 active clinical investigations underway. There are also avenues to get insurance reimbursement for the treatment of certain ailments with ultrasound therapy, including bone metastases, essential tremor, and prostate.

In order to help guide physicians that may become involved in the use of ultrasound therapies, the Bioeffects Committee of the American Institute of Ultrasound in Medicine (AIUM) has issued new and updated statements on the AIUM website. These statements help to identify what to consider when using ultrasound therapies, including what happens to the targeted tissue and safety. Some highlights from these statements include:

  • Although safe when used properly for imaging, ultrasound can cause biological effects associated with therapeutic benefits when administered at sufficient exposure levels. Ultrasound therapeutic biological effects occur through two known mechanisms: thermal and mechanical. Thermal effects occur as the result of absorption of ultrasound waves within tissue, resulting in heating. Mechanical effects, such as fluid streaming and radiation force, are initiated by the transfer of energy/momentum from the incident pulse to tissue or nearby biofluids. Indirect mechanical effects can also occur through interaction of the ultrasound pulse with microbubbles such as ultrasound contrast agents. Importantly, thermal and mechanical mechanisms can trigger biological responses that result in desired therapeutic endpoints.
  • The type of bioeffects generated by ultrasound depend on many factors, including the ultrasound source, exposure conditions, presence of cavitation nuclei, and tissue type. Different bioeffects will require different amounts of ultrasound, and thermal and mechanical mechanisms can occur simultaneously for some exposure conditions.
  • There is the possibility of adverse effects in therapeutic ultrasound for targeted and untargeted tissue. Practitioners using these modalities must be well trained on the safe and effective use of therapeutic devices, knowledgeable about potential adverse events, aware of contraindications, and diligent in performing safe procedures. Image guidance should be used to ensure accurate targeting and dosing to maximize the outcomes for patients.

The statements issued by the AIUM’s Bioeffects Committee are intended as baseline considerations when a new therapy device is being put into practice. As ultrasound therapies continue to be adopted into clinical use, the Bioeffects Committee will continue to monitor outcomes in order to inform and educate the community.

Interested in learning more about the bioeffects of ultrasound? Check out the following Official Statements from the American Institute of Ultrasound in Medicine (AIUM):

Who Runs the AIUM?

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Have you ever wondered what or who runs the AIUM? Of course you know about the elected officers, and the AIUM staff that works in the home office, but do you know that there are approximately a dozen committees and/or task forces that help the organization run throughout the year?

The volunteers may be elected or appointed to the committees and tasks forces, and they are not paid or compensated for their time. Frequently, there are many committee members who accept appointments and nominations year after year. Who would possibly be willing to take on extra work and added expense, just to help the AIUM?

Bagley_6Who are the volunteers?
Ordinary people like me! That is who! I have been volunteering with the AIUM since 2009, and have found, as they often say when you volunteer, that I get more than I give. My personal life mission is one of giving back, both to my profession and to my community. I believe anyone who volunteers for the AIUM will give you a similar answer: There is an obligation to give back because someone once gave of his or her time to help me.

How did I become a volunteer?
I did not wake up one day and think to myself, “Today is the day I should volunteer for the AIUM.” Instead, a mentor suggested to a liaison organization that I should be their representative to the AIUM Bioeffects and Safety Committee. At the first meeting, I was hooked. The work gave me new energy and excitement about my profession. I could not get enough bioeffect and safety knowledge.

When my time as a liaison ended, I asked a fellow committee member to nominate me to the committee. As luck would have it, my work proved that I was serious, and the members elected me to the committee.

How can you become a volunteer?
Maybe you are thinking to yourself right now, I am energetic and have a lot to give, but I do not know how to get involved. What should I do? If you have a mentor in the AIUM, ask him or her to nominate you to a committee.

If you do not have a mentor I suggest that you start by serving as a resource member to the committee that best matches your skills and interests. A resource member might assist the members on projects. You can offer up your talents by contacting the chair and letting him or her know that you want to help. Once your work is visible, you can ask a member to nominate you to be a committee member.

You Get More Than You Give
I have gained so much from working on a committee. I have new knowledge about bioeffects and safety that has allowed me to take on a larger advocacy role. I have new knowledge to integrate into the courses that I teach, and I have developed lectures to educate all medical imaging professionals about ultrasound bioeffects and safety. The work on the committee has inspired my own research projects that have resulted in award-winning manuscripts.

My confidence in my knowledge has improved, and I am willing to try new and difficult projects that I would not have dreamed of trying in my pre-committee life. I have made friends and have gained new mentors. I know that regardless of how much effort I have given, the committee has given me exponentially more.

Member, Pay it Forward!
None of us ever gets where we are on our own. In addition to our hard work, our mentors and our colleagues help us on our professional journeys. Volunteering is a way to pay it forward.

If you are an active volunteer, now is the time to make sure your good work is continued! Mentor a new member, and help him or her get involved. Suggest that he or she become a resource member or nominate him or her to a committee. Bringing new people into the volunteer world ensures that your good work continues, and it provides for the AIUM’s future.

What has been your volunteer experience? Comment below or let us know on Twitter: @AIUM_Ultrasound.

Jennifer Bagley, MPH, RDMS, RVT, is an associate professor for the College of Allied Health at the University of Oklahoma Health Sciences Center, Schusterman Campus in Tulsa. She currently serves on the AIUM Bioeffects Committee and is a former member of the Technical Standards Committee.