Temperature elevation measured in a tissue-mimicking phantom for transvaginal ultrasound at clinical settings

Miloro, Piero; Martin, Eleanor; Shaw, Adam

doi:10.1177/1742271x16684529

Cited by 10 publications

(13 citation statements)

References 8 publications

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“…As previously reported, 17 the maximum temperature increase is seen at the ultrasound transducer-skin interface and is likely to be due to transducer self-heating. 20 It is important to note that this effect is not considered in calculation of the TI.…”

Section: Discussionsupporting

confidence: 78%

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In vitro characterisation of ultrasound-induced heating effects in the mother and fetus: A clinical perspective

et al. 2020

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Introduction The quantification of heating effects during exposure to ultrasound is usually based on laboratory experiments in water and is assessed using extrapolated parameters such as the thermal index. In our study, we have measured the temperature increase directly in a simulator of the maternal–fetal environment, the ‘ISUOG Phantom’, using clinically relevant ultrasound scanners, transducers and exposure conditions. Methods The study was carried out using an instrumented phantom designed to represent the pregnant maternal abdomen and which enabled temperature recordings at positions in tissue mimics which represented the skin surface, sub-surface, amniotic fluid and fetal bone interface. We tested four different transducers on a commercial diagnostic scanner. The effects of scan duration, presence of a circulating fluid, pre-set and power were recorded. Results The highest temperature increase was always at the transducer–skin interface, where temperature increases between 1.4°C and 9.5°C were observed; lower temperature rises, between 0.1°C and 1.0°C, were observed deeper in tissue and at the bone interface. Doppler modes generated the highest temperature increases. Most of the heating occurred in the first 3 minutes of exposure, with the presence of a circulating fluid having a limited effect. The power setting affected the maximum temperature increase proportionally, with peak temperature increasing from 4.3°C to 6.7°C when power was increased from 63% to 100%. Conclusions Although this phantom provides a crude mimic of the in vivo conditions, the overall results showed good repeatability and agreement with previously published experiments. All studies showed that the temperature rises observed fell within the recommendations of international regulatory bodies. However, it is important that the operator should be aware of factors affecting the temperature increase.

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Section: Discussionsupporting

confidence: 78%

“…The temperature data from all thermocouples were recorded using a TC08 datalogger (PicoTech, UK) connected to a computer. The sampling period was 1 second as in the previous study by Miloro et al 17…”

Section: The Isuog Phantommentioning

confidence: 99%

In vitro characterisation of ultrasound-induced heating effects in the mother and fetus: A clinical perspective

et al. 2020

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“…It has been shown using transducers embedded in agar models, that 30 s periods of B mode colour flow and pulsed doppler resulted in average heating of 2.0°C for gynaecological presets, and 2.16° for obstetric presets. It was also found that the TI greatly underestimated the actual rise in temperature 20 . A survey of practitioners in the United Kingdom demonstrated that although there was a good understanding of the concepts of thermal and mechanical energy, and that respondents were aware of the guidelines around safe exposure, 40% of respondents reported that they rarely or never monitored the thermal or mechanical indices in their practice 18 .…”

Section: Informed Consentmentioning

confidence: 99%

Dangers in the dark: Calling for a safer practice of transvaginal ultrasonography

Collins

Hamlyn

Bruxner

et al. 2020

Australas J Ultrason Med

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Background The intimate examination is an important component of the assessment of a patient presenting with obstetric or gynaecological concerns. Ultrasound practitioners, like any other medical practitioner, are in a unique and privileged position. During the examination, the sonographers engage in a very close and personal interaction with an individual whom they have likely never met. They are also most likely unfamiliar with their social situation, cultural background, previous experiences with the healthcare profession and more importantly, any history of sexual trauma. It is an extremely sensitive area of practice which places a great deal of responsibility on the clinician to ensure that they not only protect their patient from psychological distress, but also themselves, from the threat of litigation arising from such distress. Aims This paper highlights the current governance requirements for sonographers and makes suggestions to support them in safeguarding their patients and themselves from allegations of unprofessional conduct, until such a regulatory body exists. Materials and Methods A wide‐ranging review of the literature exploring the perceptions of female patients regarding intimate sonographic examination was performed using standard search engines. Additionally, grey literature was searched for policy statements and government regulatory documents for guidance on the topic. Results Although much research has been undertaken in this field across diverse cultures and knowledge in this area is ever increasing; however, the guidelines for sonographers appear to be site specific and variable. At present, there is no overarching governance for sonographers, as there is with practitioners registered with the Australian Health Practitioner Regulation Agency. Discussion While there are practice standards for the purposes of Medicare set out by the Diagnostic Imaging Accreditation Scheme, there is no regulatory professional standard that sonographers are held accountable to. This is problematic and has the potential for inadvertent boundary transgression by the practitioner, as there is also no existing framework for management of such incidents in an equitable manner. Conclusion The intimate examination is generally well tolerated; however, there is a subset of the population who are vulnerable to psychological distress arising from the examination. The sonographer must be astute to signs of distress and act in accordance with the intimate examination guidelines set out by AHPRA, for the dual purpose of protecting their patients against harm and also themselves from the threat of litigation.

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“…Miloro at al. [27] used a phantom with attenuation, reflectivity, density, and impedance corresponding to the acoustic properties of human tissue to measure the heating caused by standard transvaginal transducers. During the study, a total of 64 transducers made by different manufacturers used in the daily routine at 17 hospitals in Great Britain were examined.…”

Section: Available Studiesmentioning

confidence: 99%

“…Miloro et al [27] hatten an einem Phantom, das in Dämpfung, Reflektivität, Dichte und Impedanz den akustischen Eigenschaften des menschlichen Gewebes entsprach, die von serienmäßig produzierten Endovaginalsonden hervorgerufene Erwärmung gemessen. Hierzu waren im Rahmen der Studie 17 Kliniken in Großbritannien aufgesucht und insgesamt 64 der in der täglichen Routine eingesetzten Sonden verschiedener Hersteller vermessen worden.…”

Section: Available Studiesunclassified

How Safe Is the Use of Ultrasound in Prenatal Medicine? Facts and Contradictions. Part 1 – Ultrasound-Induced Bioeffects

Dudwiesus

Merz²

2020

Ultraschall Med

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The “Ordinance on Protection Against the Harmful Effects of Non-Ionizing Radiation in Human Applications” will go into effect at the beginning of 2021 1. § 10 of this ordinance prohibits non-medical fetal ultrasound exposure thereby resulting in uncertainty, particularly among affected patients, with respect to the generally accepted theory regarding the lack of ultrasound side effects. Although not a single study has shown a detrimental effect on fetal or child development following exposure to ultrasound, the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety has justified the ban with the purely hypothetical possibility of an unidentified side effect. The first part of the following study shows which ultrasound-induced biophysical effects are known and which dose-dependent threshold values must be taken into consideration. In particular, the study focuses on the well-researched heat effect with some in vivo measurements in humans showing that the actual temperature increase is less than the theoretically calculated values. The planned second part of this study will discuss the non-thermal effects and present the most important epidemiological studies.

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Temperature elevation measured in a tissue-mimicking phantom for transvaginal ultrasound at clinical settings

Cited by 10 publications

References 8 publications

In vitro characterisation of ultrasound-induced heating effects in the mother and fetus: A clinical perspective

In vitro characterisation of ultrasound-induced heating effects in the mother and fetus: A clinical perspective

Dangers in the dark: Calling for a safer practice of transvaginal ultrasonography

How Safe Is the Use of Ultrasound in Prenatal Medicine? Facts and Contradictions. Part 1 – Ultrasound-Induced Bioeffects

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