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Ultrasound transducer function: annual testing is not sufficient
KTH, School of Technology and Health (STH), Medical Engineering, Medical Imaging.ORCID iD: 0000-0001-9419-910X
KTH, School of Technology and Health (STH), Medical Engineering.
2010 (English)In: European Journal of Echocardiography, ISSN 1525-2167, E-ISSN 1532-2114, Vol. 11, no 9, 801-805 p.Article in journal (Refereed) Published
Abstract [en]

The objective was to follow-up the study 'High incidence of defective ultrasound transducers in use in routine clinical practice' and evaluate if annual testing is good enough to reduce the incidence of defective ultrasound transducers in routine clinical practice to an acceptable level. A total of 299 transducers were tested in 13 clinics at five hospitals in the Stockholm area. Approximately 7000-15 000 ultrasound examinations are carried out at these clinics every year. The transducers tested in the study had been tested and classified as fully operational 1 year before and since then been in normal use in the routine clinical practice. The transducers were tested with the Sonora FirstCall Test System. There were 81 (27.1%) defective transducers found; giving a 95% confidence interval ranging from 22.1 to 32.1%. The most common transducer errors were 'delamination' of the ultrasound lens and 'break in the cable' which together constituted 82.7% of all transducer errors found. The highest error rate was found at the radiological clinics with a mean error rate of 36.0%. There was a significant difference in error rate between two observed ways the clinics handled the transducers. There was no significant difference in the error rates of the transducer brands or the transducers models. Annual testing is not sufficient to reduce the incidence of defective ultrasound transducers in routine clinical practice to an acceptable level and it is strongly advisable to create a user routine that minimizes the handling of the transducers.

Place, publisher, year, edition, pages
2010. Vol. 11, no 9, 801-805 p.
Keyword [en]
Transducer, Probe, Ultrasound, Testing, Maintenance, Service
National Category
Medical Equipment Engineering
URN: urn:nbn:se:kth:diva-26307DOI: 10.1093/ejechocard/jeq072ISI: 000282750900018ScopusID: 2-s2.0-77957981090OAI: diva2:371550

QC 20101121

Available from: 2010-11-21 Created: 2010-11-21 Last updated: 2014-12-01Bibliographically approved
In thesis
1. Evaluation of Errors and Limitations in Ultrasound Imaging Systems
Open this publication in new window or tab >>Evaluation of Errors and Limitations in Ultrasound Imaging Systems
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

There are binding regulations requiring safety and efficacy aspects of medical devices. The requirements ask for documentation that the devices are safe and effective for their intended use, i.e. if a device has a measuring function it must be correct. In addition to this there are demands for quality systems describing development, manufacturing, labelling, and manufacturing of a device. The requirements are established to guarantee that non-defective medical devices are used in the routine clinical practice. The fast rates in which the imaging modalities have evolved during the last decades have resulted in numerous new diagnostic tools, such as velocity and deformation imaging in ultrasound imaging. However, it seems as if the development of evaluation methods and test routines has not been able to keep up the same pace. Two of the studies in this thesis, Study I and IV, showed that computed tomography-based and ultrasound based volume measurements can yield very disparate measurements, and that tissue Doppler imaging-based ultrasound measurements can be unreliable.

Furthermore, the new ultrasound modalities impose higher demands on the ultrasound transducers. Transducers are known to be fragile, but defective transducers were less of a problem earlier when the ultrasound systems to a lesser extent were used for measurements. The two other studies, Study II and III, showed that serious transducer errors are very common, and that annual testing of the transducers is not sufficient to guarantee an error free function.

The studies in the thesis indicate that the system with Notified Bodies, in accordance with the EU’s Medical Device Directive, checking the function and manufacturing of medical devices does not work entirely satisfactory. They also show that the evaluation of new methods have led to the undesirable situation, where new measuring tools, such as volume rendering from imaging systems, and tissue Doppler-based velocity and deformation imaging in echocardiography are available for clinicians without proven knowledge about their accuracy.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2011. x, 74 p.
Trita-STH : report, ISSN 1653-3836 ; 2011:3
National Category
Medical Laboratory and Measurements Technologies
urn:nbn:se:kth:diva-34177 (URN)978-91-7501-026-7 (ISBN)
Public defence
2011-06-10, Sal 3-221, Alfred Nobels Allé 10, Flemingsberg, 13:00 (Swedish)
QC 20110527Available from: 2011-05-27 Created: 2011-05-27 Last updated: 2011-05-30Bibliographically approved

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Mårtensson, MattiasBrodin, Lars-Åke
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