Evaluation of Imaging Parameters of Ultrasound Scanners: Baseline for Future Testing (original) (raw)
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Objective Performance Testing and Quality Assurance of Medical Ultrasound Equipment
Ultrasound in Medicine & Biology, 2007
There is an urgent need for a measurement protocol and software analysis for objective testing of the imaging performance of medical ultrasound equipment from a user's point of view. Methods for testing of imaging performance were developed. Simple test objects were used, which have a long life expectancy. First, the elevational focus (slice thickness) of the transducer was estimated and the in-plane transmit focus was positioned at the same depth. Next, the postprocessing look-up-table (LUT) was measured and linearized. The tests performed were echo level dynamic range (dB), contrast resolution (i.e., gamma of display, number of gray levels/dB) and sensitivity, overall system sensitivity, lateral sensitivity profile, dead zone, spatial resolution and geometric conformity of display. The concept of a computational observer was used to define the lesion signal-to-noise ratio, SNR L (or Mahalanobis distance), as a measure for contrast sensitivity. All the measurements were made using digitized images and quantified by objective means, i.e., by image analysis. The whole performance measurement protocol, as well as the quantitative measurements, have been implemented in software. An extensive data-base browser was implemented from which analysis of the images can be started and reports generated. These reports contain all the information about the measurements, such as graphs, images and numbers. The approach of calibrating the gamma by using a linearized LUT was validated by processing simultaneously acquired rf data. The contrast resolution and echo level of the rf data had to be compressed by a factor of two and amplified by a gain factor corresponding to 12 dB. This resulted in contrast curves that were practically identical to those obtained from DICOM image data. The effects of changing the transducer center frequency on the spatial resolution and contrast sensitivity were estimated to illustrate the practical usefulness of the developed approach of quality assurance by measuring objective performance characteristics. The developed methods might be considered as a minimum set of objective quality assurance measures. This set might be used to predict clinical performance of medical ultrasound equipment, taking into account the performance at a unique point in space i.e., the coinciding depths of the elevation and in-plane (azimuth) foci. Furthermore, it should be investigated whether the approach might be used to compare objectively various brands of equipment and to evaluate the performance specifications given by the manufacturer. Last but not least, the developed approach can be used to monitor, in a hospital environment, the medical ultrasound equipment during its life cycle. The software package may be viewed and downloaded at the website http://www.qa4us.eu. (E-mail: j.thijssen@cukz.umcn.nl) Objective performance of medical ultrasound equipment • J. M. THIJSSEN et al. 461
BMUS guidelines for the regular quality assurance testing of ultrasound scanners by sonographers
Ultrasound, 2013
Quality Assurance of ultrasound systems is necessary to ensure the reliability of results and to check for deterioration in performance; a number of bodies have produced guidelines. Testing has traditionally been the responsibility of Medical Physics Departments but the important role of sonographers has been recognised and recent publications have included tests to be performed by ultrasound users. Since there are differences in approach between these publications the BMUS QA Working Party was established to provide a consistent set of guidelines specifically for sonographers. Three levels of testing are recommended, to include infection control and inspections for scanner and probe damage, basic display checks and further tests to assess drop-out, sensitivity and noise. These tests should form part of a programme that includes more comprehensive testing at longer intervals, perhaps by a Medical Physics Department.
Retracted: 3d-method For Determining the Imaging Quality of Ultrasound Probes
2015
Background: Monitoring ultrasonic probe quality remains an important problem which impacts diagnostic accuracy. Here we present a quantitative method to assess probe quality primarily based on measuring probe maximum contrast (dB) and dynamic range. Method: Contrast relevant parameters of 26 transducer models manufactured by five manufacturers were measured with a novel Random Void Phantom (RVP) approach. 3D-data were acquired and analysed to determine image quality. Results: Acoustic contrast values ranging from 15dB to 36dB were observed. Conclusion: By examining artefact producing side lobes, the novel RVP approach presented here permits a quantitative assessment of ultrasound probe quality. DOI : coming soon Corresponding Author: Dr. med. Eckhart Fröhlich, Department of Internal Medicine 1, University of Tübingen, Otfried-Müller-Straße 10, D 72076 Tübingen. Email: eckhart.froehlich@gmx.de
PHANTOMS AND AUTOMATED SYSTEM FOR TESTING THE RESOLUTION OF ULTRASOUND SCANNERS
1997
Tissue-mimicking phantoms and an automated system have been developed for testing the resolution performance of ultrasound scanners by determining detectability of low to higher contrast spherical lesions over the entire depth of field. Axial, lateral and elevational resolutions are accounted for simuRaneously and equally. Tissue-mimicking spherical simulated lesions are either 3 or 4 mm in diameter and have one of four different intrinsic material contrasts. For each diameter and contrast, there is a set of 109 lesions in a regular array with coplanar centers extending from 0.5-15.5 cm in depth. With the scan slice superimposed on the spheres, the image is frame-grabbed for automated analysis. A diameter-dependent lesion signal-to-noise ratio is computed for each pixel position in the image, exchrdhtg a 5-mm boundary. Two universal thresholds, resulting from maximization of agreement between the automated system and human observers, give rise to a depth range, or "resolution zone", over which detection exists for each type lesion. 0 1997 World Federation for Ultrasound in Medicine & Biology.
Ultrasound Transducer Quality Control and Performance Evaluation Using Image Metrics
Proceedings of the International Conference on Advanced Intelligent Systems and Informatics 2018, 2018
This paper aims to two main goals, first goal is to achieve the characterization of quality control of ultrasound scanners based on the potential image metrics. On the other hand, the most effective goal is how to classify ultrasound scanners based on image metrics to evaluate performance of ultra-sound transducer. The authors utilize the metrics to give information about the spatial arrangement of the gray levels in the specific interest region. The execution of ultrasound images metric based on a set of 19 metrics (i.e. contrast, gradient and Laplacian). This set reflects quality control of ultrasound scanners. The wok of this paper based on the best 6 metrics from 19 metrics which extracted from linear discriminative analysis (LDA). The classification methods used for minimum numbers of metrics are fused using support vector machine (SVM) and the highest classification method is back propagation neural network (BPNN) classifiers to get the main target of paper. Finally, the results show that objective performance evaluation of ultrasound transducer accuracy was 100% by using back propagation neural network classifier.
The open biomedical engineering journal, 2015
To check or to prevent failures in ultrasound medical systems, some tests should be scheduled for both clinical suitability and technical functionality evaluation: among them, image quality assurance tests performed by technicians through ultrasound phantoms are widespread today and their results depend on issues related to scanner settings as well as phantom features and operator experience. In the present study variations on some features of the B-mode image were measured when the ultrasound probe is handled by the technician in a routine image quality test: ultrasound phantom images from two array transducers are processed to evaluate measurement dispersion in distance accuracy, high contrast spatial resolution and penetration depth when probe is handled by the operator. All measurements are done by means of an in-house image analysis software that minimizes errors due to operator's visual acuity and subjective judgment while influences of ultrasound transducer position on qu...
Quality Control Program in Medical Ultrasound at Hamad Medical Corporation: Current Status
European Journal of Medical and Health Sciences, 2022
The main purpose of QC program in diagnostic imaging modalities such as medical ultrasound equipment is to evaluate and define the performance and safety of ultrasound equipment. Ultrasound systems contain many sensitive transducers and soft parts which may be destroyed due to poor handling or use. Over time, any machines, regardless of their quality and usage, depreciates and incurs damage in many ways. The results from the Quality Control (QC) reports for B-mode of the Ultrasound machines in the Clinical Imaging Department of Hamad Medical Corporation (HMC) has been reviewed. The average annual failures of equipment during the 4-year period includes 2.7% involved transducers and 51.3% involved mechanical integrity failures while the average annual failures rate from mechanical integrity and transducers were measured to be 12.8% and 0.7%, respectively. The main failure of the transducers could be from some artifacts or bad connection of individual elements or groups of elements. Ev...
Ultrasound in Medicine & Biology, 2011
A quantitative analysis of the ultrasound images from all nine transducers employed measurements of the resolution integral as an indication of the versatility and technology of the ultrasound scanners. Two other parameters derived from the resolution integral, the characteristic resolution and depth of field, were used to characterise imaging performance. Six of these transducers were also assessed qualitatively by ultrasonically scanning 59 female common marmosets (Callithrix jacchus) yielding a total of 215 scans. The quantitative measurements for each of the transducers were consistent with the results obtained in the qualitative in vivo assessment. Over a 0-10 mm imaging depth, the values of the resolution integral, characteristic resolution and depth of field, measured using the Edinburgh Pipe Phantom, ranged in magnitude from 7-72, 93-930 mm and 3.3-9.2 mm respectively. The largest resolution integrals were obtained using the Vevo 770 and Vevo 2100 scanners. The Edinburgh Pipe Phantom provides a quantitative method of characterising the imaging performance of preclinical imaging scanners.
Journal of The Acoustical Society of America, 2008
According to the "Guide to the Expression of Uncertainty of Measurement", known as GUM, uncertainty assessment in a given measurement is necessary, and takes into account two types of uncertainty sources: type A and type B. Type A uncertainty is obtained from the statistical analysis of a series of observations, while Type B comes from sources that cannot be evaluated considering statistical analysis, but can be obtained from previous measurements, knowledge on the behaviour of the measuring equipment, manufacturer's specifications, and data from certificates or handbooks. Herein, the Effective Radiation Area (A ER ) of ultrasound transducers has been estimated at Inmetro's Laboratory of Ultrasound using an acoustic pressure field mapping system. A ER calculation protocol was developed based on Standard IEC 61689:2007. Besides, the type A uncertainty was estimated from 4 repetitions of the full procedure for the determination of A ER . Type B uncertainty was estimated from the mathematical model for A ER calculation, itself based on IEC 61689:2007 and the GUM. Initial tests using US transducer of 1.0 MHz and 2.25 MHz indicated an expanded uncertainty inferior to 4.0%. Those preliminary results encourage further development, as broadening the frequency range of assessment.
The first goal of this paper is to investigate the potential benefit of image metrics for the characteristic of quality control of ultrasound scanners. To be effective, the second goal of this paper is to classify ultrasound images based on image metrics for the sake of objective performance evaluation of ultrasound transducer. Metrics gives information about the spatial arrangement of the gray levels in the region of interest. Methods The image metric of ultrasound images was executed using a set of 19 metrics, such as for example contrast, gradient and Laplacian, and this set reflects quality control of ultrasound scanners. Results Based upon linear discriminative analysis for 6 best metrics from a set of 19 metrics which are selected. Finally, highly ranked minimum numbers of metrics are fused using support vector machine and back propagation neural network classifiers to get the highest classification performance for objective performance evaluation of ultrasound transducer. The results show that objective performance evaluation of ultrasound transducer accuracy was 100% by using backpropagation neural network classifier.