DEVELOPMENT OF AN EXAMPLE FLOW TEST OBJECT AND COMPARISON OF 5 OF THESE TEST OBJECTS, CONSTRUCTED IN VARIOUS LABORATORIES

Doppler test objects are used to characterise Doppler systems, both st and-alone systems and the Doppler part of so-called duplex scanners. T he aim of the project partially presented here is the development and validation of an example of a Doppler test object fulfilling the requi rements of the IEC 1685. The project has been carried out by nine part ners of five European countries and has been funded by the European Co mmission. The flow Doppler test object is composed of: tissue mimickin g material (TMM), blood mimicking fluid (BMF), tube (embedded in the T MM and carrying the BMF), tank, flow system, including a pump and a fl ow meter. In the normative part of the IEC 1685, requirements are give n for the values of acoustical parameters of TMM and BMF such as sound velocity, attenuation and backscattering. For BMF, requirements are g iven also for values of density and viscosity. In an informative (but not compulsory) annex, a description is given of a flow test object me eting these requirements as an example. This 'example test object' dev eloped during the project is composed of TMM based on agar and includi ng SIC-and Al2O3-powders, BMF based on nylon particles suspended in wa ter and glycerine, and a tube of c-flex, a silicon copolymer. Two tube sizes are used: 4.0 mm ID and 8.0 mm ID. During the project, very pre cise recipes have been developed for the composition and preparation o f both TMM and BMF. Based on these recipes and a description of the co nstruction in a design five flow test objects have been constructed in the laboratories of five participants. The test objects have been com pared by measurements of the physical parameters and by Doppler measur ements of the five test objects with the same Doppler system. The meas urements have been carried out by five observers. Inter-test object an d inter-observer variabilities are determined, yielding information ab out usefulness of the parameters. (C) 1998 Elsevier Science B.V.