Interlaboratory comparison of ultrasonic backscatter, attenuation, and speed measurements

in a study involving 10 different sites, independent results of measurement s of ultrasonic properties on equivalent tissue-mimicking samples are repor ted and compared. The properties measured were propagation speed, attenuati on coefficients, and backscatter coefficients. Reasonably good agreement ex ists for attenuation coefficients, but less satisfactory results were found for propagation speeds. As anticipated, agreement was not impressive in th e case of backscatter coefficients. Results for four sites agreed rather we ll in both absolute values and frequency dependence, and results from other sites were lower by as much as an order of magnitude. The study is valuabl e for laboratories doing quantitative studies.