A test phantom for estimating changes in the effective frequency of an ultrasonic scanner

Thaddeus Wilson, James Zagzebski, Yadong Li

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Objective. Ultrasonic frequency is an important performance feature of B-mode scanners. It is particularly relevant when comparing instruments from different manufacturers and reporting clinical results. We investigated a test phantom to independently measure an effective imaging frequency, including effects of depth-dependent attenuation and frequency filtering during echo reception. Methods. The approach capitalizes on variations of the frequency dependence of backscatter with scatterer size. A tissue-mimicking phantom containing 48-μm-diameter scatterers was constructed. Embedded at depths of 1, 3, 7, and 9 cm were sets of cylindrical inclusions, each containing tissue-mimicking material with a different scatterer size and number density. Computer simulations helped establish scatterer parameters for the cylinder bodies that resulted in image contrast versus the background that varied with frequency, with each cylinder transitioning from negative to positive contrast at a different frequency. Acoustic properties of the phantom were verified by a laboratory apparatus. Initial tests of the effectiveness of the phantom were done by imaging with several scanners using various frequency and imaging settings on transducers. Results. Images were obtained with 2 clinical scanners in which modest changes in the image acquisition parameters were adjusted. Image contrast between test cylinders and background corresponded to operating frequency with a multihertz transducer. Changes in observable contrast consistent with a shift in operating frequency were not always accompanied by visual indicators that such changes in the scanning protocol had occurred. Conclusions. The test phantom performs as predicted by computer simulations and theoretical calculations of backscatter versus frequency. Contrast on images of the test phantom produced by clinical systems correlates with scanner frequency settings, showing feasibility. Relative shifts in effective frequency and operating bandwidth can be assessed from these contrast differences between settings with this test phantom.

Original languageEnglish (US)
Pages (from-to)937-945
Number of pages9
JournalJournal of Ultrasound in Medicine
Volume21
Issue number9
DOIs
StatePublished - Jan 1 2002

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Transducers
Ultrasonics
Computer Simulation
Acoustics

All Science Journal Classification (ASJC) codes

  • Radiological and Ultrasound Technology
  • Radiology Nuclear Medicine and imaging

Cite this

A test phantom for estimating changes in the effective frequency of an ultrasonic scanner. / Wilson, Thaddeus; Zagzebski, James; Li, Yadong.

In: Journal of Ultrasound in Medicine, Vol. 21, No. 9, 01.01.2002, p. 937-945.

Research output: Contribution to journalArticle

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