科研之友
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摘要
The ultrasonic property of soft tissue can be quantified by its attenuation coefficient alpha. Traditionally the backscattering signal of tissue is used to estimate alpha. To improve precision, a large number of spatially independent samples of tissue echoes are required for averaging. In this paper, we propose a new estimation method, which makes use of microbubbles to provide temporally independent samples for averaging. It is easier for temporal sampling to maintain ergodicity and provide a large number of independent samples for statistical averaging.
A stochastic model for the harmonic signals of an ideal bubble attenuated by tissue is derived based on Kuc's and Miller's works. An estimator of alpha is then presented. This estimator is consistent and could be biased because of the unknown squarelaw relation between the second and fundamental harmonics for non-ideal bubble oscillation.
In experimental works, we design a simplified phantom for demonstrating the performance of the proposed estimator. It is shown that both first and second harmonics can estimate alpha consistently. However, the interference of the tissue backscattering signal may cause additional estimation error using the first harmonic.
- 出版日期2010-12
