| 摘要 |
An apparatus and method using a backing block having a variable acoustic impedance as a function of elevation or azimuth, to achieve a desirable apodization of the aperture of an ultrasound transducer stacked with the backing block. The backing block has a gradient profile in acoustic impedance that changes from a minimum value to a maximum value along the elevation direction and/or azimuthal direction of the stacked ultrasound transducer. Typically, the backing block has an elevation gradient profile in acoustic impedance that increases from a minimum value of acoustic impedance near the center of the backing block to a maximum value of acoustic impedance at opposing lateral faces of the backing block. The backing block can be discretely segmented in acoustic impedance, with as many segments as are practically manufacturable. An individual segment can have a uniform or variable acoustic impedance. The backing block can be continuous in acoustic impedance, with a minimum acoustic impedance in the center and a maximum acoustic impedance at two or more planar lateral faces.
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