Virtually every area of ultrasonic imaging research requires accurate estimation of the spatiotemporal impulse
response of the instrument, and yet accurate measurements are difficult to achieve. The impulse response
can also be difficult to predict numerically for a specific device because small unknown perturbations in array
properties can generate significant changes in predicted pulse-echo field patterns. A typical measurement for
a 1-D array transducer employs a line scatterer oriented perpendicular to the scan plane. Echoes from line
scatterers located throughout the field of view constitute estimates of shift-varying line response functions.
We propose an inverse-problem approach to the reconstruction of point-spread functions from line-spread
functions. A collection of echoes recorded for a range of line-scatterer rotation angles are treated as projections
of sound pressure onto the transducer array surface. Although the reconstruction is mathematically
equivalent to filtered backprojection, it provides significant advantages with respect to interpolation that
confound straightforward implementations. Field II predictions used to model measurements made on commercial
systems suggest the reconstruction accuracy is with 0.32% for noiseless echo data. Application of
the method to data acquired from a commercial system are evaluated from the perspective of deconvolution.
Elasticity imaging is emerging as an important tool for breast
cancer detection and monitoring of treatment. Viscoelastic image
contrast in breast lesions is generated by disease specific
processes that modify the molecular structure of connective
tissues. We showed previously that gelatin hydrogels exhibit
mechanical behavior similar to native collagen found in breast
tissue and therefore are suitable as phantoms for elasticity
imaging. This paper summarizes our study of the viscoelastic
properties of hydrogels designed to discover molecular-scale
sources of elasticity image contrast.