20 MHz ultrasound array for medical imaging from design to image evaluation

Feasability of human endobronchial imaging with a linear‐array ultrasound catheter

“…3,15 We have developed a linear-array transducer that is to be inserted into the working channel of a bronchoscope.…”

“…[1][2][3] The development of high-frequency transducers has enabled imaging of the skin 2 or the eye with extremely high resolution, yielding details not available with other imaging techniques. Endocavitary probes are now playing a prominent role in the assessment of various organs such as the prostate, uterus and ovaries, and heart.…”

2D filter design for the reduction of beamforming artifacts in coarsely-sampled imaging apertures

“…In this formulation, diagonalizing the block matrices G k equals Fourier-transform in time-domain and block-diagonalizingḠ C equals Fourier-transform in spatialdomain. Second, with the diagonalization operation onḠ C , Equation 1 can be re-formed as…”

“…Although various array transducers for HFUS imaging applications have been proposed recently [1]- [3], the benefits of developments in materials and fabrication techniques have not been fully realized for high frequency arrays above 20 MHz. One of the primary challenges for current transducer technologies is the element size requirements in this frequency range: smaller size elements in the 30 -60 μm range may be difficult to realize using existing techniques.…”

“…Even if the fabrication problems are solved, additional problems due to increased cross coupling, increased element impedance, and increased variability in element sensitivity may arise. Therefore, it is expected that high frequency arrays in the range of 25 -35 MHz will be realized with 1.5 -3 λ pitch [1]- [3]. Conventional beamforming with these coarsely sampled arrays results in increased grating lobe levels leading to reduced dynamic range and loss of contrast.…”