Fast reflectivity imaging in 3D using SAFT

The computational burden for 3D Synthetic Aperture Focusing Technique (SAFT) is large as for each voxel the delay for each acquired A-scan has to be calculated, e.g. O(N5) for N3 voxels and N2 A-scans. For 3D reconstruction of objects which are large in terms of the wavelength, e.g. ≥ (100 )³, the computation of one volume takes several days on a current multicore PC. If the 3D distribution of speed of sound is applied to correct the delays for objects with varying speed of sound the computation time increases further. This overview paper presents the implementations for 3D SAFT developed by the KIT group and discusses their computational performance

Novel Front-End Design with High-voltage Transceiver ASICs for Ultrasound Computed Tomography

3D Ultrasound Computed Tomography (USCT) is an imaging method for early breast cancer detection. The third generation 3 USCT device is developed at Karlsruhe Institute of Technology. The USCT III device has a hemispherical transducer distribution and emits and receives nearly spherical waves. This enables reflection and transmission imaging simultaneously and fully in 3D. The main challenges for the front-end design are to integrate a large number of transducers, to allow high voltage coded excitation, and to receive low amplitude signals with high quality. These challenges were solved using a smart sensor frontend design with a custom application specific integrated circuit (ASIC)

The New Generation of the KIT 3D USCT

The first clinical studies with our current prototype, 3D USCT II, enabled us to identify the necessary improvements for transition of our method to clinical practice. The main goals are to improve the contrast of reflection and transmission tomography, and to optimize the coverage of the imaged breast by a new geometry of the transducer distribution. Furthermore, for cost-effective industrial mass production, a self-calibration method allows us to relax the precision of the positioning of the transducers to 0.1 mm. The readout of the transducer arrays is now carried out by an ASIC, developed for a more cost-effective design. The coupling of the measuring device to the patient was optimized to cover the full size of the breast up to the pectoral muscles. Finally, the data acquisition and readout time were reduced to 1.5 minutes each by new micro-TCA electronics and larger FPGAs

Dice-and-fill single element octagon transducers for next generation 3D USCT

At the Karlsruhe Institue of Technology (KIT), a 3D-Ultrasound Computer Tomography (3D-USCT) medical imaging system for early breast cancer detection is currently developed. With the next generation of 3D-USCT 2.5, the current region of interest (ROI) of 10 x 10 x 10 cm³ shall be increased to 20 x 20 x 20 cm³ to allow reliable imaging results also for bigger female breasts. Therefore, the opening angle (OA) of the future transducers should be increased to approx. 60° at 3 dB while other characteristics such as bandwidth (BW) and resonance frequency should be preserved or even improved. Based on the current dice-andfill approach in transducer production, optimization is performed on piezoelectric sensor geometry and size, type and structure of matching and backing layer and interconnection technology of the several parts of the transducer

3D Ultrasound Computer Tomography for Breast Cancer Diagnosis at KIT: an Overview

3D Ultrasound Computer Tomography (USCT) emitting and receiving spherical wave fronts overcomes the limitations of 2D systems by offering a nearly isotropic 3D point spread function, a large depth of field, less loss of out-of-plane reflections, and fast 3D data acquisition. 3D devices for clinical practice require a more complex hard- and software due to the huge data rate, time-consuming image reconstruction, and large number of small transducers. The here reviewed KIT 3D USCT is a prototype for clinical studies, which realizes for the first time the full benefits of a 3D system

Piezofibre composite transducers for next generation 3D USCT

At the Karlsruhe Institue of Technology (KIT), a 3D-Ultrasound Computer Tomography (3D-USCT) medical imaging system for early breast cancer detection is currently developed. With the next generation of 3D-USCT 2.5, the current region of interest (ROI) of 10 x 10 x 10 cm³ shall be increased to 20 x 20 x 20 cm³ to allow reliable imaging results also for bigger female breasts. Therefore, the opening angle (OA) of the future transducers should be increased to approx. 60 ° at 3 dB while other characteristics such as bandwidth (BW) and resonance frequency should be preserved or even improved. Based on Fraunhofer IKTS Piezofibre composites utilized for transducer production, an optimization is performed on piezoelectric sensor geometry and size, type and structure of matching and backing layer and interconnection technology of the several parts of the transduce

The USCT reference database

Ultrasound Computer Tomography (USCT) is an emerging technology mostly aimed at breast cancer imaging. Following the idea of open science a USCT reference database is established with open and easy to use data and code interfaces. The aim is to promote and facilitate the exchange of available reconstruction algorithms and raw data sets from different USCT devices throughout the growing USCT community. Additionally, the feedback about data and system architecture of the scientists working on reconstruction methods will be published online to help to drive further development of the various measurement setups