title: Synthetic tracked aperture ultrasound imaging: design, simulation, and experimental evaluation.
abstract: Ultrasonography is a widely used imaging modality to visualize anatomical structures due to its low cost and ease of use; however, it is challenging to acquire acceptable image quality in deep tissue. Synthetic aperture (SA) is a technique used to increase image resolution by synthesizing information from multiple subapertures, but the resolution improvement is limited by the physical size of the array transducer. With a large F-number, it is difficult to achieve high resolution in deep regions without extending the effective aperture size. We propose a method to extend the available aperture size for SA-called synthetic tracked aperture ultrasound (STRATUS) imaging-by sweeping an ultrasound transducer while tracking its orientation and location. Tracking information of the ultrasound probe is used to synthesize the signals received at different positions. Considering the practical implementation, we estimated the effect of tracking and ultrasound calibration error to the quality of the final beamformed image through simulation. In addition, to experimentally validate this approach, a 6 degree-of-freedom robot arm was used as a mechanical tracker to hold an ultrasound transducer and to apply in-plane lateral translational motion. Results indicate that STRATUS imaging with robotic tracking has the potential to improve ultrasound image quality.
authors.affiliation: Johns Hopkins University , Department of Computer Science, 3400 North Charles Street, Baltimore, Maryland 21218, United States.
authors.forename: Haichong K
authors.initials: HK
authors.lastname: Zhang
authors.affiliation: Johns Hopkins University , Department of Computer Science, 3400 North Charles Street, Baltimore, Maryland 21218, United States.
authors.forename: Alexis
authors.initials: A
authors.lastname: Cheng
authors.affiliation: Duke University , Department of Biomedical Engineering, 101 Science Drive Campus Box 90281, Durham, North Carolina 27708, United States.
authors.forename: Nick
authors.initials: N
authors.lastname: Bottenus
authors.affiliation: Johns Hopkins University , Department of Electrical and Computer Engineering, 3400 North Charles Street, Baltimore, Maryland 21218, United States.
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Guo
authors.affiliation: Duke University , Department of Biomedical Engineering, 101 Science Drive Campus Box 90281, Durham, North Carolina 27708, United States.
authors.forename: Gregg E
authors.initials: GE
authors.lastname: Trahey
authors.affiliation: Johns Hopkins University, Department of Computer Science, 3400 North Charles Street, Baltimore, Maryland 21218, United States; Johns Hopkins University, Department of Electrical and Computer Engineering, 3400 North Charles Street, Baltimore, Maryland 21218, United States; Johns Hopkins University, Department of Radiology, 601 North Caroline Street, Baltimore, Maryland 21287, United States.
authors.forename: Emad M
authors.initials: EM
authors.lastname: Boctor
keywords: medical robotics; robotic ultrasound; synthetic aperture; tracking technique; ultrasound calibration; ultrasound imaging