Design and fabrication of a low-frequency (1-3 MHz) ultrasound transducer for accurate placement of screw implants in the spine

Amir Manbachi, Mike Lee, F. Stuart Foster, Howard J. Ginsberg, Richard S.C. Cobbold

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Scopus citations


In 2012 approximately 800,000 spinal fusion surgeries were performed in the United States, requiring the insertion of screws into the pedicles. Their exact placement is critical and made complex due to limited visibility of the spine, continuous bleeding in the exposed regions, and variability in morphologies. The alarmingly high rate of screw misplacements (up to 20%) reported in the literature is of major concern since such misplacements can place the surrounding vital structures at risk. A potential guidance method for determining the best screw trajectory is by the use of real-time ultrasound imaging similar to that used for intravascular imaging. An endovascular transducer could be inserted into the pedicle to image the anatomy from within and identify bone boundaries. A major challenge of imaging within bone is high signal attenuation. The rapid increase of attenuation with frequency requires much lower frequencies (1-3 MHz) than those used in intravascular imaging. This study describes the custom design and fabrication of 2 MHz ultrasound probes (3.5 mm diameter/11 Fr) for pedicle screw guidance. Three transducer designs are explored to provide improved sensitivity and signal to noise ratio, compared to the previously tested transducer within the pedicle. Experimental measurements are compared with the results obtained using various simulation tools. The work reported in this paper represents the first stage in our ultimate goal of developing a 32-element phased array that is capable of generating a radial B-mode image.

Original languageEnglish (US)
Title of host publicationMedical Imaging 2014
Subtitle of host publicationUltrasonic Imaging and Tomography
ISBN (Print)9780819498335
StatePublished - 2014
Externally publishedYes
EventMedical Imaging 2014: Ultrasonic Imaging and Tomography - San Diego, CA, United States
Duration: Feb 18 2014Feb 20 2014

Publication series

NameProgress in Biomedical Optics and Imaging - Proceedings of SPIE
ISSN (Print)1605-7422


OtherMedical Imaging 2014: Ultrasonic Imaging and Tomography
Country/TerritoryUnited States
CitySan Diego, CA


  • Bandwidth
  • Bone sonography
  • Composite transducers
  • Design
  • Fabrication
  • Pedicle screw
  • Screw implants
  • Sensitivity
  • Spine surgery
  • Ultrasound transducer

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Atomic and Molecular Physics, and Optics
  • Radiology Nuclear Medicine and imaging


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