In vitro comparative study of vibro-acoustography versus pulse-echo ultrasound in imaging permanent prostate brachytherapy seeds

F. G. Mitri, B. J. Davis, J. F. Greenleaf, M. Fatemi

Research output: Contribution to journalArticle

30 Scopus citations

Abstract

Background: Permanent prostate brachytherapy (PPB) is a common treatment for early stage prostate cancer. While the modern approach using trans-rectal ultrasound guidance has demonstrated excellent outcome, the efficacy of PPB depends on achieving complete radiation dose coverage of the prostate by obtaining a proper radiation source (seed) distribution. Currently, brachytherapy seed placement is guided by trans-rectal ultrasound imaging and fluoroscopy. A significant percentage of seeds are not detected by trans-rectal ultrasound because certain seed orientations are invisible making accurate intra-operative feedback of radiation dosimetry very difficult, if not impossible. Therefore, intra-operative correction of suboptimal seed distributions cannot easily be done with current methods. Vibro-acoustography (VA) is an imaging modality that is capable of imaging solids at any orientation, and the resulting images are speckle free. Objective and methods: The purpose of this study is to compare the capabilities of VA and pulse-echo ultrasound in imaging PPB seeds at various angles and show the sensitivity of detection to seed orientation. In the VA experiment, two intersecting ultrasound beams driven at f1 = 3.00 MHz and f2 = 3.020 MHz respectively were focused on the seeds attached to a latex membrane while the amplitude of the acoustic emission produced at the difference frequency 20 kHz was detected by a low frequency hydrophone. Results: Finite element simulations and results of experiments conducted under well-controlled conditions in a water tank on a series of seeds indicate that the seeds can be detected at any orientation with VA, whereas pulse-echo ultrasound is very sensitive to the seed orientation. Conclusion: It is concluded that vibro-acoustography is superior to pulse-echo ultrasound for detection of PPB seeds.

Original languageEnglish (US)
Pages (from-to)31-38
Number of pages8
JournalUltrasonics
Volume49
Issue number1
DOIs
StatePublished - Jan 2009

Keywords

  • Acoustic emission
  • Brachytherapy
  • Finite element
  • Pulse-echo
  • Ultrasound imaging
  • Vibro-acoustography

ASJC Scopus subject areas

  • Acoustics and Ultrasonics

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