Mitri FG, Davis BJ, Greenleaf JF, Fatemi M. In vitro comparative study of
vibro-acoustography versus pulse-echo ultrasound in imaging permanent prostate brachytherapy seeds.
Ultrasonics 2009;
49:31-8. [PMID:
18538365 PMCID:
PMC2828366 DOI:
10.1016/j.ultras.2008.04.008]
[Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2008] [Revised: 04/08/2008] [Accepted: 04/11/2008] [Indexed: 05/13/2023]
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 f(1)=3.00 MHz and f(2)=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.
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