In vivo liver tracking with a high volume rate 4D ultrasound scanner and a 2D matrix array probe.
Bell, MA, Byram, BC, Harris, EJ, Evans, PM and Bamber, JC (2012) In vivo liver tracking with a high volume rate 4D ultrasound scanner and a 2D matrix array probe. Phys Med Biol, 57 (5). pp. 1359-1374.
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The effectiveness of intensity-modulated radiation therapy (IMRT) is compromised by involuntary motion (e.g. respiration, cardiac activity). The feasibility of processing ultrasound echo data to automatically estimate 3D liver motion for real-time IMRT guidance was previously demonstrated, but performance was limited by an acquisition speed of 2 volumes per second due to hardware restrictions of a mechanical linear array probe. Utilizing a 2D matrix array probe with parallel receive beamforming offered increased acquisition speeds and an opportunity to investigate the benefits of higher volume rates. In vivo livers of three volunteers were scanned with and without respiratory motion at volume rates of 24 and 48 Hz, respectively. Respiration was suspended via voluntary breath hold. Correlation-based, phase-sensitive 3D speckle tracking was applied to consecutively acquired volumes of echo data. Volumes were omitted at fixed intervals and 3D speckle tracking was re-applied to study the effect of lower scan rates. Results revealed periodic motion that corresponded with the heart rate or breathing cycle in the absence or presence of respiration, respectively. For cardiac-induced motion, volume rates for adequate tracking ranged from 8 to 12 Hz and was limited by frequency discrepancies between tracking estimates from higher and lower frequency scan rates. Thus, the scan rate of volume data acquired without respiration was limited by the need to sample the frequency induced by the beating heart. In respiratory-dominated motion, volume rate limits ranged from 4 to 12 Hz, interpretable from the root-mean-squared deviation (RMSD) from tracking estimates at 24 Hz. While higher volume rates yielded RMSD values less than 1 mm in most cases, lower volume rates yielded RMSD values of 2-6 mm.
|Divisions :||Faculty of Engineering and Physical Sciences > Electronic Engineering > Centre for Vision Speech and Signal Processing|
|Date :||7 March 2012|
|Identification Number :||10.1088/0031-9155/57/5/1359|
|Uncontrolled Keywords :||Cardiovascular System, Humans, Image Processing, Computer-Assisted, Imaging, Three-Dimensional, Liver, Motion, Radiotherapy, Intensity-Modulated, Reproducibility of Results, Respiration, Time Factors, Ultrasonography|
|Additional Information :||Copyright 2012 Institute of Physics. This is the author's accepted manuscript.|
|Depositing User :||Symplectic Elements|
|Date Deposited :||29 Jan 2013 10:32|
|Last Modified :||23 Sep 2013 19:53|
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