A CT based correction method for speed of sound aberration for ultrasound based image guided radiotherapy

Fontanarosa, Davide; Meer, Skadi van der; Harris, Emma; Verhaegen, Frank

doi:10.1118/1.3583475

Cited by 30 publications

(38 citation statements)

References 27 publications

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“…CT-informed corrections to the speed of sound may ameliorate inaccuracy due to human tissue heterogeneities. 25 The 5 mPa data reported here are averaged over 2048 averages, where each proton pulse contained ∼1.2 × 10 7 protons and deposited a dose of 1.9 cGy at the Bragg peak. This number of averages was unnecessarily high.…”

Section: Discussionmentioning

confidence: 99%

Experimental observation of acoustic emissions generated by a pulsed proton beam from a hospital‐based clinical cyclotron

et al. 2015

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Purpose: To measure the acoustic signal generated by a pulsed proton spill from a hospital-based clinical cyclotron. Methods: An electronic function generator modulated the IBA C230 isochronous cyclotron to create a pulsed proton beam. The acoustic emissions generated by the proton beam were measured in water using a hydrophone. The acoustic measurements were repeated with increasing proton current and increasing distance between detector and beam. Results: The cyclotron generated proton spills with rise times of 18 µs and a maximum measured instantaneous proton current of 790 nA. Acoustic emissions generated by the proton energy deposition were measured to be on the order of mPa. The origin of the acoustic wave was identified as the proton beam based on the correlation between acoustic emission arrival time and distance between the hydrophone and proton beam. The acoustic frequency spectrum peaked at 10 kHz, and the acoustic pressure amplitude increased monotonically with increasing proton current. Conclusions: The authors report the first observation of acoustic emissions generated by a proton beam from a hospital-based clinical cyclotron. When modulated by an electronic function generator, the cyclotron is capable of creating proton spills with fast rise times (18 µs) and high instantaneous currents (790 nA). Measurements of the proton-generated acoustic emissions in a clinical setting may provide a method for in vivo proton range verification and patient monitoring. C 2015 American Association of Physicists in Medicine. [http://dx

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Section: Discussionmentioning

confidence: 99%

Experimental observation of acoustic emissions generated by a pulsed proton beam from a hospital‐based clinical cyclotron

et al. 2015

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“…The Clarity 3DUS guidance system is a robust IGRT device that guides the patient to the correct treatment position under the following conditions: the metal markers are used for the registration of the CT; SOS aberrations are taken into account 12,15 in intermodality image fusion, and preferably also during the intramodality procedures (both US images); and the CT scan and (SOS corrected) US ref scan match. In the case of a mismatch, it is advised to rescan the patient with both CT and US ref in direct succession with good patient stabilization to prevent patient motion in between the scans.…”

Section: Resultsmentioning

confidence: 99%

Consequences of Intermodality Registration Errors for Intramodality 3D Ultrasound IGRT

Meer

Seravalli

Fontanarosa

et al. 2016

Technol Cancer Res Treat

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Intramodality ultrasound image-guided radiotherapy systems compare daily ultrasound to reference ultrasound images. Nevertheless, because the actual treatment planning is based on a reference computed tomography image, and not on a reference ultrasound image, their accuracy depends partially on the correct intermodality registration of the reference ultrasound and computed tomography images for treatment planning. The error propagation in daily patient positioning due to potential registration errors at the planning stage was assessed in this work. Five different scenarios were simulated involving shifts or rotations of ultrasound or computed tomography images. The consequences of several workflow procedures were tested with a phantom setup. As long as the reference ultrasound and computed tomography images are made to match, the patient will be in the correct treatment position. In an example with a phantom measurement, the accuracy of the performed manual fusion was found to be 2 mm. In clinical practice, manual registration of patient images is expected to be more difficult. Uncorrected mismatches will lead to a systematically incorrect final patient position because there will be no indication that there was a misregistration between the computed tomography and reference ultrasound images. In the treatment room, the fusion with the computed tomography image will not be visible and based on the ultrasound images the patient position seems correct.

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“…37 These DBT images might then be used to correct errors in the speed of sound images because of the approximately linear relationship between density from x rays and speed of sound of breast and other soft tissues. 41,42 Cross modality segmentation also offers promise. 43 As noted, the methods should work well with data from full, circular, cylindrical or spherical apertures.…”

Section: Discussionmentioning

confidence: 99%

Acoustic attenuation imaging of tissue bulk properties with a priori information

Hooi

Kripfgans

Carson

2016

The Journal of the Acoustical Society of America

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Attenuation of ultrasound waves traversing a medium is not only a result of absorption and scattering within a given tissue, but also of coherent scattering, including diffraction, refraction, and reflection of the acoustic wave at tissue boundaries. This leads to edge enhancement and other artifacts in most reconstruction algorithms, other than 3D wave migration with currently impractical, implementations. The presented approach accounts for energy loss at tissue boundaries by normalizing data based on variable sound speed, and potential density, of the medium using a k-space wave solver. Coupled with a priori knowledge of major sound speed distributions, physical attenuation values within broad ranges, and the assumption of homogeneity within segmented regions, an attenuation image representative of region bulk properties is constructed by solving a penalized weighted least squares optimization problem. This is in contradistinction to absorption or to conventional attenuation coefficient based on overall insertion loss with strong dependence on sound speed and impedance mismatches at tissue boundaries. This imaged property will be referred to as the bulk attenuation coefficient. The algorithm is demonstrated on an opposed array setup, with mean-squared-error improvements from 0.6269 to 0.0424 (dB/cm/MHz) 2 for a cylindrical phantom, and 0.1622 to 0.0256 (dB/cm/MHz) 2 for a windowed phantom.

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A CT based correction method for speed of sound aberration for ultrasound based image guided radiotherapy

Abstract: The SOS correction presented increases quantitative accuracy in US imaging which may lead to small but systematic improvements in patient positioning.

Cited by 30 publications

References 27 publications

Experimental observation of acoustic emissions generated by a pulsed proton beam from a hospital‐based clinical cyclotron

Experimental observation of acoustic emissions generated by a pulsed proton beam from a hospital‐based clinical cyclotron

Consequences of Intermodality Registration Errors for Intramodality 3D Ultrasound IGRT

Acoustic attenuation imaging of tissue bulk properties with a priori information

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