High Resolution X-ray-Induced Acoustic Tomography

Xiang, Liangzhong; Tang, Shanshan; Ahmad, Moiz; Li, Xing

doi:10.1038/srep26118

Cited by 57 publications

(83 citation statements)

References 25 publications

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“…While XACT using BP has been studied extensively due to its potential for relative dosimetry, it has not been studied for its potential for absolute dosimetry. By comparing results from both BP and ITR imaging algorithms for their accuracy in the dose reconstruction, we investigated the feasibility of using XACT imaging for absolute dosimetry.…”

Section: Discussionmentioning

confidence: 99%

“…Also, the effects of acoustic noise on the accuracy of dose reconstruction are not investigated in this work. While noise is an important problem in XA imaging, it can be suppressed by filtering techniques or averaging the signal from multiple measurement …”

Section: Discussionmentioning

confidence: 99%

“…Various groups have performed simulations of the XA signals generated from LINAC irradiation using a combination of Monte Carlo dose deposition simulations and 2D acoustic wave transport simulations. To the best of author's knowledge, all currently published works regarding XACT imaging modality use back projection (BP) techniques for 2D dose reconstruction which show potential for relative dosimetry . Here, we explored the potential of XA tomographic techniques for 3D absolute dosimetry.…”

Section: Introductionmentioning

confidence: 99%

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Simulation of x‐ray‐induced acoustic imaging for absolute dosimetry: Accuracy of image reconstruction methods

et al. 2020

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Purpose Three‐dimensional in‐vivo dose verification is one of the standing challenges in radiation therapy. X‐ray‐induced acoustic tomography has recently been proposed as an imaging method for use in in‐vivo dosimetry. The aim of this study was to investigate the accuracy of reconstructing three‐dimensional (3D) absolute dose using x‐ray‐induced acoustic tomography. We performed this investigation using two different tomographic dose reconstruction techniques. Methods Two examples of 3D dose reconstruction techniques for x‐ray acoustic imaging are investigated. Dose distributions are calculated for varying field sizes using a clinical treatment planning system. The induced acoustic pressure waves which are generated by the increase in temperature due to the absorption of pulsed MV x‐rays are simulated using an advanced numerical modeling package for acoustic wave propagation in the time domain. Two imaging techniques, back projection and iterative time reversal, are used to reconstruct the 3D dose distribution in a water phantom with open fields. Image analysis is performed and reconstructed depth dose curves from x‐ray acoustic imaging are compared to the depth dose curves calculated from the treatment planning system. Calculated field sizes from the reconstructed dose profiles by back projection and time reversal are compared to the planned field size to determine their accuracy. The iterative time reversal imaging technique is also used to reconstruct dose in an example clinical dose distribution. Image analysis of this clinical test case is performed using the gamma passing rate. In addition, gamma passing rates are used to validate the stopping criteria in the iterative time reversal method. Results Water phantom simulations showed that back projection does not adequately reconstruct the shape and intensity of the depth dose. When compared to the depth of maximum dose calculated by a treatment planning system, the maximum dose depth by back projection is shifted deeper by 55 and 75 mm for 4 × 4 cm and 10 × 10 cm field sizes, respectively. The reconstructed depth dose by iterative time reversal accurately agrees with the planned depth dose for a 4 × 4 cm field size and is shifted deeper by 12 mm for the 10 × 10 cm field size. When reconstructing field sizes, the back projection method leads to 18% and 35% larger sizes for the 4 × 4 cm and 10 × 10 cm fields, respectively, whereas the iterative time reversal method reconstructs both field sizes with < 2% error. For the clinical dose distribution, we were able to reconstruct the dose delivered by a 1 degree sub‐arc with a good accuracy. The reconstructed and planned doses were compared using gamma analysis, with> 96% gamma passing rate at 3%/2 mm. Conclusions Our results show that the 3D x‐ray acoustic reconstructed dose by iterative time reversal is considerably more accurate than the dose reconstructed by back projection. Iterative time reversal imaging has a potential for use in 3D absolute dosimetry.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Simulation of x‐ray‐induced acoustic imaging for absolute dosimetry: Accuracy of image reconstruction methods

et al. 2020

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“…They showed a preliminary demonstration of XACT by imaging a lead rod embedded in chicken breast tissue. XACT using pulsed x‐ray tubes in the keV energy range has also been recently proposed as a novel imaging modality, and a resolution of 350 μm has been achieved using a 60 ns x‐ray pulse …”

Section: Introductionmentioning

confidence: 99%

Experimental evaluation of x‐ray acoustic computed tomography for radiotherapy dosimetry applications

et al. 2017

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Purpose: The aim of this work was to experimentally demonstrate the feasibility of x-ray acoustic computed tomography (XACT) as a dosimetry tool in a clinical radiotherapy environment. Methods: The acoustic waves induced following a single pulse of linear accelerator irradiation in a water tank were detected with an immersion ultrasound transducer. By rotating the collimator and keeping the transducer stationary, acoustic signals at varying angles surrounding the field were detected and reconstructed to form an XACT image. Simulated XACT images were obtained using a previously developed simulation workflow. Profiles extracted from experimental and simulated XACT images were compared to profiles measured with an ion chamber. A variety of radiation field sizes and shapes were investigated. Results: XACT images resembling the geometry of the delivered radiation field were obtained for fields ranging from simple squares to more complex shapes. When comparing profiles extracted from simulated and experimental XACT images of a 4 cm 9 4 cm field, 97% of points were found to pass a 3%/3 mm gamma test. Agreement between simulated and experimental XACT images worsened when comparing fields with fine details. Profiles extracted from experimental XACT images were compared to profiles obtained through clinical ion chamber measurements, confirming that the intensity of XACT images is related to deposited radiation dose. Seventy-seven percent of the points in a profile extracted from an experimental XACT image of a 4 cm 9 4 cm field passed a 7%/4 mm gamma test when compared to an ion chamber measured profile. In a complicated puzzle-piece shaped field, 86% of the points in an XACT extracted profile passed a 7%/4 mm gamma test. Conclusions: XACT images with intensity related to the spatial distribution of deposited dose in a water tank were formed for a variety of field sizes and shapes. XACT has the potential to be a useful tool for absolute, relative and in vivo dosimetry.

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“…Recently, measurements by individual receivers with lateral and distal offsets from the Bragg peak were simulated with an eye towards range verification. A mathematically complete set of measurements including both lateral and distal offsets was simulated to demonstrate feasibility of dosimetry for ion therapy, and for x‐rays . Thermoacoustic emissions from 20 MeV pulses as short as 8 ns duration and microsecond‐duration pulses of protons with energies exceeding 200 MeV into water baths have been detected using single element piezoelectric transducers and hydrophones , respectively.…”

Section: Introductionmentioning

confidence: 99%

Two‐stage ionoacoustic range verification leveraging Monte Carlo and acoustic simulations to stably account for tissue inhomogeneity and accelerator–specific time structure – A simulation study

et al. 2017

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Ionoacoustic range verification may improve current practice. Ionoacoustic range estimates can be inherently co-registered to ultrasound images of underlying anatomy. To ensure estimates are robust in clinical practice, dose maps based upon the planning CT should be overlaid onto ultrasound volumes acquired at time of treatment and acoustic simulations re-computed to provide a database of control points and corresponding thermoacoustic emissions. Computation times for beamformed estimates are already fast enough for online range verification, but are not accurate enough for a measurement aperture limited to the surface of a transrectal ultrasound probe. Accelerated acoustic simulations will be required to enable online two-stage correction, but offline calculation is already suitable for adaptive planning.

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High Resolution X-ray-Induced Acoustic Tomography

Cited by 57 publications

References 25 publications

Simulation of x‐ray‐induced acoustic imaging for absolute dosimetry: Accuracy of image reconstruction methods

Simulation of x‐ray‐induced acoustic imaging for absolute dosimetry: Accuracy of image reconstruction methods

Experimental evaluation of x‐ray acoustic computed tomography for radiotherapy dosimetry applications

Two‐stage ionoacoustic range verification leveraging Monte Carlo and acoustic simulations to stably account for tissue inhomogeneity and accelerator–specific time structure – A simulation study

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