Toward <i>in vivo</i> dosimetry in external beam radiotherapy using x‐ray acoustic computed tomography: A soft‐tissue phantom study validation

Lei, Hao; Zhang, Wei; Oraiqat, Ibrahim; Liu, Zhipeng; Ni, Jun; Wang, Xueding; Naqa, Issam El

doi:10.1002/mp.13070

Cited by 27 publications

(46 citation statements)

References 36 publications

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“…where C v is specific heat capacity, and λ is the thermal conductivity. Following our previous approach, 13 this can be rewritten as:…”

Section: A Theorymentioning

confidence: 99%

“…Ionizing radiation acoustic imaging (iRAI) is an emerging medical imaging and real-time dosimetry modality that allows for such online in vivo deep tissue dosimetry. 13,14 As ionizing radiation from the linac goes through tissue, it is attenuated, depositing energy. This absorbed energy, which is quantified as dose, in the targeted tissue will cause local, transient temperature rise in the irradiated volume.…”

Section: Introductionmentioning

confidence: 99%

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An ionizing radiation acoustic imaging (iRAI) technique for real‐time dosimetric measurements for FLASH radiotherapy

et al. 2020

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Purpose: FLASH radiotherapy (FLASH-RT) is a novel irradiation modality with ultra-high dose rates (>40 Gy/s) that have shown tremendous promise for its ability to enhance normal tissue sparing while maintaining comparable tumor cell eradication toconventional radiotherapy (CONV-RT). Due to its extremely high dose rates, clinical translation of FLASH-RT is hampered by risky delivery and current limitations in dosimetric devices, which cannot accurately measure, in real time, dose at deeper tissue. This work aims to investigate ionizing radiation acoustic imaging (iRAI) as a promising image-guidance modality for real-time deep tissue dose measurements during FLASH-RT. The underlying hypothesis is that iRAI can enable mapping of dose deposition with respect to surrounding tissue with a single linear accelerator (linac) pulse precision in real time. In this work, the relationship between iRAI signal response and deposited dose was investigated as well as the feasibility of using a proof-of-concept dual-modality imaging system of ultrasound and iRAI for treatment beam co-localization with respect to underlying anatomy. Methods: Two experimental setups were used to study the feasibility of iRAI for FLASH-RT using 6 MeV electrons from a modified Varian Clinac. First, experiments were conducted using a single element focused transducer to take a series of point measurements in a gelatin phantom, which was compared with independent dose measurements using GAFchromic film. Secondly, an ultrasound and iRAI dual-modality imaging system utilizing a phased array transducer was used to take coregistered two-dimensional (2D) iRAI signal amplitude images as well as ultrasound B-mode images, to map the dose deposition with respect to surrounding anatomy in an ex vivo rabbit liver model with a single linac pulse precision. Results: Using a single element transducer, iRAI measurements showed a highly linear relationship between the iRAI signal amplitude and the linac dose per pulse (r 2 = 0.9998) with a repeatability precision of 1% and a dose resolution error <2.5% in a homogenous phantom when compared to GAFchromic film dose measurements. These phantom results were used to develop a calibration curve between the iRAI signal response and the delivered dose per pulse. Subsequently, a normalized depth dose curve was generated that agreed with film measurements with an RMSE of 0.0243, using correction factors to account for deviations in measurement conditions with respect to calibration. Experiments on the ex-vivo rabbit liver model demonstrated that a 2D iRAI image could be generated successfully from a single linac pulse, which was fused with the B-mode ultrasound image to provide information about the beam position with respect to surrounding anatomy in real time.

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“…where C v is specific heat capacity, and λ is the thermal conductivity. Following our previous approach, 13 this can be rewritten as:…”

Section: A Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

An ionizing radiation acoustic imaging (iRAI) technique for real‐time dosimetric measurements for FLASH radiotherapy

et al. 2020

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“…13,14 X-ray acoustic computed tomography has been proposed as an in vivo dosimetry tool and has been investigated by several different groups. [15][16][17][18][19] It has been discovered that XACT signals are linearly proportional to x-ray dose deposition. 15 Initial studies applying XACT to linear accelerator (LINAC) photon beam dosimetry focused on the detection of the acoustic waves induced following the irradiation of metal blocks, due to the high Gr€ uneisen coefficient of metals.…”

Section: Introductionmentioning

confidence: 99%

“…20 Recently, XACT with biological tissue phantoms as a sample has been demonstrated by Lei et al on veal liver. 17 In their study, the authors employed conventional ultrasound imaging combined with XACT imaging. The beam intensity and its position relative to the fat tissue mass was clearly visible, and beam alignment could be monitored in addition to dose distribution, representing the first XACT deployment in a biological sample.…”

Section: Introductionmentioning

confidence: 99%

“…However, it currently takes tens of minutes to get a two-dimensional (2D) image with the current XACT imaging system, which renders real-time mapping of the dose during radiation therapy impossible. [15][16][17]21 In this paper, we developed a simulation workflow to assess the ability of XACT to act as a 3D in vivo dosimetry tool for SPBI. First, the radiation dose distribution in the 3D digital breast phantom was converted to an initial pressure distribution using thermoacoustic equations.…”

Section: Introductionmentioning

confidence: 99%

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X‐ray‐induced acoustic computed tomography for guiding prone stereotactic partial breast irradiation: a simulation study

et al. 2020

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The aim of this study is to investigate the feasibility of x-ray-induced acoustic computed tomography (XACT) as an image guidance tool for tracking x-ray beam location and monitoring radiation dose delivered to the patient during stereotactic partial breast irradiation (SPBI). Methods: An in-house simulation workflow was developed to assess the ability of XACT to act as an in vivo dosimetry tool for SPBI. To evaluate this simulation workflow, a three-dimensional (3D) digital breast phantom was created by a series of two-dimensional (2D) breast CT slices from a patient. Three different tissue types (skin, adipose tissue, and glandular tissue) were segmented and the postlumpectomy seroma was simulated inside the digital breast phantom. A treatment plan was made with three beam angles to deliver radiation dose to the seroma in breast to simulate SPBI. The three beam angles for 2D simulations were 17°, 90°and 159°(couch angles were 0 degrees) while the angles were 90 degrees (couch angles were 0°, 27°, 90°) in 3D simulation. A multi-step simulation platform capable of modelling XACT was developed. First, the dose distribution was converted to an initial pressure distribution. The propagation of this pressure disturbance in the form of induced acoustic waves was then modeled using the k-wave MATLAB toolbox. The waves were then detected by a hemispherical-shaped ultrasound transducer array (6320 transducer locations distributed on the surface of the breast). Finally, the time-varying pressure signals detected at each transducer location were used to reconstruct an image of the initial pressure distribution using a 3D time-reversal reconstruction algorithm. Finally, the reconstructed XACT images of the radiation beams were overlaid onto the structure breast CT. Results: It was found that XACT was able to reconstruct the dose distribution of SPBI in 3D. In the reconstructed 3D volumetric dose distribution, the average doses in the GTV (Gross Target Volume) and PTV (Planning Target Volume) were 86.15% and 80.89%, respectively. When compared to the treatment plan, the XACT reconstructed dose distribution in the GTV and PTV had a RMSE (root mean square error) of 2.408 % and 2.299 % over all pixels. The 3D breast XACT imaging reconstruction with time-reversal reconstruction algorithm can be finished within several minutes. Conclusions: This work explores the feasibility of using the novel imaging modality of XACT as an in vivo dosimeter for SPBI radiotherapy. It shows that XACT imaging can provide the x-ray beam location and dose information in deep tissue during the treatment in real time in 3D. This study lays the groundwork for a variety of future studies related to the use of XACT as a dosimeter at different cancer sites.

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Imaging approaches for monitoring three‐dimensional cell and tissue culture systems

Hilzenrat

Gill

McArthur

2022

Journal of Biophotonics

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The past decade has seen an increasing demand for more complex, reproducible and physiologically relevant tissue cultures that can mimic the structural and biological features of living tissues. Monitoring the viability, development and responses of such tissues in real‐time are challenging due to the complexities of cell culture physical characteristics and the environments in which these cultures need to be maintained in. Significant developments in optics, such as optical manipulation, improved detection and data analysis, have made optical imaging a preferred choice for many three‐dimensional (3D) cell culture monitoring applications. The aim of this review is to discuss the challenges associated with imaging and monitoring 3D tissues and cell culture, and highlight topical label‐free imaging tools that enable bioengineers and biophysicists to non‐invasively characterise engineered living tissues.

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Toward in vivo dosimetry in external beam radiotherapy using x‐ray acoustic computed tomography: A soft‐tissue phantom study validation

Cited by 27 publications

References 36 publications

An ionizing radiation acoustic imaging (iRAI) technique for real‐time dosimetric measurements for FLASH radiotherapy

An ionizing radiation acoustic imaging (iRAI) technique for real‐time dosimetric measurements for FLASH radiotherapy

X‐ray‐induced acoustic computed tomography for guiding prone stereotactic partial breast irradiation: a simulation study

Imaging approaches for monitoring three‐dimensional cell and tissue culture systems

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