Susannah Hickling1, Hao Lei2, Maritza Hobson3, Pierre Léger3, Xueding Wang4, Issam El Naqa5. 1. Department of Physics and Medical Physics Unit, McGill University, Cedars Cancer Centre, Montreal, QC, Canada, H4A 3J1. 2. Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, 48109, USA. 3. Medical Physics Unit, McGill University Health Centre, Cedars Cancer Centre, Montreal, QC, H4A 3J1, Canada. 4. Departments of Radiology and Biomedical Engineering, University of Michigan, Ann Arbor, MI, 48109-0600, USA. 5. Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, 48103-4943, USA.
Abstract
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 × 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 × 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.
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 × 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 × 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.
Authors: Noora H Ba Sunbul; Wei Zhang; Ibrahim Oraiqat; Dale W Litzenberg; Kwok L Lam; Kyle Cuneo; Jean M Moran; Paul L Carson; Xueding Wang; Shaun D Clarke; Martha M Matuszak; Sara A Pozzi; Issam El Naqa Journal: Med Phys Date: 2021-09-08 Impact factor: 4.071
Authors: Mucong Li; Nikhila Nyayapathi; Hailey I Kilian; Jun Xia; Jonathan F Lovell; Junjie Yao Journal: Mol Imaging Date: 2020 Jan-Dec Impact factor: 3.250