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Wang S, Gonzalez G, Owen DR, Sun L, Liu Y, Zwart T, Chen Y, Xiang L. Toward real-time, volumetric dosimetry for FLASH-capable clinical synchrocyclotrons using protoacoustic imaging. Med Phys 2024. [PMID: 39073707 DOI: 10.1002/mp.17318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 06/27/2024] [Accepted: 06/27/2024] [Indexed: 07/30/2024] Open
Abstract
BACKGROUND Fast low angle shot hyperfractionation (FLASH) radiotherapy (RT) holds promise for improving treatment outcomes and reducing side effects but poses challenges in radiation delivery accuracy due to its ultra-high dose rates. This necessitates the development of novel imaging and verification technologies tailored to these conditions. PURPOSE Our study explores the effectiveness of proton-induced acoustic imaging (PAI) in tracking the Bragg peak in three dimensions and in real time during FLASH proton irradiations, offering a method for volumetric beam imaging at both conventional and FLASH dose rates. METHODS We developed a three-dimensional (3D) PAI technique using a 256-element ultrasound detector array for FLASH dose rate proton beams. In the study, we tested protoacoustic signal with a beamline of a FLASH-capable synchrocyclotron, setting the distal 90% of the Bragg peak around 35 mm away from the ultrasound array. This configuration allowed us to assess various total proton radiation doses, maintaining a consistent beam output of 21 pC/pulse. We also explored a spectrum of dose rates, from 15 Gy/s up to a FLASH rate of 48 Gy/s, by administering a set number of pulses. Furthermore, we implemented a three-dot scanning beam approach to observe the distinct movements of individual Bragg peaks using PAI. All these procedures utilized a proton beam energy of 180 MeV to achieve the maximum possible dose rate. RESULTS Our findings indicate a strong linear relationship between protoacoustic signal amplitudes and delivered doses (R2 = 0.9997), with a consistent fit across different dose rates. The technique successfully provided 3D renderings of Bragg peaks at FLASH rates, validated through absolute Gamma index values. CONCLUSIONS The protoacoustic system demonstrates effectiveness in 3D visualization and tracking of the Bragg peak during FLASH proton therapy, representing a notable advancement in proton therapy quality assurance. This method promises enhancements in protoacoustic image guidance and real-time dosimetry, paving the way for more accurate and effective treatments in ultra-high dose rate therapy environments.
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Affiliation(s)
- Siqi Wang
- The Department of Biomedical Engineering, University of California, Irvine, California, USA
| | - Gilberto Gonzalez
- Department of Radiation Oncology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | | | - Leshan Sun
- The Department of Biomedical Engineering, University of California, Irvine, California, USA
| | - Yan Liu
- Mevion Medical Systems, Littleton, Massachusetts, USA
| | | | - Yong Chen
- Department of Radiation Oncology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Liangzhong Xiang
- The Department of Biomedical Engineering, University of California, Irvine, California, USA
- Beckman Laser Institute & Medical Clinic, University of California, Irvine, California, USA
- Department of Radiological Sciences, University of California, Irvine, California, USA
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Sueyasu S, Kasamatsu K, Takayanagi T, Chen Y, Kuriyama Y, Ishi Y, Uesugi T, Rohringer W, Unlu MB, Kudo N, Yokokawa K, Takao S, Miyamoto N, Matsuura T. Technical note: Application of an optical hydrophone to ionoacoustic range detection in a tissue-mimicking agar phantom. Med Phys 2024; 51:5130-5141. [PMID: 38127935 DOI: 10.1002/mp.16892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 11/07/2023] [Accepted: 11/29/2023] [Indexed: 12/23/2023] Open
Abstract
BACKGROUND Ionoacoustics is a promising approach to reduce the range uncertainty in proton therapy. A miniature-sized optical hydrophone (OH) was used as a measuring device to detect weak ionoacoustic signals with a high signal-to-noise ratio in water. However, further development is necessary to prevent wave distortion because of nearby acoustic impedance discontinuities while detection is conducted on the patient's skin. PURPOSE A prototype of the probe head attached to an OH was fabricated and the required dimensions were experimentally investigated using a 100-MeV proton beam from a fixed-field alternating gradient accelerator and k-Wave simulations. The beam range of the proton in a tissue-mimicking phantom was estimated by measuring γ-waves and spherical ionoacoustic waves with resonant frequency (SPIRE). METHODS Four sizes of probe heads were fabricated from agar blocks for the OH. Using the prototype, the γ-wave was detected at distal and lateral positions to the Bragg peak on the phantom surface for proton beams delivered at seven positions. For SPIRE, independent measurements were performed at distal on- and off-axis positions. The range positions were estimated by solving the linear equation using the sensitive matrix for the γ-wave and linear fitting of the correlation curve for SPIRE; they were compared with those measured using a film. RESULTS The first peak of the γ-wave was undistorted with the 3 × 3 × 3-cm3 probe head used at the on-axis and 3-cm off-axis positions. The range positions estimated by the γ-wave agreed with the film-based range in the depth direction (the maximum deviation was 0.7 mm), although a 0.6-2.1 mm deviation was observed in the lateral direction. For SPIRE, the deviation was <1 mm for the two measurement positions. CONCLUSIONS The attachment of a relatively small-sized probe head allowed the OH to measure the beam range on the phantom surface.
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Affiliation(s)
- Shota Sueyasu
- Graduate School of Engineering, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Koki Kasamatsu
- Graduate School of Biomedical Science and Engineering, Hokkaido University, Sapporo, Hokkaido, Japan
- Institute for Quantum Medical Science, Quantum Life and Medical Science Directorate, National Institutes for Quantum Science and Technology (QST), Chiba, Japan
| | - Taisuke Takayanagi
- Hitachi Ltd, Research and Development Group, Center for Technology Innovation-Energy, Hitachi-shi, Ibaraki, Japan
| | - Ye Chen
- Faculty of Engineering, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Yasutoshi Kuriyama
- Institute for Integrated Radiation and Nuclear Science, Kyoto University, Osaka, Japan
| | - Yoshihiro Ishi
- Institute for Integrated Radiation and Nuclear Science, Kyoto University, Osaka, Japan
| | - Tomonori Uesugi
- Institute for Integrated Radiation and Nuclear Science, Kyoto University, Osaka, Japan
| | | | - Mehmet Burcin Unlu
- Faculty of Engineering, Hokkaido University, Sapporo, Hokkaido, Japan
- Faculty of Engineering, Ozyegin University, Istanbul, Turkey
- Faculty of Aviation and Aeronautical Sciences, Ozyegin University, Istanbul, Turkey
| | - Nobuki Kudo
- Faculty of Information Science and Technology, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Kohei Yokokawa
- Faculty of Engineering, Hokkaido University, Sapporo, Hokkaido, Japan
- Department of Medical Physics, Hokkaido University Hospital, Sapporo, Hokkaido, Japan
| | - Seishin Takao
- Faculty of Engineering, Hokkaido University, Sapporo, Hokkaido, Japan
- Department of Medical Physics, Hokkaido University Hospital, Sapporo, Hokkaido, Japan
| | - Naoki Miyamoto
- Faculty of Engineering, Hokkaido University, Sapporo, Hokkaido, Japan
- Department of Medical Physics, Hokkaido University Hospital, Sapporo, Hokkaido, Japan
| | - Taeko Matsuura
- Faculty of Engineering, Hokkaido University, Sapporo, Hokkaido, Japan
- Department of Medical Physics, Hokkaido University Hospital, Sapporo, Hokkaido, Japan
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