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Dong S, Sun J, Ming X, Weber U, Schuy C, Hu W, Sheng Y. Development of porous structure for broadening Bragg-peak in scanning carbon-ion radiotherapy: Monte Carlo simulation and experimental validation. Phys Med 2024; 120:103325. [PMID: 38493583 DOI: 10.1016/j.ejmp.2024.103325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 01/15/2024] [Accepted: 03/04/2024] [Indexed: 03/19/2024] Open
Abstract
PURPOSE The present study aimed to develop a porous structure with plug-ins (PSP) to broaden the Bragg peak width (BPW, defined as the distance in water between the proximal and distal 80% dose) of the carbon ion beam while maintaining a sharp distal falloff width (DFW, defined as the distance along the beam axis where the dose in water reduces from 80% to 20%). METHODS The binary voxel models of porous structure (PS) and PSP were established in the Monte Carlo code FLUKA and the corresponding physical models were manufactured by 3D printing. Both experiment and simulation were performed for evaluating the modulation capacity of PS and PSP. BPWs and DFWs derived from each integral depth dose curves were compared. Fluence homogeneity of 430 MeV/u carbon-ion beam passing through the PSP was recorded by analyzing radiochromic films at six different locations downstream the PSP in the experiment. Additionally, by changing the beam spot size and incident position on the PSP, totally 48 different carbon-ion beams were simulated and corresponding deviations of beam metrics were evaluated to test the modulating stability of PSP. RESULTS According to the measurement data, the use of PSP resulted in an average increase of 0.63 mm in BPW and a decrease of 0.74 mm in DFW compared to PS. The 2D radiation field inhomogeneities were lower than 3 % when the beam passing through a ≥ 10 cm PMMA medium. Furthermore, employing a spot size of ≥ 6 mm ensures that beam metric deviations, including BPW, DFW, and range, remain within a deviation of 0.1 mm across various incident positions. CONCLUSION The developed PSP demonstrated its capability to effectively broaden the BPW of carbon ion beams while maintaining a sharp DFW comparing to PS. The superior performance of PSP, indicates its potential for clinical use in the future.
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Affiliation(s)
- Sixue Dong
- Department of Medical Physics, Shanghai Proton and Heavy Ion Center, Fudan University Cancer Hospital, Shanghai 201315, China; Shanghai Key Laboratory of radiation oncology(20dz2261000); Shanghai Engineering Research Center of Proton and Heavy Ion Radiation Therapy
| | - Jiayao Sun
- Department of Medical Physics, Shanghai Proton and Heavy Ion Center, Fudan University Cancer Hospital, Shanghai 201315, China; Shanghai Key Laboratory of radiation oncology(20dz2261000); Shanghai Engineering Research Center of Proton and Heavy Ion Radiation Therapy
| | - Xue Ming
- Department of Medical Physics, Shanghai Proton and Heavy Ion Center, Fudan University Cancer Hospital, Shanghai 201315, China; Shanghai Key Laboratory of radiation oncology(20dz2261000); Shanghai Engineering Research Center of Proton and Heavy Ion Radiation Therapy
| | - Uli Weber
- Biophysics GSI Helmholtz Center for Heavy Ion Research GmbH, Darmstadt, Germany
| | - Christoph Schuy
- Biophysics GSI Helmholtz Center for Heavy Ion Research GmbH, Darmstadt, Germany
| | - Weigang Hu
- Shanghai Key Laboratory of radiation oncology(20dz2261000); Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Shanghai 200032, China; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China; Shanghai Clinical Research Center for Radiation Oncology.
| | - Yinxiangzi Sheng
- Department of Medical Physics, Shanghai Proton and Heavy Ion Center, Fudan University Cancer Hospital, Shanghai 201315, China; Shanghai Key Laboratory of radiation oncology(20dz2261000); Shanghai Engineering Research Center of Proton and Heavy Ion Radiation Therapy.
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Gungor Price GM, Sarigul N. The effect of voxelization in Monte Carlo simulation to validate Bragg peak characteristics for a pencil proton beam. Rep Pract Oncol Radiother 2023; 28:102-113. [PMID: 37122904 PMCID: PMC10132192 DOI: 10.5603/rpor.a2023.0007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 02/06/2023] [Indexed: 05/02/2023] Open
Abstract
Background The purpose of this research was to show how the Bragg peak (BP) characteristics were affected by changing the voxel size in longitudinal and transverse directions in Monte Carlo (MC) simulations by using Geant4 and to calculate BP characteristics accurately by considering the voxel size effect for 68 MeV and 235.81 MeV. Materials and methods Different interpolation techniques were applied to simulation data to find the closest results to the experimental data. Results When the x-size of the voxel was increased 2 times at low energy, the maximum dose increase in the entrance and plateau regions were 17.8% and 17%, respectively, while BP curve shifted to the shallower region, resulting in a 0.5 mm reduction in the curable tumor width (W80pd). At high energy, the maximum dose increase at the entrance and plateau regions were 0.4% and 0.6%, respectively, while it was observed that W80pd did not change. When the y-z sizes of the voxel were increased 2 times at low energy, the maximum dose reduction at the entrance and plateau regions was 3.4%, but no change was observed in W80pd. At high energy, when the y-z sizes of the voxel were increased 2.2 times, the maximum dose reduction at the entrance and plateau regions were 8.9% and 9.1%, respectively, while W80pd increased by 0.5 mm. When linear, cubic spline, and Akima interpolations were applied to the simulation data, it was found that the results closest to the experimental data were obtained for Akima interpolations for both energies. Conclusion it has been shown that the voxel size effect for the longitudinal direction was more effective at low energy than at high energy. However, the voxel size effect for the transverse direction was more effective for high energy.
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Affiliation(s)
- Gumec M Gungor Price
- Arts-Sciences Faculty, Physics Department, Cukurova University, Saricam, Adana, Türkiye
| | - Neslihan Sarigul
- Institute of Nuclear Science, Hacettepe University, Ankara Türkiye
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Fuse H, Otsuki S, Fujisaki T, Yasue K, Hanada K, Tomita F, Abe S. Verification of morphological and physical properties for the development of a lung substitute phantom using microspheres. Rev Sci Instrum 2022; 93:064101. [PMID: 35778036 DOI: 10.1063/5.0090471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 05/07/2022] [Indexed: 06/15/2023]
Abstract
This paper proposes a new concept of phantom development, along with the utilization of new materials that can reproduce lung morphology and density. A lung substitute phantom using microspheres was fabricated; then, its dosimetric utility in radiotherapy was investigated, during which the density was adjusted to closely resemble the morphology of the actual human lung. Microspheres were used to reproduce alveoli, which are the main components of the lung. By changing the ratio of urethane, which is commonly used in soft tissue phantoms, to microspheres, we reproduced the density change of the lungs due to respiration. Here, we fabricated two slab-like lung substitutes to emulate commercially used phantoms. Although there is room for improvement in terms of practicality, the substitutes were easy to fabricate. Microscopic observation of the cut surface of the phantoms showed that the morphology of the phantoms mimicked the alveoli more faithfully than commercial phantoms. Furthermore, to compensate for the energy-independent mass attenuation and mass collision inhibition ability required by the tissue substitute phantom, we examined the physical properties of the phantom and confirmed that there was negligible energy dependence.
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Affiliation(s)
- Hiraku Fuse
- Department of Radiological Sciences, Ibaraki Prefectural University of Health Sciences, 4669-2, Ami-machi, Inashiki-gun, Ibaraki 300-3094, Japan
| | - Shohei Otsuki
- Department of Radiological Sciences, Ibaraki Prefectural University of Health Sciences, 4669-2, Ami-machi, Inashiki-gun, Ibaraki 300-3094, Japan
| | - Tatsuya Fujisaki
- Department of Radiological Sciences, Ibaraki Prefectural University of Health Sciences, 4669-2, Ami-machi, Inashiki-gun, Ibaraki 300-3094, Japan
| | - Kenji Yasue
- Graduate School of Health Sciences, Department of Radiological Sciences, Ibaraki Prefectural University of Health Sciences, 4669-2, Ami-machi, Inashiki-gun, Ibaraki 300-3094, Japan
| | - Koichi Hanada
- Graduate School of Health Sciences, Department of Radiological Sciences, Ibaraki Prefectural University of Health Sciences, 4669-2, Ami-machi, Inashiki-gun, Ibaraki 300-3094, Japan
| | - Fumihiro Tomita
- Graduate School of Health Sciences, Department of Radiological Sciences, Ibaraki Prefectural University of Health Sciences, 4669-2, Ami-machi, Inashiki-gun, Ibaraki 300-3094, Japan
| | - Shinji Abe
- Department of Radiological Sciences, Ibaraki Prefectural University of Health Sciences, 4669-2, Ami-machi, Inashiki-gun, Ibaraki 300-3094, Japan
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Taphorn K, Mechlem K, Sellerer T, De Marco F, Viermetz M, Pfeiffer F, Pfeiffer D, Herzen J. Direct Differentiation of Pathological Changes in the Human Lung Parenchyma With Grating-Based Spectral X-ray Dark-Field Radiography. IEEE Trans Med Imaging 2021; 40:1568-1578. [PMID: 33617451 DOI: 10.1109/tmi.2021.3061253] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Diagnostic lung imaging is often associated with high radiation dose and lacks sensitivity, especially for diagnosing early stages of structural lung diseases. Therefore, diagnostic imaging methods are required which provide sound diagnosis of lung diseases with a high sensitivity as well as low patient dose. In small animal experiments, the sensitivity of grating-based X-ray dark-field imaging to structural changes in the lung tissue was demonstrated. The energy-dependence of the X-ray dark-field signal of lung tissue is a function of its microstructure and not yet known. Furthermore, conventional X-ray dark-field imaging is not capable of differentiating different types of pathological changes, such as fibrosis and emphysema. Here we demonstrate the potential diagnostic power of grating-based X-ray dark-field in combination with spectral imaging in human chest radiography for the direct differentiation of lung diseases. We investigated the energy-dependent linear diffusion coefficient of simulated lung tissue with different diseases in wave-propagation simulations and validated the results with analytical calculations. Additionally, we modeled spectral X-ray dark-field chest radiography scans to exploit these differences in energy-dependency. The results demonstrate the potential to directly differentiate structural changes in the human lung. Consequently, grating-based spectral X-ray dark-field imaging potentially contributes to the differential diagnosis of structural lung diseases at a clinically relevant dose level.
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Hranek A, Resch AF, Georg D, Knäusl B. Investigation of the Bragg peak degradation caused by homogeneous and heterogeneous lung tissue substitutes: proton beam experiments and comparison to current clinical dose calculation. Phys Med Biol 2020; 65. [PMID: 33171454 DOI: 10.1088/1361-6560/abc938] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 11/10/2020] [Indexed: 12/25/2022]
Abstract
Submillimetre structures of lung tissue are not represented in computed tomography images used for radiotherapeutic dose calculation. In order to study the effect experimentally, lung substitutes with properties similar to lung tissue were chosen, namely two types of commercial lung tissue equivalent plates (LTEPs) (CIRS, USA), two types of cork, balsawood, floral foam and konjac sponge. Laterally integrated dose profiles were measured as a function of depth for proton pencil beams (PBs) with an initial nominal energy of 97.4 and 148.2 MeV, respectively. The obtained dose profiles were investigated for their shifting and degradation of the Bragg peak (BP) caused by the materials, expressed as water equivalent thickness (WET) and full width half maximum. The set-up was simulated in the treatment planning system (TPS) RayStation using the Monte Carlo (MC) dose calculation algorithm. While the WET between experiment and dose calculation agreed within 0.5 mm, except for floral foam, the full width half maximum was underestimated in the TPS by up to 2.3 mm. Normalisation to the same mass thickness of the lung substitutes allowed to classify LTEPs and balsawood as homogeneous and cork, floral foam and konjac sponge as heterogeneous materials. The material specific BP degradation was up to 3.4 times higher for the heterogeneous samples. The modulation power as a measure for the heterogeneity was compared to the spectrum of Hounsfield units (HU) of the materials. A clear correlation was not found, but with further improvements the HU spectrum may serve as an indicator for the material heterogeneity. Further, MC simulations of binary voxel models using GATE/Geant4 were performed to investigate the influence of grain size and mass density. For mass densities similar to lung tissue the BP degradation had a maximum at 3 and 7 mm grain size.
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Affiliation(s)
- A Hranek
- Division Medical Radiation Physics, Department of Radiation Oncology, Medical University of Vienna/AKH Vienna, Vienna, Austria
| | - A F Resch
- Division Medical Radiation Physics, Department of Radiation Oncology, Medical University of Vienna/AKH Vienna, Vienna, Austria
| | - D Georg
- Division Medical Radiation Physics, Department of Radiation Oncology, Medical University of Vienna/AKH Vienna, Vienna, Austria
| | - B Knäusl
- Division Medical Radiation Physics, Department of Radiation Oncology, Medical University of Vienna/AKH Vienna, Vienna, Austria.,MedAustron Center for Ion Therapy and Research, Wiener Neustadt, Austria
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