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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] [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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Burg JM, Flatten V, Witt M, Derksen L, Weber U, Engenhart-Cabillic R, Vorwerk H, Zink K, Baumann KS. Experimental determination of modulation power of lung tissue for particle therapy. Phys Med Biol 2021; 66. [PMID: 34844221 DOI: 10.1088/1361-6560/ac3e0d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 11/29/2021] [Indexed: 12/25/2022]
Abstract
In particle therapy of lung tumors, modulating effects on the particle beam may occur due to the microscopic structure of the lung tissue. These effects are caused by the heterogeneous nature of the lung tissue and cannot be completely taken into account during treatment planning, because these micro structures are too small to be fully resolved in the planning CT. In several publications, a new material parameter called modulation power (Pmod) was introduced to characterize the effect. For various artificial lung surrogates, this parameter was measured and published by other groups and ranges up to approximately 1000μm. Studies investigating the influence of the modulation power on the dose distribution during irradiation are using this parameter in the rang of 100-800μm. More precise measurements forPmodon real lung tissue have not yet been published. In this work, the modulation power of real lung tissue was measured using porcine lungs in order to produce more reliable data ofPmodfor real lung tissue. For this purpose,ex-vivoporcine lungs were frozen in a ventilated state and measurements in a carbon ion-beam were performed. Due to the way the lungs were prepared and transferred to a solid state, the lung structures that modulate the beam could also be examined in detail using micro CT imaging. An optimization of the established methods of measuring the modulation power, which takes better account of the typical structures within lung tissue, was developed as well.
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Affiliation(s)
- Jan Michael Burg
- University of Applied Sciences Giessen, Institute of Medical Physics and Radiation Protection, Germany.,University Medical Center Giessen and Marburg, Department of Radiotherapy and Radiation Oncology, Germany
| | - Veronika Flatten
- University of Applied Sciences Giessen, Institute of Medical Physics and Radiation Protection, Germany.,University Medical Center Giessen and Marburg, Department of Radiotherapy and Radiation Oncology, Germany.,Marburg Ion-Beam Therapy Center, Marburg, Germany
| | - Matthias Witt
- University of Applied Sciences Giessen, Institute of Medical Physics and Radiation Protection, Germany.,University Medical Center Giessen and Marburg, Department of Radiotherapy and Radiation Oncology, Germany.,Marburg Ion-Beam Therapy Center, Marburg, Germany
| | - Larissa Derksen
- University of Applied Sciences Giessen, Institute of Medical Physics and Radiation Protection, Germany
| | - Uli Weber
- GSI Helmholtzzentrum für Schwerionenforschung, Biophysics Department, Darmstadt, Germany
| | - Rita Engenhart-Cabillic
- University Medical Center Giessen and Marburg, Department of Radiotherapy and Radiation Oncology, Germany.,Marburg Ion-Beam Therapy Center, Marburg, Germany
| | - Hilke Vorwerk
- University Medical Center Giessen and Marburg, Department of Radiotherapy and Radiation Oncology, Germany.,Marburg Ion-Beam Therapy Center, Marburg, Germany
| | - Klemens Zink
- University of Applied Sciences Giessen, Institute of Medical Physics and Radiation Protection, Germany.,University Medical Center Giessen and Marburg, Department of Radiotherapy and Radiation Oncology, Germany.,Marburg Ion-Beam Therapy Center, Marburg, Germany
| | - Kilian-Simon Baumann
- University of Applied Sciences Giessen, Institute of Medical Physics and Radiation Protection, Germany.,University Medical Center Giessen and Marburg, Department of Radiotherapy and Radiation Oncology, Germany.,Marburg Ion-Beam Therapy Center, Marburg, Germany
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Flatten V, Burg JM, Witt M, Derksen L, Fragoso Costa P, Wulff J, Bäumer C, Timmermann B, Weber U, Vorwerk H, Engenhart-Cabillic R, Zink K, Baumann KS. Estimating the modulating effect of lung tissue in particle therapy using a clinical CT voxel histogram analysis. Phys Med Biol 2021; 66. [PMID: 34298533 DOI: 10.1088/1361-6560/ac176e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 07/23/2021] [Indexed: 11/12/2022]
Abstract
To treat lung tumours with particle therapy, different additional tasks and challenges in treatment planning and application have to be addressed thoroughly. One of these tasks is the quantification and consideration of the Bragg peak degradation due to lung tissue: As lung is an heterogeneous tissue, the Bragg peak is broadened when particles traverse the microscopic alveoli. These are not fully resolved in clinical CT images and thus, the effect is not considered in the dose calculation. In this work, a correlation between the CT histograms of heterogeneous material and the impact on the Bragg peak curve is presented. Different inorganic materials were scanned with a conventional CT scanner and additionally, the Bragg peak degradation was measured in a proton beam and was then quantified. A model is proposed that allows an estimation of the modulation power by performing a histogram analysis on the CT scan. To validate the model for organic samples, a second measurement series was performed with frozen porcine lunge samples. This allows to investigate the possible limits of the proposed model in a set-up closer to clinical conditions. For lung substitutes, the agreement between model and measurement is within ±0.05 mm and for the organic lung samples, within ±0.15 mm. This work presents a novel, simple and efficient method to estimate if and how much a material or a distinct region (within the lung) is degrading the Bragg peak on the basis of a common clinical CT image. Up until now, only a direct in-beam measurement of the region or material of interest could answer this question.
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Affiliation(s)
- Veronika Flatten
- Department of Radiotherapy and Radiooncology, University Hospital of Giessen and Marburg Campus Marburg, Marburg, GERMANY
| | - Jan Michael Burg
- , University of Applied Sciences, Institute of Medical Physics and Radiation Protection, Giessen, GERMANY
| | - Matthias Witt
- Department of Radiotherapy and Radiooncology, University Hospital of Giessen and Marburg Campus Marburg, Marburg, GERMANY
| | - Larissa Derksen
- , University of Applied Sciences, Institute of Medical Physics and Radiation Protection, Giessen, GERMANY
| | | | - Jörg Wulff
- Medical Physics, Westdeutsches Protonentherapiezentrum Essen gGmbH, Essen, GERMANY
| | | | - Beate Timmermann
- Deparment of Particle Therapy, University Hospital Essen, Essen, GERMANY
| | - Uli Weber
- , GSI Helmholtzzentrum fur Schwerionenforschung GmbH, Darmstadt, Hessen, GERMANY
| | - Hilke Vorwerk
- Department of Radiotherapy and Radiooncology, University Medical Center Giessen-Marburg, Marburg, GERMANY
| | - Rita Engenhart-Cabillic
- University Medical Center Giessen-Marburg, Department of Radiotherapy and Radiooncology, Marburg, GERMANY
| | - Klemens Zink
- University Medical Center Giessen-Marburg, Department of Radiotherapy and Radiooncology, Marburg, GERMANY
| | - Kilian-Simon Baumann
- Department of Radiotherapy and Radiooncology, University Medical Center Giessen-Marburg, Marburg, GERMANY
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Analytical modeling of depth-dose degradation in heterogeneous lung tissue for intensity-modulated proton therapy planning. PHYSICS & IMAGING IN RADIATION ONCOLOGY 2021; 14:32-38. [PMID: 33458311 PMCID: PMC7807882 DOI: 10.1016/j.phro.2020.05.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 05/02/2020] [Accepted: 05/07/2020] [Indexed: 01/06/2023]
Abstract
Background and purpose Proton therapy may be promising for treating non-small-cell lung cancer due to lower doses to the lung and heart, as compared to photon therapy. A reported challenge is degradation, i.e., a smoothing of the depth-dose distribution due to heterogeneous lung tissue. For pencil beams, this causes a distal falloff widening and a peak-to-plateau ratio decrease, not considered in clinical treatment planning systems. Materials and methods We present a degradation model implemented into an analytical dose calculation, fully integrated into a treatment planning workflow. Degradation effects were investigated on target dose, distal dose falloffs, and mean lung dose for ten patient cases with varying anatomical characteristics. Results For patients with pronounced range straggling (in our study large tumors, or lesions close to the mediastinum), degradation effects were restricted to a maximum decrease in target coverage (D 95 of the planning target volume) of 1.4%. The median broadening of the distal 80-20% dose falloffs was 0.5 mm at the maximum. For small target volumes deep inside lung tissue, however, the target underdose increased considerably by up to 26%. The mean lung dose was not negatively affected by degradation in any of the investigated cases. Conclusion For most cases, dose degradation due to heterogeneous lung tissue did not yield critical organ at risk overdosing or overall target underdosing. However, for small and deep-seated tumors which can only be reached by penetrating lung tissue, we have seen substantial local underdose, which deserves further investigation, also considering other prevalent sources of uncertainty.
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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: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [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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Baumann KS, Flatten V, Weber U, Lautenschläger S, Eberle F, Zink K, Engenhart-Cabillic R. Effects of the Bragg peak degradation due to lung tissue in proton therapy of lung cancer patients. Radiat Oncol 2019; 14:183. [PMID: 31653229 PMCID: PMC6814996 DOI: 10.1186/s13014-019-1375-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 09/06/2019] [Indexed: 12/25/2022] Open
Abstract
Purpose To quantify the effects of the Bragg peak degradation due to lung tissue on treatment plans of lung cancer patients with spot scanning proton therapy and to give a conservative approximation of these effects. Methods and materials Treatment plans of five lung cancer patients (tumors of sizes 2.7–46.4 cm3 at different depths in the lung) were optimized without consideration of the Bragg peak degradation. These treatment plans were recalculated with the Monte Carlo code TOPAS in two scenarios: in a first scenario, the treatment plans were calculated without including the Bragg peak degradation to reproduce the dose distribution predicted by the treatment-planning system (TPS). In a second scenario, the treatment plans were calculated while including the Bragg peak degradation. Subsequently, the plans were compared by means of Dmean, D98% and D2% in the clinical target volume (CTV) and organs at risk (OAR). Furthermore, isodose lines were investigated and a gamma index analysis was performed. Results The Bragg peak degradation leads to a lower dose in the CTV and higher doses in OARs distal to the CTV compared to the prediction from the TPS. The reduction of the mean dose in the CTV was − 5% at maximum and − 2% on average. The deeper a tumor was located in the lung and the smaller its volume the bigger was the effect on the CTV. The enhancement of the mean dose in OARs distal to the CTV was negligible for the cases investigated. Conclusions Effects of the Bragg peak degradation due to lung tissue were investigated for lung cancer treatment plans in proton therapy. This study confirms that these effects are clinically tolerable to a certain degree in the current clinical context considering the various more critical dose uncertainties due to motion and range uncertainties in proton therapy.
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Affiliation(s)
- Kilian-Simon Baumann
- University Medical Center Giessen-Marburg, Department of Radiotherapy and Radiooncology, Marburg, Germany. .,University of Applied Sciences, Institute of Medical Physics and Radiation Protection, Giessen, Germany.
| | - Veronika Flatten
- University Medical Center Giessen-Marburg, Department of Radiotherapy and Radiooncology, Marburg, Germany.,University of Applied Sciences, Institute of Medical Physics and Radiation Protection, Giessen, Germany
| | - Uli Weber
- GSI Helmholtzzentrum für Schwerionenforschung, Biophysics Division, Darmstadt, Germany
| | - Stefan Lautenschläger
- University Medical Center Giessen-Marburg, Department of Radiotherapy and Radiooncology, Marburg, Germany.,Marburg Ion-Beam Therapy Center (MIT), Marburg, Germany
| | - Fabian Eberle
- University Medical Center Giessen-Marburg, Department of Radiotherapy and Radiooncology, Marburg, Germany.,Marburg Ion-Beam Therapy Center (MIT), Marburg, Germany
| | - Klemens Zink
- University Medical Center Giessen-Marburg, Department of Radiotherapy and Radiooncology, Marburg, Germany.,University of Applied Sciences, Institute of Medical Physics and Radiation Protection, Giessen, Germany.,Frankfurt Institute of Advanced Studies - FIAS, Frankfurt, Germany
| | - Rita Engenhart-Cabillic
- University Medical Center Giessen-Marburg, Department of Radiotherapy and Radiooncology, Marburg, Germany.,Marburg Ion-Beam Therapy Center (MIT), Marburg, Germany
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Flatten V, Baumann KS, Weber U, Engenhart-Cabillic R, Zink K. Quantification of the dependencies of the Bragg peak degradation due to lung tissue in proton therapy on a CT-based lung tumor phantom. Phys Med Biol 2019; 64:155005. [PMID: 31151126 DOI: 10.1088/1361-6560/ab2611] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The fine, sub-millimeter sized structure of lung tissue causes a degradation of the Bragg peak curve in particle therapy. The Bragg peak is degraded because particles of the same energy traverse lung tissue of different compositions of high and low density materials. Hence, they experience different energy losses resulting in variable ranges and a broadened Bragg peak. Since this fine structure of lung tissue is not resolved in standard treatment-planning CTs, current state-of-the-art dose calculation procedures used in the clinical routine are unable to account for this degradation. Neglecting this Bragg peak degradation in treatment planning can lead to an underdose in the target volume and an overdose distal to the target. Aim of this work is to systematically investigate the potential effects of the Bragg peak degradation on the dose distribution in dependence of different parameters like the tumor volume and its depth in lung. Proton plans were optimized on CT based phantoms without considering the Bragg peak degradation and afterwards recalculated with the Monte Carlo toolkit TOPAS: first, without consideration of the degradation and second, with the Bragg peak degradation accounted for. The direct comparison of these two dose distributions enables a quantification of the degradation effect. To carve out the dependencies of various parameters that could influence the Bragg peak degradation and thus the target dose, the simulations were performed for a variety of tumor sizes and shapes, as well as different positions within the lung. The results show that due to the Bragg peak degradation the mean dose in the target volume can be reduced by a few percent up to 14% (for extreme cases) depending on the geometry. It was shown that this effect increases with a decreasing tumor volume and increasing depth of the tumor. For the first time, a tumor specific estimation of the effect on the dose distribution due to the Bragg peak degradation in lung tissue is presented.
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Affiliation(s)
- Veronika Flatten
- Department of Radiotherapy and Radiooncology, University Medical Center Giessen-Marburg, Marburg, Germany. Institute of Medical Physics and Radiation Protection, University of Applied Sciences, Giessen, Germany. Author to whom any correspondence should be addressed
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Baumann KS, Witt M, Weber U, Engenhart-Cabillic R, Zink K. An efficient method to predict and include Bragg curve degradation due to lung-equivalent materials in Monte Carlo codes by applying a density modulation. Phys Med Biol 2017; 62:3997-4016. [DOI: 10.1088/1361-6560/aa641f] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Printz Ringbæk T, Simeonov Y, Witt M, Engenhart-Cabillic R, Kraft G, Zink K, Weber U. Modulation power of porous materials and usage as ripple filter in particle therapy. Phys Med Biol 2017; 62:2892-2909. [DOI: 10.1088/1361-6560/aa5c28] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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