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Schafasand M, Resch AF, Nachankar A, Góra J, Martino G, Traneus E, Glimelius L, Georg D, Fossati P, Carlino A, Stock M. Dose averaged linear energy transfer optimization for large sacral chordomas in carbon ion therapy. Med Phys 2024; 51:3950-3960. [PMID: 38696546 DOI: 10.1002/mp.17102] [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: 12/29/2023] [Revised: 04/16/2024] [Accepted: 04/17/2024] [Indexed: 05/04/2024] Open
Abstract
BACKGROUND Carbon ion beams are well accepted as densely ionizing radiation with a high linear energy transfer (LET). However, the current clinical practice does not fully exploit the highest possible dose-averaged LET (LETd) and, consequently, the biological potential in the target. This aspect becomes worse in larger tumors for which inferior clinical outcomes and corresponding lower LETd was reported. PURPOSE The vicinity to critical organs in general and the inferior overall survival reported for larger sacral chordomas treated with carbon ion radiotherapy (CIRT), makes the treatment of such tumors challenging. In this work it was aimed to increase the LETd in large volume tumors while maintaining the relative biological effectiveness (RBE)-weighted dose, utilizing the LETd optimization functions of a commercial treatment planning system (TPS). METHODS Ten reference sequential boost carbon ion treatment plans, designed to mimic clinical plans for large sacral chordoma tumors, were generated. High dose clinical target volumes (CTV-HD) larger than250 cm 3 $250 \,{\rm cm}^{3}$ were considered as large targets. The total RBE-weighted median dose prescription with the local effect model (LEM) wasD RBE , 50 % = 73.6 Gy $\textrm {D}_{\rm RBE, 50\%}=73.6 \,{\rm Gy}$ in 16 fractions (nine to low dose and seven to high dose planning target volume). No LETd optimization was performed in the reference plans, while LETd optimized plans used the minimum LETd (Lmin) optimization function in RayStation 2023B. Three different Lmin values were investigated and specified for the seven boost fractions:L min = 60 keV / μ m $\textrm {L}_{\rm min}=60 \,{\rm keV}/{\umu }{\rm m}$ ,L min = 80 keV / μ m $\textrm {L}_{\rm min}=80 \,{\rm keV}/{\umu }{\rm m}$ andL min = 100 keV / μ m $\textrm {L}_{\rm min}=100 \,{\rm keV}/{\umu }{\rm m}$ . To compare the LETd optimized against reference plans, LETd and RBE-weighted dose based goals similar to and less strict than clinical ones were specified for the target. The goals for the organs at risk (OAR) remained unchanged. Robustness evaluation was studied for eight scenarios (± 3.5 % $\pm 3.5\%$ range uncertainty and± 3 mm $\pm 3 \,{\rm mm}$ setup uncertainty along the main three axes). RESULTS The optimization method withL min = 60 keV / μ m $\textrm {L}_{\rm min}=60 \,{\rm keV}/{\umu }{\rm m}$ resulted in an optimal LETd distribution with an average increase ofLET d , 98 % ${\rm {LET}}_{{\rm {d,}}98\%}$ (andLET d , 50 % ${\rm {LET}}_{{\rm {d,}}50\%}$ ) in the CTV-HD by8.9 ± 1.5 keV / μ m $8.9\pm 1.5 \,{\rm keV}/{\umu }{\rm m}$ (27 % $27\%$ ) (and6.9 ± 1.3 keV / μ m $6.9\pm 1.3 \,{\rm keV}/{\umu }{\rm m}$ (17 % $17\%$ )), without significant difference in the RBE-weighted dose. By allowing± 5 % $\pm 5\%$ over- and under-dosage in the target, theLET d , 98 % ${\rm {LET}}_{{\rm {d,}}98\%}$ (andLET d , 50 % ${\rm {LET}}_{{\rm {d,}}50\%}$ ) can be increased by11.3 ± 1.2 keV / μ m $11.3\pm 1.2 \,{\rm keV}/{\umu }{\rm m}$ (34 % $34\%$ ) (and11.7 ± 3.4 keV / μ m $11.7\pm 3.4 \,{\rm keV}/{\umu }{\rm m}$ (29 % $29\%$ )), using the optimization parametersL min = 80 keV / μ m $\textrm {L}_{\rm min}=80 \,{\rm keV}/{\umu }{\rm m}$ . The pass rate for the OAR goals in the LETd optimized plans was in the same level as the reference plans. LETd optimization lead to less robust plans compared to reference plans. CONCLUSIONS Compared to conventionally optimized treatment plans, the LETd in the target was increased while maintaining the RBE-weighted dose using TPS LETd optimization functionalities. Regularly assessing RBE-weighted dose robustness and acquiring more in-room images remain crucial and inevitable aspects during treatment.
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Affiliation(s)
- Mansure Schafasand
- Department of General and Translational Oncology and Hematology, Karl Landsteiner University of Health Sciences, Krems an der Donau, Austria
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
- Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
| | | | - Ankita Nachankar
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
- ACMIT Gmbh, Wiener Neustadt, Austria
| | - Joanna Góra
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
| | | | | | | | - Dietmar Georg
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
- Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
| | - Piero Fossati
- Department of General and Translational Oncology and Hematology, Karl Landsteiner University of Health Sciences, Krems an der Donau, Austria
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
| | | | - Markus Stock
- Department of General and Translational Oncology and Hematology, Karl Landsteiner University of Health Sciences, Krems an der Donau, Austria
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
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Dreindl R, Bolsa‐Ferruz M, Fayos‐Sola R, Padilla Cabal F, Scheuchenpflug L, Elia A, Amico A, Carlino A, Stock M, Grevillot L. Commissioning and clinical implementation of an independent dose calculation system for scanned proton beams. J Appl Clin Med Phys 2024; 25:e14328. [PMID: 38553788 PMCID: PMC11087175 DOI: 10.1002/acm2.14328] [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: 10/10/2023] [Revised: 01/31/2024] [Accepted: 02/07/2024] [Indexed: 05/12/2024] Open
Abstract
PURPOSE Experimental patient-specific QA (PSQA) is a time and resource-intensive process, with a poor sensitivity in detecting errors. Radiation therapy facilities aim to substitute it by means of independent dose calculation (IDC) in combination with a comprehensive beam delivery QA program. This paper reports on the commissioning of the IDC software tool myQA iON (IBA Dosimetry) for proton therapy and its clinical implementation at the MedAustron Ion Therapy Center. METHODS The IDC commissioning work included the validation of the beam model, the implementation and validation of clinical CT protocols, and the evaluation of patient treatment data. Dose difference maps, gamma index distributions, and pass rates (GPR) have been reviewed. The performance of the IDC tool has been assessed and clinical workflows, simulation settings, and GPR tolerances have been defined. RESULTS Beam model validation showed agreement of ranges within ± 0.2 mm, Bragg-Peak widths within ± 0.1 mm, and spot sizes at various air gaps within ± 5% compared to physical measurements. Simulated dose in 2D reference fields deviated by -0.3% ± 0.5%, while 3D dose distributions differed by 1.8% on average to measurements. Validation of the CT calibration resulted in systematic differences of 2.0% between IDC and experimental data for tissue like samples. GPRs of 99.4 ± 0.6% were found for head, head and neck, and pediatric CT protocols on a 2%/2 mm gamma criterion. GPRs for the adult abdomen protocol were at 98.9% on average with 3%/3 mm. Root causes of GPR outliers, for example, implants were identified and evaluated. CONCLUSION IDC has been successfully commissioned and integrated into the MedAustron clinical workflow for protons in 2021. IDC has been stepwise and safely substituting experimental PSQA since February 2021. The initial reduction of proton experimental PSQA was about 25% and reached up to 90% after 1 year.
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Affiliation(s)
- Ralf Dreindl
- MedAustron Ion Therapy CenterWiener NeustadtAustria
| | | | - Rosa Fayos‐Sola
- MedAustron Ion Therapy CenterWiener NeustadtAustria
- Department of Medical Physics and Radiation ProtectionHospital Universitario La PrincesaMadridSpain
| | - Fatima Padilla Cabal
- MedAustron Ion Therapy CenterWiener NeustadtAustria
- Division Medical Radiation PhysicsDepartment of Radiation OncologyMedical University of Vienna/AKH WienViennaAustria
| | - Lukas Scheuchenpflug
- MedAustron Ion Therapy CenterWiener NeustadtAustria
- Department of Isotope PhysicsFaculty of PhysicsUniversity of ViennaViennaAustria
| | - Alessio Elia
- MedAustron Ion Therapy CenterWiener NeustadtAustria
| | - Antonio Amico
- MedAustron Ion Therapy CenterWiener NeustadtAustria
- Medical Physics DepartmentVeneto Institute of Oncology IOV ‐ IRCCSPaduaItaly
| | | | - Markus Stock
- MedAustron Ion Therapy CenterWiener NeustadtAustria
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Thwaites DI, Prokopovich DA, Garrett RF, Haworth A, Rosenfeld A, Ahern V. The rationale for a carbon ion radiation therapy facility in Australia. J Med Radiat Sci 2024; 71 Suppl 2:59-76. [PMID: 38061984 PMCID: PMC11011608 DOI: 10.1002/jmrs.744] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Accepted: 11/17/2023] [Indexed: 04/13/2024] Open
Abstract
Australia has taken a collaborative nationally networked approach to achieve particle therapy capability. This supports the under-construction proton therapy facility in Adelaide, other potential proton centres and an under-evaluation proposal for a hybrid carbon ion and proton centre in western Sydney. A wide-ranging overview is presented of the rationale for carbon ion radiation therapy, applying observations to the case for an Australian facility and to the clinical and research potential from such a national centre.
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Affiliation(s)
- David I. Thwaites
- Institute of Medical Physics, School of PhysicsUniversity of SydneySydneyNew South WalesAustralia
- Department of Radiation OncologySydney West Radiation Oncology NetworkWestmeadNew South WalesAustralia
- Radiotherapy Research Group, Institute of Medical ResearchSt James's Hospital and University of LeedsLeedsUK
| | | | - Richard F. Garrett
- Australian Nuclear Science and Technology OrganisationLucas HeightsNew South WalesAustralia
| | - Annette Haworth
- Institute of Medical Physics, School of PhysicsUniversity of SydneySydneyNew South WalesAustralia
- Department of Radiation OncologySydney West Radiation Oncology NetworkWestmeadNew South WalesAustralia
| | - Anatoly Rosenfeld
- Centre for Medical Radiation Physics, School of PhysicsUniversity of WollongongSydneyNew South WalesAustralia
| | - Verity Ahern
- Department of Radiation OncologySydney West Radiation Oncology NetworkWestmeadNew South WalesAustralia
- Westmead Clinical School, Faculty of Medicine and HealthUniversity of SydneySydneyNew South WalesAustralia
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Chen L, Platzer P, Reschl C, Schafasand M, Nachankar A, Lukas Hajdusich C, Kuess P, Stock M, Habraken S, Carlino A. Validation of a deep-learning segmentation model for adult and pediatric head and neck radiotherapy in different patient positions. Phys Imaging Radiat Oncol 2024; 29:100527. [PMID: 38222671 PMCID: PMC10787237 DOI: 10.1016/j.phro.2023.100527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 12/15/2023] [Accepted: 12/18/2023] [Indexed: 01/16/2024] Open
Abstract
Background and purpose Autocontouring for radiotherapy has the potential to significantly save time and reduce interobserver variability. We aimed to assess the performance of a commercial autocontouring model for head and neck (H&N) patients in eight orientations relevant to particle therapy with fixed beam lines, focusing on validation and implementation for routine clinical use. Materials and methods Autocontouring was performed on sixteen organs at risk (OARs) for 98 adult and pediatric patients with 137 H&N CT scans in eight orientations. A geometric comparison of the autocontours and manual segmentations was performed using the Hausdorff Distance 95th percentile, Dice Similarity Coefficient (DSC) and surface DSC and compared to interobserver variability where available. Additional qualitative scoring and dose-volume-histogram (DVH) parameters analyses were performed for twenty patients in two positions, consisting of scoring on a 0-3 scale based on clinical usability and comparing the mean (Dmean) and near-maximum (D2%) dose, respectively. Results For the geometric analysis, the model performance in head-first-supine straight and hyperextended orientations was in the same range as the interobserver variability. HD95, DSC and surface DSC was heterogeneous in other orientations. No significant geometric differences were found between pediatric and adult autocontours. The qualitative scoring yielded a median score of ≥ 2 for 13/16 OARs while 7/32 DVH parameters were significantly different. Conclusions For head-first-supine straight and hyperextended scans, we found that 13/16 OAR autocontours were suited for use in daily clinical practice and subsequently implemented. Further development is needed for other patient orientations before implementation.
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Affiliation(s)
- Linda Chen
- MedAustron Ion Therapy Center, Department of Medical Physics, Wiener Neustadt, Austria
- Erasmus MC Cancer Institute, University Medical Center, Department of Radiotherapy, Rotterdam, the Netherlands
- Delft University of Technology, Faculty of Mechanical, Maritime and Materials Engineering, Delft, the Netherlands
- Leiden University Medical Center, Faculty of Medicine, Leiden, the Netherlands
| | - Patricia Platzer
- MedAustron Ion Therapy Center, Department of Medical Physics, Wiener Neustadt, Austria
- Fachhochschule Wiener Neustadt, Department MedTech, Wiener Neustadt, Austria
| | - Christian Reschl
- MedAustron Ion Therapy Center, Department of Medical Physics, Wiener Neustadt, Austria
| | - Mansure Schafasand
- MedAustron Ion Therapy Center, Department of Medical Physics, Wiener Neustadt, Austria
- Medical University of Vienna, Department of Radiation Oncology, Vienna, Austria
- Karl Landsteiner University of Health Sciences, Department of Oncology, Krems an der Donau, Austria
| | - Ankita Nachankar
- MedAustron Ion Therapy Center, Department of Medical Physics, Wiener Neustadt, Austria
- ACMIT Gmbh, Department of Medicine, Wiener Neustadt, Austria
| | | | - Peter Kuess
- Medical University of Vienna, Department of Radiation Oncology, Vienna, Austria
| | - Markus Stock
- MedAustron Ion Therapy Center, Department of Medical Physics, Wiener Neustadt, Austria
- Karl Landsteiner University of Health Sciences, Department of Oncology, Krems an der Donau, Austria
| | - Steven Habraken
- Erasmus MC Cancer Institute, University Medical Center, Department of Radiotherapy, Rotterdam, the Netherlands
- Holland Proton Therapy Center, Department of Medical Physics & Informatics, Delft, the Netherlands
| | - Antonio Carlino
- MedAustron Ion Therapy Center, Department of Medical Physics, Wiener Neustadt, Austria
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Schafasand M, Resch AF, Nachankar A, Gora J, Traneus E, Glimelius L, Georg D, Stock M, Carlino A, Fossati P. Investigation on the physical dose filtered by linear energy transfer for treatment plan evaluation in carbon ion therapy. Med Phys 2024; 51:556-565. [PMID: 37727137 DOI: 10.1002/mp.16751] [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: 04/05/2023] [Revised: 08/22/2023] [Accepted: 09/01/2023] [Indexed: 09/21/2023] Open
Abstract
BACKGROUND Large tumor size has been reported as a predicting factor for inferior clinical outcome in carbon ion radiotherapy (CIRT). Besides the clinical factors accompanied with such tumors, larger tumors receive typically more low linear energy transfer (LET) contributions than small ones which may be the underlying physical cause. Although dose averaged LET is often used as a single parameter descriptor to quantify the beam quality, there is no evidence that this parameter is the optimal clinical predictor for the complex mixed radiation fields in CIRT. PURPOSE Purpose of this study was to investigate on a novel dosimetric quantity, namely high-LET-dose (D > L thr $\textrm {D}_{>\textrm {L}_{\textrm {thr}}}$ , the physical dose filtered based on an LET threshold) as a single parameter estimator to differentiate between carbon ion treatment plans (cTP) with a small and large tumor volume. METHODS Ten cTPs with a planning target volume,PTV ≥ 500 cm 3 $\mathrm{PTV}\ge {500}\,{{\rm cm}^{3}}$ (large) and nine with aPTV < 500 cm 3 $\mathrm{PTV}<{500}\,{{\rm cm}^{3}}$ (small) were selected for this study. To find a reasonable LET threshold (L thr $\textrm {L}_{\textrm {thr}}$ ) that results in a significant difference in terms ofD > L thr $\textrm {D}_{>\textrm {L}_{\textrm {thr}}}$ , the voxel based normalized high-LET-dose (D ̂ > L thr $\hat{\textrm {D}}_{>\textrm {L}_{\textrm {thr}}}$ ) distribution in the clinical target volume (CTV) was studied on a subset (12 out of 19 cTPs) for 18 LET thresholds, using standard distribution descriptors (mean, variance and skewness). The classical dose volume histogram concept was used to evaluate theD > L thr $\textrm {D}_{>\textrm {L}_{\textrm {thr}}}$ andD ̂ > L thr $\hat{\textrm {D}}_{>\textrm {L}_{\textrm {thr}}}$ distributions within the target of all 19 cTPs at the before determinedL thr $\textrm {L}_{\textrm {thr}}$ . Statistical significance of the difference between the two groups in terms of meanD > L thr $\textrm {D}_{>\textrm {L}_{\textrm {thr}}}$ andD ̂ > L thr $\hat{\textrm {D}}_{>\textrm {L}_{\textrm {thr}}}$ volume histogram parameters was evaluated by means of (two-sided) t-test or Mann-Whitney-U-test. In addition, the minimum target coverage at the above determinedL thr $\textrm {L}_{\textrm {thr}}$ was compared and validated against three other thresholds to verify its potential in differentiation between small and large volume tumors. RESULTS AnL thr $\textrm {L}_{\textrm {thr}}$ of approximately30 keV / μ m ${30}\,{\rm keV/}\umu {\rm m}$ was found to be a reasonable threshold to classify the two groups. At this threshold, theD > L thr $\textrm {D}_{>\textrm {L}_{\textrm {thr}}}$ andD ̂ > L thr $\hat{\textrm {D}}_{>\textrm {L}_{\textrm {thr}}}$ were significantly larger (p < 0.05 $p<0.05$ ) in small CTVs. For the small tumor group, the near-minimum and medianD > L thr $\textrm {D}_{>\textrm {L}_{\textrm {thr}}}$ (andD ̂ > L thr $\hat{\textrm {D}}_{>\textrm {L}_{\textrm {thr}}}$ ) in the CTV were in average9.3 ± 1.5 Gy $9.3\pm {1.5}\,{\rm Gy}$ (0.31 ± 0.08) and13.6 ± 1.6 Gy $13.6\pm {1.6}\,{\rm Gy}$ (0.46 ± 0.06), respectively. For the large tumors, these parameters were6.6 ± 0.2 Gy $6.6\pm {0.2}\,{\rm Gy}$ (0.20 ± 0.01) and8.6 ± 0.4 Gy $8.6\pm {0.4}\,{\rm Gy}$ (0.28 ± 0.02). The difference between the two groups in terms of mean near-minimum and medianD > L thr $\textrm {D}_{>\textrm {L}_{\textrm {thr}}}$ (D ̂ > L thr $\hat{\textrm {D}}_{>\textrm {L}_{\textrm {thr}}}$ ) was 2.7 Gy (11%) and 5.0 Gy (18%), respectively. CONCLUSIONS The feasibility of high-LET-dose based evaluation was shown in this study where a lowerD > L thr $\textrm {D}_{>\textrm {L}_{\textrm {thr}}}$ was found in cTPs with a large tumor size. Further investigation is needed to draw clinical conclusions. The proposed methodology in this work can be utilized for future high-LET-dose based studies.
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Affiliation(s)
- Mansure Schafasand
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
- Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
| | | | - Ankita Nachankar
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
- ACMIT Gmbh, Wiener Neustadt, Austria
| | - Joanna Gora
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
| | | | | | - Dietmar Georg
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
- Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
| | - Markus Stock
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
- Department of Oncology, Karl Landsteiner University of Health Sciences, Krems an der Donau, Austria
| | | | - Piero Fossati
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
- Department of Oncology, Karl Landsteiner University of Health Sciences, Krems an der Donau, Austria
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Belotti G, Rossi M, Pella A, Cerveri P, Baroni G. A new system for in-room image guidance in particle therapy at CNAO. Phys Med 2023; 114:103162. [PMID: 37820507 DOI: 10.1016/j.ejmp.2023.103162] [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: 05/10/2023] [Revised: 09/22/2023] [Accepted: 10/06/2023] [Indexed: 10/13/2023] Open
Abstract
This paper describes the design, installation, and commissioning of an in-room imaging device developed at the Centro Nazionale di Adroterapia Oncologica (CNAO, Pavia, Italy). The system is an upgraded version of the one previously installed in 2014, and its design accounted for the experience gained in a decade of clinical practice of patient setup verification and correction through robotic-supported, off-isocenter in-room image guidance. The system's basic feature consists of image-based setup correction through 2D/3D and 3D/3D registration through a dedicated HW/SW platform. The major update with respect to the device already under clinical usage resides in the implementation of a functionality for extending the field of view of the reconstructed Cone Beam CT (CBCT) volume, along with improved overall safety and functional optimization. We report here details on the procedures implemented for system calibration under all imaging modalities and the results of the technical and preclinical commissioning of the device performed on two different phantoms. In the technical commissioning, specific attention was given to the assessment of the accuracy with which the six-degrees-of-freedom correction vector computed at the off-isocenter imaging position was propagated to the planned isocentric irradiation geometry. During the preclinical commissioning, the entire clinical-like procedure for detecting and correcting imposed, known setup deviation was tested on an anthropomorphic radioequivalent phantom. Results showed system performance within the sub-millimeter and sub-degree range according to project specifications under each imaging modality, making it ready for clinical application.
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Affiliation(s)
- Gabriele Belotti
- Department of Electronics, Information and Bioengineering, CartCasLab, Politecnico di Milano, MI, Italy.
| | - Matteo Rossi
- Department of Electronics, Information and Bioengineering, CartCasLab, Politecnico di Milano, MI, Italy; Istituto Auxologico Italiano, IRCCS, Milan, Italy
| | - Andrea Pella
- Bioengineering Unit - Centro Nazionale di Adroterapia Oncologica (CNAO), Pavia, PV, Italy
| | - Pietro Cerveri
- Department of Electronics, Information and Bioengineering, CartCasLab, Politecnico di Milano, MI, Italy; Istituto Auxologico Italiano, IRCCS, Milan, Italy
| | - Guido Baroni
- Department of Electronics, Information and Bioengineering, CartCasLab, Politecnico di Milano, MI, Italy; Bioengineering Unit - Centro Nazionale di Adroterapia Oncologica (CNAO), Pavia, PV, Italy
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Etschmaier V, Glänzer D, Eck N, Schäfer U, Leithner A, Georg D, Lohberger B. Proton and Carbon Ion Irradiation Changes the Process of Endochondral Ossification in an Ex Vivo Femur Organotypic Culture Model. Cells 2023; 12:2301. [PMID: 37759523 PMCID: PMC10527791 DOI: 10.3390/cells12182301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 09/13/2023] [Accepted: 09/15/2023] [Indexed: 09/29/2023] Open
Abstract
Particle therapy (PT) that utilizes protons and carbon ions offers a promising way to reduce the side effects of radiation oncology, especially in pediatric patients. To investigate the influence of PT on growing bone, we exposed an organotypic rat ex vivo femur culture model to PT. After irradiation, histological staining, immunohistochemical staining, and gene expression analysis were conducted following 1 or 14 days of in vitro culture (DIV). Our data indicated a significant loss of proliferating chondrocytes at 1 DIV, which was followed by regeneration attempts through chondrocytic cluster formation at 14 DIV. Accelerated levels of mineralization were observed, which correlated with increased proteoglycan production and secretion into the pericellular matrix. Col2α1 expression, which increased during the cultivation period, was significantly inhibited by PT. Additionally, the decrease in ColX expression over time was more pronounced compared to the non-IR control. The chondrogenic markers BMP2, RUNX2, OPG, and the osteogenic marker ALPL, showed a significant reduction in the increase in expression after 14 DIV due to PT treatment. It was noted that carbon ions had a stronger influence than protons. Our bone model demonstrated the occurrence of pathological and regenerative processes induced by PT, thus building on the current understanding of the biological mechanisms of bone.
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Affiliation(s)
- Vanessa Etschmaier
- Department of Orthopaedics and Trauma, Medical University Graz, 8036 Graz, Austria; (V.E.); (D.G.); (N.E.); (A.L.)
| | - Dietmar Glänzer
- Department of Orthopaedics and Trauma, Medical University Graz, 8036 Graz, Austria; (V.E.); (D.G.); (N.E.); (A.L.)
| | - Nicole Eck
- Department of Orthopaedics and Trauma, Medical University Graz, 8036 Graz, Austria; (V.E.); (D.G.); (N.E.); (A.L.)
| | - Ute Schäfer
- Department of Neurosurgery, Research Unit for Experimental Neurotraumatology, Medical University of Graz, 8036 Graz, Austria;
| | - Andreas Leithner
- Department of Orthopaedics and Trauma, Medical University Graz, 8036 Graz, Austria; (V.E.); (D.G.); (N.E.); (A.L.)
| | - Dietmar Georg
- Department of Radiation Oncology, Medical University of Vienna, 1090 Vienna, Austria;
- MedAustron Ion Therapy Center, 2700 Wiener Neustadt, Austria
| | - Birgit Lohberger
- Department of Orthopaedics and Trauma, Medical University Graz, 8036 Graz, Austria; (V.E.); (D.G.); (N.E.); (A.L.)
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Knäusl B, Langgartner L, Stock M, Janson M, Furutani KM, Beltran CJ, Georg D, Resch AF. Requirements for dose calculation on an active scanned proton beamline for small, shallow fields. Phys Med 2023; 113:102659. [PMID: 37598612 DOI: 10.1016/j.ejmp.2023.102659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 06/18/2023] [Accepted: 08/05/2023] [Indexed: 08/22/2023] Open
Abstract
INTRODUCTION A growing interest in using proton pencil beam scanning in combination with collimators for the treatment of small, shallow targets, such as ocular melanoma or pre-clinical research emerged recently. This study aims at demonstrating that the dose of a synchrotron-based PBS system with a dedicated small, shallow field nozzle can be accurately predicted by a commercial treatment planning system (TPS) following appropriate tuning of both, nozzle and TPS. MATERIALS A removable extension to the clinical nozzle was developed to modify the beam shape passively. Five circular apertures with diameters between 5 to 34mm, mounted 72cm downstream of a range shifter were used. For each collimator treatment plans with spread-out Bragg peaks (SOBP) with a modulation of 3 to 30mm were measured and calculated with GATE/Geant4 and the research TPS RayStation (RS11B-R). The dose grid, multiple coulomb scattering and block discretization resolution were varied to find the optimal balance between accuracy and performance. RESULTS For SOBPs deeper than 10mm, the dose in the target agreed within 1% between RS11B-R, GATE/Geant4 and measurements for aperture diameters between 8 to 34mm, but deviated up to 5% for smaller apertures. A plastic taper was introduced reducing scatter contributions to the patient (from the pipe) and improving the dose calculation accuracy of the TPS to a 5% level in the entrance region for large apertures. CONCLUSION The commercial TPS and GATE/Geant4 can accurately calculate the dose for shallow, small proton fields using a collimator and pencil beam scanning.
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Affiliation(s)
- B Knäusl
- Medical University of Vienna, Department of Radiation Oncology, Vienna, Austria; MedAustron Ion Therapy Center, Wiener Neustadt, Austria.
| | - L Langgartner
- Medical University of Vienna, Department of Radiation Oncology, Vienna, Austria
| | - M Stock
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria; Karl Landsteiner University of Health Sciences, Krems, Austria
| | - M Janson
- RaySearch Laboratories, Stockholm, Sweden
| | - K M Furutani
- Mayo Clinic, Department of Radiation Oncology, Jacksonville, FL, United States of America
| | - C J Beltran
- Mayo Clinic, Department of Radiation Oncology, Jacksonville, FL, United States of America
| | - D Georg
- Medical University of Vienna, Department of Radiation Oncology, Vienna, Austria
| | - A F Resch
- Medical University of Vienna, Department of Radiation Oncology, Vienna, Austria; MedAustron Ion Therapy Center, Wiener Neustadt, Austria
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Herrick M, Penfold S, Santos A, Hickson K. A systematic review of volumetric image guidance in proton therapy. Phys Eng Sci Med 2023; 46:963-975. [PMID: 37382744 PMCID: PMC10480289 DOI: 10.1007/s13246-023-01294-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Accepted: 06/19/2023] [Indexed: 06/30/2023]
Abstract
In recent years, proton therapy centres have begun to shift from conventional 2D-kV imaging to volumetric imaging systems for image guided proton therapy (IGPT). This is likely due to the increased commercial interest and availability of volumetric imaging systems, as well as the shift from passively scattered proton therapy to intensity modulated proton therapy. Currently, there is no standard modality for volumetric IGPT, leading to variation between different proton therapy centres. This article reviews the reported clinical use of volumetric IGPT, as available in published literature, and summarises their utilisation and workflow where possible. In addition, novel volumetric imaging systems are also briefly summarised highlighting their potential benefits for IGPT and the challenges that need to be overcome before they can be used clinically.
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Affiliation(s)
- Mitchell Herrick
- Department of Radiation Oncology, Royal Adelaide Hospital, Adelaide, Australia.
- Department of Physics, University of Adelaide, Adelaide, Australia.
| | - Scott Penfold
- Department of Physics, University of Adelaide, Adelaide, Australia
- Australian Bragg Centre for Proton Therapy and Research, Adelaide, Australia
| | - Alexandre Santos
- Department of Radiation Oncology, Royal Adelaide Hospital, Adelaide, Australia
- Department of Physics, University of Adelaide, Adelaide, Australia
- Australian Bragg Centre for Proton Therapy and Research, Adelaide, Australia
| | - Kevin Hickson
- SA Medical Imaging, Adelaide, Australia
- University of South Australia, Allied Health & Human Performance, Adelaide, Australia
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10
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Knäusl B, Lebbink F, Fossati P, Engwall E, Georg D, Stock M. Patient Breathing Motion and Delivery Specifics Influencing the Robustness of a Proton Pancreas Irradiation. Cancers (Basel) 2023; 15:cancers15092550. [PMID: 37174016 PMCID: PMC10177445 DOI: 10.3390/cancers15092550] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 04/24/2023] [Accepted: 04/28/2023] [Indexed: 05/15/2023] Open
Abstract
Motion compensation strategies in particle therapy depend on the anatomy, motion amplitude and underlying beam delivery technology. This retrospective study on pancreas patients with small moving tumours analysed existing treatment concepts and serves as a basis for future treatment strategies for patients with larger motion amplitudes as well as the transition towards carbon ion treatments. The dose distributions of 17 hypofractionated proton treatment plans were analysed using 4D dose tracking (4DDT). The recalculation of clinical treatment plans employing robust optimisation for mitigating different organ fillings was performed on phased-based 4D computed tomography (4DCT) data considering the accelerator (pulsed scanned pencil beams delivered by a synchrotron) and the breathing-time structure. The analysis confirmed the robustness of the included treatment plans concerning the interplay of beam and organ motion. The median deterioration of D50% (ΔD50%) for the clinical target volume (CTV) and the planning target volume (PTV) was below 2%, while the only outlier was observed for ΔD98% with -35.1%. The average gamma pass rate over all treatment plans (2%/ 2 mm) was 88.8% ± 8.3, while treatment plans for motion amplitudes larger than 1 mm performed worse. For organs at risk (OARs), the median ΔD2% was below 3%, but for single patients, essential changes, e.g., up to 160% for the stomach were observed. The hypofractionated proton treatment for pancreas patients based on robust treatment plan optimisation and 2 to 4 horizontal and vertical beams showed to be robust against intra-fractional movements up to 3.7 mm. It could be demonstrated that the patient's orientation did not influence the motion sensitivity. The identified outliers showed the need for continuous 4DDT calculations in clinical practice to identify patient cases with more significant deviations.
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Affiliation(s)
- Barbara Knäusl
- Department of Radiation Oncology, Medical University of Vienna, 1090 Vienna, Austria
- MedAustron Ion Therapy Centre, Medical Physics, 2700 Wiener Neustadt, Austria
| | - Franciska Lebbink
- Department of Radiation Oncology, Medical University of Vienna, 1090 Vienna, Austria
- MedAustron Ion Therapy Centre, Medical Physics, 2700 Wiener Neustadt, Austria
| | - Piero Fossati
- MedAustron Ion Therapy Centre, Medical Physics, 2700 Wiener Neustadt, Austria
- Division Medical Physics, Karl Landsteiner University of Health Sciences, 2700 Wiener Neustadt, Austria
| | | | - Dietmar Georg
- Department of Radiation Oncology, Medical University of Vienna, 1090 Vienna, Austria
| | - Markus Stock
- MedAustron Ion Therapy Centre, Medical Physics, 2700 Wiener Neustadt, Austria
- Division Medical Physics, Karl Landsteiner University of Health Sciences, 2700 Wiener Neustadt, Austria
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11
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Grevillot L, Moreno JO, Fuchs H, Dreindl R, Elia A, Bolsa-Ferruz M, Stock M, Palmans H. Implementation of Sphinx/Lynx as daily QA equipment for scanned proton and carbon ion beams. J Appl Clin Med Phys 2023; 24:e13896. [PMID: 36704919 PMCID: PMC10113702 DOI: 10.1002/acm2.13896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 12/16/2022] [Accepted: 12/20/2022] [Indexed: 01/28/2023] Open
Abstract
PURPOSE Reporting on the first implementation of a proton dedicated commercial device (IBA Sphinx/Lynx) for daily Quality Assurance (QA) of scanned proton and carbon ion beams. METHODS Daily QA trendlines over more than 3 years for protons and more than 2 years for carbon ions have been acquired. Key daily QA parameters were reviewed, namely the spot size and position, beam range, Bragg peak width, coincidence (between beam and imaging system isocenters), homogeneity and dose. RESULTS The performance of the QA equipment for protons and carbon ions was evaluated. Daily QA trendlines allowed us to detect machine performance drifts and changes. The definition of tolerances and action levels is provided and compared with levels used in the literature. CONCLUSION The device has been successfully implemented for routine daily QA activities in a dual particle therapy facility for more than 2 years. It improved the efficiency of daily QA and provides a comprehensive QA process.
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Affiliation(s)
| | | | - Hermann Fuchs
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria.,Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, Wiener Neustadt, Austria.,Department of Radiation Oncology, Medical University of Vienna/AKH Vienna, Wiener Neustadt, Austria
| | - Ralf Dreindl
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
| | - Alessio Elia
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
| | | | - Markus Stock
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria.,Department of Oncology, Karl Landsteiner University of Health Sciences, Wiener Neustadt, Austria
| | - Hugo Palmans
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria.,National Physical Laboratory, Teddington, UK
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12
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Resch AF, Padilla Cabal F, Regodic M, Lechner W, Heilemann G, Kuess P, Georg D, Palmans H. Accelerating and improving radiochromic film calibration by utilizing the dose ratio in photon and proton beams. Med Phys 2022; 49:6150-6160. [PMID: 35754376 PMCID: PMC9543697 DOI: 10.1002/mp.15828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 06/08/2022] [Accepted: 06/09/2022] [Indexed: 11/12/2022] Open
Abstract
Purpose Radiochromic films are versatile 2D dosimeters with high‐resolution and near tissue equivalence. To assure high precision and accuracy, a time‐consuming calibration process is required. To improve the time efficiency, a novel calibration method utilizing the ratio of the same dose profile measured at different monitor units (MUs) is introduced and tested in a proton and photon beam. Methods The calibration procedure employs the dose ratio of film measurements of the same relative profile for different absolute dose values. Hence, the ratio of the dose is constant at any point of the profile, but the ratio of the net optical densities is not constant. The key idea of the method is to optimize the calibration function until the ratio of the calculated doses is constant. The proposed method was tested in the dose range between 0.25–12 and 1–6 Gy in a proton and photon beam, respectively. A radial symmetric profile and a rectangular profile were created, both having a central plateau region of about 3 cm diameter and a dose falloff of about 1.5 cm at larger distances. The dose falloff region was used as input for the optimization method and the central plateau region served as dose reference points. Only the plateau region of the highest dose entered the optimization as an additional objective. The measured data were randomly split into differently sized training and test sets. The optimization was repeated 1000 times with random start value initialization using the same start values for the standard and the gradient method. Finally, a proton plan with four dose levels was created, which were separated spatially, to test the possibility of a full calibration within a single measurement. Results Parameter estimation was possible with as low as one dose ratio used for optimization in both the photon and the proton case, yet exhibiting a high sensitivity on the dose level. The root mean squared deviation (RMSD) of the dose was less than 1% when the dose ratio was in the order of 20, whereas the median RMSD of all optimizations was 1.7%. Using four dose levels for optimization resulted in a median RMSD of 1% when randomly selecting the dose levels. Having at least one dose ratio of about 20 included in the optimization considerably improved the RMSD of the calibration function. Using six or eight dose levels reduced the sensitivity on the dose level selection and the median RMSD was 0.8%. A full calibration was possible in a single measurement having four dose levels in one plan but spatially separated. Conclusions The number of measurements required to obtain an EBT3 film calibration function could be reduced using the proposed dose ratio method while maintaining the same accuracy as with the standard method.
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Affiliation(s)
- Andreas F. Resch
- Division Medical Radiation PhysicsDepartment of Radiation OncologyMedical University of Vienna/AKH WienViennaAustria
| | - Fatima Padilla Cabal
- Division Medical Radiation PhysicsDepartment of Radiation OncologyMedical University of Vienna/AKH WienViennaAustria
| | - Milovan Regodic
- Division Medical Radiation PhysicsDepartment of Radiation OncologyMedical University of Vienna/AKH WienViennaAustria
| | - Wolfgang Lechner
- Division Medical Radiation PhysicsDepartment of Radiation OncologyMedical University of Vienna/AKH WienViennaAustria
| | - Gerd Heilemann
- Division Medical Radiation PhysicsDepartment of Radiation OncologyMedical University of Vienna/AKH WienViennaAustria
| | - Peter Kuess
- Division Medical Radiation PhysicsDepartment of Radiation OncologyMedical University of Vienna/AKH WienViennaAustria
| | - Dietmar Georg
- Division Medical Radiation PhysicsDepartment of Radiation OncologyMedical University of Vienna/AKH WienViennaAustria
| | - Hugo Palmans
- MedAustron Ion Therapy CentreWiener NeustadtAustria
- Medical Radiation ScienceNational Physical LaboratoryTeddingtonUnited Kingdom
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13
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Possibilities and challenges when using synthetic computed tomography in an adaptive carbon-ion treatment workflow. Z Med Phys 2022:S0939-3889(22)00064-2. [PMID: 35764469 DOI: 10.1016/j.zemedi.2022.05.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 05/29/2022] [Accepted: 05/29/2022] [Indexed: 11/23/2022]
Abstract
BACKGROUND AND PURPOSE Anatomical surveillance during ion-beam therapy is the basis for an effective tumor treatment and optimal organ at risk (OAR) sparing. Synthetic computed tomography (sCT) based on magnetic resonance imaging (MRI) can replace the X-ray based planning CT (X-rayCT) in photon radiotherapy and improve the workflow efficiency without additional imaging dose. The extension to carbon-ion radiotherapy is highly challenging; complex patient positioning, unique anatomical situations, distinct horizontal and vertical beam incidence directions, and limited training data are only few problems. This study gives insight into the possibilities and challenges of using sCTs in carbon-ion therapy. MATERIALS AND METHODS For head and neck patients immobilised with thermoplastic masks 30 clinically applied actively scanned carbon-ion treatment plans on 15 CTs comprising 60 beams were analyzed. Those treatment plans were re-calculated on MRI based sCTs which were created employing a 3D U-Net. Dose differences and carbon-ion spot displacements between sCT and X-rayCT were evaluated on a patient specific basis. RESULTS Spot displacement analysis showed a peak displacement by 0.2 cm caused by the immobilisation mask not measurable with the MRI. 95.7% of all spot displacements were located within 1 cm. For the clinical target volume (CTV) the median D50% agreed within -0.2% (-1.3 to 1.4%), while the median D0.01cc differed up to 4.2% (-1.3 to 25.3%) comparing the dose distribution on the X-rayCT and the sCT. OAR deviations depended strongly on the position and the dose gradient. For three patients no deterioration of the OAR parameters was observed. Other patients showed large deteriorations, e.g. for one patient D2% of the chiasm differed by 28.1%. CONCLUSION The usage of sCTs opens several new questions, concluding that we are not ready yet for an MR-only workflow in carbon-ion therapy, as envisaged in photon therapy. Although omitting the X-rayCT seems unfavourable in the case of carbon-ion therapy, an sCT could be advantageous for monitoring, re-planning, and adaptation.
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14
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Efficient full Monte Carlo modelling and multi-energy generative model development of an advanced X-ray device. Z Med Phys 2022:S0939-3889(22)00061-7. [DOI: 10.1016/j.zemedi.2022.04.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 04/28/2022] [Accepted: 04/28/2022] [Indexed: 11/22/2022]
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15
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Lebbink F, Stock M, Georg D, Knäusl B. The Influence of Motion on the Delivery Accuracy When Comparing Actively Scanned Carbon Ions versus Protons at a Synchrotron-Based Radiotherapy Facility. Cancers (Basel) 2022; 14:cancers14071788. [PMID: 35406558 PMCID: PMC8997550 DOI: 10.3390/cancers14071788] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 03/28/2022] [Accepted: 03/28/2022] [Indexed: 02/06/2023] Open
Abstract
Simple Summary The interplay of breathing and beam motion reduces the efficacy of particle irradiation in moving tumours. The effect of motion on protons and carbon ion treatments was investigated dosimetrically and the results were benchmarked against each other by employing an anthropomorphic thorax phantom that was able to simulate tumour, rib, and lung motion. The critical question was whether target coverage and organ-at-risk sparing could be maintained when the application of simple motion mitigation was addressed. Special focus was put on unique synchrotron characteristics, such as pulsed beam delivery and beam intensity variations. It could be demonstrated that the effect of motion was greater for carbon ions than for protons. These findings demonstrated the need for applying motion mitigation techniques depending on the motion amplitude, particle type, and treatment prescription considering complex time correlations. Abstract Motion amplitudes, in need of mitigation for moving targets irradiated with pulsed carbon ions and protons, were identified to guide the decision on treatment and motion mitigation strategy. Measurements with PinPoint ionisation chambers positioned in an anthropomorphic breathing phantom were acquired to investigate different tumour motion scenarios, including rib and lung movements. The effect of beam delivery dynamics and spot characteristics was considered. The dose in the tumour centre was deteriorated up to 10% for carbon ions but only up to 5% for protons. Dose deviations in the penumbra increased by a factor of two when comparing carbon ions to protons, ranging from 2 to 30% for an increasing motion amplitude that was strongly dependent on the beam intensity. Layer rescanning was able to diminish the dose distortion caused by tumour motion, but an increase in spot size could reduce it even further to 5% within the target and 10% at the penumbra. An increased need for motion mitigation of carbon ions compared to protons was identified to assure target coverage and sparing of adjacent organs at risk in the penumbra region and outside the target. For the clinical implementation of moving target treatments at a synchrotron-based particle facility complex, time dependencies needed to be considered.
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Affiliation(s)
- Franciska Lebbink
- MedAustron Ion Therapy Centre, Medical Physics, 2700 Wiener Neustadt, Austria; (F.L.); (M.S.)
- Department of Radiation Oncology, Medical University of Vienna, 1090 Vienna, Austria;
| | - Markus Stock
- MedAustron Ion Therapy Centre, Medical Physics, 2700 Wiener Neustadt, Austria; (F.L.); (M.S.)
| | - Dietmar Georg
- Department of Radiation Oncology, Medical University of Vienna, 1090 Vienna, Austria;
| | - Barbara Knäusl
- MedAustron Ion Therapy Centre, Medical Physics, 2700 Wiener Neustadt, Austria; (F.L.); (M.S.)
- Department of Radiation Oncology, Medical University of Vienna, 1090 Vienna, Austria;
- Correspondence:
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16
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Lohberger B, Glänzer D, Eck N, Kerschbaum-Gruber S, Mara E, Deycmar S, Madl T, Kashofer K, Georg P, Leithner A, Georg D. Activation of efficient DNA repair mechanisms after photon and proton irradiation of human chondrosarcoma cells. Sci Rep 2021; 11:24116. [PMID: 34916568 PMCID: PMC8677811 DOI: 10.1038/s41598-021-03529-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 11/24/2021] [Indexed: 01/02/2023] Open
Abstract
Although particle therapy with protons has proven to be beneficial in the treatment of chondrosarcoma compared to photon-based (X-ray) radiation therapy, the cellular and molecular mechanisms have not yet been sufficiently investigated. Cell viability and colony forming ability were analyzed after X-ray and proton irradiation (IR). Cell cycle was analyzed using flow cytometry and corresponding regulator genes and key players of the DNA repair mechanisms were measured using next generation sequencing, protein expression and immunofluorescence staining. Changes in metabolic phenotypes were determined with nuclear magnetic resonance spectroscopy. Both X-ray and proton IR resulted in reduced cell survival and a G2/M phase arrest of the cell cycle. Especially 1 h after IR, a significant dose-dependent increase of phosphorylated γH2AX foci was observed. This was accompanied with a reprogramming in cellular metabolism. Interestingly, within 24 h the majority of clearly visible DNA damages were repaired and the metabolic phenotype restored. Involved DNA repair mechanisms are, besides the homology directed repair (HDR) and the non-homologous end-joining (NHEJ), especially the mismatch mediated repair (MMR) pathway with the key players EXO1, MSH3, and PCNA. Chondrosarcoma cells regenerates the majority of DNA damages within 24 h. These molecular mechanisms represent an important basis for an improved therapy.
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Affiliation(s)
- Birgit Lohberger
- Department of Orthopedics and Trauma, Medical University of Graz, Auenbruggerplatz 5-7, 8036, Graz, Austria.
| | - Dietmar Glänzer
- Department of Orthopedics and Trauma, Medical University of Graz, Auenbruggerplatz 5-7, 8036, Graz, Austria
| | - Nicole Eck
- Department of Orthopedics and Trauma, Medical University of Graz, Auenbruggerplatz 5-7, 8036, Graz, Austria
| | - Sylvia Kerschbaum-Gruber
- Department of Radiation Oncology, Medical University of Vienna, 1090, Vienna, Austria
- MedAustron Ion Therapy Center, 2700, Wiener Neustadt, Austria
| | - Elisabeth Mara
- MedAustron Ion Therapy Center, 2700, Wiener Neustadt, Austria
- University of Applied Science, 2700, Wiener Neustadt, Austria
| | - Simon Deycmar
- Laboratory for Applied Radiobiology, University Zurich, 8006, Zurich, Switzerland
| | - Tobias Madl
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging Molecular Biology and Biochemistry, Medical University of Graz, 8010, Graz, Austria
- BioTechMed-Graz, 8010, Graz, Austria
| | - Karl Kashofer
- Institute of Pathology, Medical University of Graz, 8010, Graz, Austria
| | - Petra Georg
- MedAustron Ion Therapy Center, 2700, Wiener Neustadt, Austria
| | - Andreas Leithner
- Department of Orthopedics and Trauma, Medical University of Graz, Auenbruggerplatz 5-7, 8036, Graz, Austria
| | - Dietmar Georg
- Department of Radiation Oncology, Medical University of Vienna, 1090, Vienna, Austria
- MedAustron Ion Therapy Center, 2700, Wiener Neustadt, Austria
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17
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Zimmermann L, Knäusl B, Stock M, Lütgendorf-Caucig C, Georg D, Kuess P. An MRI sequence independent convolutional neural network for synthetic head CT generation in proton therapy. Z Med Phys 2021; 32:218-227. [PMID: 34920940 PMCID: PMC9948837 DOI: 10.1016/j.zemedi.2021.10.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 10/11/2021] [Accepted: 10/19/2021] [Indexed: 12/11/2022]
Abstract
A magnetic resonance imaging (MRI) sequence independent deep learning technique was developed and validated to generate synthetic computed tomography (sCT) scans for MR guided proton therapy. 47 meningioma patients previously undergoing proton therapy based on pencil beam scanning were divided into training (33), validation (6), and test (8) cohorts. T1, T2, and contrast enhanced T1 (T1CM) MRI sequences were used in combination with the planning CT (pCT) data to train a 3D U-Net architecture with ResNet-Blocks. A hyperparameter search was performed including two loss functions, two group sizes of normalisation, and depth of the network. Training outcome was compared between models trained for each individual MRI sequence and for all sequences combined. The performance was evaluated based on a metric and dosimetric analysis as well as spot difference maps. Furthermore, the influence of immobilisation masks that are not visible on MRIs was investigated. Based on the hyperparameter search, the final model was trained with fixed features per group for the group normalisation, six down-convolution steps, an input size of 128×192×192, and feature loss. For the test dataset for body/bone the mean absolute error (MAE) values were on average 79.8/216.3Houndsfield unit (HU) when trained using T1 images, 71.1/186.1HU for T2, and 82.9/236.4HU for T1CM. The structural similarity metric (SSIM) ranged from 0.95 to 0.98 for all sequences. The investigated dose parameters of the target structures agreed within 1% between original proton treatment plans and plans recalculated on sCTs. The spot difference maps had peaks at ±0.2cm and for 98% of all spots the difference was less than 1cm. A novel MRI sequence independent sCT generator was developed, which suggests that the training phase of neural networks can be disengaged from specific MRI acquisition protocols. In contrast to previous studies, the patient cohort consisted exclusively of actual proton therapy patients (i.e. "real-world data").
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Affiliation(s)
- Lukas Zimmermann
- Medical University of Vienna, Department of Radiation Oncology, Vienna, Austria,Faculty of Engineering, University of Applied Sciences Wiener Neustadt, Austria,Competence Center for Preclinical Imaging and Biomedical Engineering, University of Applied Sciences Wiener Neustadt, Austria
| | - Barbara Knäusl
- Medical University of Vienna, Department of Radiation Oncology, Vienna, Austria,MedAustron Ion Therapy Center, Wiener Neustadt, Austria
| | - Markus Stock
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
| | | | - Dietmar Georg
- Medical University of Vienna, Department of Radiation Oncology, Vienna, Austria
| | - Peter Kuess
- Medical University of Vienna, Department of Radiation Oncology, Vienna, Austria; MedAustron Ion Therapy Center, Wiener Neustadt, Austria.
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18
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Nenoff L, Matter M, Charmillot M, Krier S, Uher K, Weber DC, Lomax AJ, Albertini F. Experimental validation of daily adaptive proton therapy. Phys Med Biol 2021; 66. [PMID: 34587589 DOI: 10.1088/1361-6560/ac2b84] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Accepted: 09/29/2021] [Indexed: 11/12/2022]
Abstract
Anatomical changes during proton therapy require rapid treatment plan adaption to mitigate the associated dosimetric impact. This in turn requires a highly efficient workflow that minimizes the time between imaging and delivery. At the Paul Scherrer Institute, we have developed an online adaptive workflow, which is specifically designed for treatments in the skull-base/cranium, with the focus set on simplicity and minimizing changes to the conventional workflow. The dosimetric and timing performance of this daily adaptive proton therapy (DAPT) workflow has been experimentally investigated using an in-house developed DAPT software and specifically developed anthropomorphic phantom. After a standard treatment preparation, which includes the generation of a template plan, the treatment can then be adapted each day, based on daily imaging acquired on an in-room CT. The template structures are then rigidly propagated to this CT and the daily plan is fully re-optimized using the same field arrangement, DVH constraints and optimization settings of the template plan. After a dedicated plan QA, the daily plan is delivered. To minimize the time between imaging and delivery, clinically integrated software for efficient execution of all online adaption steps, as well as tools for comprehensive and automated QA checks, have been developed. Film measurements of an end-to-end validation of a multi-fraction DAPT treatment showed high agreement to the calculated doses. Gamma pass rates with a 3%/3 mm criteria were >92% when comparing the measured dose to the template plan. Additionally, a gamma pass rate >99% was found comparing measurements to the Monte Carlo dose of the daily plans reconstructed from the logfile, accumulated over the delivered fractions. With this, we experimentally demonstrate that the described adaptive workflow can be delivered accurately in a timescale similar to a standard delivery.
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Affiliation(s)
- Lena Nenoff
- Paul Scherrer Institute, Center for Proton Therapy, Switzerland.,Department of Physics, ETH Zurich, Switzerland
| | - Michael Matter
- Paul Scherrer Institute, Center for Proton Therapy, Switzerland.,Department of Physics, ETH Zurich, Switzerland
| | | | - Serge Krier
- Department of Physics, ETH Zurich, Switzerland
| | - Klara Uher
- Department of Physics, ETH Zurich, Switzerland
| | - Damien Charles Weber
- Paul Scherrer Institute, Center for Proton Therapy, Switzerland.,Department of Radiation Oncology, University Hospital Zurich, Switzerland.,Department of Radiation Oncology, University Hospital Bern, Switzerland
| | - Antony John Lomax
- Paul Scherrer Institute, Center for Proton Therapy, Switzerland.,Department of Physics, ETH Zurich, Switzerland
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19
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Ruangchan S, Palmans H, Knäusl B, Georg D, Clausen M. Dose calculation accuracy in particle therapy: Comparing carbon ions with protons. Med Phys 2021; 48:7333-7345. [PMID: 34482555 PMCID: PMC9291072 DOI: 10.1002/mp.15209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 06/02/2021] [Accepted: 08/18/2021] [Indexed: 11/18/2022] Open
Abstract
Purpose This work presents the validation of an analytical pencil beam dose calculation algorithm in a commercial treatment planning system (TPS) for carbon ions by measurements of dose distributions in heterogeneous phantom geometries. Additionally, a comparison study of carbon ions versus protons is performed considering current best solutions in commercial TPS. Methods All treatment plans were optimized and calculated using the RayStation TPS (RaySearch, Sweden). The dose distributions calculated with the TPS were compared with measurements using a 24‐pinpoint ionization chamber array (T31015, PTW, Germany). Tissue‐like inhomogeneities (bone, lung, and soft tissue) were embedded in water, while a target volume of 4 x 4 x 4 cm3 was defined at two different depths behind the heterogeneities. In total, 10 different test cases, with and without range shifter as well as different air gaps, were investigated. Dose distributions inside as well as behind the target volume were evaluated. Results Inside the target volume, the mean dose difference between calculations and measurements, averaged over all test cases, was 1.6% for carbon ions. This compares well to the final agreement of 1.5% obtained in water at the commissioning stage of the TPS for carbon ions and is also within the clinically acceptable interval of 3%. The mean dose difference and maximal dose difference obtained outside the target area were 1.8% and 13.4%, respectively. The agreement of dose distributions for carbon ions in the target volumes was comparable or better to that between Monte Carlo (MC) dose calculations and measurements for protons. Percentage dose differences of more than 10% were present outside the target area behind bone–lung structures, where the carbon ion calculations systematically over predicted the dose. MC dose calculations for protons were superior to carbon ion beams outside the target volumes. Conclusion The pencil beam dose calculations for carbon ions in RayStation were found to be in good agreement with dosimetric measurements in heterogeneous geometries for points of interest located within the target. Large local discrepancies behind the target may contribute to incorrect dose predictions for organs at risk.
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Affiliation(s)
- Sirinya Ruangchan
- Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria.,Department of Radiology, King Chulalongkorn Memorial Hospital, Bangkok, Thailand
| | - Hugo Palmans
- Division of Medical Physics, MedAustron Ion Therapy Center, Wiener Neustadt, Austria.,Medical Radiation Science, National Physical Laboratory, Teddington, UK
| | - Barbara Knäusl
- Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria.,Division of Medical Physics, MedAustron Ion Therapy Center, Wiener Neustadt, Austria
| | - Dietmar Georg
- Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria.,Division of Medical Physics, MedAustron Ion Therapy Center, Wiener Neustadt, Austria
| | - Monika Clausen
- Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
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20
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Fuchs H, Padilla‐Cabal F, Zimmermann L, Palmans H, Georg D. MR-guided proton therapy: Impact of magnetic fields on the detector response. Med Phys 2021; 48:2572-2579. [PMID: 33326614 PMCID: PMC8251909 DOI: 10.1002/mp.14660] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 12/03/2020] [Accepted: 12/03/2020] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To investigate the response of detectors for proton dosimetry in the presence of magnetic fields. MATERIAL AND METHODS Four ionization chambers (ICs), two thimble-type and two plane-parallel-type, and a diamond detector were investigated. All detectors were irradiated with homogeneous single-energy-layer fields, using 252.7 MeV proton beams. A Farmer IC was additionally irradiated in the same geometrical configuration, but with a lower nominal energy of 97.4 MeV. The beams were subjected to magnetic field strengths of 0, 0.25, 0.5, 0.75, and 1 T produced by a research dipole magnet placed at the room's isocenter. Detectors were positioned at 2 cm water equivalent depth, with their stem perpendicular to both the magnetic field lines and the proton beam's central axis, in the direction of the Lorentz force. Normality and two sample statistical Student's t tests were performed to assess the influence of the magnetic field on the detectors' responses. RESULTS For all detectors, a small but significant magnetic field-dependent change of their response was found. Observed differences compared to the no magnetic field case ranged from +0.5% to -0.7%. The magnetic field dependence was found to be nonlinear and highest between 0.25 and 0.5 T for 252.7 MeV proton beams. A different variation of the Farmer chamber response with magnetic field strength was observed for irradiations using lower energy (97.4 MeV) protons. The largest magnetic field effects were observed for plane-parallel ionization chambers. CONCLUSION Small magnetic field-dependent changes in the detector response were identified, which should be corrected for dosimetric applications.
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Affiliation(s)
- Hermann Fuchs
- Division of Medical PhysicsDepartment of Radiation OncologyMedical University of Vienna1090ViennaAustria
- Division of Medical PhysicsMedAustron Ion Therapy Center2700Wiener NeustadtAustria
| | - Fatima Padilla‐Cabal
- Division of Medical PhysicsDepartment of Radiation OncologyMedical University of Vienna1090ViennaAustria
| | - Lukas Zimmermann
- Division of Medical PhysicsDepartment of Radiation OncologyMedical University of Vienna1090ViennaAustria
| | - Hugo Palmans
- Division of Medical PhysicsMedAustron Ion Therapy Center2700Wiener NeustadtAustria
- National Physical LaboratoryTW11 0LWTeddingtonUnited Kingdom
| | - Dietmar Georg
- Division of Medical PhysicsDepartment of Radiation OncologyMedical University of Vienna1090ViennaAustria
- Division of Medical PhysicsMedAustron Ion Therapy Center2700Wiener NeustadtAustria
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Zechner A, Ziegler I, Hug E, Lütgendorf-Caucig C, Stock M. Evaluation of the inter- and intrafraction displacement for head patients treated at the particle therapy centre MedAustron based on the comparison of different commercial immobilisation devices. Z Med Phys 2021; 32:39-51. [PMID: 33640219 PMCID: PMC9948876 DOI: 10.1016/j.zemedi.2021.01.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 12/14/2020] [Accepted: 01/25/2021] [Indexed: 02/03/2023]
Abstract
In December 2016 the clinical operation has started at the particle therapy centre MedAustron, Wiener Neustadt, Austria. Different commercial immobilisation devices are used for head patients. These immobilisation devices are a combination of table tops (Qfix BoS™ Headframe, Elekta HeadStep™), pillows (BoS™ Standard pillow, Moldcare®, HeadStep™ pillow) and thermoplastic masks (Klarity Green™, Qfix Fibreplast™, HeadStep™ iCAST double). For each patient image-guided radiotherapy (IGRT) is performed by acquiring orthogonal X-ray imaging and 2D3D registration and the application of the resulting 6-degree of freedom (DOF) position correction on the robotic couch. The inter- and intrafraction displacement of 101 adult head patients and 27 paediatric sedated head patients were evaluated and compared among each other regarding reproducibility during the entire treatment and stability during each fraction. For the comparison, statistical methods (Shapiro-Wilk test, Mann-Whitney U-test) were applied on the position corrections as well as on the position verifications. The actual planning target volume margins of 3mm (adults) and 2mm (children) were evaluated by applying the van Herk formula on the intrafraction displacement results and performing treatment plan robustness simulations of twelve different translational offset scenarios including a HU uncertainty of 3.5%. Statistically significant differences between the immobilisation devices were found, but they turned out to be clinically irrelevant. The margin calculation for adult head patients resulted in 0.8mm (lateral), 1.2mm (cranio-caudal) and 0.6mm (anterior-posterior), and for paediatric head patients under anaesthesia in 0.8mm (lateral), 0.5mm (cranio-caudal) and 0.9mm (anterior-posterior). Based on these values, robustness evaluations of selected adult head patients and sedated children showed the validity of the currently used PTV margins.
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Affiliation(s)
- Andrea Zechner
- MedAustron Ion Therapy Centre, Wiener Neustadt, Austria.
| | - Ingrid Ziegler
- University Clinic for Radiotherapy and Radio-Oncology, Paracelsus Medical University, Salzburg, Austria
| | - Eugen Hug
- MedAustron Ion Therapy Centre, Wiener Neustadt, Austria
| | | | - Markus Stock
- MedAustron Ion Therapy Centre, Wiener Neustadt, Austria
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Zimmermann L, Buschmann M, Herrmann H, Heilemann G, Kuess P, Goldner G, Nyholm T, Georg D, Nesvacil N. An MR-only acquisition and artificial intelligence based image-processing protocol for photon and proton therapy using a low field MR. Z Med Phys 2021; 31:78-88. [PMID: 33455822 DOI: 10.1016/j.zemedi.2020.10.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 09/14/2020] [Accepted: 10/27/2020] [Indexed: 10/22/2022]
Abstract
OBJECTIVE Recent developments on synthetically generated CTs (sCT), hybrid MRI linacs and MR-only simulations underlined the clinical feasibility and acceptance of MR guided radiation therapy. However, considering clinical application of open and low field MR with a limited field of view can result in truncation of the patient's anatomy which further affects the MR to sCT conversion. In this study an acquisition protocol and subsequent MR image stitching is proposed to overcome the limited field of view restriction of open MR scanners, for MR-only photon and proton therapy. MATERIAL AND METHODS 12 prostate cancer patients scanned with an open 0.35T scanner were included. To obtain the full body contour an enhanced imaging protocol including two repeated scans after bilateral table movement was introduced. All required structures (patient contour, target and organ at risk) were delineated on a post-processed combined transversal image set (stitched MRI). The postprocessed MR was converted into a sCT by a pretrained neural network generator. Inversely planned photon and proton plans (VMAT and SFUD) were designed using the sCT and recalculated for rigidly and deformably registered CT images and compared based on D2%, D50%, V70Gy for organs at risk and based on D2%, D50%, D98% for the CTV and PTV. The stitched MRI and the untruncated MRI were compared to the CT, and the maximum surface distance was calculated. The sCT was evaluated with respect to delineation accuracy by comparing on stitched MRI and sCT using the DICE coefficient for femoral bones and the whole body. RESULTS Maximum surface distance analysis revealed uncertainties in lateral direction of 1-3mm on average. DICE coefficient analysis confirms good performance of the sCT conversion, i.e. 92%, 93%, and 100% were obtained for femoral bone left and right and whole body. Dose comparison resulted in uncertainties below 1% between deformed CT and sCT and below 2% between rigidly registered CT and sCT in the CTV for photon and proton treatment plans. DISCUSSION A newly developed acquisition protocol for open MR scanners and subsequent Sct generation revealed good acceptance for photon and proton therapy. Moreover, this protocol tackles the restriction of the limited FOVs and expands the capacities towards MR guided proton therapy with horizontal beam lines.
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Affiliation(s)
- Lukas Zimmermann
- Division of Medical Radiation Physics, Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria.
| | - Martin Buschmann
- Division of Medical Radiation Physics, Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
| | - Harald Herrmann
- Division of Medical Radiation Physics, Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
| | - Gerd Heilemann
- Division of Medical Radiation Physics, Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
| | - Peter Kuess
- Division of Medical Radiation Physics, Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
| | - Gregor Goldner
- Division of Medical Radiation Physics, Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
| | - Tufve Nyholm
- Department of Radiation Sciences, Umeå University, Umeå, Sweden
| | - Dietmar Georg
- Division of Medical Radiation Physics, Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
| | - Nicole Nesvacil
- Division of Medical Radiation Physics, Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
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Fuchs H, Elia A, Resch AF, Kuess P, Lühr A, Vidal M, Grevillot L, Georg D. Computer-assisted beam modeling for particle therapy. Med Phys 2020; 48:841-851. [PMID: 33283910 PMCID: PMC7986420 DOI: 10.1002/mp.14647] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 05/17/2020] [Accepted: 06/22/2020] [Indexed: 11/15/2022] Open
Abstract
Purpose To develop a computer‐driven and thus less user‐dependent method, allowing for a simple and straightforward generation of a Monte Carlo (MC) beam model of a scanned proton and carbon ion beam delivery system. Methods In a first step, experimental measurements were performed for proton and carbon ion energies in the available energy ranges. Data included depth dose profiles measured in water and spot sizes in air at various isocenter distances. Using an automated regularization‐based optimization process (AUTO‐BEAM), GATE/Geant4 beam models of the respective beam lines were generated. These were obtained sequentially by using least square weighting functions with and without regularization, to iteratively tune the beam parameters energy, energy spread, beam sigma, divergence, and emittance until a user‐defined agreement was reached. Based on the parameter tuning for a set of energies, a beam model was semi‐automatically generated. The resulting beam models were validated for all centers comparing to independent measurements of laterally integrated depth dose curves and spot sizes in air. For one representative center, three‐dimensional dose cubes were measured and compared to simulations. The method was applied on one research as well as four different clinical beam lines for proton and carbon ions of three different particle therapy centers using synchrotron or cyclotron accelerator systems: (a) MedAustron ion therapy center, (b) University Proton Therapy Dresden, and (c) Center Antoine Lacassagne Nice. Results Particle beam ranges in the MC beam models agreed on average within 0.2 mm compared to measurements for all energies and beam lines. Spot sizes in air (full‐width at half maximum) at all positions differed by less than 0.4% from the measurements. Dose calculation with the beam model for the clinical beam line at MedAustron agreed better than 1.7% in absolute dose for a representative clinical case treated with protons. For protons, beam model generation, including geometry creation, data conversion, and validation, was possible within three working days. The number of iterations required for the optimization process to converge, was found to be similar for all beam line geometries and particle types. Conclusion The presented method was demonstrated to work independently of the beam optics behavior of the different beam lines, particle types, and geometries. Furthermore, it is suitable for non‐expert users and requires only limited user interaction. Beam model validation for different beam lines based on different beam delivery systems, showed good agreement.
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Affiliation(s)
- Hermann Fuchs
- Division of Medical Radiation Physics, Department of Radiation Oncology, Medical University of Vienna, Währinger Gürtel 18-20, Vienna, 1090, Austria
| | - Alessio Elia
- MedAustron Ion Therapy Center, Wiener Neustadt, 2700, Austria
| | - Andreas F Resch
- Division of Medical Radiation Physics, Department of Radiation Oncology, Medical University of Vienna, Währinger Gürtel 18-20, Vienna, 1090, Austria
| | - Peter Kuess
- Division of Medical Radiation Physics, Department of Radiation Oncology, Medical University of Vienna, Währinger Gürtel 18-20, Vienna, 1090, Austria
| | - Armin Lühr
- OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, 01309, Germany.,Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiooncology - OncoRay, Dresden, 01309, Germany.,Department of Medical Physics, Faculty of Physics, TU Dortmund University, Dortmund, 44227, Germany
| | - Marie Vidal
- Center Antoine Lacassagne, Nice, 06189, France
| | - Loïc Grevillot
- MedAustron Ion Therapy Center, Wiener Neustadt, 2700, Austria
| | - Dietmar Georg
- Division of Medical Radiation Physics, Department of Radiation Oncology, Medical University of Vienna, Währinger Gürtel 18-20, Vienna, 1090, Austria
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Thummerer A, de Jong BA, Zaffino P, Meijers A, Marmitt GG, Seco J, Steenbakkers RJHM, Langendijk JA, Both S, Spadea MF, Knopf AC. Comparison of the suitability of CBCT- and MR-based synthetic CTs for daily adaptive proton therapy in head and neck patients. ACTA ACUST UNITED AC 2020; 65:235036. [DOI: 10.1088/1361-6560/abb1d6] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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25
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Kuess P, Haupt S, Osorio J, Grevillot L, Fuchs H, Georg D, Palmans H. Characterization of the PTW-34089 type 147 mm diameter large-area ionization chamber for use in light-ion beams. ACTA ACUST UNITED AC 2020; 65:17NT02. [DOI: 10.1088/1361-6560/ab9852] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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26
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Experimental benchmarking of RayStation proton dose calculation algorithms inside and outside the target region in heterogeneous phantom geometries. Phys Med 2020; 76:182-193. [DOI: 10.1016/j.ejmp.2020.07.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 07/03/2020] [Accepted: 07/07/2020] [Indexed: 11/18/2022] Open
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27
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Beam monitor calibration of a synchrotron-based scanned light-ion beam delivery system. Z Med Phys 2020; 31:154-165. [PMID: 32747175 DOI: 10.1016/j.zemedi.2020.06.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 05/20/2020] [Accepted: 06/15/2020] [Indexed: 11/23/2022]
Abstract
PURPOSE This paper presents the implementation and comparison of two independent methods of beam monitor calibration in terms of number of particles for scanned proton and carbon ion beams. METHODS In the first method, called the single-layer method, dose-area-product to water (DAPw) is derived from the absorbed dose to water determined using a Roos-type plane-parallel ionization chamber in single-energy scanned beams. This is considered the reference method for the beam monitor calibration in the clinically relevant proton and carbon energy ranges. In the second method, called the single-spot method, DAPw of a single central spot is determined using a Bragg-peak (BP) type large-area plane-parallel ionization chamber. Emphasis is given to the detailed characterization of the ionization chambers used for the beam monitor calibration. For both methods a detailed uncertainty budget on the DAPw determination is provided as well as on the derivation of the number of particles. RESULTS Both calibration methods agreed on average within 1.1% for protons and within 2.6% for carbon ions. The uncertainty on DAPw using single-layer beams is 2.1% for protons and 3.1% for carbon ions with major contributions from the available values of kQ and the average spot spacing in both lateral directions. The uncertainty using the single-spot method is 2.2% for protons and 3.2% for carbon ions with major contributions from the available values of kQ and the non-uniformity of the BP chamber response, which can lead to a correction of up-to 3.2%. For the number of particles, an additional dominant uncertainty component for the mean stopping power per incident proton (or the CEMA) needs to be added. CONCLUSION The agreement between both methods enhances confidence in the beam monitor calibration and the estimated uncertainty. The single-layer method can be used as a reference and the single-spot method is an alternative that, when more accumulated knowledge and data on the method becomes available, can be used as a redundant dose monitor calibration method. This work, together with the overview of information from the literature provided here, is a first step towards comprehensive information on the single-spot method.
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van der Heyden B, Uray M, Fonseca GP, Huber P, Us D, Messner I, Law A, Parii A, Reisz N, Rinaldi I, Vilches Freixas G, Deutschmann H, Verhaegen F, Steininger P. A Monte Carlo based scatter removal method for non-isocentric cone-beam CT acquisitions using a deep convolutional autoencoder. ACTA ACUST UNITED AC 2020; 65:145002. [DOI: 10.1088/1361-6560/ab8954] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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29
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The practical radius of a pencil beam in proton therapy. Z Med Phys 2020; 31:166-174. [PMID: 32651058 DOI: 10.1016/j.zemedi.2020.06.003] [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: 09/20/2019] [Revised: 06/03/2020] [Accepted: 06/05/2020] [Indexed: 11/22/2022]
Abstract
The central Gaussian shaped high dose region of a pencil beam (PB) in light ion beam therapy (LIBT) is enveloped by a low dose region causing non-negligible field size effects and impairs the dose calculation accuracy considerably if the low dose envelope is not well modeled. The purpose of this study was to calculate the practical radius, Rc, at which a PB does not influence a field more than a certain accuracy level. Lateral dose profiles of proton beams in water were simulated using GATE/Geant4. Those lateral dose profiles were integrated numerically and used to calculate field size factors (FSFs). The Rc was then determined such, that the lateral dose at radii exceeding Rc can be neglected without compromising the FSF of a 20cm×20cm field more than a desired accuracy level c. The practical radius Rc yielding c=0.5% was compared to the frequently applied concept of full width at a ratio x of the maximum (FWxM). The sensitivity to variations of the beam width was tested by increasing the initial beam width σC of the clinical beam model by 0.5 and 1mm, respectively. Neglecting the dose at radii exceeding Rc resulted in the desired FSF accuracy, whereas using the FW0.01%M cut resulted in varying accuracy. In order to yield a constant FSF accuracy, the ratio x in FWxM ranged from 0.003% to 0.065% of the maximum. In contrast to Rc, FWxM was sensitive to variations of the initial beam width. The maximum Rc over all depths was less than 7cm for the low(62.4MeV) and medium(148.2MeV) proton energy beam, which suggests that a plane parallel ionization chamber exceeding that radius is sufficient to acquire laterally integrated depth dose distributions for those energies. However, this holds not true for the highest energy (252.7MeV) or when including a range shifter (RaShi). The values of Rc are specific to our beam line configuration as the maximum Rc was depending on both, the scattering material in the Nozzle as well as the distance of the air-gap between Nozzle and phantom.
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30
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Kostiukhina N, Palmans H, Stock M, Knopf A, Georg D, Knäusl B. Time-resolved dosimetry for validation of 4D dose calculation in PBS proton therapy. Phys Med Biol 2020; 65:125015. [PMID: 32340002 DOI: 10.1088/1361-6560/ab8d79] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Four-dimensional dose calculation (4D-DC) is crucial for predicting the dosimetric outcome in the presence of intra-fractional organ motion. Time-resolved dosimetry can provide significant insights into 4D pencil beam scanning dose accumulation and is therefore irreplaceable for benchmarking 4D-DC. In this study a novel approach of time-resolved dosimetry using five PinPoint ionization chambers (ICs) embedded in an anthropomorphic dynamic phantom was employed and validated against beam delivery details. Beam intensity variations as well as the beam delivery time structure were well reflected with an accuracy comparable to the temporal resolution of the IC measurements. The 4D dosimetry approach was further applied for benchmarking the 4D-DC implemented in the RayStation 6.99 treatment planning system. Agreement between computed values and measurements was investigated for (i) partial doses based on individual breathing phases, and (ii) temporally distributed cumulative doses. For varied beam delivery and patient-related parameters the average unsigned dose difference for (i) was 0.04 ± 0.03 Gy over all considered IC measurement values, while the prescribed physical dose was 2 Gy. By implementing (ii), a strong effect of the dose gradient on measurement accuracy was observed. The gradient originated from scanned beam energy modulation and target motion transversal to the beam. Excluding measurements in the high gradient the relative dose difference between measurements and 4D-DCs for a given treatment plan at the end of delivery was 3.5% on average and 6.6% at maximum over measurement points inside the target. Overall, the agreement between 4D dose measurements in the moving phantom and retrospective 4D-DC was found to be comparable to the static dose differences for all delivery scenarios. The presented 4D-DC has been proven to be suitable for simulating treatment deliveries with various beam- as well as patient-specific parameters and can therefore be employed for dosimetric validation of different motion mitigation techniques.
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Affiliation(s)
- N Kostiukhina
- Division of Medical Radiation Physics, Department of Radiation Oncology, Medical University of Vienna/AKH Vienna, Vienna, Austria. Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, Vienna, Austria
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31
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Thummerer A, Zaffino P, Meijers A, Marmitt GG, Seco J, Steenbakkers RJHM, Langendijk JA, Both S, Spadea MF, Knopf AC. Comparison of CBCT based synthetic CT methods suitable for proton dose calculations in adaptive proton therapy. Phys Med Biol 2020; 65:095002. [PMID: 32143207 DOI: 10.1088/1361-6560/ab7d54] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
In-room imaging is a prerequisite for adaptive proton therapy. The use of onboard cone-beam computed tomography (CBCT) imaging, which is routinely acquired for patient position verification, can enable daily dose reconstructions and plan adaptation decisions. Image quality deficiencies though, hamper dose calculation accuracy and make corrections of CBCTs a necessity. This study compared three methods to correct CBCTs and create synthetic CTs that are suitable for proton dose calculations. CBCTs, planning CTs and repeated CTs (rCT) from 33 H&N cancer patients were used to compare a deep convolutional neural network (DCNN), deformable image registration (DIR) and an analytical image-based correction method (AIC) for synthetic CT (sCT) generation. Image quality of sCTs was evaluated by comparison with a same-day rCT, using mean absolute error (MAE), mean error (ME), Dice similarity coefficient (DSC), structural non-uniformity (SNU) and signal/contrast-to-noise ratios (SNR/CNR) as metrics. Dosimetric accuracy was investigated in an intracranial setting by performing gamma analysis and calculating range shifts. Neural network-based sCTs resulted in the lowest MAE and ME (37/2 HU) and the highest DSC (0.96). While DIR and AIC generated images with a MAE of 44/77 HU, a ME of -8/1 HU and a DSC of 0.94/0.90. Gamma and range shift analysis showed almost no dosimetric difference between DCNN and DIR based sCTs. The lower image quality of AIC based sCTs affected dosimetric accuracy and resulted in lower pass ratios and higher range shifts. Patient-specific differences highlighted the advantages and disadvantages of each method. For the set of patients, the DCNN created synthetic CTs with the highest image quality. Accurate proton dose calculations were achieved by both DCNN and DIR based sCTs. The AIC method resulted in lower image quality and dose calculation accuracy was reduced compared to the other methods.
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Affiliation(s)
- Adrian Thummerer
- Department of Radiation Oncology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
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Grau C, Durante M, Georg D, Langendijk JA, Weber DC. Particle therapy in Europe. Mol Oncol 2020; 14:1492-1499. [PMID: 32223048 PMCID: PMC7332216 DOI: 10.1002/1878-0261.12677] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 12/17/2019] [Accepted: 03/22/2020] [Indexed: 12/16/2022] Open
Abstract
Particle therapy using protons or heavier ions is currently the most advanced form of radiotherapy and offers new opportunities for improving cancer care and research. Ions deposit the dose with a sharp maximum – the Bragg peak – and normal tissue receives a much lower dose than what is delivered by X‐ray therapy. Particle therapy has also biological advantages due to the high linear energy transfer of the charged particles around the Bragg peak. The introduction of particle therapy has been slow in Europe, but within the last decade, more than 20 clinical facilities have opened and facilitated access to this frontline therapy. In this review article, the basic concepts of particle therapy are reviewed along with a presentation of the current clinical indications, the European clinical research, and the established networks.
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Affiliation(s)
- Cai Grau
- Department of Oncology and Danish Center for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark
| | - Marco Durante
- Biophysics Department, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany.,Institut für Festkörperphysik, Technische Universität Darmstadt, Germany
| | - Dietmar Georg
- Department of Radiation Oncology, Medical University of Vienna/AKH Wien, Vienna, Austria
| | - Johannes A Langendijk
- Department of Radiation Oncology, University Medical Centrum Groningen, Groningen, The Netherlands
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Resch AF, Heyes PD, Fuchs H, Bassler N, Georg D, Palmans H. Dose- rather than fluence-averaged LET should be used as a single-parameter descriptor of proton beam quality for radiochromic film dosimetry. Med Phys 2020; 47:2289-2299. [PMID: 32166764 PMCID: PMC7318138 DOI: 10.1002/mp.14097] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 01/24/2020] [Accepted: 02/05/2020] [Indexed: 11/06/2022] Open
Abstract
PURPOSE The dose response of Gafchromic EBT3 films exposed to proton beams depends on the dose, and additionally on the beam quality, which is often quantified with the linear energy transfer (LET) and, hence, also referred to as LET quenching. Fundamentally different methods to determine correction factors for this LET quenching effect have been reported in literature and a new method using the local proton fluence distribution differential in LET is presented. This method was exploited to investigate whether a more practical correction based on the dose- or fluence-averaged LET is feasible in a variety of clinically possible beam arrangements. METHODS The relative effectiveness (RE) was characterized within a high LET spread-out Bragg peak (SOBP) in water made up by the six lowest available energies (62.4-67.5 MeV, configuration " b 1 ") resulting in one of the highest clinically feasible dose-averaged LET distributions. Additionally, two beams were measured where a low LET proton beam (252.7 MeV) was superimposed on " b 1 ", which contributed either 50% of the initial particle fluence or 50% of the dose in the SOBP, referred to as configuration " b 2 " and " b 3 ," respectively. The proton LET spectrum was simulated with GATE/Geant4 at all measurement positions. The net optical density change differential in LET was integrated over the local proton spectrum to calculate the net optical density and therefrom the beam quality correction factor. The LET dependence of the film response was accounted for by an LET dependence of one of the three parameters in the calibration function and was determined from inverse optimization using measurement " b 1 ." This method was then validated on the measurements of " b 2 " and " b 3 " and subsequently used to calculate the RE at 900 positions in nine clinically relevant beams. The extrapolated RE set was used to derive a simple linear correction function based on dose-averaged LET ( L d ) and verify the validity in all points of the comprehensive RE set. RESULTS The uncorrected film dose deviated up to 26% from the reference dose, whereas the corrected film dose agreed within 3% in all three beams in water (" b 1 ", " b 2 " and " b 3 "). The LET dependence of the calibration function started to strongly increase around 5 keV/μm and flatten out around 30 keV/μm. All REs calculated from the proton fluence in the nine simulated beams could be approximated with a linear function of dose-averaged LET (RE = 1.0258-0.0211 μm/keV L d ). However, no functional relationship of RE- and fluence-averaged LET could be found encompassing all beam energies and modulations. CONCLUSIONS The film quenching was found to be nonlinear as a function of proton LET as well as of the dose-averaged LET. However, the linear relation of RE on dose-averaged LET was a good approximation in all cases. In contrast to dose-averaged LET, fluence-averaged LET could not describe the RE when multiple beams were applied.
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Affiliation(s)
- Andreas Franz Resch
- Division Medical Radiation Physics, Department of Radiotherapy, Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna/AKH Wien, Währinger Gürtel 18-20, 1090, Vienna, Austria
| | - Paul David Heyes
- Division Medical Radiation Physics, Department of Radiotherapy, Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna/AKH Wien, Währinger Gürtel 18-20, 1090, Vienna, Austria
| | - Hermann Fuchs
- Division Medical Radiation Physics, Department of Radiotherapy, Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna/AKH Wien, Währinger Gürtel 18-20, 1090, Vienna, Austria
| | - Niels Bassler
- Medical Radiation Physics, Department of Physics, Stockholm University, Stockholm, Sweden.,Department of Oncology and Pathology, Medical Radiation Physics, Karolinska Institutet, Stockholm, Sweden.,Department of Experimental Clinical Oncology, Aarhus University Hospital, Aarhus, Denmark
| | - Dietmar Georg
- Division Medical Radiation Physics, Department of Radiotherapy, Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna/AKH Wien, Währinger Gürtel 18-20, 1090, Vienna, Austria
| | - Hugo Palmans
- MedAustron Ion Therapy Centre/EBG MedAustron, Marie-Curie-Straße 5, 2700, Wiener Neustadt, Austria.,Medical Radiation Science, National Physical Laboratory, Hampton Road, TW11 0LW, Teddington, United Kingdom
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Albertini F, Matter M, Nenoff L, Zhang Y, Lomax A. Online daily adaptive proton therapy. Br J Radiol 2020; 93:20190594. [PMID: 31647313 PMCID: PMC7066958 DOI: 10.1259/bjr.20190594] [Citation(s) in RCA: 80] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 10/15/2019] [Accepted: 10/22/2019] [Indexed: 12/11/2022] Open
Abstract
It is recognized that the use of a single plan calculated on an image acquired some time before the treatment is generally insufficient to accurately represent the daily dose to the target and to the organs at risk. This is particularly true for protons, due to the physical finite range. Although this characteristic enables the generation of steep dose gradients, which is essential for highly conformal radiotherapy, it also tightens the dependency of the delivered dose to the range accuracy. In particular, the use of an outdated patient anatomy is one of the most significant sources of range inaccuracy, thus affecting the quality of the planned dose distribution. A plan should be ideally adapted as soon as anatomical variations occur, ideally online. In this review, we describe in detail the different steps of the adaptive workflow and discuss the challenges and corresponding state-of-the art developments in particular for an online adaptive strategy.
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Affiliation(s)
| | | | | | - Ye Zhang
- Paul Scherrer Institute, Center for Proton Therapy, Switzerland
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35
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Grevillot L, Osorio Moreno J, Letellier V, Dreindl R, Elia A, Fuchs H, Carlino A, Kragl G, Palmans H, Vatnitsky S, Stock M. Clinical implementation and commissioning of the MedAustron Particle Therapy Accelerator for non‐isocentric scanned proton beam treatments. Med Phys 2019; 47:380-392. [DOI: 10.1002/mp.13928] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 10/01/2019] [Accepted: 11/11/2019] [Indexed: 11/08/2022] Open
Affiliation(s)
- Loïc Grevillot
- EBG MedAustron GmbH Marie Curie‐Straße 5 A‐2700 Wiener Neustadt Austria
| | | | - Virgile Letellier
- EBG MedAustron GmbH Marie Curie‐Straße 5 A‐2700 Wiener Neustadt Austria
| | - Ralf Dreindl
- EBG MedAustron GmbH Marie Curie‐Straße 5 A‐2700 Wiener Neustadt Austria
| | - Alessio Elia
- EBG MedAustron GmbH Marie Curie‐Straße 5 A‐2700 Wiener Neustadt Austria
| | - Hermann Fuchs
- EBG MedAustron GmbH Marie Curie‐Straße 5 A‐2700 Wiener Neustadt Austria
- Department of Radiation Therapy Medical University of Vienna/AKH Vienna Vienna Austria
| | - Antonio Carlino
- EBG MedAustron GmbH Marie Curie‐Straße 5 A‐2700 Wiener Neustadt Austria
| | - Gabriele Kragl
- EBG MedAustron GmbH Marie Curie‐Straße 5 A‐2700 Wiener Neustadt Austria
| | - Hugo Palmans
- EBG MedAustron GmbH Marie Curie‐Straße 5 A‐2700 Wiener Neustadt Austria
- National Physical Laboratory Hampton Road TW11 0LW Teddington UK
| | | | - Markus Stock
- EBG MedAustron GmbH Marie Curie‐Straße 5 A‐2700 Wiener Neustadt Austria
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Padilla-Cabal F, Alejandro Fragoso J, Franz Resch A, Georg D, Fuchs H. Benchmarking a GATE/Geant4 Monte Carlo model for proton beams in magnetic fields. Med Phys 2019; 47:223-233. [PMID: 31661559 PMCID: PMC7003833 DOI: 10.1002/mp.13883] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 10/23/2019] [Accepted: 10/24/2019] [Indexed: 12/16/2022] Open
Abstract
Purpose Magnetic resonance guidance in proton therapy (MRPT) is expected to improve its current performance. The combination of magnetic fields with clinical proton beam lines poses several challenges for dosimetry, treatment planning and dose delivery. Proton beams are deflected by magnetic fields causing considerable changes in beam trajectories and also a retraction of the Bragg peak positions. A proper prediction and compensation of these effects is essential to ensure accurate dose calculations. This work aims to develop and benchmark a Monte Carlo (MC) beam model for dose calculation of MRPT for static magnetic fields up to 1 T. Methods Proton beam interactions with magnetic fields were simulated using the GATE/Geant4 toolkit. The transport of charged particle in custom 3D magnetic field maps was implemented for the first time in GATE. Validation experiments were done using a horizontal proton pencil beam scanning system with energies between 62.4 and 252.7 MeV and a large gap dipole magnet (B = 0–1 T), positioned at the isocenter and creating magnetic fields transverse to the beam direction. Dose was measured with Gafchromic EBT3 films within a homogeneous PMMA phantom without and with bone and tissue equivalent material slab inserts. Linear energy transfer (LET) quenching of EBT3 films was corrected using a linear model on dose‐averaged LET method to ensure a realistic dosimetric comparison between simulations and experiments. Planar dose distributions were measured with the films in two different configurations: parallel and transverse to the beam direction using single energy fields and spread‐out Bragg peaks. The MC model was benchmarked against lateral deflections and spot sizes in air of single beams measured with a Lynx PT detector, as well as dose distributions using EBT3 films. Experimental and calculated dose distributions were compared to test the accuracy of the model. Results Measured proton beam deflections in air at distances of 465, 665, and 1155 mm behind the isocenter after passing the magnetic field region agreed with MC‐predicted values within 4 mm. Differences between calculated and measured beam full width at half maximum (FWHM) were lower than 2 mm. For the homogeneous phantom, measured and simulated in‐depth dose profiles showed range and average dose differences below 0.2 mm and 1.2%, respectively. Simulated central beam positions and widths differed <1 mm to the measurements with films. For both heterogenous phantoms, differences within 1 mm between measured and simulated central beam positions and widths were obtained, confirming a good agreement of the MC model. Conclusions A GATE/Geant4 beam model for protons interacting with magnetic fields up to 1 T was developed and benchmarked to experimental data. For the first time, the GATE/Geant4 model was successfully validated not only for single energy beams, but for SOBP, in homogeneous and heterogeneous phantoms. EBT3 film dosimetry demonstrated to be a powerful dosimetric tool, once the film response function is LET corrected, for measurements in‐line and transverse to the beam direction in magnetic fields. The proposed MC beam model is foreseen to support treatment planning and quality assurance (QA) activities toward MRPT.
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Affiliation(s)
- Fatima Padilla-Cabal
- Department of Radiotherapy, Medical University of Vienna/AKH, Vienna, Austria.,Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, Vienna, Austria
| | - Jose Alejandro Fragoso
- Department of Nuclear Physics, Higher Institute of Technologies and Applied Science, Havana, Cuba
| | - Andreas Franz Resch
- Department of Radiotherapy, Medical University of Vienna/AKH, Vienna, Austria.,Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, Vienna, Austria
| | - Dietmar Georg
- Department of Radiotherapy, Medical University of Vienna/AKH, Vienna, Austria.,Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, Vienna, Austria
| | - Hermann Fuchs
- Department of Radiotherapy, Medical University of Vienna/AKH, Vienna, Austria.,Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, Vienna, Austria
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Clausen M, Khachonkham S, Gruber S, Kuess P, Seemann R, Knäusl B, Mara E, Palmans H, Dörr W, Georg D. Phantom design and dosimetric characterization for multiple simultaneous cell irradiations with active pencil beam scanning. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2019; 58:563-573. [PMID: 31541343 PMCID: PMC6768893 DOI: 10.1007/s00411-019-00813-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 09/09/2019] [Indexed: 05/04/2023]
Abstract
A new phantom was designed for in vitro studies on cell lines in horizontal particle beams. The phantom enables simultaneous irradiation at multiple positions along the beam path. The main purpose of this study was the detailed dosimetric characterization of the phantom which consists of various heterogeneous structures. The dosimetric measurements described here were performed under non-reference conditions. The experiment involved a CT scan of the phantom, dose calculations performed with the treatment planning system (TPS) RayStation employing both the Pencil Beam (PB) and Monte Carlo (MC) algorithms, and proton beam delivery. Two treatment plans reflecting the typical target location for head and neck cancer and prostate cancer treatment were created. Absorbed dose to water and dose homogeneity were experimentally assessed within the phantom along the Bragg curve with ionization chambers (ICs) and EBT3 films. LETd distributions were obtained from the TPS. Measured depth dose distributions were in good agreement with the Monte Carlo-based TPS data. Absorbed dose calculated with the PB algorithm was 4% higher than the absorbed dose measured with ICs at the deepest measurement point along the spread-out Bragg peak. Results of experiments using melanoma (SKMel) cell line are also presented. The study suggested a pronounced correlation between the relative biological effectiveness (RBE) and LETd, where higher LETd leads to elevated cell death and cell inactivation. Obtained RBE values ranged from 1.4 to 1.8 at the survival level of 10% (RBE10). It is concluded that dosimetric characterization of a phantom before its use for RBE experiments is essential, since a high dosimetric accuracy contributes to reliable RBE data and allows for a clearer differentiation between physical and biological uncertainties.
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Affiliation(s)
- Monika Clausen
- Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria.
| | - Suphalak Khachonkham
- Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
- Division of Radiation Therapy, Department of Diagnostic and Therapeutic Radiology, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Sylvia Gruber
- Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
| | - Peter Kuess
- Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
- EBG MedAustron GmbH, Wiener Neustadt, Austria
| | | | - Barbara Knäusl
- Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
- EBG MedAustron GmbH, Wiener Neustadt, Austria
| | - Elisabeth Mara
- Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
- University of Applied Science, Wiener Neustadt, Austria
| | - Hugo Palmans
- EBG MedAustron GmbH, Wiener Neustadt, Austria
- National Physical Laboratory, Teddington, UK
| | - Wolfgang Dörr
- Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
| | - Dietmar Georg
- Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
- EBG MedAustron GmbH, Wiener Neustadt, Austria
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Nenoff L, Matter M, Hedlund Lindmar J, Weber DC, Lomax AJ, Albertini F. Daily adaptive proton therapy - the key to innovative planning approaches for paranasal cancer treatments. Acta Oncol 2019; 58:1423-1428. [PMID: 31364904 DOI: 10.1080/0284186x.2019.1641217] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Background: For proton therapy of paranasal tumors, field directions avoiding volumes that might change during therapy are typically used. If the plan is optimized on the daily anatomy using daily adapted proton therapy (DAPT) however, field directions crossing the nasal cavities might be feasible. In this study, we investigated the effectiveness of DAPT for enabling narrow-field treatment approaches. Material and methods: For five paranasal tumor patients, representing a wide patient spectrum, anatomically robust 4-field-star and narrow-field plans were calculated and their robustness to anatomical and setup uncertainties was compared with and without DAPT. Based on the nominal planning CTs, per patient up to 125 simulated CTs (simCTs) with different nasal cavity fillings were created and random translations and rotations due to patient setup uncertainties were further simulated. Plans were recalculated or re-optimized on all error scenarios, representing non-adapted and DAPT fractions, respectively. From these, 100 possible treatments (60 GyRBE, 30 fx) were simulated and changes in integral dose, target and organs at risk (OARs) doses evaluated. Results: In comparison to the 4-field-star approach, the use of narrow-fields reduced integral dose between 29% and 56%. If OARs did not overlap with the target, OAR doses were also reduced. Finally, the significantly reduced target coverage in non-adapted treatments (mean V95 reductions of up to 34%) could be almost fully restored with DAPT in all cases (differences <1%). Conclusions: DAPT was found to be not only an effective way to increase plan robustness to anatomical and positional uncertainties, but also opened the possibility to use improved and more conformal field arrangements.
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Affiliation(s)
- Lena Nenoff
- Center for Proton Therapy, Paul Scherrer Institute, Villigen, Switzerland
- Department of Physics, ETH Zurich, Zurich, Switzerland
| | - Michael Matter
- Center for Proton Therapy, Paul Scherrer Institute, Villigen, Switzerland
- Department of Physics, ETH Zurich, Zurich, Switzerland
| | - Johanna Hedlund Lindmar
- Center for Proton Therapy, Paul Scherrer Institute, Villigen, Switzerland
- Department of Physics, ETH Zurich, Zurich, Switzerland
| | - Damien Charles Weber
- Center for Proton Therapy, Paul Scherrer Institute, Villigen, Switzerland
- Department of Radiation Oncology, University Hospital Zurich, Zurich, Switzerland
- Department of Radiation Oncology, University Hospital Bern, Bern, Switzerland
| | - Antony John Lomax
- Center for Proton Therapy, Paul Scherrer Institute, Villigen, Switzerland
- Department of Physics, ETH Zurich, Zurich, Switzerland
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Carlino A, Böhlen T, Vatnitsky S, Grevillot L, Osorio J, Dreindl R, Palmans H, Stock M, Kragl G. Commissioning of pencil beam and Monte Carlo dose engines for non-isocentric treatments in scanned proton beam therapy. ACTA ACUST UNITED AC 2019; 64:17NT01. [DOI: 10.1088/1361-6560/ab3557] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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40
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Padilla-Cabal F, Kuess P, Georg D, Palmans H, Fetty L, Fuchs H. Characterization of EBT3 radiochromic films for dosimetry of proton beams in the presence of magnetic fields. Med Phys 2019; 46:3278-3284. [PMID: 31055847 PMCID: PMC6852248 DOI: 10.1002/mp.13567] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 04/04/2019] [Accepted: 04/20/2019] [Indexed: 11/05/2022] Open
Abstract
PURPOSE Radiochromic film dosimetry is extensively used for quality assurance in photon and proton beam therapy. So far, GafchromicTM EBT3 film appears as a strong candidate to be used in future magnetic resonance (MR) based therapy systems. The response of Gafchromic EBT3 films in the presence of magnetic fields has already been addressed for different MR-linacs systems. However, a detailed evaluation of the influence of external magnetic fields on the film response and calibration curves for proton therapy has not yet been reported. This study aims to determine the dose responses of EBT3 films for clinical proton beams exposed to magnetic field strengths up to 1 T in order to investigate the feasibility of EBT3 film as an accurate dosimetric tool for a future MR particle therapy system (MRPT). METHODS The dosimetric characteristics of EBT3 films were studied for a proton beam passing through magnetic field strengths of B = 0, 0.5, and 1 T. Absorbed dose calibration and measurements were performed using clinical proton beams in the nominal energy range of 62.4-252.6 MeV. Irradiations were done using an in-house developed PMMA slab phantom placed in the center of a dipole research magnet. Monte Carlo (MC) simulations using the GATE/Geant4 toolkit were performed to predict the effect of magnetic fields on the energy deposited by proton beams in the phantom. Planned and measured doses from 3D box cube irradiations were compared to assess the accuracy of the dosimetric method using EBT3 films with/without the external magnetic field. RESULTS Neither for the mean pixel value nor for the net optical density, any significant deviations were observed due to the presence of an external magnetic field (B ≤ 1T) for doses up to 10 Gy. Dose-response curves for the red channel were fitted by a three-parameter function for the field-free case and for B = 1T, showing for both cases an R-square coefficient of unity and almost identical fitting parameters. Independently of the magnetic field, EBT3 films showed an under-response as high as 8% in the Bragg peak region, similarly to previously reported effects for particle therapy. No noticeable influence of the magnetic field strength was observed on the quenching effect of the EBT3 films. CONCLUSIONS For the first time detailed absorbed dose calibrations of EBT3 films for proton beams in magnetic field regions were performed. Results showed that EBT3 films represent an attractive solution for the dosimetry of a future MRPT system. As film response functions for protons are not affected by the magnetic field strenght, they can be used for further investigations to evaluate the dosimetric effects induced due to particle beams bending in magnetic fields regions.
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Affiliation(s)
- Fatima Padilla-Cabal
- Department of Radiotherapy, Medical University of Vienna/AKH, Vienna, Austria.,Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, Vienna, Austria
| | - Peter Kuess
- Department of Radiotherapy, Medical University of Vienna/AKH, Vienna, Austria.,Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, Vienna, Austria
| | - Dietmar Georg
- Department of Radiotherapy, Medical University of Vienna/AKH, Vienna, Austria.,Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, Vienna, Austria
| | - Hugo Palmans
- EBG MedAustron GmbH, Wiener Neustadt, Austria.,National Physical Laboratory, Teddington, TW 11 0LW, UK
| | - Lukas Fetty
- Department of Radiotherapy, Medical University of Vienna/AKH, Vienna, Austria.,Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, Vienna, Austria
| | - Hermann Fuchs
- Department of Radiotherapy, Medical University of Vienna/AKH, Vienna, Austria.,Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, Vienna, Austria
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Landry G, Hansen D, Kamp F, Li M, Hoyle B, Weller J, Parodi K, Belka C, Kurz C. Comparing Unet training with three different datasets to correct CBCT images for prostate radiotherapy dose calculations. Phys Med Biol 2019; 64:035011. [PMID: 30523998 DOI: 10.1088/1361-6560/aaf496] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Image intensity correction is crucial to enable cone beam computed tomography (CBCT) based radiotherapy dose calculations. This study evaluated three different deep learning based correction methods using a U-shaped convolutional neural network architecture (Unet) in terms of their photon and proton dose calculation accuracy. CT and CBCT imaging data of 42 prostate cancer patients were included. For target ground truth data generation, a CBCT correction method based on CT to CBCT deformable image registration (DIR) was used. The method yields a deformed CT called (i) virtual CT (vCT) which is used to generate (ii) corrected CBCT projections allowing the reconstruction of (iii) a final corrected CBCT image. The single Unet architecture was trained using these three different datasets: (Unet1) raw and corrected CBCT projections, (Unet2) raw CBCT and vCT image slices and (Unet3) raw and reference corrected CBCT image slices. Volumetric arc therapy (VMAT) and proton pencil beam scanning (PBS) single field uniform dose (SFUD) plans were optimized on the reference corrected image and recalculated on the obtained Unet-corrected CBCT images. The mean error (ME) and mean absolute error (MAE) for Unet1/2/3 were [Formula: see text] Hounsfield units (HU) and [Formula: see text] HU. The 1% dose difference pass rates were better than 98.4% for VMAT for 8 test patients not seen during training, with little difference between Unets. Gamma evaluation results were even better. For protons a gamma evaluation was employed to account for small range shifts, and [Formula: see text] mm pass rates for Unet1/2/3 were better than [Formula: see text] and 91%. A 3 mm range difference threshold was established. Only for Unet3 the 5th and 95th percentiles of the range difference distributions over all fields, test patients and dose profiles were within this threshold. A single Unet architecture was successfully trained using both CBCT projections and CBCT image slices. Since the results of the other Unets were poorer than Unet3, we conclude that training using corrected CBCT image slices as target data is optimal for PBS SFUD proton dose calculations, while for VMAT all Unets provided sufficient accuracy.
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Affiliation(s)
- Guillaume Landry
- Department of Medical Physics, Fakultät für Physik, Ludwig-Maximilians-Universität München (LMU Munich), Garching, Germany
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Matter M, Nenoff L, Meier G, Weber DC, Lomax AJ, Albertini F. Alternatives to patient specific verification measurements in proton therapy: a comparative experimental study with intentional errors. ACTA ACUST UNITED AC 2018; 63:205014. [DOI: 10.1088/1361-6560/aae2f4] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Hansen DC, Landry G, Kamp F, Li M, Belka C, Parodi K, Kurz C. ScatterNet: A convolutional neural network for cone‐beam CT intensity correction. Med Phys 2018; 45:4916-4926. [DOI: 10.1002/mp.13175] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 07/05/2018] [Accepted: 08/29/2018] [Indexed: 12/25/2022] Open
Affiliation(s)
- David C. Hansen
- Department of Medical Physics Aarhus University Hospital Aarhus 8200Denmark
| | - Guillaume Landry
- Department of Medical Physics Faculty of Physics Ludwig‐Maximilians‐Universität München (LMU Munich) Garching bei München 85748Germany
| | - Florian Kamp
- Department of Radiation Oncology University Hospital LMU Munich Munich 81377Germany
| | - Minglun Li
- Department of Radiation Oncology University Hospital LMU Munich Munich 81377Germany
| | - Claus Belka
- Department of Radiation Oncology University Hospital LMU Munich Munich 81377Germany
- German Cancer Consortium (DKTK) Munich Germany
| | - Katia Parodi
- Department of Medical Physics Faculty of Physics Ludwig‐Maximilians‐Universität München (LMU Munich) Garching bei München 85748Germany
| | - Christopher Kurz
- Department of Medical Physics Faculty of Physics Ludwig‐Maximilians‐Universität München (LMU Munich) Garching bei München 85748Germany
- Department of Radiation Oncology University Hospital LMU Munich Munich 81377Germany
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Carlino A, Stock M, Zagler N, Marrale M, Osorio J, Vatnitsky S, Palmans H. Characterization of PTW-31015 PinPoint ionization chambers in photon and proton beams. ACTA ACUST UNITED AC 2018; 63:185020. [DOI: 10.1088/1361-6560/aadd39] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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45
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Pötter R, Balosso J, Baumann M, Bert C, Davies J, Enghardt W, Fossati P, Harris S, Jones B, Krämer M, Mayer R, Mock U, Pullia M, Schreiner T, Dosanjh M, Debus J, Orecchia R, Georg D. Union of light ion therapy centers in Europe (ULICE EC FP7) – Objectives and achievements of joint research activities. Radiother Oncol 2018; 128:83-100. [DOI: 10.1016/j.radonc.2018.04.027] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2018] [Accepted: 04/21/2018] [Indexed: 12/25/2022]
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