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Kraus KM, Oechsner M, Wilkens JJ, Kessel KA, Münch S, Combs SE. Patient individual phase gating for stereotactic radiation therapy of early stage non-small cell lung cancer (NSCLC). Sci Rep 2021; 11:5870. [PMID: 33712667 PMCID: PMC7955128 DOI: 10.1038/s41598-021-85031-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 02/23/2021] [Indexed: 12/25/2022] Open
Abstract
Stereotactic body radiotherapy (SBRT) applies high doses and requires advanced techniques to spare surrounding tissue in the presence of organ motion. In this work patient individual phase gating is investigated. We studied peripheral and central primary lung tumors. The internal target volume (ITV) was defined including different numbers of phases picked from a 4D Computed tomography (CT) defining the gating window (gw). Planning target volume (PTV) reductions depending on the gw were analyzed. A treatment plan was calculated on a reference phase CT (rCT) and the dose for each breathing phase was calculated and accumulated on the rCT. We compared the dosimetric results with the dose calculated when all breathing phases were included for ITV definition. GWs including 1 to 10 breathing phases were analyzed. We found PTV reductions up to 38.4%. The mean reduction of the lung volume receiving 20 Gy due to gating was found to be 25.7% for peripheral tumors and 16.7% for central tumors. Gating considerably reduced esophageal doses. However, we found that simple reduction of the gw does not necessarily influence the dose in a clinically relevant range. Thus, we suggest a patient individual definition of the breathing phases included within the gw.
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Affiliation(s)
- K M Kraus
- School of Medicine and Klinikum Rechts Der Isar, Department of Radiation Oncology, Technichal University of Munich (TUM), Munich, Germany.
| | - M Oechsner
- School of Medicine and Klinikum Rechts Der Isar, Department of Radiation Oncology, Technichal University of Munich (TUM), Munich, Germany
| | - J J Wilkens
- School of Medicine and Klinikum Rechts Der Isar, Department of Radiation Oncology, Technichal University of Munich (TUM), Munich, Germany
| | - K A Kessel
- School of Medicine and Klinikum Rechts Der Isar, Department of Radiation Oncology, Technichal University of Munich (TUM), Munich, Germany.,Institute of Radiation Medicine (IRM), Department of Radiation Sciences (DRS), Helmholtz Zentrum München (HMGU), Neuherberg, Germany.,Deutsches Konsortium für Translationale Krebsforschung (DKTK), Partner Site Munich, Munich, Germany
| | - S Münch
- School of Medicine and Klinikum Rechts Der Isar, Department of Radiation Oncology, Technichal University of Munich (TUM), Munich, Germany
| | - S E Combs
- School of Medicine and Klinikum Rechts Der Isar, Department of Radiation Oncology, Technichal University of Munich (TUM), Munich, Germany.,Institute of Radiation Medicine (IRM), Department of Radiation Sciences (DRS), Helmholtz Zentrum München (HMGU), Neuherberg, Germany.,Deutsches Konsortium für Translationale Krebsforschung (DKTK), Partner Site Munich, Munich, Germany
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Wank M, Schilling D, Reindl J, Meyer B, Gempt J, Motov S, Alexander F, Wilkens JJ, Schlegel J, Schmid TE, Combs SE. Evaluation of radiation-related invasion in primary patient-derived glioma cells and validation with established cell lines: impact of different radiation qualities with differing LET. J Neurooncol 2018; 139:583-590. [PMID: 29882045 DOI: 10.1007/s11060-018-2923-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Accepted: 06/05/2018] [Indexed: 11/29/2022]
Abstract
PURPOSE Glioblastoma multiforme (GBM) is the most common primary brain tumor and has a very poor overall prognosis. Multimodal treatment is still inefficient and one main reason is the invasive nature of GBM cells, enabling the tumor cells to escape from the treatment area causing tumor progression. This experimental study describes the effect of low- and high-LET irradiation on the invasion of primary GBM cells with a validation in established cell systems. METHODS Seven patient derived primary GBM as well as three established cell lines (LN229, LN18 and U87) were used in this study. Invasion was investigated using Matrigel® coated transwell chambers. Irradiation was performed with low- (X-ray) and high-LET (alpha particles) radiation. The colony formation assay was chosen to determine the corresponding alpha particle dose equivalent to the X-ray dose. RESULTS 4 Gy X-ray irradiation increased the invasive potential of six patient derived GBM cells as well as two of the established lines. In contrast, alpha particle irradiation with an equivalent dose of 1.3 Gy did not show any effect on the invasive behavior. The findings were validated with established cell lines. CONCLUSION Our results show that in contrast to low-LET irradiation high-LET irradiation does not enhance the invasion of established and primary glioblastoma cell lines. We therefore suggest that high-LET irradiation could become an alternative treatment option. To fully exploit the benefits of high-LET irradiation concerning the invasion of GBM further molecular studies should be performed.
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Affiliation(s)
- M Wank
- Institute of Innovative Radiotherapy (iRT), Department of Radiation Sciences (DRS), Helmholtz Zentrum München, Oberschleißheim, Germany.,Department of Radiation Oncology, Technical University of Munich (TUM), Klinikum rechts der Isar, Munich, Germany.,Deutsches Konsortium für Translationale Krebsforschung (DKTK), Partner Site, Munich, Germany
| | - D Schilling
- Institute of Innovative Radiotherapy (iRT), Department of Radiation Sciences (DRS), Helmholtz Zentrum München, Oberschleißheim, Germany.,Department of Radiation Oncology, Technical University of Munich (TUM), Klinikum rechts der Isar, Munich, Germany.,Deutsches Konsortium für Translationale Krebsforschung (DKTK), Partner Site, Munich, Germany
| | - J Reindl
- Institute for Applied Physics and Metrology, Bundeswehr University Munich, Neubiberg, Germany
| | - B Meyer
- Department of Neurosurgery, Technical University of Munich (TUM), Klinikum rechts der Isar, Munich, Germany
| | - J Gempt
- Department of Neurosurgery, Technical University of Munich (TUM), Klinikum rechts der Isar, Munich, Germany
| | - S Motov
- Department of Neurosurgery, Technical University of Munich (TUM), Klinikum rechts der Isar, Munich, Germany
| | - F Alexander
- Department of Radiation Oncology, Technical University of Munich (TUM), Klinikum rechts der Isar, Munich, Germany
| | - J J Wilkens
- Department of Radiation Oncology, Technical University of Munich (TUM), Klinikum rechts der Isar, Munich, Germany
| | - J Schlegel
- Department of Neuropathology, Technical University of Munich (TUM), Munich, Germany
| | - T E Schmid
- Institute of Innovative Radiotherapy (iRT), Department of Radiation Sciences (DRS), Helmholtz Zentrum München, Oberschleißheim, Germany.,Department of Radiation Oncology, Technical University of Munich (TUM), Klinikum rechts der Isar, Munich, Germany
| | - S E Combs
- Institute of Innovative Radiotherapy (iRT), Department of Radiation Sciences (DRS), Helmholtz Zentrum München, Oberschleißheim, Germany. .,Department of Radiation Oncology, Technical University of Munich (TUM), Klinikum rechts der Isar, Munich, Germany. .,Deutsches Konsortium für Translationale Krebsforschung (DKTK), Partner Site, Munich, Germany.
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Masood U, Cowan TE, Enghardt W, Hofmann KM, Karsch L, Kroll F, Schramm U, Wilkens JJ, Pawelke J. A light-weight compact proton gantry design with a novel dose delivery system for broad-energetic laser-accelerated beams. Phys Med Biol 2017; 62:5531-5555. [DOI: 10.1088/1361-6560/aa7124] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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Kamp F, Carlson DJ, Wilkens JJ. Rapid implementation of the repair-misrepair-fixation (RMF) model facilitating online adaption of radiosensitivity parameters in ion therapy. Phys Med Biol 2017; 62:N285-N296. [PMID: 28561011 DOI: 10.1088/1361-6560/aa716b] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
INTRODUCTION Treatment planning for ion therapy must account for physical properties of the beam as well as differences in the relative biological effectiveness (RBE) of ions compared to photons. In this work, we present a fast RBE calculation approach, based on the decoupling of physical properties and the [Formula: see text] ratio commonly used to describe the radiosensitivity of irradiated cells or organs. MATERIAL AND METHODS In the framework of the mechanistic repair-misrepair-fixation (RMF) model, the biological modeling can be decoupled from the physical dose. This was implemented into a research treatment planning system for carbon ion therapy. RESULTS The presented implementation of the RMF model is very fast, allowing online changes of [Formula: see text]. For example, a change of [Formula: see text] including a complete biological modeling and a recalculation of RBE for [Formula: see text] voxel takes 4 ms on a 4 CPU, 3.2 GHz workstation. DISCUSSION AND CONCLUSION The derived decoupling within the RMF model allows fast changes in [Formula: see text], facilitating online adaption by the user. This provides new options for radiation oncologists, facilitating online variations of the radiobiological input parameters during the treatment plan evaluation process as well as uncertainty and sensitivity analyses.
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Affiliation(s)
- F Kamp
- Department of Radiation Oncology, Technical University of Munich, Klinikum rechts der Isar, Ismaninger Str. 22, 81675 München, Germany. Physik-Department, Technical University of Munich, James-Frank-Str. 1, 85748 Garching, Germany. Department of Radiation Oncology, Klinikum der Universität München, LMU Munich, Marchioninistr. 15, 81377 München, Germany
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Togno M, Wilkens JJ, Menichelli D, Oechsner M, Perez-Andujar A, Morin O. Development and clinical evaluation of an ionization chamber array with 3.5 mm pixel pitch for quality assurance in advanced radiotherapy techniques. Med Phys 2017; 43:2283. [PMID: 27147340 DOI: 10.1118/1.4945414] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To characterize a new air vented ionization chamber technology, suitable to build detector arrays with small pixel pitch and independence of sensitivity on dose per pulse. METHODS The prototype under test is a linear array of air vented ionization chambers, consisting of 80 pixels with 3.5 mm pixel pitch distance and a sensitive volume of about 4 mm(3). The detector has been characterized with (60)Co radiation and MV x rays from different linear accelerators (with flattened and unflattened beam qualities). Sensitivity dependence on dose per pulse has been evaluated under MV x rays by changing both the source to detector distance and the beam quality. Bias voltage has been varied in order to evaluate the charge collection efficiency in the most critical conditions. Relative dose profiles have been measured for both flattened and unflattened distributions with different field sizes. The reference detectors were a commercial array of ionization chambers and an amorphous silicon flat panel in direct conversion configuration. Profiles of dose distribution have been measured also with intensity modulated radiation therapy (IMRT), stereotactic radiosurgery (SRS), and volumetric modulated arc therapy (VMAT) patient plans. Comparison has been done with a commercial diode array and with Gafchromic EBT3 films. RESULTS Repeatability and stability under continuous gamma irradiation are within 0.3%, in spite of low active volume and sensitivity (∼200 pC/Gy). Deviation from linearity is in the range [0.3%, -0.9%] for a dose of at least 20 cGy, while a worsening of linearity is observed below 10 cGy. Charge collection efficiency with 2.67 mGy/pulse is higher than 99%, leading to a ±0.9% sensitivity change in the range 0.09-2.67 mGy/pulse (covering all flattened and unflattened beam qualities). Tissue to phantom ratios show an agreement within 0.6% with the reference detector up to 34 cm depth. For field sizes in the range 2 × 2 to 15 × 15 cm(2), the output factors are in agreement with a thimble chamber within 2%, while with 25 × 25 cm(2) field size, an underestimation of 4.0% was found. Agreement of field and penumbra width measurements with the flat panel is of the order of 1 mm down to 1 × 1 cm(2) field size. Flatness and symmetry values measured with the 1D array and the reference detectors are comparable, and differences are always smaller than 1%. Angular dependence of the detector, when compared to measurements taken with a cylindrical chamber in the same phantom, is as large as 16%. This includes inhomogeneity and asymmetry of the design, which during plan verification are accounted for by the treatment planning system (TPS). The detector is capable to reproduce the dose distributions of IMRT and VMAT plans with a maximum deviation from TPS of 3.0% in the target region. In the case of VMAT and SRS plans, an average (maximum) deviation of the order of 1% (4%) from films has been measured. CONCLUSIONS The investigated technology appears to be useful both for Linac QA and patient plan verification, especially in treatments with steep dose gradients and nonuniform dose rates such as VMAT and SRS. Major limitations of the present prototype are the linearity at low dose, which can be solved by optimizing the readout electronics, and the underestimation of output factors with large field sizes. The latter problem is presently not completely understood and will require further investigations.
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Affiliation(s)
- M Togno
- Physik-Department, Technische Universität München, Munich 85748, Germany; Department of Radiation Oncology, Technische Universität München, Klinikum rechts der Isar, Munich 81675, Germany; and IBA Dosimetry GmbH, Schwarzenbruck 90592, Germany
| | - J J Wilkens
- Physik-Department, Technische Universität München, Munich 85748, Germany and Department of Radiation Oncology, Technische Universität München, Klinikum rechts der Isar, Munich 81675, Germany
| | - D Menichelli
- IBA Dosimetry GmbH, Schwarzenbruck 90592, Germany
| | - M Oechsner
- Department of Radiation Oncology, Technische Universität München, Klinikum rechts der Isar, Munich 81675, Germany
| | - A Perez-Andujar
- Department of Radiation Oncology, University of California, San Francisco, San Francisco, California 94143
| | - O Morin
- Department of Radiation Oncology, University of California, San Francisco, San Francisco, California 94143
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Alexander F, Villagrasa C, Rabus H, Wilkens JJ. Local weighting of nanometric track structure properties in macroscopic voxel geometries for particle beam treatment planning. Phys Med Biol 2015; 60:9145-56. [DOI: 10.1088/0031-9155/60/23/9145] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Müller BS, Wilkens JJ. SU-F-BRD-10: Improving Plan Delivery Efficiency of Intensity Modulated Proton Plans with Prioritized Optimization. Med Phys 2015. [DOI: 10.1118/1.4925189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Girst S, Marx C, Bräuer-Krisch E, Bravin A, Bartzsch S, Oelfke U, Greubel C, Reindl J, Siebenwirth C, Zlobinskaya O, Multhoff G, Dollinger G, Schmid TE, Wilkens JJ. Improved normal tissue protection by proton and X-ray microchannels compared to homogeneous field irradiation. Phys Med 2015; 31:615-20. [PMID: 25936621 DOI: 10.1016/j.ejmp.2015.04.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2014] [Revised: 04/02/2015] [Accepted: 04/10/2015] [Indexed: 11/30/2022] Open
Abstract
The risk of developing normal tissue injuries often limits the radiation dose that can be applied to the tumour in radiation therapy. Microbeam Radiation Therapy (MRT), a spatially fractionated photon radiotherapy is currently tested at the European Synchrotron Radiation Facility (ESRF) to improve normal tissue protection. MRT utilizes an array of microscopically thin and nearly parallel X-ray beams that are generated by a synchrotron. At the ion microprobe SNAKE in Munich focused proton microbeams ("proton microchannels") are studied to improve normal tissue protection. Here, we comparatively investigate microbeam/microchannel irradiations with sub-millimetre X-ray versus proton beams to minimize the risk of normal tissue damage in a human skin model, in vitro. Skin tissues were irradiated with a mean dose of 2 Gy over the irradiated area either with parallel synchrotron-generated X-ray beams at the ESRF or with 20 MeV protons at SNAKE using four different irradiation modes: homogeneous field, parallel lines and microchannel applications using two different channel sizes. Normal tissue viability as determined in an MTT test was significantly higher after proton or X-ray microchannel irradiation compared to a homogeneous field irradiation. In line with these findings genetic damage, as determined by the measurement of micronuclei in keratinocytes, was significantly reduced after proton or X-ray microchannel compared to a homogeneous field irradiation. Our data show that skin irradiation using either X-ray or proton microchannels maintain a higher cell viability and DNA integrity compared to a homogeneous irradiation, and thus might improve normal tissue protection after radiation therapy.
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Affiliation(s)
- S Girst
- Universität der Bundeswehr München, Neubiberg, Germany
| | - C Marx
- Department of Radiation Oncology, Technische Universität München, Klinikum rechts der Isar, Munich, Germany
| | - E Bräuer-Krisch
- European Synchrotron Radiation Facility, Grenoble Cedex, France
| | - A Bravin
- European Synchrotron Radiation Facility, Grenoble Cedex, France
| | - S Bartzsch
- German Cancer Research Centre (DKFZ), Heidelberg, Germany; The Institute of Cancer Research, Sutton, United Kingdom
| | - U Oelfke
- German Cancer Research Centre (DKFZ), Heidelberg, Germany; The Institute of Cancer Research, Sutton, United Kingdom
| | - C Greubel
- Universität der Bundeswehr München, Neubiberg, Germany
| | - J Reindl
- Universität der Bundeswehr München, Neubiberg, Germany
| | - C Siebenwirth
- Universität der Bundeswehr München, Neubiberg, Germany; Department of Radiation Oncology, Technische Universität München, Klinikum rechts der Isar, Munich, Germany
| | - O Zlobinskaya
- Universität der Bundeswehr München, Neubiberg, Germany
| | - G Multhoff
- Department of Radiation Oncology, Technische Universität München, Klinikum rechts der Isar, Munich, Germany
| | - G Dollinger
- Universität der Bundeswehr München, Neubiberg, Germany
| | - T E Schmid
- Department of Radiation Oncology, Technische Universität München, Klinikum rechts der Isar, Munich, Germany
| | - J J Wilkens
- Department of Radiation Oncology, Technische Universität München, Klinikum rechts der Isar, Munich, Germany.
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Reinhardt S, Würl M, Greubel C, Humble N, Wilkens JJ, Hillbrand M, Mairani A, Assmann W, Parodi K. Investigation of EBT2 and EBT3 films for proton dosimetry in the 4-20 MeV energy range. Radiat Environ Biophys 2015; 54:71-79. [PMID: 25572031 DOI: 10.1007/s00411-014-0581-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Accepted: 12/16/2014] [Indexed: 06/04/2023]
Abstract
Radiochromic films such as Gafchromic EBT2 or EBT3 films are widely used for dose determination in radiation therapy because they offer a superior spatial resolution compared to any other digital dosimetric 2D detector array. The possibility to detect steep dose gradients is not only attractive for intensity-modulated radiation therapy with photons but also for intensity-modulated proton therapy. Their characteristic dose rate-independent response makes radiochromic films also attractive for dose determination in cell irradiation experiments using laser-driven ion accelerators, which are currently being investigated as future medical ion accelerators. However, when using these films in ion beams, the energy-dependent dose response in the vicinity of the Bragg peak has to be considered. In this work, the response of these films for low-energy protons is investigated. To allow for reproducible and background-free irradiation conditions, the films were exposed to mono-energetic protons from an electrostatic accelerator, in the 4-20 MeV energy range. For comparison, irradiation with clinical photons was also performed. It turned out that in general, EBT2 and EBT3 films show a comparable performance. For example, dose-response curves for photons and protons with energies as low as 11 MeV show almost no differences. However, corrections are required for proton energies below 11 MeV. Care has to be taken when correction factors are related to an average LET from depth-dose measurements, because only the dose-averaged LET yields similar results as obtained in mono-energetic measurements.
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Affiliation(s)
- S Reinhardt
- Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians Universität München, 85748, Garching, Germany.
| | - M Würl
- Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians Universität München, 85748, Garching, Germany
| | - C Greubel
- Institut für Angewandte Physik und Messtechnik (LRT2), Universität der Bundeswehr München, 85779, Neubiberg, Germany
| | - N Humble
- Department of Radiation Oncology, Technische Universität München, Klinikum rechts der Isar, Munich, Germany
| | - J J Wilkens
- Department of Radiation Oncology, Technische Universität München, Klinikum rechts der Isar, Munich, Germany
| | - M Hillbrand
- Rinecker Proton Therapy Center, Munich, Germany
| | - A Mairani
- Medical Physics Unit CNAO Foundation, Pavia, Italy
| | - W Assmann
- Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians Universität München, 85748, Garching, Germany
| | - K Parodi
- Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians Universität München, 85748, Garching, Germany
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Palmans H, Rabus H, Belchior AL, Bug MU, Galer S, Giesen U, Gonon G, Gruel G, Hilgers G, Moro D, Nettelbeck H, Pinto M, Pola A, Pszona S, Schettino G, Sharpe PHG, Teles P, Villagrasa C, Wilkens JJ. Future development of biologically relevant dosimetry. Br J Radiol 2014; 88:20140392. [PMID: 25257709 DOI: 10.1259/bjr.20140392] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Proton and ion beams are radiotherapy modalities of increasing importance and interest. Because of the different biological dose response of these radiations as compared with high-energy photon beams, the current approach of treatment prescription is based on the product of the absorbed dose to water and a biological weighting factor, but this is found to be insufficient for providing a generic method to quantify the biological outcome of radiation. It is therefore suggested to define new dosimetric quantities that allow a transparent separation of the physical processes from the biological ones. Given the complexity of the initiation and occurrence of biological processes on various time and length scales, and given that neither microdosimetry nor nanodosimetry on their own can fully describe the biological effects as a function of the distribution of energy deposition or ionization, a multiscale approach is needed to lay the foundation for the aforementioned new physical quantities relating track structure to relative biological effectiveness in proton and ion beam therapy. This article reviews the state-of-the-art microdosimetry, nanodosimetry, track structure simulations, quantification of reactive species, reference radiobiological data, cross-section data and multiscale models of biological response in the context of realizing the new quantities. It also introduces the European metrology project, Biologically Weighted Quantities in Radiotherapy, which aims to investigate the feasibility of establishing a multiscale model as the basis of the new quantities. A tentative generic expression of how the weighting of physical quantities at different length scales could be carried out is presented.
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Affiliation(s)
- H Palmans
- 1 Acoustics and Ionising Radiation Division, National Physical Laboratory (NPL), Teddington, Middlesex, UK
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Zlobinskaya O, Siebenwirth C, Greubel C, Hable V, Hertenberger R, Humble N, Reinhardt S, Michalski D, Röper B, Multhoff G, Dollinger G, Wilkens JJ, Schmid TE. The Effects of Ultra-High Dose Rate Proton Irradiation on Growth Delay in the Treatment of Human Tumor Xenografts in Nude Mice. Radiat Res 2014; 181:177-83. [DOI: 10.1667/rr13464.1] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Reinhardt S, Hillbrand M, Wilkens JJ, Assmann W. Comparison of Gafchromic EBT2 and EBT3 films for clinical photon and proton beams. Med Phys 2012; 39:5257-62. [PMID: 22894450 DOI: 10.1118/1.4737890] [Citation(s) in RCA: 176] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Dose verification in highly conformal radiation therapy such as IMRT or proton therapy can benefit from the high spatial resolution offered by radio-chromic films such as Gafchromic EBT or EBT2. Recently, a new generation of these films, EBT3, has become available. The composition and thickness of the sensitive layer are the same as for the previous EBT2 films. The most important change is the symmetric layer configuration to eliminate side orientation dependence, which is reported for EBT2 films. METHODS The general film characteristics such as sensitivity to read-out orientation and postexposure darkening evolution of the new EBT3 film are evaluated. Film response has been investigated in clinical photon and proton beams and compared to former EBT2 films. Quenching effects in the proton Bragg peak region have been studied for both, EBT2 and EBT3 films. RESULTS The general performance of EBT3 is comparable to EBT2, and the orientation dependence with respect to film side is completely eliminated in EBT3 films. Response differences of EBT2 and EBT3 films are of the same order of magnitude as batch-to-batch variations observed for EBT2 films. No significant difference has been found for both generations of EBT films between photon and proton exposure. Depth dose measurements of EBT2 and EBT3 show an excellent agreement, though underestimating dose by up to 20% in the Bragg peak region. CONCLUSIONS The symmetric configuration of EBT3 presents a major improvement for film handling. EBT3 has similar dosimetric performance as its precursor EBT2 and can, thus, be applied to dose verification in IMRT in the same way. For dose verification in proton therapy the underresponse in the Bragg peak region has to be taken into account.
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Affiliation(s)
- S Reinhardt
- Fakultät für Physik, Ludwig-Maximilians Universität München, 85748 Garching, Germany.
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Affiliation(s)
- S Schell
- Department of Radiation Oncology, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675 München, Germany.
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Schell S, Wilkens JJ. Modifying proton fluence spectra to generate spread-out Bragg peaks with laser accelerated proton beams. Phys Med Biol 2009; 54:N459-66. [PMID: 19741280 DOI: 10.1088/0031-9155/54/19/n04] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Pflugfelder D, Wilkens JJ, Oelfke U. Worst case optimization: a method to account for uncertainties in the optimization of intensity modulated proton therapy. Phys Med Biol 2008; 53:1689-700. [PMID: 18367797 DOI: 10.1088/0031-9155/53/6/013] [Citation(s) in RCA: 188] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The sharp dose gradients which are possible in intensity modulated proton therapy (IMPT) not only offer the possibility of generating excellent target coverage while sparing neighbouring organs at risk, but can also lead to treatment plans which are very sensitive to uncertainties in treatment variables such as the range of individual Bragg peaks. We developed a method to account for uncertainties of treatment variables in the optimization based on a worst case dose distribution. The worst case dose distribution is calculated using several possible realizations of the uncertainties. This information is used by the objective function of the inverse treatment planning system to generate treatment plans which are acceptable under all considered realizations of the uncertainties. The worst case optimization method was implemented in our in-house treatment planning software KonRad in order to demonstrate the usefulness of this approach for clinical cases. In this paper, we investigated range uncertainties, setup uncertainties and a combination of both uncertainties. Using our method the sensitivity of the resulting treatment plans to these uncertainties is considerably reduced.
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Affiliation(s)
- D Pflugfelder
- Department of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.
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Abstract
In radiotherapy with scanned particle beams, tissue heterogeneities lateral to the beam direction are problematic in two ways: they pose a challenge to dose calculation algorithms, and they lead to a high sensitivity to setup errors. In order to quantify and avoid these problems, a heterogeneity number H(i) as a method to quantify lateral tissue heterogeneities of single beam spot i is introduced. To evaluate this new concept, two kinds of potential errors were investigated for single beam spots: First, the dose calculation error has been obtained by comparing the dose distribution computed by a simple pencil beam algorithm to more accurate Monte Carlo simulations. The resulting error is clearly correlated with H(i). Second, the analysis of the sensitivity to setup errors of single beam spots also showed a dependence on H(i). From this data it is concluded that H(i) can be used as a criterion to assess the risks of a compromised delivered dose due to lateral tissue heterogeneities. Furthermore, a method how to incorporate this information into the inverse planning process for intensity modulated proton therapy is presented. By suppressing beam spots with a high value of H(i), the unfavorable impact of lateral tissue heterogeneities can be reduced, leading to treatment plans which are more robust to dose calculation errors of the pencil beam algorithm. Additional possibilities to use the information of H(i) are outlined in the discussion.
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Affiliation(s)
- D Pflugfelder
- Department of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.
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Wilkens JJ, Oelfke U. TU-C-224A-01: Fast Multifield Optimization of the Biological Effect in IMRT with Ion Beams. Med Phys 2006. [DOI: 10.1118/1.2241525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Wilkens JJ, Alaly J, Deasy JO. TU-D-ValA-07: Prioritized Prescription-Goal Treatment Planning for IMRT: The Effect of Constraint Moderation. Med Phys 2006. [DOI: 10.1118/1.2241576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Abstract
To study the effects of a variable relative biological effectiveness (RBE) in inverse treatment planning for proton therapy, fast methods for three-dimensional RBE calculations are required. We therefore propose a simple phenomenological model for the RBE in therapeutic proton beams. It describes the RBE as a function of the dose, the linear energy transfer (LET) and tissue specific parameters. Published experimental results for the dependence of the parameters alpha and beta from the linear-quadratic model on the dose averaged LET were evaluated. Using a linear function for alpha(LET) in the relevant LET region below 30 keV per micrometre and a constant beta, a simple formula for the RBE could be derived. The new model was able to reproduce the basic dependences of RBE on dose and LET, and the RBE values agreed well with experimental results. The model was also applied to spread-out Bragg peaks (SOBP), where the main effects of a variable RBE are an increase of the RBE along the SOBP plateau, and a shift in depth of the distal falloff. The new method allows fast RBE estimations and has therefore potential applications in iterative treatment planning for proton therapy.
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Affiliation(s)
- J J Wilkens
- German Cancer Research Center (DKFZ), Department of Medical Physics, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.
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