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Stengl C, Arbes E, Thai LYJ, Echner G, Vedelago J, Jansen J, Jäkel O, Seco J. Development and characterization of a versatile mini-beam collimator for pre-clinical photon beam irradiation. Med Phys 2023; 50:5222-5237. [PMID: 37145971 DOI: 10.1002/mp.16432] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 04/05/2023] [Accepted: 04/06/2023] [Indexed: 05/07/2023] Open
Abstract
BACKGROUND Interest in spatial fractionation radiotherapy has exponentially increased over the last decade as a significant reduction of healthy tissue toxicity was observed by mini-beam irradiation. Published studies, however, mostly use rigid mini-beam collimators dedicated to their exact experimental arrangement such that changing the setup or testing new mini-beam collimator configurations becomes challenging and expensive. PURPOSE In this work, a versatile, low-cost mini-beam collimator was designed and manufactured for pre-clinical applications with X-ray beams. The mini-beam collimator enables variability of the full width at half maximum (FWHM), the center-to-center distance (ctc), the peak-to-valley dose ratio (PVDR), and the source-to-collimator distance (SCD). METHODS The mini-beam collimator is an in-house development, which was constructed of 10 × 40 mm2 tungsten or brass plates. These metal plates were combined with 3D-printed plastic plates that can be stacked together in the desired order. A standard X-ray source was used for the dosimetric characterization of four different configurations of the collimator, including a combination of plastic plates of 0.5, 1, or 2 mm width, assembled with 1 or 2 mm thick metal plates. Irradiations were done at three different SCDs for characterizing the performance of the collimator. For the SCDs closer to the radiation source, the plastic plates were 3D-printed with a dedicated angle to compensate for the X-ray beam divergence, making it possible to study ultra-high dose rates of around 40 Gy/s. All dosimetric quantifications were performed using EBT-XD films. Additionally, in vitro studies with H460 cells were carried out. RESULTS Characteristic mini-beam dose distributions were obtained with the developed collimator using a conventional X-ray source. With the exchangeable 3D-printed plates, FWHM and ctc from 0.52 to 2.11 mm, and from 1.77 to 4.61 mm were achieved, with uncertainties ranging from 0.01% to 8.98%, respectively. The FWHM and ctc obtained with the EBT-XD films are in agreement with the design of each mini-beam collimator configuration. For dose rates in the order of several Gy/min, the highest PVDR of 10.09 ± 1.08 was achieved with a collimator configuration of 0.5 mm thick plastic plates and 2 mm thick metal plates. Exchanging the tungsten plates with the lower-density metal brass reduced the PVDR by approximately 50%. Also, increasing the dose rate to ultra-high dose rates was feasible with the mini-beam collimator, where a PVDR of 24.26 ± 2.10 was achieved. Finally, it was possible to deliver and quantify mini-beam dose distribution patterns in vitro. CONCLUSIONS With the developed collimator, we achieved various mini-beam dose distributions that can be adjusted according to the needs of the user in regards to FWHM, ctc, PVDR and SCD, while accounting for beam divergence. Therefore, the designed mini-beam collimator may enable low-cost and versatile pre-clinical research on mini-beam irradiation.
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Affiliation(s)
- Christina Stengl
- Division of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Faculty of Medicine, University of Heidelberg, Heidelberg, Germany
- Heidelberg Institute for Radiation Oncology (HIRO), National Center for Radiation Research in Oncology (NCRO), Heidelberg, Germany
| | - Eric Arbes
- Biomedical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Department for Physics and Astronomy, University of Heidelberg, Heidelberg, Germany
| | - Long-Yang Jan Thai
- Biomedical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Department for Physics and Astronomy, University of Heidelberg, Heidelberg, Germany
| | - Gernot Echner
- Division of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Heidelberg Institute for Radiation Oncology (HIRO), National Center for Radiation Research in Oncology (NCRO), Heidelberg, Germany
| | - José Vedelago
- Division of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Heidelberg Institute for Radiation Oncology (HIRO), National Center for Radiation Research in Oncology (NCRO), Heidelberg, Germany
| | - Jeannette Jansen
- Biomedical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Oliver Jäkel
- Division of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Heidelberg Institute for Radiation Oncology (HIRO), National Center for Radiation Research in Oncology (NCRO), Heidelberg, Germany
- Heidelberg Ion Beam Therapy Center (HIT), Heidelberg University Hospital, Heidelberg, Germany
| | - Joao Seco
- Biomedical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Department for Physics and Astronomy, University of Heidelberg, Heidelberg, Germany
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Gomes ER, Franco MS. Combining Nanocarrier-Assisted Delivery of Molecules and Radiotherapy. Pharmaceutics 2022; 14:pharmaceutics14010105. [PMID: 35057001 PMCID: PMC8781448 DOI: 10.3390/pharmaceutics14010105] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 12/23/2021] [Accepted: 12/29/2021] [Indexed: 12/12/2022] Open
Abstract
Cancer is responsible for a significant proportion of death all over the world. Therefore, strategies to improve its treatment are highly desired. The use of nanocarriers to deliver anticancer treatments has been extensively investigated and improved since the approval of the first liposomal formulation for cancer treatment in 1995. Radiotherapy (RT) is present in the disease management strategy of around 50% of cancer patients. In the present review, we bring the state-of-the-art information on the combination of nanocarrier-assisted delivery of molecules and RT. We start with formulations designed to encapsulate single or multiple molecules that, once delivered to the tumor site, act directly on the cells to improve the effects of RT. Then, we describe formulations designed to modulate the tumor microenvironment by delivering oxygen or to boost the abscopal effect. Finally, we present how RT can be employed to trigger molecule delivery from nanocarriers or to modulate the EPR effect.
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Affiliation(s)
- Eliza Rocha Gomes
- Department of Pharmaceutical Products, Faculty of Pharmacy, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Brazil;
| | - Marina Santiago Franco
- Department of Radiation Sciences (DRS), Institute of Radiation Medicine (IRM), 85764 München, Germany
- Correspondence: ; Tel.: +49-89-3187-48767
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Steel H, Brüningk SC, Box C, Oelfke U, Bartzsch SH. Quantification of Differential Response of Tumour and Normal Cells to Microbeam Radiation in the Absence of FLASH Effects. Cancers (Basel) 2021; 13:3238. [PMID: 34209502 PMCID: PMC8268803 DOI: 10.3390/cancers13133238] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 06/11/2021] [Accepted: 06/24/2021] [Indexed: 12/12/2022] Open
Abstract
Microbeam radiotherapy (MRT) is a preclinical method of delivering spatially-fractionated radiotherapy aiming to improve the therapeutic window between normal tissue complication and tumour control. Previously, MRT was limited to ultra-high dose rate synchrotron facilities. The aim of this study was to investigate in vitro effects of MRT on tumour and normal cells at conventional dose rates produced by a bench-top X-ray source. Two normal and two tumour cell lines were exposed to homogeneous broad beam (BB) radiation, MRT, or were separately irradiated with peak or valley doses before being mixed. Clonogenic survival was assessed and compared to BB-estimated surviving fractions calculated by the linear-quadratic (LQ)-model. All cell lines showed similar BB sensitivity. BB LQ-model predictions exceeded the survival of cell lines following MRT or mixed beam irradiation. This effect was stronger in tumour compared to normal cell lines. Dose mixing experiments could reproduce MRT survival. We observed a differential response of tumour and normal cells to spatially fractionated irradiations in vitro, indicating increased tumour cell sensitivity. Importantly, this was observed at dose rates precluding the presence of FLASH effects. The LQ-model did not predict cell survival when the cell population received split irradiation doses, indicating that factors other than local dose influenced survival after irradiation.
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Affiliation(s)
- Harriet Steel
- Division of Radiotherapy and Imaging, The Institute of Cancer Research, 123 Old Brompton Road, London SW7 3RP, UK; (C.B.); (U.O.)
| | - Sarah C. Brüningk
- Machine Learning & Computational Biology, Department of Biosystems Science and Engineering, ETH Zurich, 4058 Basel, Switzerland;
- Swiss Institute for Bioinformatics (SIB), 1015 Lausanne, Switzerland
| | - Carol Box
- Division of Radiotherapy and Imaging, The Institute of Cancer Research, 123 Old Brompton Road, London SW7 3RP, UK; (C.B.); (U.O.)
| | - Uwe Oelfke
- Division of Radiotherapy and Imaging, The Institute of Cancer Research, 123 Old Brompton Road, London SW7 3RP, UK; (C.B.); (U.O.)
| | - Stefan H. Bartzsch
- Department of Radiation Oncology, School of Medicine, Klinikum Rechts der Isar, Technical University of Munich, Ismaninger Straße 22, 81675 Munich, Germany;
- Helmholtz Centre Munich, Institute for Radiation Medicine, Ingolstädter Landstraße 1, 85764 Munich, Germany
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Pellicioli P, Donzelli M, Davis JA, Estève F, Hugtenburg R, Guatelli S, Petasecca M, Lerch MLF, Bräuer-Krisch E, Krisch M. Study of the X-ray radiation interaction with a multislit collimator for the creation of microbeams in radiation therapy. JOURNAL OF SYNCHROTRON RADIATION 2021; 28:392-403. [PMID: 33650550 DOI: 10.1107/s1600577520016811] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 12/31/2020] [Indexed: 06/12/2023]
Abstract
Microbeam radiation therapy (MRT) is a developing radiotherapy, based on the use of beams only a few tens of micrometres wide, generated by synchrotron X-ray sources. The spatial fractionation of the homogeneous beam into an array of microbeams is possible using a multislit collimator (MSC), i.e. a machined metal block with regular apertures. Dosimetry in MRT is challenging and previous works still show differences between calculated and experimental dose profiles of 10-30%, which are not acceptable for a clinical implementation of treatment. The interaction of the X-rays with the MSC may contribute to the observed discrepancies; the present study therefore investigates the dose contribution due to radiation interaction with the MSC inner walls and radiation leakage of the MSC. Dose distributions inside a water-equivalent phantom were evaluated for different field sizes and three typical spectra used for MRT studies at the European Synchrotron Biomedical beamline ID17. Film dosimetry was utilized to determine the contribution of radiation interaction with the MSC inner walls; Monte Carlo simulations were implemented to calculate the radiation leakage contribution. Both factors turned out to be relevant for the dose deposition, especially for small fields. Photons interacting with the MSC walls may bring up to 16% more dose in the valley regions, between the microbeams. Depending on the chosen spectrum, the radiation leakage close to the phantom surface can contribute up to 50% of the valley dose for a 5 mm × 5 mm field. The current study underlines that a detailed characterization of the MSC must be performed systematically and accurate MRT dosimetry protocols must include the contribution of radiation leakage and radiation interaction with the MSC in order to avoid significant errors in the dose evaluation at the micrometric scale.
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Affiliation(s)
- P Pellicioli
- ID17 Biomedical Beamline, ESRF - The European Synchrotron, 71 avenue des Martyrs, Grenoble, France
| | - M Donzelli
- ID17 Biomedical Beamline, ESRF - The European Synchrotron, 71 avenue des Martyrs, Grenoble, France
| | - J A Davis
- School of Physics, University of Wollongong, Wollongong, Australia
| | - F Estève
- STROBE - Synchrotron Radiation for Biomedicine, Grenoble, France
| | - R Hugtenburg
- Swansea University Medical School, Singleton Park, Swansea, United Kingdom
| | - S Guatelli
- School of Physics, University of Wollongong, Wollongong, Australia
| | - M Petasecca
- School of Physics, University of Wollongong, Wollongong, Australia
| | - M L F Lerch
- School of Physics, University of Wollongong, Wollongong, Australia
| | - E Bräuer-Krisch
- ID17 Biomedical Beamline, ESRF - The European Synchrotron, 71 avenue des Martyrs, Grenoble, France
| | - M Krisch
- ID17 Biomedical Beamline, ESRF - The European Synchrotron, 71 avenue des Martyrs, Grenoble, France
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Treibel F, Nguyen M, Ahmed M, Dombrowsky A, Wilkens JJ, Combs SE, Schmid TE, Bartzsch S. Establishment of Microbeam Radiation Therapy at a Small-Animal Irradiator. Int J Radiat Oncol Biol Phys 2021; 109:626-636. [PMID: 33038461 DOI: 10.1016/j.ijrobp.2020.09.039] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 07/03/2020] [Accepted: 09/21/2020] [Indexed: 11/27/2022]
Abstract
PURPOSE Microbeam radiation therapy is a preclinical concept in radiation oncology. It spares normal tissue more effectively than conventional radiation therapy at equal tumor control. The radiation field consists of peak regions with doses of several hundred gray, whereas doses between the peaks (valleys) are below the tissue tolerance level. Widths and distances of the beams are in the submillimeter range for microbeam radiation therapy. A similar alternative concept with beam widths and distances in the millimeter range is presented by minibeam radiation therapy. Although both methods were developed at large synchrotron facilities, compact alternative sources have been proposed recently. METHODS AND MATERIALS A small-animal irradiator was fitted with a special 3-layered collimator that is used for preclinical research and produces microbeams of flexible width of up to 100 μm. Film dosimetry provided measurements of the dose distributions and was compared with Monte Carlo dose predictions. Moreover, the micronucleus assay in Chinese hamster CHO-K1 cells was used as a biological dosimeter. The focal spot size and beam emission angle of the x-ray tube were modified to optimize peak dose rate, peak-to-valley dose ratio (PVDR), beam shape, and field homogeneity. An equivalent collimator with slit widths of up to 500 μm produced minibeams and allowed for comparison of microbeam and minibeam field characteristics. RESULTS The setup achieved peak entrance dose rates of 8 Gy/min and PVDRs >30 for microbeams. Agreement between Monte Carlo simulations and film dosimetry is generally better for larger beam widths; qualitative measurements validated Monte Carlo predicted results. A smaller focal spot enhances PVDRs and reduces beam penumbras but substantially reduces the dose rate. A reduction of the beam emission angle improves the PVDR, beam penumbras, and dose rate without impairing field homogeneity. Minibeams showed similar field characteristics compared with microbeams at the same ratio of beam width and distance but had better agreement with simulations. CONCLUSION The developed setup is already in use for in vitro experiments and soon for in vivo irradiations. Deviations between Monte Carlo simulations and film dosimetry are attributed to scattering at the collimator surface and manufacturing inaccuracies and are a matter of ongoing research.
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Affiliation(s)
- Franziska Treibel
- School of Medicine, Klinikum rechts der Isar, Department of Radiation Oncology, Technical University of Munich, Munich, Germany; Institute for Radiation Medicine, Helmholtz Centre Munich, Munich, Germany; Physics Department, Technical University of Munich, Garching, Germany
| | - Mai Nguyen
- School of Medicine, Klinikum rechts der Isar, Department of Radiation Oncology, Technical University of Munich, Munich, Germany; Institute for Radiation Medicine, Helmholtz Centre Munich, Munich, Germany
| | - Mabroor Ahmed
- School of Medicine, Klinikum rechts der Isar, Department of Radiation Oncology, Technical University of Munich, Munich, Germany; Institute for Radiation Medicine, Helmholtz Centre Munich, Munich, Germany; Physics Department, Technical University of Munich, Garching, Germany
| | - Annique Dombrowsky
- School of Medicine, Klinikum rechts der Isar, Department of Radiation Oncology, Technical University of Munich, Munich, Germany; Institute for Radiation Medicine, Helmholtz Centre Munich, Munich, Germany
| | - Jan J Wilkens
- School of Medicine, Klinikum rechts der Isar, Department of Radiation Oncology, Technical University of Munich, Munich, Germany; Physics Department, Technical University of Munich, Garching, Germany
| | - Stephanie E Combs
- School of Medicine, Klinikum rechts der Isar, Department of Radiation Oncology, Technical University of Munich, Munich, Germany; Institute for Radiation Medicine, Helmholtz Centre Munich, Munich, Germany
| | - Thomas E Schmid
- School of Medicine, Klinikum rechts der Isar, Department of Radiation Oncology, Technical University of Munich, Munich, Germany; Institute for Radiation Medicine, Helmholtz Centre Munich, Munich, Germany
| | - Stefan Bartzsch
- School of Medicine, Klinikum rechts der Isar, Department of Radiation Oncology, Technical University of Munich, Munich, Germany; Institute for Radiation Medicine, Helmholtz Centre Munich, Munich, Germany.
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Clinical microbeam radiation therapy with a compact source: specifications of the line-focus X-ray tube. PHYSICS & IMAGING IN RADIATION ONCOLOGY 2021; 14:74-81. [PMID: 33458318 PMCID: PMC7807643 DOI: 10.1016/j.phro.2020.05.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 05/20/2020] [Accepted: 05/29/2020] [Indexed: 02/02/2023]
Abstract
Line-focus X-ray tubes are suitable for clinical microbeam radiation therapy (MRT). A modular high-voltage supply safely enables high electron beam powers. An electron accelerator was designed to generate an eccentric focal spot. We simulated a peak-to-valley dose ratio above 20 for single-field MRT. Microbeam arc therapy spares healthy brain tissue compared to single-field MRT.
Background and purpose Microbeam radiotherapy (MRT) is a preclinical concept in radiation oncology with arrays of alternating micrometer-wide high-dose peaks and low-dose valleys. Experiments demonstrated a superior normal tissue sparing at similar tumor control rates with MRT compared to conventional radiotherapy. Possible clinical applications are currently limited to large third-generation synchrotrons. Here, we investigated the line-focus X-ray tube as an alternative microbeam source. Materials and methods We developed a concept for a high-voltage supply and an electron source. In Monte Carlo simulations, we assessed the influence of X-ray spectrum, focal spot size, electron incidence angle, and photon emission angle on the microbeam dose distribution. We further assessed the dose distribution of microbeam arc therapy and suggested to interpret this complex dose distribution by equivalent uniform dose. Results An adapted modular multi-level converter can supply high-voltage powers in the megawatt range for a few seconds. The electron source with a thermionic cathode and a quadrupole can generate an eccentric, high-power electron beam of several 100 keV energy. Highest dose rates and peak-to-valley dose ratios (PVDRs) were achieved for an electron beam impinging perpendicular onto the target surface and a focal spot smaller than the microbeam cross-section. The line-focus X-ray tube simulations demonstrated PVDRs above 20. Conclusion The line-focus X-ray tube is a suitable compact source for clinical MRT. We demonstrated its technical feasibility based on state-of-the-art high-voltage and electron-beam technology. Microbeam arc therapy is an effective concept to increase the target-to-entrance dose ratio of orthovoltage microbeams.
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Moradi F, Khandaker M, Abdul Sani S, Uguru E, Sulieman A, Bradley D. Feasibility study of a minibeam collimator design for a 60Co gamma irradiator. Radiat Phys Chem Oxf Engl 1993 2021. [DOI: 10.1016/j.radphyschem.2020.109026] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Burger K, Urban T, Dombrowsky AC, Dierolf M, Günther B, Bartzsch S, Achterhold K, Combs SE, Schmid TE, Wilkens JJ, Pfeiffer F. Technical and dosimetric realization of in vivo x-ray microbeam irradiations at the Munich Compact Light Source. Med Phys 2020; 47:5183-5193. [PMID: 32757280 DOI: 10.1002/mp.14433] [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: 12/11/2019] [Revised: 04/15/2020] [Accepted: 07/20/2020] [Indexed: 12/20/2022] Open
Abstract
PURPOSE X-ray microbeam radiation therapy is a preclinical concept for tumor treatment promising tissue sparing and enhanced tumor control. With its spatially separated, periodic micrometer-sized pattern, this method requires a high dose rate and a collimated beam typically available at large synchrotron radiation facilities. To treat small animals with microbeams in a laboratory-sized environment, we developed a dedicated irradiation system at the Munich Compact Light Source (MuCLS). METHODS A specially made beam collimation optic allows to increase x-ray fluence rate at the position of the target. Monte Carlo simulations and measurements were conducted for accurate microbeam dosimetry. The dose during irradiation is determined by a calibrated flux monitoring system. Moreover, a positioning system including mouse monitoring was built. RESULTS We successfully commissioned the in vivo microbeam irradiation system for an exemplary xenograft tumor model in the mouse ear. By beam collimation, a dose rate of up to 5.3 Gy/min at 25 keV was achieved. Microbeam irradiations using a tungsten collimator with 50 μm slit size and 350 μm center-to-center spacing were performed at a mean dose rate of 0.6 Gy/min showing a high peak-to-valley dose ratio of about 200 in the mouse ear. The maximum circular field size of 3.5 mm in diameter can be enlarged using field patching. CONCLUSIONS This study shows that we can perform in vivo microbeam experiments at the MuCLS with a dedicated dosimetry and positioning system to advance this promising radiation therapy method at commercially available compact microbeam sources. Peak doses of up to 100 Gy per treatment seem feasible considering a recent upgrade for higher photon flux. The system can be adapted for tumor treatment in different animal models, for example, in the hind leg.
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Affiliation(s)
- Karin Burger
- Department of Radiation Oncology, School of Medicine & Klinikum rechts der Isar, Technical University of Munich, Munich, 81675, Germany.,Chair of Biomedical Physics, Department of Physics and Munich School of BioEngineering, Technical University of Munich, Garching, 85748, Germany
| | - Theresa Urban
- Department of Radiation Oncology, School of Medicine & Klinikum rechts der Isar, Technical University of Munich, Munich, 81675, Germany.,Chair of Biomedical Physics, Department of Physics and Munich School of BioEngineering, Technical University of Munich, Garching, 85748, Germany
| | - Annique C Dombrowsky
- Department of Radiation Oncology, School of Medicine & Klinikum rechts der Isar, Technical University of Munich, Munich, 81675, Germany.,Institute of Radiation Medicine (IRM), Department of Radiation Sciences (DRS), Helmholtz Zentrum München, Neuherberg, 85764, Germany
| | - Martin Dierolf
- Chair of Biomedical Physics, Department of Physics and Munich School of BioEngineering, Technical University of Munich, Garching, 85748, Germany
| | - Benedikt Günther
- Chair of Biomedical Physics, Department of Physics and Munich School of BioEngineering, Technical University of Munich, Garching, 85748, Germany
| | - Stefan Bartzsch
- Department of Radiation Oncology, School of Medicine & Klinikum rechts der Isar, Technical University of Munich, Munich, 81675, Germany.,Institute of Radiation Medicine (IRM), Department of Radiation Sciences (DRS), Helmholtz Zentrum München, Neuherberg, 85764, Germany
| | - Klaus Achterhold
- Chair of Biomedical Physics, Department of Physics and Munich School of BioEngineering, Technical University of Munich, Garching, 85748, Germany
| | - Stephanie E Combs
- Department of Radiation Oncology, School of Medicine & Klinikum rechts der Isar, Technical University of Munich, Munich, 81675, Germany.,Institute of Radiation Medicine (IRM), Department of Radiation Sciences (DRS), Helmholtz Zentrum München, Neuherberg, 85764, Germany
| | - Thomas E Schmid
- Department of Radiation Oncology, School of Medicine & Klinikum rechts der Isar, Technical University of Munich, Munich, 81675, Germany.,Institute of Radiation Medicine (IRM), Department of Radiation Sciences (DRS), Helmholtz Zentrum München, Neuherberg, 85764, Germany
| | - Jan J Wilkens
- Department of Radiation Oncology, School of Medicine & Klinikum rechts der Isar, Technical University of Munich, Munich, 81675, Germany.,Chair of Biomedical Physics, Department of Physics and Munich School of BioEngineering, Technical University of Munich, Garching, 85748, Germany
| | - Franz Pfeiffer
- Chair of Biomedical Physics, Department of Physics and Munich School of BioEngineering, Technical University of Munich, Garching, 85748, Germany.,Department of Diagnostic and Interventional Radiology, School of Medicine & Klinikum rechts der Isar, Technical University of Munich, München, 81675, Germany
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Bartzsch S, Corde S, Crosbie JC, Day L, Donzelli M, Krisch M, Lerch M, Pellicioli P, Smyth LML, Tehei M. Technical advances in x-ray microbeam radiation therapy. Phys Med Biol 2020; 65:02TR01. [PMID: 31694009 DOI: 10.1088/1361-6560/ab5507] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
In the last 25 years microbeam radiation therapy (MRT) has emerged as a promising alternative to conventional radiation therapy at large, third generation synchrotrons. In MRT, a multi-slit collimator modulates a kilovoltage x-ray beam on a micrometer scale, creating peak dose areas with unconventionally high doses of several hundred Grays separated by low dose valley regions, where the dose remains well below the tissue tolerance level. Pre-clinical evidence demonstrates that such beam geometries lead to substantially reduced damage to normal tissue at equal tumour control rates and hence drastically increase the therapeutic window. Although the mechanisms behind MRT are still to be elucidated, previous studies indicate that immune response, tumour microenvironment, and the microvasculature may play a crucial role. Beyond tumour therapy, MRT has also been suggested as a microsurgical tool in neurological disorders and as a primer for drug delivery. The physical properties of MRT demand innovative medical physics and engineering solutions for safe treatment delivery. This article reviews technical developments in MRT and discusses existing solutions for dosimetric validation, reliable treatment planning and safety. Instrumentation at synchrotron facilities, including beam production, collimators and patient positioning systems, is also discussed. Specific solutions reviewed in this article include: dosimetry techniques that can cope with high spatial resolution, low photon energies and extremely high dose rates of up to 15 000 Gy s-1, dose calculation algorithms-apart from pure Monte Carlo Simulations-to overcome the challenge of small voxel sizes and a wide dynamic dose-range, and the use of dose-enhancing nanoparticles to combat the limited penetrability of a kilovoltage energy spectrum. Finally, concepts for alternative compact microbeam sources are presented, such as inverse Compton scattering set-ups and carbon nanotube x-ray tubes, that may facilitate the transfer of MRT into a hospital-based clinical environment. Intensive research in recent years has resulted in practical solutions to most of the technical challenges in MRT. Treatment planning, dosimetry and patient safety systems at synchrotrons have matured to a point that first veterinary and clinical studies in MRT are within reach. Should these studies confirm the promising results of pre-clinical studies, the authors are confident that MRT will become an effective new radiotherapy option for certain patients.
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Affiliation(s)
- Stefan Bartzsch
- Department of Radiation Oncology, School of Medicine, Technical University of Munich, Klinikum rechts der Isar, Munich, Germany. Helmholtz Centre Munich, Institute for Radiation Medicine, Munich, Germany
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Minibeam radiation therapy at a conventional irradiator: Dose-calculation engine and first tumor-bearing animals irradiation. Phys Med 2020; 69:256-261. [PMID: 31918378 DOI: 10.1016/j.ejmp.2019.12.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 12/11/2019] [Accepted: 12/17/2019] [Indexed: 01/31/2023] Open
Abstract
PURPOSE Minibeam radiation therapy (MBRT) is a novel therapeutic strategy, whose exploration was hindered due to its restriction to large synchrotrons. Our recent implementation of MBRT in a wide-spread small animal irradiator offers the possibility of performing systematic radiobiological studies. The aim of this research was to develop a set of dosimetric tools to reliably guide biological experiments in the irradiator. METHODS A Monte Carlo (Geant4)-based dose calculation engine was developed. It was then benchmarked against a series of dosimetric measurements performed with gafchromic films. Two voxelized rat phantoms (ROBY, computer tomography) were used to evaluate the treatment plan of F98 tumor-bearing rats. The response of a group of 7 animals receiving a unilateral irradiation of 58 Gy was compared to a group of non-irradiated controls. RESULTS The good agreement between calculations and the experimental data allowed the validation of the dose-calculation engine. The latter was first used to compare the dose distributions in computer tomography images of a rat's head and in a digital model of a rat's head (ROBY), obtaining a good general agreement. Finally, with respect to the in vivo experiment, the increase of mean survival time of the treated group with respect to the controls was modest but statistically significant. CONCLUSIONS The developed dosimetric tools were used to reliably guide the first MBRT treatments of intracranial glioma-bearing rats outside synchrotrons. The significant tumor response obtained with respect to the non-irradiated controls, despite the heterogenous dose coverage of the target, might indicate the participation of non-targeted effects.
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Flynn S, Price T, Allport PP, Silvestre Patallo I, Thomas R, Subiel A, Bartzsch S, Treibel F, Ahmed M, Jacobs-Headspith J, Edwards T, Jones I, Cathie D, Guerrini N, Sedgwick I. Evaluation of a pixelated large format CMOS sensor for x-ray microbeam radiotherapy. Med Phys 2019; 47:1305-1316. [PMID: 31837272 PMCID: PMC7078942 DOI: 10.1002/mp.13971] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 12/06/2019] [Accepted: 12/06/2019] [Indexed: 01/15/2023] Open
Abstract
PURPOSE Current techniques and procedures for dosimetry in microbeams typically rely on radiochromic film or small volume ionization chambers for validation and quality assurance in 2D and 1D, respectively. Whilst well characterized for clinical and preclinical radiotherapy, these methods are noninstantaneous and do not provide real time profile information. The objective of this work is to determine the suitability of the newly developed vM1212 detector, a pixelated CMOS (complementary metal-oxide-semiconductor) imaging sensor, for in situ and in vivo verification of x-ray microbeams. METHODS Experiments were carried out on the vM1212 detector using a 220 kVp small animal radiation research platform (SARRP) at the Helmholtz Centre Munich. A 3 x 3 cm2 square piece of EBT3 film was placed on top of a marked nonfibrous card overlaying the sensitive silicon of the sensor. One centimeter of water equivalent bolus material was placed on top of the film for build-up. The response of the detector was compared to an Epson Expression 10000XL flatbed scanner using FilmQA Pro with triple channel dosimetry. This was also compared to a separate exposure using 450 µm of silicon as a surrogate for the detector and a Zeiss Axio Imager 2 microscope using an optical microscopy method of dosimetry. Microbeam collimator slits with range of nominal widths of 25, 50, 75, and 100 µm were used to compare beam profiles and determine sensitivity of the detector and both film measurements to different microbeams. RESULTS The detector was able to measure peak and valley profiles in real-time, a significant reduction from the 24 hr self-development required by the EBT3 film. Observed full width at half maximum (FWHM) values were larger than the nominal slit widths, ranging from 130 to 190 µm due to divergence. Agreement between the methods was found for peak-to-valley dose ratio (PVDR), peak to peak separation and FWHM, but a difference in relative intensity of the microbeams was observed between the detectors. CONCLUSIONS The investigation demonstrated that pixelated CMOS sensors could be applied to microbeam radiotherapy for real-time dosimetry in the future, however the relatively large pixel pitch of the vM1212 detector limit the immediate application of the results.
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Affiliation(s)
- Samuel Flynn
- School of Physics and Astronomy, University of Birmingham, Birmingham, B15 2TT, UK.,Medical Physics Department, National Physical Laboratory, Teddington, TW11 0LW, UK
| | - Tony Price
- School of Physics and Astronomy, University of Birmingham, Birmingham, B15 2TT, UK.,Medical Physics Department, National Physical Laboratory, Teddington, TW11 0LW, UK
| | - Philip P Allport
- School of Physics and Astronomy, University of Birmingham, Birmingham, B15 2TT, UK
| | - Ileana Silvestre Patallo
- Medical Physics Department, National Physical Laboratory, Teddington, TW11 0LW, UK.,UCL Cancer Institute, University College London, London, WC1E 6AG, UK
| | - Russell Thomas
- Medical Physics Department, National Physical Laboratory, Teddington, TW11 0LW, UK
| | - Anna Subiel
- Medical Physics Department, National Physical Laboratory, Teddington, TW11 0LW, UK
| | - Stefan Bartzsch
- Helmholtz Centre Munich, Institute for Radiation Medicine, Munich, 85764, Germany.,School of Medicine, Klinikum rechts der Isar, Department of Radiation Oncology, Technical University of Munich, Munich, 80333, Germany
| | - Franziska Treibel
- School of Medicine, Klinikum rechts der Isar, Department of Radiation Oncology, Technical University of Munich, Munich, 80333, Germany
| | - Mabroor Ahmed
- School of Medicine, Klinikum rechts der Isar, Department of Radiation Oncology, Technical University of Munich, Munich, 80333, Germany
| | | | | | | | | | | | - Iain Sedgwick
- Rutherford Appleton Laboratory, Didcot, OX11 0QX, UK
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12
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Esplen NM, Chergui L, Johnstone CD, Bazalova-Carter M. Monte Carlo optimization of a microbeam collimator design for use on the small animal radiation research platform (SARRP). ACTA ACUST UNITED AC 2018; 63:175004. [DOI: 10.1088/1361-6560/aad7e2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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13
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Ghita M, Fernandez-Palomo C, Fukunaga H, Fredericia PM, Schettino G, Bräuer-Krisch E, Butterworth KT, McMahon SJ, Prise KM. Microbeam evolution: from single cell irradiation to pre-clinical studies. Int J Radiat Biol 2018; 94:708-718. [PMID: 29309203 DOI: 10.1080/09553002.2018.1425807] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
PURPOSE This review follows the development of microbeam technology from the early days of single cell irradiations, to investigations of specific cellular mechanisms and to the development of new treatment modalities in vivo. A number of microbeam applications are discussed with a focus on pre-clinical modalities and translation towards clinical application. CONCLUSIONS The development of radiation microbeams has been a valuable tool for the exploration of fundamental radiobiological response mechanisms. The strength of micro-irradiation techniques lies in their ability to deliver precise doses of radiation to selected individual cells in vitro or even to target subcellular organelles. These abilities have led to the development of a range of microbeam facilities around the world allowing the delivery of precisely defined beams of charged particles, X-rays, or electrons. In addition, microbeams have acted as mechanistic probes to dissect the underlying molecular events of the DNA damage response following highly localized dose deposition. Further advances in very precise beam delivery have also enabled the transition towards new and exciting therapeutic modalities developed at synchrotrons to deliver radiotherapy using plane parallel microbeams, in Microbeam Radiotherapy (MRT).
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Affiliation(s)
- Mihaela Ghita
- a Centre for Cancer Research and Cell Biology , Queen's University Belfast , Belfast , UK
| | | | - Hisanori Fukunaga
- a Centre for Cancer Research and Cell Biology , Queen's University Belfast , Belfast , UK
| | - Pil M Fredericia
- c Centre for Nuclear Technologies , Technical University of Denmark , Roskilde , Denmark
| | | | | | - Karl T Butterworth
- a Centre for Cancer Research and Cell Biology , Queen's University Belfast , Belfast , UK
| | - Stephen J McMahon
- a Centre for Cancer Research and Cell Biology , Queen's University Belfast , Belfast , UK
| | - Kevin M Prise
- a Centre for Cancer Research and Cell Biology , Queen's University Belfast , Belfast , UK
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14
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Single floating cell irradiation technique with an X-ray microbeam. JOURNAL OF RADIATION RESEARCH AND APPLIED SCIENCES 2018. [DOI: 10.1016/j.jrras.2017.11.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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15
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Prezado Y, Dos Santos M, Gonzalez W, Jouvion G, Guardiola C, Heinrich S, Labiod D, Juchaux M, Jourdain L, Sebrie C, Pouzoulet F. Transfer of Minibeam Radiation Therapy into a cost-effective equipment for radiobiological studies: a proof of concept. Sci Rep 2017; 7:17295. [PMID: 29229965 PMCID: PMC5725561 DOI: 10.1038/s41598-017-17543-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 11/23/2017] [Indexed: 01/13/2023] Open
Abstract
Minibeam radiation therapy (MBRT) is an innovative synchrotron radiotherapy technique able to shift the normal tissue complication probability curves to significantly higher doses. However, its exploration was hindered due to the limited and expensive beamtime at synchrotrons. The aim of this work was to develop a cost-effective equipment to perform systematic radiobiological studies in view of MBRT. Tumor control for various tumor entities will be addressable as well as studies to unravel the distinct biological mechanisms involved in normal and tumor tissues responses when applying MBRT. With that aim, a series of modifications of a small animal irradiator were performed to make it suitable for MBRT experiments. In addition, the brains of two groups of rats were irradiated. Half of the animals received a standard irradiation, the other half, MBRT. The animals were followed-up for 6.5 months. Substantial brain damage was observed in the group receiving standard RT, in contrast to the MBRT group, where no significant lesions were observed. This work proves the feasibility of the transfer of MBRT outside synchrotron sources towards a small animal irradiator.
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Affiliation(s)
- Y Prezado
- Laboratoire d'Imagerie et Modélisation en Neurobiologie et Cancérologie (IMNC), Centre National de la Recherche Scientifique (CNRS), Universités Paris 11 and Paris 7, Campus d'Orsay, 91405, Orsay, France.
| | - M Dos Santos
- Laboratoire d'Imagerie et Modélisation en Neurobiologie et Cancérologie (IMNC), Centre National de la Recherche Scientifique (CNRS), Universités Paris 11 and Paris 7, Campus d'Orsay, 91405, Orsay, France
| | - W Gonzalez
- Laboratoire d'Imagerie et Modélisation en Neurobiologie et Cancérologie (IMNC), Centre National de la Recherche Scientifique (CNRS), Universités Paris 11 and Paris 7, Campus d'Orsay, 91405, Orsay, France
| | - G Jouvion
- Histopathologie Humaine et Modèles Animaux, Institut Pasteur, 28 Rue du Docteur Roux, 75015, Paris, France
| | - C Guardiola
- Laboratoire d'Imagerie et Modélisation en Neurobiologie et Cancérologie (IMNC), Centre National de la Recherche Scientifique (CNRS), Universités Paris 11 and Paris 7, Campus d'Orsay, 91405, Orsay, France
| | - S Heinrich
- Institut Curie, PSL Research University, Translational Research Department, Experimental Radiotherapy Platform, Orsay, France
- Paris Sud University, Paris -Saclay University, 91405, Orsay, France
| | - D Labiod
- Institut Curie, PSL Research University, Translational Research Department, Experimental Radiotherapy Platform, Orsay, France
- Paris Sud University, Paris -Saclay University, 91405, Orsay, France
| | - M Juchaux
- Laboratoire d'Imagerie et Modélisation en Neurobiologie et Cancérologie (IMNC), Centre National de la Recherche Scientifique (CNRS), Universités Paris 11 and Paris 7, Campus d'Orsay, 91405, Orsay, France
| | - L Jourdain
- Imagerie par Résonance Magnétique Médicale et Multi-modalités (IR4M-UMR8081), Université Paris Sud, 91405, Orsay, France
| | - C Sebrie
- Imagerie par Résonance Magnétique Médicale et Multi-modalités (IR4M-UMR8081), Université Paris Sud, 91405, Orsay, France
| | - F Pouzoulet
- Institut Curie, PSL Research University, Translational Research Department, Experimental Radiotherapy Platform, Orsay, France
- Paris Sud University, Paris -Saclay University, 91405, Orsay, France
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16
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Meyer J, Stewart RD, Smith D, Eagle J, Lee E, Cao N, Ford E, Hashemian R, Schuemann J, Saini J, Marsh S, Emery R, Dorman E, Schwartz J, Sandison G. Biological and dosimetric characterisation of spatially fractionated proton minibeams. Phys Med Biol 2017; 62:9260-9281. [PMID: 29053105 DOI: 10.1088/1361-6560/aa950c] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The biological effectiveness of proton beams varies with depth, spot size and lateral distance from the beam central axis. The aim of this work is to incorporate proton relative biological effectiveness (RBE) and equivalent uniform dose (EUD) considerations into comparisons of broad beam and highly modulated proton minibeams. A Monte Carlo model of a small animal proton beamline is presented. Dose and variable RBE is calculated on a per-voxel basis for a range of energies (30-109 MeV). For an open beam, the RBE values at the beam entrance ranged from 1.02-1.04, at the Bragg peak (BP) from 1.3 to 1.6, and at the distal end of the BP from 1.4 to 2.0. For a 50 MeV proton beam, a minibeam collimator designed to produce uniform dose at the depth of the BP peak, had minimal impact on the open beam RBE values at depth. RBE changes were observed near the surface when the collimator was placed flush with the irradiated object, due to a higher neutron contribution derived from proton interactions with the collimator. For proton minibeams, the relative mean RBE weighted entrance dose (RWD) was ~25% lower than the physical mean dose. A strong dependency of the EUD with fraction size was observed. For 20 Gy fractions, the EUD varied widely depending on the radiosensitivity of the cells. For radiosensitive cells, the difference was up to ~50% in mean dose and ~40% in mean RWD and the EUD trended towards the valley dose rather than the mean dose. For comparative studies of uniform dose with spatially fractionated proton minibeams, EUD derived from a per-voxel RWD distribution is recommended for biological assessments of reproductive cell survival and related endpoints.
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Affiliation(s)
- Juergen Meyer
- Department of Radiation Oncology, University of Washington, 1959 NE Pacific Street, Box 356043, Seattle, WA 98195, United States of America
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17
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Bazyar S, Inscoe CR, O’Brian ET, Zhou O, Lee YZ. Minibeam radiotherapy with small animal irradiators; in vitro and in vivo feasibility studies. ACTA ACUST UNITED AC 2017; 62:8924-8942. [DOI: 10.1088/1361-6560/aa926b] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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18
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Bartzsch S, Oelfke U. Line focus x-ray tubes-a new concept to produce high brilliance x-rays. Phys Med Biol 2017; 62:8600-8615. [PMID: 28976915 PMCID: PMC5659237 DOI: 10.1088/1361-6560/aa910b] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Revised: 09/25/2017] [Accepted: 10/04/2017] [Indexed: 11/11/2022]
Abstract
Currently hard coherent x-ray radiation at high photon fluxes can only be produced with large and expensive radiation sources, such as 3[Formula: see text] generation synchrotrons. Especially in medicine, this limitation prevents various promising developments in imaging and therapy from being translated into clinical practice. Here we present a new concept of highly brilliant x-ray sources, line focus x-ray tubes (LFXTs), which may serve as a powerful and cheap alternative to synchrotrons and a range of other existing technologies. LFXTs employ an extremely thin focal spot and a rapidly rotating target for the electron beam which causes a change in the physical mechanism of target heating, allowing higher electron beam intensities at the focal spot. Monte Carlo simulations and numeric solutions of the heat equation are used to predict the characteristics of the LFXT. In terms of photon flux and coherence length, the performance of the line focus x-ray tube compares with inverse Compton scattering sources. Dose rates of up to 180 Gy [Formula: see text] can be reached in 50 cm distance from the focal spot. The results demonstrate that the line focus tube can serve as a powerful compact source for phase contrast imaging and microbeam radiation therapy. The production of a prototype seems technically feasible.
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Affiliation(s)
- Stefan Bartzsch
- The Institute Of Cancer Research, 123 Old Brompton Road, London SW7 3RP, United Kingdom
- Department of Radiation Oncology, Klinikum rechts der Isar, Technical University of Munich, Ismaninger Straße 22, 81675 Munich, Germany
| | - Uwe Oelfke
- The Institute Of Cancer Research, 123 Old Brompton Road, London SW7 3RP, United Kingdom
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