50 results on '"Siegbahn E"'
Search Results
2. Monte Carlo code comparison of dose delivery prediction for Microbeam Radiation Therapy.
- Author
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de Felici, M, Siegbahn, E, Spiga, J, Hanson, A, Felici, R, Ferrero, C, Tartari, A, Gambaccini, M, Keyrilaeinen, J, Braeuer-Krisch, E, Randaccio, P, Bravin, A, BA Verhaegen, F, Seuntjens, J, de Felici M., Siegbahn E. A., Spiga J., Hanson A. L., Felici R., Ferrero C., Tartari A., Gambaccini M., Keyrilaeinen J., Braeuer-Krisch E., Randaccio P., Bravin A, BA Verhaegen F, Seuntjens J, de Felici, M, Siegbahn, E, Spiga, J, Hanson, A, Felici, R, Ferrero, C, Tartari, A, Gambaccini, M, Keyrilaeinen, J, Braeuer-Krisch, E, Randaccio, P, Bravin, A, BA Verhaegen, F, Seuntjens, J, de Felici M., Siegbahn E. A., Spiga J., Hanson A. L., Felici R., Ferrero C., Tartari A., Gambaccini M., Keyrilaeinen J., Braeuer-Krisch E., Randaccio P., Bravin A, BA Verhaegen F, and Seuntjens J
- Abstract
Preclinical Microbeam Radiation Therapy (MRT) research programs are carried out at the European Synchrotron Radiation Facility (ESRF) and at a few other synchrotron facilities. MRT needs an accurate evaluation of the doses delivered to biological tissues for carrying out pre-clinical studies. This point is crucial for determining the effect induced by changing any of the physical irradiation parameters. The doses of interest in MRT are normally calculated using Monte Carlo (MC) methods. A few MC packages have been used in the last decade for MRT dose evaluations in independent studies. The aim of this investigation is to provide a preliminary basis to perform a systematic comparison of the dose results obtained, under identical irradiation conditions and for the same scoring geometries with the following five MC codes: EGS4, PENELOPE, GEANT4, EGSnrc, and MCNPX. Dose profiles have been calculated in an in-depth region of cylindrical phantoms made of water or PMMA. Beams in both cylindrical and planar geometry have been considered. This comparison shows an overall agreement among the different codes although minor differences occur, which need further investigations. © 2008 IOP Publishing Ltd.
- Published
- 2008
3. The GEANT4 toolkit for microdosimetry calculations: Application to microbeam radiation therapy (MRT)
- Author
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Spiga, J, Siegbahn, E, Braeuer-Krisch, E, Randaccio, P, Bravin, A, Spiga J., Siegbahn E. A., Braeuer-Krisch E., Randaccio P., Bravin A, Spiga, J, Siegbahn, E, Braeuer-Krisch, E, Randaccio, P, Bravin, A, Spiga J., Siegbahn E. A., Braeuer-Krisch E., Randaccio P., and Bravin A
- Abstract
Theoretical dose distributions for microbeam radiation therapy (MRT) are computed in this paper using the GEANT4 Monte Carlo (MC) simulation toolkit. MRT is an innovative experimental radiotherapy technique carried out using an array of parallel microbeams of synchrotron-wiggler-generated x rays. Although the biological mechanisms underlying the effects of microbeams are still largely unknown, the effectiveness of MRT can be traced back to the natural ability of normal tissues to rapidly repair small damages to the vasculature, and on the lack of a similar healing process in tumoral tissues. Contrary to conventional therapy, in which each beam is at least several millimeters wide, the narrowness of the microbeams allows a rapid regeneration of the blood vessels along the beams' trajectories. For this reason the calculation of the "valley" dose is of crucial importance and the correct use of MC codes for such purposes must be understood. GEANT4 offers, in addition to the standard libraries, a specialized package specifically designed to deal with electromagnetic interactions of particles with matter for energies down to 250 eV. This package implements two different approaches for electron and photon transport, one based on evaluated data libraries, the other adopting analytical models. These features are exploited to cross-check theoretical computations for MRT. The lateral and depth dose profiles are studied for the irradiation of a 20 cm diameter, 20 cm long cylindrical phantom, with cylindrical sources of different size and energy. Microbeam arrays are simulated with the aid of superposition algorithms, and the ratios of peak-to-valley doses are computed for typical cases used in preclinical assays. Dose profiles obtained using the GEANT4 evaluated data libraries and analytical models are compared with simulation results previously obtained using the PENELOPE code. The results show that dose profiles computed with GEANT4's analytical model are almost indistinguish
- Published
- 2007
4. Erratum: “Characterization of a tungsten/gas multislit collimator (TMSC) for microbeam radiation therapy at the European Synchrotron Radiation Facility”[Rev. Sci. Instrum. 76, 064303 (2005)]
- Author
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Brauer-Krisch, E, Bravin, A, Zhang, L, Siegbahn, E, Stepanek, J, Blattmann, H, Slatkin, D, Gebbers, J, Jasmin, M, Laissue, J, Brauer-Krisch E, Bravin a, Zhang L, Siegbahn E, Stepanek J, Blattmann H, Slatkin DN, Gebbers JO, Jasmin M, Laissue JA, Brauer-Krisch, E, Bravin, A, Zhang, L, Siegbahn, E, Stepanek, J, Blattmann, H, Slatkin, D, Gebbers, J, Jasmin, M, Laissue, J, Brauer-Krisch E, Bravin a, Zhang L, Siegbahn E, Stepanek J, Blattmann H, Slatkin DN, Gebbers JO, Jasmin M, and Laissue JA
- Published
- 2006
5. Erratum: “Characterization of a tungsten/gas multislit collimator (TMSC) for microbeam radiation therapy at the European Synchrotron Radiation Facility”[Rev. Sci. Instrum. 76, 064303 (2005)]
- Author
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Brauer-Krisch E, Brauer-Krisch, E, Bravin, A, Zhang, L, Siegbahn, E, Stepanek, J, Blattmann, H, Slatkin, D, Gebbers, J, Jasmin, M, Laissue, J, Brauer-Krisch E, Bravin a, Zhang L, Siegbahn E, Stepanek J, Blattmann H, Slatkin DN, Gebbers JO, Jasmin M, Laissue JA, Brauer-Krisch E, Brauer-Krisch, E, Bravin, A, Zhang, L, Siegbahn, E, Stepanek, J, Blattmann, H, Slatkin, D, Gebbers, J, Jasmin, M, Laissue, J, Brauer-Krisch E, Bravin a, Zhang L, Siegbahn E, Stepanek J, Blattmann H, Slatkin DN, Gebbers JO, Jasmin M, and Laissue JA
- Published
- 2006
6. Characterization of a tungsten/gas multislit collimator for microbeam radiation therapy at the European Synchrotron Radiation Facility
- Author
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Brauer-Krisch, E, Bravin, A, Zhang, L, Siegbahn, E, Stepanek, J, Blattmann, H, Slatkin, D, Gebbers, J, Jasmin, M, Laissue, J, Brauer-Krisch E, Bravin A, Zhang L, Siegbahn E, Stepanek J, Blattmann H, Slatkin DN, Gebbers JO, Jasmin M, Laissue JA, Brauer-Krisch, E, Bravin, A, Zhang, L, Siegbahn, E, Stepanek, J, Blattmann, H, Slatkin, D, Gebbers, J, Jasmin, M, Laissue, J, Brauer-Krisch E, Bravin A, Zhang L, Siegbahn E, Stepanek J, Blattmann H, Slatkin DN, Gebbers JO, Jasmin M, and Laissue JA
- Abstract
Clinical microbeam radiation therapy (MRT) will require a multislit collimator with adjustable uniform slit widths to enable reliable Monte Carlo-based treatment planning. Such a collimator has been designed, fabricated of >99% tungsten [W] by Tecomet/Viasys (Woburn, Massachusetts, USA) and installed at the 6 GeV electron-wiggler-generated hard x-ray ID17 beamline of the European Synchrotron Radiation Facility. Its pair of 125 parallel, 8 mm deep, 0.100 mm wide radiolucent slits, 0.400 mm on center, are perfused with nitrogen gas [N2] to dissipate heat during irradiation. Major improvements in uniformity of microbeam widths and good peak/valley dose ratios combined with a very high dose rate in targeted tissues have been achieved.
- Published
- 2005
7. New irradiation geometry for microbeam radiation therapy
- Author
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Brauer-Krisch, E, Requardt, H, Regnard, P, Corde, S, Siegbahn, E, Leduc, G, Brochard, T, Blattmann, H, Laissue, J, Bravin, A, Brauer-Krisch E, Requardt H, Regnard P, Corde S, Siegbahn E, LeDuc G, Brochard T, Blattmann H, Laissue J, Bravin A, Brauer-Krisch, E, Requardt, H, Regnard, P, Corde, S, Siegbahn, E, Leduc, G, Brochard, T, Blattmann, H, Laissue, J, Bravin, A, Brauer-Krisch E, Requardt H, Regnard P, Corde S, Siegbahn E, LeDuc G, Brochard T, Blattmann H, Laissue J, and Bravin A
- Abstract
Microbeam radiation therapy (MRT) has the potential to treat infantile brain tumours when other kinds of radiotherapy would be excessively toxic to the developing normal brain. MRT uses extraordinarily high doses of x-rays but provides unusual resistance to radioneurotoxicity, presumably from the migration of endothelial cells from 'valleys' into 'peaks', i.e., into directly irradiated microslices of tissues. We present a novel irradiation geometry which results in a tolerable valley dose for the normal tissue and a decreased peak-to-valley dose ratio (PVDR) in the tumour area by applying an innovative cross-firing technique. We propose an MRT technique to orthogonally crossfire two arrays of parallel, nonintersecting, mutually interspersed microbeams that produces tumouricidal doses with small PVDRs where the arrays meet and tolerable radiation doses to normal tissues between the microbeams proximal and distal to the tumour in the paths of the arrays.
- Published
- 2005
8. Determination of dosimetrical quantities used in microbeam radiation therapy (MRT) with Monte Carlo simulations
- Author
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Siegbahn E. A., Stepanek J., Brauer-Krisch E., Bravin A, Siegbahn, E, Stepanek, J, Brauer-Krisch, E, and Bravin, A
- Subjects
Models, Statistical ,Radiotherapy ,Synchrotron radiation ,Radiotherapy Planning, Computer-Assisted ,FIS/07 - FISICA APPLICATA (A BENI CULTURALI, AMBIENTALI, BIOLOGIA E MEDICINA) ,Reproducibility of Results ,Radiotherapy Dosage ,PENELOPE ,Models, Biological ,Sensitivity and Specificity ,Dosimetry ,Microbeam ,Body Burden ,Humans ,Computer Simulation ,Radiotherapy, Conformal ,Radiometry ,Monte Carlo Method ,Monte Carlo simulation ,Algorithms ,Relative Biological Effectiveness - Abstract
Microbeam radiation therapy (MRT) is being performed by using an array of narrow rectangular x-ray beams (typical beam sizes 25 microm X 1 cm), positioned close to each other (typically 200 microm separation), to irradiate a target tissue. The ratio of peak-to-valley doses (PVDR's) in the composite dose distribution has been found to be strongly correlated with the normal tissue tolerance and the therapeutic effect of MRT. In this work a Monte Carlo (MC) study of the depth- and lateral-dose profiles in water for single x-ray microbeams of different shapes and energies has been performed with the MC code PENELOPE. The contributions to the dose deposition from different interaction types have been determined at different distances from the center of the microbeam. The dependence of the peak dose, in a water phantom, on the microbeam field size used in the preclinical trials, has been demonstrated. Composite dose distributions for an array of microbeams were obtained using superposition algorithms and PVDR's were determined and compared with literature results obtained with other Monte Carlo codes. The dependence of the PVDR's on microbeam width, x-ray energy used, and on the separation between adjacent microbeams has been studied in detail.
- Published
- 2006
9. Spatial and temporal distribution of gamma H2AX fluorescence in human cell cultures following synchrotron-generated X-ray microbeams : lack of correlation between persistent gamma H2AX foci and apoptosis
- Author
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Anderson, Danielle L., Mirzayans, Razmik, Andrais, Bonnie, Siegbahn, E. Albert, Fallone, B. Gino, Warkentin, Brad, Anderson, Danielle L., Mirzayans, Razmik, Andrais, Bonnie, Siegbahn, E. Albert, Fallone, B. Gino, and Warkentin, Brad
- Abstract
Formation of gamma H2AX foci (a marker of DNA double-strand breaks), rates of foci clearance and apoptosis were investigated in cultured normal human fibroblasts and p53 wild-type malignant glioma cells after exposure to high-dose synchrotron-generated microbeams. Doses up to 283 Gy were delivered using beam geometries that included a microbeam array (50 mu m wide, 400 mu m spacing), single microbeams (60-570 mu m wide) and a broad beam (32 mm wide). The two cell types exhibited similar trends with respect to the initial formation and time-dependent clearance of gamma H2AX foci after irradiation. High levels of gamma H2AX foci persisted as late as 72 h post-irradiation in the majority of cells within cultures of both cell types. Levels of persistent foci after irradiation via the 570 mu m microbeam or broad beam were higher when compared with those observed after exposure to the 60 mu m microbeam or microbeam array. Despite persistence of gamma H2AX foci, these irradiation conditions triggered apoptosis in only a small proportion (<5%) of cells within cultures of both cell types. These results contribute to the understanding of the fundamental biological consequences of high-dose microbeam irradiations, and implicate the importance of non-apoptotic responses such as p53-mediated growth arrest (premature senescence)., AuthorCount:6
- Published
- 2014
- Full Text
- View/download PDF
10. Use of the GEANT4 toolkit at the CMRP: application to radiation protection, radiation oncology and medical imaging
- Author
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Cornelius, I., Wroe, A., Prokovich, D., Kwan, I., Painuly, N., Perera, L., Howie, A., Siegbahn, E., Reinhard, M., Lerch, M., Takas, G., Marchetto, F., Cirio, Roberto, Bourhaleb, F., and Rosenfeld, A.
- Published
- 2005
11. Spatial and temporal distribution of γH2AX fluorescence in human cell cultures following synchrotron-generated X-ray microbeams: lack of correlation between persistent γH2AX foci and apoptosis
- Author
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Anderson, Danielle L., primary, Mirzayans, Razmik, additional, Andrais, Bonnie, additional, Siegbahn, E. Albert, additional, Fallone, B. Gino, additional, and Warkentin, Brad, additional
- Published
- 2014
- Full Text
- View/download PDF
12. In-line phase-contrast stereoscopic X-ray imaging for radiological purposes: An initial experimental study
- Author
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Siegbahn, E, Coan, P, Zhou, S, Bravin, A, Brahme, A, Siegbahn EA, Coan P, Zhou S-A, Bravin A, Brahme A, Siegbahn, E, Coan, P, Zhou, S, Bravin, A, Brahme, A, Siegbahn EA, Coan P, Zhou S-A, Bravin A, and Brahme A
- Abstract
We report results from a pilot study in which the in-line propagation-based phase-contrast imaging technique is combined with the stereoscopic method. Two phantoms were imaged at several sampledetector distances using monochromatic, 30 keV, X-rays. High contrast- and spatial-resolution phase-contrast stereoscopic pairs of X-ray images were constructed using the anaglyph approach and a vivid stereoscopic effect was demonstrated. On the other hand, images of the same phantoms obtained with a shorter sample-to-detector distance, but otherwise the same experimental conditions (i.e. the same X-ray energy and absorbed radiation dose), corresponding to the conventional attenuation-based imaging mode, hardly revealed stereoscopic effects because of the lower image contrast produced. These results have confirmed our hypothesis that stereoscopic X-ray images of samples with objects composed of low-atomic-number elements are considerably improved if phase-contrast imaging is used. It is our belief that the high-resolution phase-contrast stereoscopic method will be a valuable new medical imaging tool for radiologists and that it will be of help to enhance the diagnostic capability in the examination of patients in future clinical practice, even though further efforts will be needed to optimize the system performance.
- Published
- 2011
13. GafChromic® film measurements for Microbeam Radiation Therapy (MRT)
- Author
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Dössel, O, Schlegel, WC, Bräuer-Krisch, E, Siegbahn, E, Bravin, A, Bräuer-Krisch E, Siegbahn EA, Bravin A, Dössel, O, Schlegel, WC, Bräuer-Krisch, E, Siegbahn, E, Bravin, A, Bräuer-Krisch E, Siegbahn EA, and Bravin A
- Abstract
Microbeam Radiation Therapy (MRT) is a preclinical synchrotron radiation based therapy technique in its preclinical stage with the potential to treat brain tumours in children when other kinds of radiotherapy would be excessively toxic to the developing normal brain. The most promising feature of MRT lies in its unusual resistance of MRT irradiated tissues to radioneurotoxicity even for peak doses of several hundreds of Gray. Results obtained with the spatially fractionated beams indicate a superior therapeutic effect compared to conventional radiotherapy. MRT, solely possible at SR sources with negligible beam divergence, is profiting from the dose volume effect and most probably from some differences in the tumour and the normal tissue responses, yet to be fully understood. This paper demonstrates that dosimetric measurements requiring a spatial resolution of a few microns is feasible with the use of GafChromic® films together with a high resolution scanner system. The data so obtained can be used to benchmark Monte Carlo calculations. © 2009 Springer-Verlag.
- Published
- 2009
14. Comparison of two methods for measuring γ-H2AX nuclear fluorescence as a marker of DNA damage in cultured human cells: applications for microbeam radiation therapy
- Author
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Anderson, D, primary, Andrais, B, additional, Mirzayans, R, additional, Siegbahn, E A, additional, Fallone, B G, additional, and Warkentin, B, additional
- Published
- 2013
- Full Text
- View/download PDF
15. Geant4 simulations for microbeam radiation therapy (MRT) dosimetry
- Author
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Spiga, J, Siegbahn, E, Brauer-Krisch, E, Randaccio, P, Bravin, A, Spiga J, Siegbahn EA, Brauer-Krisch E, Randaccio P, Bravin A, Spiga, J, Siegbahn, E, Brauer-Krisch, E, Randaccio, P, Bravin, A, Spiga J, Siegbahn EA, Brauer-Krisch E, Randaccio P, and Bravin A
- Abstract
Radiation therapy is one of the techniques most commonly used in the treatment of various types of tumors. The microbeam radiation therapy (MRT) is a very promising variant, which exploits the property that tissues can tolerate high doses of radiation in small volumes. The effectiveness of MRT is well represented by the peak-to-valley dose ratios (PVDRs), which are one of the crucial parameters associated with the outcome of the treatment. In this study, we investigate on the factors that influence PVDRs, such as different beam energies and geometries. MRT experiments typically employ rectangular (planar) microbeams of different sizes, but, for convenience of analysis, preliminary computations have been performed also using arrays of cylindrical microbeams. This work shows that the shape of the impinging irradiation field largely influences the dose distribution. It highlights that a bundle of larger microbeams, with a small separation, produces more scattered radiation and therefore lower PVDRs. The study of how dose distributions vary with different setups and irradiation parameters is an essential step in enhancing the comparability of experimental data and simulation results.
- Published
- 2007
16. Microdosimetry for Microbeam Radiation Therapy (MRT): theoretical calculations using the Monte Carlo toolkit
- Author
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Spiga, J, Siegbahn, E, Brauer-Krisch, E, Randaccio, P, Bravin, A, Spiga J, Siegbahn EA, Brauer-Krisch E, Randaccio P, Bravin A, Spiga, J, Siegbahn, E, Brauer-Krisch, E, Randaccio, P, Bravin, A, Spiga J, Siegbahn EA, Brauer-Krisch E, Randaccio P, and Bravin A
- Abstract
Radiation therapy is widely used in the treatment of very different types of cancer. Recent developments in this field are aiming at delivering high doses to the target volume while sparing the surrounding healthy tissues. The Microbeam Radiation Therapy (MRT) is a new kind of radiotherapy which could be used for treating infantile brain tumors, as other kinds of radiotherapy would be extremely dangerous to the normal brain development. MRT is carried out using an array of parallel microbeams of synchrotron-wiggler-generated X-rays. In this work, Monte Carlo simulations using the Geant4 toolkit are carried out to estimate the dose deposition on a 20-cm-diameter, 20-cm-long cylindrical PMMA phantom, mimicking an infantile head. A set of physics processes is implemented in Geant4 to extend the range of validity of electromagnetic interactions down to 250 eV. The dose distribution in MRT is computed to prepare the treatment planning of preclinical trials. Primary photon histories are simulated for the different experimental setups, scoring the dose in cylindrical shells. We used cylindrical monoenergetic microbeams of 50, 100 and 150 keV and one microbeam with energies sampled from the measured spectrum at the ESRF ID17 beamline. The depth- and lateral-dose profiles have been studied, and for a few typical cases, the simulation results have been compared with those obtained with other codes.
- Published
- 2006
17. New irradiation geometry for microbeam radiation therapy
- Author
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Brauer-Krish, E, Requardt, H, Regnard, P, corde, s, Siegbahn, E, LeDuc, G, Brochard, T, Blattmann, H, Laissue, J, Bravin, A, Brauer-Krish, E, Requardt, H, Regnard, P, corde, s, Siegbahn, E, LeDuc, G, Brochard, T, Blattmann, H, Laissue, J, and Bravin, A
- Abstract
Microbeam radiation therapy (MRT) has the potential to treat infantile brain tumours when other kinds of radiotherapy would be excessively toxic to the developing normal brain. MRT uses extraordinarily high doses of x-rays but provides unusual resistance to radioneurotoxicity, presumably from the migration of endothelial cells from 'valleys' into 'peaks', i.e., into directly irradiated microslices of tissues. We present a novel irradiation geometry which results in a tolerable valley dose for the normal tissue and a decreased peak-to-valley dose ratio (PVDR) in the tumour area by applying an innovative cross-firing technique. We propose anMRT technique to orthogonally crossfire two arrays of parallel, nonintersecting, mutually interspersed microbeams that produces tumouricidal doses with small PVDRs where the arrays meet and tolerable radiation doses to normal tissues between the microbeams proximal and distal to the tumour in the paths of the arrays.
- Published
- 2005
18. Exploiting geometrical irradiation possibilities in MRT application
- Author
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Brauer-Krish, E, Requardt, H, Regnard, P, corde, s, Siegbahn, E A, LeDuc, G, Blattmann, H, Laissue, J, Bravin, A, Brauer-Krish, E, Requardt, H, Regnard, P, corde, s, Siegbahn, E A, LeDuc, G, Blattmann, H, Laissue, J, and Bravin, A
- Abstract
Microbeam Radiation Therapy (MRT) has the potential to treat infantile brain tumors when other kinds of radiotherapy would be excessively toxic to the developing normal brain. MRT uses extraordinarily high doses of X-rays but provides unusual resistance to radioneurotoxicity, presumably from the rapid migration of regenerative endothelial cells from dose ''valleys'' into dose ''peaks'', i.e., into directly irradiated micro-slices of tissues. We will present a novel irradiation geometry which results in a tolerable valley dose for the normal tissue and a decreased peak-to-valley dose ratio (PVDR) in the tumor area by applying an innovative cross-firing technique. We propose an MRT technique to orthogonally crossfire two arrays of parallel, nonintersecting, mutually interspersed microbeams that produces tumoricidal doses with small PVDRs where the arrays meet and tolerable radiation doses to normal tissues between the microbeams proximal and distal to the tumor in the paths of the arrays.
- Published
- 2005
19. Edge-on face-to-face MOSFET for synchrotron microbeam dosimetry: MC modeling
- Author
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Rosenfeld, Anatoly B., Siegbahn, E. A., Brauer-Krisch, E., Holmes-Siedle, A., Lerch, M. L., Bravin, A., Cornelius, I., Takacs, G. J., Painuly, N., Nettleback, H., Kron, T., Rosenfeld, Anatoly B., Siegbahn, E. A., Brauer-Krisch, E., Holmes-Siedle, A., Lerch, M. L., Bravin, A., Cornelius, I., Takacs, G. J., Painuly, N., Nettleback, H., and Kron, T.
- Abstract
The dosimetry of X-ray microbeams using MOSFETs results in an asymmetrical beam profile due to a lack of lateral charged particle equilibrium. Monte Carlo simulations were carried out using PENELOPE and GEANT4 codes to study this effect and a MOSFET on a micropositioner was scanned in the microbeam. Based on the simulations a new method of microbeam dosimetry is proposed. The proposed edge-on face-to-face (EOFF) MOSFET detector, a die arrangement proposed here for the first time, should alleviate the asymmetry. Further improvement is possible by thinning the silicon body of the MOSFET.
- Published
- 2005
20. Dosimetric studies of microbeam radiation therapy (MRT) with Monte Carlo simulations
- Author
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Siegbahn, E, Brauer-Krisch, E, Stepanek, J, Blattmann, H, Laissue, J, Bravin, A, Siegbahn EA, Brauer-Krisch E, Stepanek J, Blattmann H, Laissue JA, Bravin A, Siegbahn, E, Brauer-Krisch, E, Stepanek, J, Blattmann, H, Laissue, J, Bravin, A, Siegbahn EA, Brauer-Krisch E, Stepanek J, Blattmann H, Laissue JA, and Bravin A
- Abstract
Microbeam Radiation Therapy (MRT) is a technique utilizing the fact that normal tissue can sustain high doses of radiation in small volumes without significant damage. The synchrotron generated X-ray beam, used for the treatment, is collimated and delivered in an array of narrow micrometer-sized planar rectangular fields. In this work, the Monte Carlo code PENELOPE was used for simulating the dose deposition. This code provides an accurate treatment of low-energy electron transport which is important when performing dose calculations in micron-sized ranges. A comparison with earlier results was done for a few typical cases. The buildup of dose near the phantom surface and the lateral variation of dose around the microbeams were also studied. It was confirmed that the dose in the valley region mainly depends on Compton scattered electrons and that the electron scattering model used in the MC code is a key point. Finally a comparison between MC simulations and experimental microdosimetry, with radiochromic films and MOSFET detectors, gave important indications on possible refinements of the MC simulations for future investigations.
- Published
- 2005
21. Edge-on Face-to-Face MOSFET for synchrotron microbeam dosimetry: MC modeling
- Author
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Rosenfeld, A, Siegbahn, E, Brauer-Krish, E, Holmes-Siedle, A, Lerch, M, Bravin, A, Cornelius, I, Takacs, G, Painuly, N, Nettelback, H, Kron, T, Rosenfeld AB, Siegbahn EA, Brauer-Krish E, Holmes-Siedle A, Lerch MLF, Bravin A, Cornelius IM, Takacs GJ, Painuly N, Nettelback H, Kron T, Rosenfeld, A, Siegbahn, E, Brauer-Krish, E, Holmes-Siedle, A, Lerch, M, Bravin, A, Cornelius, I, Takacs, G, Painuly, N, Nettelback, H, Kron, T, Rosenfeld AB, Siegbahn EA, Brauer-Krish E, Holmes-Siedle A, Lerch MLF, Bravin A, Cornelius IM, Takacs GJ, Painuly N, Nettelback H, and Kron T
- Abstract
The dosimetry of X-ray microbeams using MOSFETs results in an asymmetrical beam profile due to a lack of lateral charged particle equilibrium. Monte Carlo simulations were carried out using PENELOPE and GEANT4 codes to study this effect and a MOSFET on a micropositioner was scanned in the microbeam. Based on the simulations a new method of microbeam dosimetry is proposed. The proposed edge-on face-to-face (EOFF) MOSFET detector, a die arrangement proposed here for the first time, should alleviate the asymmetry. Further improvement is possible by thinning the silicon body of the MOSFET.
- Published
- 2005
22. Evaluation of dose-volume metrics for microbeam radiation therapy dose distributions in head phantoms of various sizes using Monte Carlo simulations
- Author
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Anderson, Danielle, primary, Siegbahn, E Albert, additional, Fallone, B Gino, additional, Serduc, Raphael, additional, and Warkentin, Brad, additional
- Published
- 2012
- Full Text
- View/download PDF
23. Exploiting geometrical irradiation possibilities in MRT application
- Author
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Brauer-Krisch, E, Requardt, H, Regnard, P, Corde, S, Siegbahn, E, Leduc, G, Blattmann, H, Laissue, J, Bravin, A, Brauer-Krisch E, Requardt H, Regnard P, Corde S, Siegbahn EA, LeDuc G, Blattmann H, Laissue J, Bravin A, Brauer-Krisch, E, Requardt, H, Regnard, P, Corde, S, Siegbahn, E, Leduc, G, Blattmann, H, Laissue, J, Bravin, A, Brauer-Krisch E, Requardt H, Regnard P, Corde S, Siegbahn EA, LeDuc G, Blattmann H, Laissue J, and Bravin A
- Abstract
Microbeam Radiation Therapy (MRT) has the potential to treat infantile brain tumors when other kinds of radiotherapy would be excessively toxic to the developing normal brain. MRT uses extraordinarily high doses of X-rays but provides unusual resistance to radioneurotoxicity, presumably from the rapid migration of regenerative endothelial cells from dose "valleys" into dose "peaks", i.e., into directly irradiated micro-slices of tissues. We will present a novel irradiation geometry which results in a tolerable valley dose for the normal tissue and a decreased peak-to-valley dose ratio (PVDR) in the tumor area by applying an innovative cross-firing technique. We propose an MRT technique to orthogonally crossfire two arrays of parallel, nonintersecting, mutually interspersed microbeams that produces tumoricidal doses with small PVDRs where the arrays meet and tolerable radiation doses to normal tissues between the microbeams proximal and distal to the tumor in the paths of the arrays.
- Published
- 2004
24. SU-E-T-313: Ionization Chamber Measurements in a Small, Non-Uniform Beam - Applications for Synchrotron Beam Dosimetry
- Author
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Anderson, D, primary, Warkentin, B, additional, Siegbahn, E A, additional, and Fallone, B G, additional
- Published
- 2011
- Full Text
- View/download PDF
25. SU‐E‐T‐314: Challenges in Radiochromic Film Dosimetry Applied to Microbeam Radiation Therapy (MRT)
- Author
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Anderson, D, primary, Warkentin, B, additional, Siegbahn, E A, additional, and Fallone, B G, additional
- Published
- 2011
- Full Text
- View/download PDF
26. Potential High Resolution Dosimeters For MRT
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Bräuer-Krisch, E., primary, Rosenfeld, A., additional, Lerch, M., additional, Petasecca, M., additional, Akselrod, M., additional, Sykora, J., additional, Bartz, J., additional, Ptaszkiewicz, M., additional, Olko, P., additional, Berg, A., additional, Wieland, M., additional, Doran, S., additional, Brochard, T., additional, Kamlowski, A., additional, Cellere, G., additional, Paccagnella, A., additional, Siegbahn, E. A., additional, Prezado, Y., additional, Martinez-Rovira, I., additional, Bravin, A., additional, Dusseau, L., additional, Berkvens, P., additional, and Siu, Karen K. W., additional
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- 2010
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27. MOSFET dosimetry with high spatial resolution in intense synchrotron-generated x-ray microbeams
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Siegbahn, E. A., primary, Bräuer-Krisch, E., additional, Bravin, A., additional, Nettelbeck, H., additional, Lerch, M. L. F., additional, and Rosenfeld, A. B., additional
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- 2009
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28. Accurate Effective Core Potential for Germanium. Application to the Singlet-Triplet Splitting in GeH2
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Pettersson, Lars G. M and Siegbahn, E. M
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Solid-State Physics - Abstract
An accurate effective core potential (ECP), including frozen 3s, 3p orbitals and a single-zeta contracted 3d orbital, has been developed for germanium. The ECP with associated valence basis set reproduces the corresponding all-electron results for the atomic excitations and the geometry and excitation energies of GeH2. At the SCF, CAS SCF and CI levels the maximum difference from the all-electron results is 0.5 kcal/mol in the (sup 1)A(sub 1) - (sup 3)B(sub 1) excitation energy. Finally, the ECP description is used with an extended valence basis set and large-scale CAS SCF and multi-reference CI wavefunctions to compute the singlet-triplet separation; the final CI result including the Davidson correction is 22.5 kcal/mol.
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- 1986
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29. Monte Carlo code comparison of dose delivery prediction for microbeam radiation therapy
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Felici, M De, primary, Siegbahn, E A, additional, Spiga, J, additional, Hanson, A L, additional, Felici, R, additional, Ferrero, C, additional, Tartari, A, additional, Gambaccini, M, additional, Keyriläinen, J, additional, Bräuer-Krisch, E, additional, Randaccio, P, additional, and Bravin, A, additional
- Published
- 2008
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- View/download PDF
30. The GEANT4 toolkit for microdosimetry calculations: Application to microbeam radiation therapy (MRT)
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Spiga, J., primary, Siegbahn, E. A., additional, Bräuer-Krisch, E., additional, Randaccio, P., additional, and Bravin, A., additional
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- 2007
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- View/download PDF
31. Geant4 simulations for microbeam radiation therapy (MRT) dosimetry
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Spiga, J., primary, Siegbahn, E. A., additional, Brauer-Krisch, E., additional, Randaccio, P., additional, and Bravin, A., additional
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- 2007
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- View/download PDF
32. Erratum: “Characterization of a tungsten/gas multislit collimator (TMSC) for microbeam radiation therapy at the European Synchrotron Radiation Facility”[Rev. Sci. Instrum. 76, 064303 (2005)]
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Bräuer-Krisch, E., primary, Bravin, A., additional, Zhang, L., additional, Siegbahn, E., additional, Stepanek, J., additional, Blattmann, H., additional, Slatkin, D. N., additional, Gebbers, J.-O., additional, Jasmin, M., additional, and Laissue, J. A., additional
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- 2006
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- View/download PDF
33. Microdosimetry for Microbeam Radiation Therapy (MRT): theoretical calculations using the Monte Carlo toolkit
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Spiga, J., primary, Siegbahn, E. A., additional, Brauer-Krisch, E., additional, Randaccio, P., additional, and Bravin, A., additional
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- 2006
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- View/download PDF
34. New irradiation geometry for microbeam radiation therapy
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Bräuer-Krisch, E, primary, Requardt, H, additional, Régnard, P, additional, Corde, S, additional, Siegbahn, E, additional, LeDuc, G, additional, Brochard, T, additional, Blattmann, H, additional, Laissue, J, additional, and Bravin, A, additional
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- 2005
- Full Text
- View/download PDF
35. Characterization of a tungsten/gas multislit collimator for microbeam radiation therapy at the European Synchrotron Radiation Facility
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Bräuer-Krisch, E., primary, Bravin, A., additional, Zhang, L., additional, Siegbahn, E., additional, Stepanek, J., additional, Blattmann, H., additional, Slatkin, D. N., additional, Gebbers, J.-O., additional, Jasmin, M., additional, and Laissue, J. A., additional
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- 2005
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- View/download PDF
36. Calculations of electron fluence correction factors using the Monte Carlo code PENELOPE
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Siegbahn, E A, primary, Nilsson, B, additional, Fern ndez-Varea, J M, additional, and Andreo, P, additional
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- 2003
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37. Potential High Resolution Dosimeters For MRT
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Siegbahn, E [Department of Medical Physics, Karolinska Universitetssjukhuset, 17176 Stockholm (Sweden)]
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- 2010
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- View/download PDF
38. Edge-on face-to-face MOSFET for synchrotron microbeam dosimetry: MC modeling
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Tomas Kron, E.A. Siegbahn, Michael L. F Lerch, Alberto Bravin, George J. Takacs, Iwan Cornelius, H. Nettelback, Anatoly B. Rosenfeld, E. Brauer-Krish, N. Painuly, A. Holmes-Siedle, Rosenfeld, A, Siegbahn, E, Brauer-Krish, E, Holmes-Siedle, A, Lerch, M, Bravin, A, Cornelius, I, Takacs, G, Painuly, N, Nettelback, H, and Kron, T
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Nuclear and High Energy Physics ,medicine.medical_specialty ,Monte Carlo method ,FIS/07 - FISICA APPLICATA (A BENI CULTURALI, AMBIENTALI, BIOLOGIA E MEDICINA) ,Dose enhancement effects (DEEs) ,Die (integrated circuit) ,Synchrotron ,law.invention ,MOSFET ,Optics ,law ,Dosimetry ,Microbeam ,medicine ,Medical physics ,Electrical and Electronic Engineering ,Physics ,Radiotherapy ,business.industry ,Detector ,Nuclear Energy and Engineering ,Charged-particle equilibrium (CPE) ,business ,Beam (structure) - Abstract
The dosimetry of X-ray microbeams using MOSFETs results in an asymmetrical beam profile due to a lack of lateral charged particle equilibrium. Monte Carlo simulations were carried out using PENELOPE and GEANT4 codes to study this effect and a MOSFET on a micropositioner was scanned in the microbeam. Based on the simulations a new method of microbeam dosimetry is proposed. The proposed edge-on face-to-face (EOFF) MOSFET detector, a die arrangement proposed here for the first time, should alleviate the asymmetry. Further improvement is possible by thinning the silicon body of the MOSFET.
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- 2005
39. New irradiation geometry for microbeam radiation therapy
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Elke Bräuer-Krisch, Herwig Requardt, Stéphanie Corde, Thierry Brochard, E.A. Siegbahn, Hans Blattmann, G. LeDuc, Jean A. Laissue, Pierrick Regnard, A. Bravin, Brauer-Krisch, E, Requardt, H, Regnard, P, Corde, S, Siegbahn, E, Leduc, G, Brochard, T, Blattmann, H, Laissue, J, and Bravin, A
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Materials science ,medicine.medical_treatment ,Normal tissue ,FIS/07 - FISICA APPLICATA (A BENI CULTURALI, AMBIENTALI, BIOLOGIA E MEDICINA) ,irradiation geometry, x-rays ,Geometry ,Radiation ,Radiation Dosage ,Microbeam radiation therapy ,High doses ,medicine ,Animals ,Radiology, Nuclear Medicine and imaging ,Irradiation ,Radiation Injuries ,Radiological and Ultrasound Technology ,Brain Neoplasms ,business.industry ,Radiotherapy Planning, Computer-Assisted ,Brain ,Rats ,Radiation therapy ,Treatment Outcome ,Feasibility Studies ,Radiotherapy, Conformal ,Nuclear medicine ,business - Abstract
Microbeam radiation therapy (MRT) has the potential to treat infantile brain tumours when other kinds of radiotherapy would be excessively toxic to the developing normal brain. MRT uses extraordinarily high doses of x-rays but provides unusual resistance to radioneurotoxicity, presumably from the migration of endothelial cells from 'valleys' into 'peaks', i.e., into directly irradiated microslices of tissues. We present a novel irradiation geometry which results in a tolerable valley dose for the normal tissue and a decreased peak-to-valley dose ratio (PVDR) in the tumour area by applying an innovative cross-firing technique. We propose an MRT technique to orthogonally crossfire two arrays of parallel, nonintersecting, mutually interspersed microbeams that produces tumouricidal doses with small PVDRs where the arrays meet and tolerable radiation doses to normal tissues between the microbeams proximal and distal to the tumour in the paths of the arrays.
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- 2005
40. Exploiting geometrical irradiation possibilities in MRT application
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Pierrick Regnard, Elke Bräuer-Krisch, Herwig Requardt, Hans Blattmann, Stéphanie Corde, Alberto Bravin, E.A. Siegbahn, Jean A. Laissue, G. LeDuc, Brauer-Krisch, E, Requardt, H, Regnard, P, Corde, S, Siegbahn, E, Leduc, G, Blattmann, H, Laissue, J, and Bravin, A
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Cross-firing ,Physics ,Nuclear and High Energy Physics ,Synchrotron radiation ,business.industry ,medicine.medical_treatment ,Normal tissue ,FIS/07 - FISICA APPLICATA (A BENI CULTURALI, AMBIENTALI, BIOLOGIA E MEDICINA) ,Radiation ,Radiation therapy ,Optics ,Microbeam radiation therapy ,medicine ,High doses ,Irradiation ,business ,Instrumentation ,Biomedical engineering - Abstract
Microbeam Radiation Therapy (MRT) has the potential to treat infantile brain tumors when other kinds of radiotherapy would be excessively toxic to the developing normal brain. MRT uses extraordinarily high doses of X-rays but provides unusual resistance to radioneurotoxicity, presumably from the rapid migration of regenerative endothelial cells from dose “valleys” into dose “peaks”, i.e., into directly irradiated micro-slices of tissues. We will present a novel irradiation geometry which results in a tolerable valley dose for the normal tissue and a decreased peak-to-valley dose ratio (PVDR) in the tumor area by applying an innovative cross-firing technique. We propose an MRT technique to orthogonally crossfire two arrays of parallel, nonintersecting, mutually interspersed microbeams that produces tumoricidal doses with small PVDRs where the arrays meet and tolerable radiation doses to normal tissues between the microbeams proximal and distal to the tumor in the paths of the arrays.
- Published
- 2005
41. In-line phase-contrast stereoscopic X-ray imaging for radiological purposes: An initial experimental study
- Author
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Anders Brahme, E.A. Siegbahn, Shu-Ang Zhou, P. Coan, Alberto Bravin, Siegbahn, E, Coan, P, Zhou, S, Bravin, A, and Brahme, A
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Physics ,Nuclear and High Energy Physics ,business.industry ,Phase contrast microscopy ,Attenuation ,X-ray imaging ,X-ray ,FIS/07 - FISICA APPLICATA (A BENI CULTURALI, AMBIENTALI, BIOLOGIA E MEDICINA) ,Stereoscopy ,law.invention ,Optics ,law ,Phase contrast ,Line (geometry) ,Medical imaging ,Monochromatic color ,business ,Instrumentation ,Anaglyph 3D - Abstract
We report results from a pilot study in which the in-line propagation-based phase-contrast imaging technique is combined with the stereoscopic method. Two phantoms were imaged at several sample–detector distances using monochromatic, 30 keV, X-rays. High contrast- and spatial-resolution phase-contrast stereoscopic pairs of X-ray images were constructed using the anaglyph approach and a vivid stereoscopic effect was demonstrated. On the other hand, images of the same phantoms obtained with a shorter sample-to-detector distance, but otherwise the same experimental conditions (i.e. the same X-ray energy and absorbed radiation dose), corresponding to the conventional attenuation-based imaging mode, hardly revealed stereoscopic effects because of the lower image contrast produced. These results have confirmed our hypothesis that stereoscopic X-ray images of samples with objects composed of low-atomic-number elements are considerably improved if phase-contrast imaging is used. It is our belief that the high-resolution phase-contrast stereoscopic method will be a valuable new medical imaging tool for radiologists and that it will be of help to enhance the diagnostic capability in the examination of patients in future clinical practice, even though further efforts will be needed to optimize the system performance.
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- 2011
42. Effects of pulsed, spatially fractionated, microscopic synchrotron X-ray beams on normal and tumoral brain tissue
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Yolanda Prezado, Hans Blattmann, G. Le Duc, E.A. Siegbahn, Elke Bräuer-Krisch, Raphaël Serduc, Jean A. Laissue, Alberto Bravin, European Synchrotron Radiation Facility (ESRF), Department of Medical Physics, Karolinska Universitetssjukhuset, Oncology - Pathology - Anatomy, Institute of Pathology-University of Bern, We thank the European Synchrotron Radiation Facility (ESRF) for supporting the MRT project., Braeuer-Krisch, E, Serduc, R, Siegbahn, E, Le Duc, G, Prezado, Y, Bravin, A, Blattmann, H, Laissue, J, and Serduc, Raphael
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Radiobiology ,MESH: Radiotherapy ,Health, Toxicology and Mutagenesis ,medicine.medical_treatment ,Grid therapy ,Synchrotron radiation ,030218 nuclear medicine & medical imaging ,law.invention ,0302 clinical medicine ,law ,Neoplasms ,MESH: Dose Fractionation ,MESH: Animals ,MESH: Neoplasms ,Brain Neoplasms ,Brain ,Synchrotron ,030220 oncology & carcinogenesis ,MESH: Brain Neoplasms ,MESH: Synchrotrons ,MESH: History, 20th Century ,[SDV.IB]Life Sciences [q-bio]/Bioengineering ,Microbeam radiation therapy ,MESH: History, 21st Century ,MRT ,FIS/07 - FISICA APPLICATA (A BENI CULTURALI, AMBIENTALI, BIOLOGIA E MEDICINA) ,Biology ,Radiosurgery ,History, 21st Century ,Collimated light ,03 medical and health sciences ,MESH: X-Rays ,MESH: Brain ,Genetics ,medicine ,Dosimetry ,Animals ,Humans ,Irradiation ,Radiometry ,Technology, Radiologic ,[SDV.IB] Life Sciences [q-bio]/Bioengineering ,MESH: Humans ,Radiotherapy ,MESH: Technology, Radiologic ,X-Rays ,MESH: Radiometry ,MESH: Blood Vessels ,History, 20th Century ,equipment and supplies ,Radiation therapy ,Blood Vessels ,Dose Fractionation, Radiation ,Synchrotrons ,Biomedical engineering - Abstract
International audience; Microbeam radiation therapy (MRT) uses highly collimated, quasi-parallel arrays of X-ray microbeams of 50-600keV, produced by third generation synchrotron sources, such as the European Synchrotron Radiation Facility (ESRF), in France. The main advantages of highly brilliant synchrotron sources are an extremely high dose rate and very small beam divergence. High dose rates are necessary to deliver therapeutic doses in microscopic volumes, to avoid spreading of the microbeams by cardiosynchronous movement of the tissues. The minimal beam divergence results in the advantage of steeper dose gradients delivered to a tumor target, thus achieving a higher dose deposition in the target volume in fractions of seconds, with a sharper penumbra than that produced in conventional radiotherapy. MRT research over the past 20 years has yielded many results from preclinical trials based on different animal models, including mice, rats, piglets and rabbits. Typically, MRT uses arrays of narrow ( approximately 25-100 microm wide) microplanar beams separated by wider (100-400 microm centre-to-centre) microplanar spaces. The height of these microbeams typically varies from 1 to 100 mm, depending on the target and the desired preselected field size to be irradiated. Peak entrance doses of several hundreds of Gy are surprisingly well tolerated by normal tissues, up to approximately 2 yr after irradiation, and at the same time show a preferential damage of malignant tumor tissues; these effects of MRT have now been extensively studied over nearly two decades. More recently, some biological in vivo effects of synchrotron X-ray beams in the millimeter range (0.68-0.95 mm, centre-to-centre distances 1.2-4 mm), which may differ to some extent from those of microscopic beams, have been followed up to approximately 7 months after irradiation. Comparisons between broad-beam irradiation and MRT indicate a higher tumor control for the same sparing of normal tissue in the latter, even if a substantial fraction of tumor cells are not receiving a radiotoxic level of radiation. The hypothesis of a selective radiovulnerability of the tumor vasculature versus normal blood vessels by MRT, and of the cellular and molecular mechanisms involved remains under investigation. The paper highlights the history of MRT including salient biological findings after microbeam irradiation with emphasis on the vascular components and the tolerance of the central nervous system. Details on experimental and theoretical dosimetry of microbeams, core issues and possible therapeutic applications of MRT are presented.
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- 2010
43. Potential High Resolution Dosimeters For MRT
- Author
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E. Bräuer-Krisch, A. Rosenfeld, M. Lerch, M. Petasecca, M. Akselrod, J. Sykora, J. Bartz, M. Ptaszkiewicz, P. Olko, A. Berg, M. Wieland, S. Doran, T. Brochard, A. Kamlowski, G. Cellere, A. Paccagnella, E. A. Siegbahn, Y. Prezado, I. Martinez-Rovira, A. Bravin, L. Dusseau, P. Berkvens, Karen K. W. Siu, European Synchrotron Radiation Facility (ESRF), Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie (MBI), Forschungsverbund Berlin e.V. (FVB) (FVB)-Leibniz Gemeinschaft, Czech Technical University in Prague (CTU), Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, 31-342 Krakow, Poland, Centre Interdisciplinaire de Nanoscience de Marseille (CINaM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), CERN [Genève], Imagerie et Modélisation en Neurobiologie et Cancérologie (IMNC (UMR_8165)), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institut d’Electronique et des Systèmes (IES), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Radiations et composants (RADIAC), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Forschungsverbund Berlin e.V.-Leibniz Gemeinschaft, K.K.W. Siu, Bräuer-Krisch, E, Rosenfeld, A, Lerch, M, Petasecca, M, Akselrod, M, Sykora, J, Bartz, J, Ptaszkiewicz, M, Olko, P, Berg, A, Wieland, M, Doran, S, Brochard, T, Kamlowski, A, Cellere, G, Paccagnella, A, Siegbahn, E, Prezado, Y, Martinez-Rovira, I, Bravin, A, Dusseau, L, and Berkvens, P
- Subjects
Gafchromic® film ,Radiation Therapy ,FIS/07 - FISICA APPLICATA (A BENI CULTURALI, AMBIENTALI, BIOLOGIA E MEDICINA) ,Synchrotron radiation ,Dose profile ,Microdosimetry ,Particle detector ,Collimated light ,law.invention ,Synchrotron Radiation ,Nuclear magnetic resonance ,Optics ,law ,Dosimetry ,ComputingMilieux_MISCELLANEOUS ,Physics ,Dosimeter ,mrt ,business.industry ,Microbeam ,Flash memory ,Synchrotron ,[SPI.TRON]Engineering Sciences [physics]/Electronics ,business - Abstract
Microbeam Radiation Therapy (MRT) uses highly collimated, quasi-parallel arrays of X-ray microbeams of 50-600 keV, produced by 2nd and 3rd generation synchrotron sources, such as the National Synchrotron Light Source (NSLS) in the U.S., and the European Synchrotron Radiation Facility (ESRF) in France, respectively. High dose rates are necessary to deliver therapeutic doses in microscopic volumes, to avoid spreading of the microbeams by cardiosynchronous movement of the tissues. A small beam divergence and a filtered white beam spectrum in the energy range between 30 and 250 keV results in the advantage of steep dose gradients with a sharper penumbra than that produced in conventional radiotherapy. MRT research over the past 20 years has allowed a vast number of results from preclinical trials on different animal models, including mice, rats, piglets and rabbits. Microbeams in the range between 10 and 100 micron width show an unprecedented sparing of normal radiosensitive tissues as well as preferential damage to malignant tumor tissues. Typically, MRT uses arrays of narrow ({approx}25-100 micron-wide) microplanar beams separated by wider (100-400 microns centre-to-centre, c-t-c) microplanar spaces. We note that thicker microbeams of 0.1-0.68 mm used by investigators at the NSLS are still called microbeams, although some invesigators inmore » the community prefer to call them minibeams. This report, however, limits it discussion to 25-100 {mu}m microbeams. Peak entrance doses of several hundreds of Gy are surprisingly well tolerated by normal tissues. High resolution dosimetry has been developed over the last two decades, but typical dose ranges are adapted to dose delivery in conventional Radiation Therapy (RT). Spatial resolution in the sub-millimetric range has been achieved, which is currently required for quality assurance measurements in Gamma-knife RT. Most typical commercially available detectors are not suitable for MRT applications at a dose rate of 16000 Gy/s, micron resolution and a dose range over several orders of magnitude. This paper will give an overview of all dosimeters tested in the past at the ESRF with their advantages and drawbacks. These detectors comprise: Ionization chambers, Alanine Dosimeters, MOSFET detectors, Gafchromic registered films, Radiochromic polymers, TLDs, Polymer gels, Fluorescent Nuclear Track Detectors (Al{sub 2}O{sub 3}:C, Mg single crystal detectors), OSL detectors and Floating Gate-based dosimetry system. The aim of such a comparison shall help with a decision on which of these approaches is most suitable for high resolution dose measurements in MRT. The principle of these detectors will be presented including a comparison for some dosimeters exposed with the same irradiation geometry, namely a 1x1 cm{sup 5} field size with microbeam exposures at the surface, 0.1 cm and 1 cm in depth of a PMMA phantom. For these test exposures, the most relevant irradiation parameters for future clinical trials have been chosen: 50 micron FWHM and 400 micron c-t-c distance. The experimental data are compared with Monte Carlo calculations.« less
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- 2010
44. GafChromic® film measurements for Microbeam Radiation Therapy (MRT)
- Author
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Elke Bräuer-Krisch, E.A. Siegbahn, Alberto Bravin, Dössel, O, Schlegel, WC, Bräuer-Krisch, E, Siegbahn, E, and Bravin, A
- Subjects
Scanner ,Materials science ,Synchrotron radiation ,business.industry ,medicine.medical_treatment ,Monte Carlo method ,FIS/07 - FISICA APPLICATA (A BENI CULTURALI, AMBIENTALI, BIOLOGIA E MEDICINA) ,GafChromic® film ,Radiation therapy ,Dosimetry ,medicine ,Irradiation ,Nuclear medicine ,business ,Microbeam radiation therapy ,Image resolution ,Beam divergence ,Biomedical engineering - Abstract
Microbeam Radiation Therapy (MRT) is a preclinical synchrotron radiation based therapy technique in its preclinical stage with the potential to treat brain tumours in children when other kinds of radiotherapy would be excessively toxic to the developing normal brain. The most promising feature of MRT lies in its unusual resistance of MRT irradiated tissues to radioneurotoxicity even for peak doses of several hundreds of Gray. Results obtained with the spatially fractionated beams indicate a superior therapeutic effect compared to conventional radiotherapy. MRT, solely possible at SR sources with negligible beam divergence, is profiting from the dose volume effect and most probably from some differences in the tumour and the normal tissue responses, yet to be fully understood. This paper demonstrates that dosimetric measurements requiring a spatial resolution of a few microns is feasible with the use of GafChromic® films together with a high resolution scanner system. The data so obtained can be used to benchmark Monte Carlo calculations. © 2009 Springer-Verlag.
- Published
- 2009
45. Geant4 simulations for microbeam radiation therapy (MRT) dosimetry
- Author
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Jenny Spiga, Alberto Bravin, Paolo Randaccio, Elke Bräuer-Krisch, E.A. Siegbahn, Spiga, J, Siegbahn, E, Brauer-Krisch, E, Randaccio, P, and Bravin, A
- Subjects
Materials science ,business.industry ,medicine.medical_treatment ,microbeam radiation therapy, dosimetry, X-rays ,FIS/07 - FISICA APPLICATA (A BENI CULTURALI, AMBIENTALI, BIOLOGIA E MEDICINA) ,Dose distribution ,Radiation ,equipment and supplies ,Radiation therapy ,Planar ,Optics ,Microbeam radiation therapy ,medicine ,Dosimetry ,Irradiation ,Nuclear medicine ,business ,Beam (structure) - Abstract
Radiation therapy is one of the techniques most commonly used in the treatment of various types of tumors. The microbeam radiation therapy (MRT) is a very promising variant, which exploits the property that tissues can tolerate high doses of radiation in small volumes. The effectiveness of MRT is well represented by the peak-to-valley dose ratios (PVDRs), which are one of the crucial parameters associated with the outcome of the treatment. In this study, we investigate on the factors that influence PVDRs, such as different beam energies and geometries. MRT experiments typically employ rectangular (planar) microbeams of different sizes, but, for convenience of analysis, preliminary computations have been performed also using arrays of cylindrical microbeams. This work shows that the shape of the impinging irradiation field largely influences the dose distribution. It highlights that a bundle of larger microbeams, with a small separation, produces more scattered radiation and therefore lower PVDRs. The study of how dose distributions vary with different setups and irradiation parameters is an essential step in enhancing the comparability of experimental data and simulation results.
- Published
- 2007
46. Microdosimetry for Microbeam Radiation Therapy (MRT): theoretical calculations using the Monte Carlo toolkit
- Author
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Elke Bräuer-Krisch, Paolo Randaccio, Alberto Bravin, E.A. Siegbahn, J. Spiga, Spiga, J, Siegbahn, E, Brauer-Krisch, E, Randaccio, P, and Bravin, A
- Subjects
Physics ,business.industry ,medicine.medical_treatment ,Monte Carlo method ,FIS/07 - FISICA APPLICATA (A BENI CULTURALI, AMBIENTALI, BIOLOGIA E MEDICINA) ,Microdosimetry, Monte Carlo, Geant ,Microbeam ,equipment and supplies ,Imaging phantom ,Radiation therapy ,Optics ,Beamline ,Microbeam radiation therapy ,medicine ,Dosimetry ,Radiation treatment planning ,business ,Nuclear medicine - Abstract
Radiation therapy is widely used in the treatment of very different types of cancer. Recent developments in this field are aiming at delivering high doses to the target volume while sparing the surrounding healthy tissues. The Microbeam Radiation Therapy (MRT) is a new kind of radiotherapy which could be used for treating infantile brain tumors, as other kinds of radiotherapy would be extremely dangerous to the normal brain development. MRT is carried out using an array of parallel microbeams of synchrotron-wiggler-generated X-rays. In this work, Monte Carlo simulations using the Geant4 toolkit are carried out to estimate the dose deposition on a 20-cm-diameter, 20-cm-long cylindrical PMMA phantom, mimicking an infantile head. A set of physics processes is implemented in Geant4 to extend the range of validity of electromagnetic interactions down to 250 eV. The dose distribution in MRT is computed to prepare the treatment planning of preclinical trials. Primary photon histories are simulated for the different experimental setups, scoring the dose in cylindrical shells. We used cylindrical monoenergetic microbeams of 50, 100 and 150 keV and one microbeam with energies sampled from the measured spectrum at the ESRF ID17 beamline. The depth- and lateral-dose profiles have been studied, and for a few typical cases, the simulation results have been compared with those obtained with other codes.
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- 2006
47. Dosimetric studies of microbeam radiation therapy (MRT) with Monte Carlo simulations
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Alberto Bravin, Jean A. Laissue, Elke Bräuer-Krisch, H. Blattmann, J. Stepanek, E.A. Siegbahn, Siegbahn, E, Brauer-Krisch, E, Stepanek, J, Blattmann, H, Laissue, J, and Bravin, A
- Subjects
Physics ,Nuclear and High Energy Physics ,MRT ,Monte Carlo method ,FIS/07 - FISICA APPLICATA (A BENI CULTURALI, AMBIENTALI, BIOLOGIA E MEDICINA) ,Electron ,Radiation ,equipment and supplies ,Imaging phantom ,Collimated light ,Synchrotron ,Computational physics ,law.invention ,law ,Dosimetry ,Statistical physics ,Instrumentation ,Electron scattering ,Beam (structure) ,Monte Carlo simulation - Abstract
Microbeam Radiation Therapy (MRT) is a technique utilizing the fact that normal tissue can sustain high doses of radiation in small volumes without significant damage. The synchrotron generated X-ray beam, used for the treatment, is collimated and delivered in an array of narrow micrometer-sized planar rectangular fields. In this work, the Monte Carlo code PENELOPE was used for simulating the dose deposition. This code provides an accurate treatment of low-energy electron transport which is important when performing dose calculations in micron-sized ranges. A comparison with earlier results was done for a few typical cases. The buildup of dose near the phantom surface and the lateral variation of dose around the microbeams were also studied. It was confirmed that the dose in the valley region mainly depends on Compton scattered electrons and that the electron scattering model used in the MC code is a key point. Finally a comparison between MC simulations and experimental microdosimetry, with radiochromic films and MOSFET detectors, gave important indications on possible refinements of the MC simulations for future investigations.
- Published
- 2005
48. Characterization of a tungsten/gas multislit collimator for microbeam radiation therapy at the European Synchrotron Radiation Facility
- Author
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Daniel N. Slatkin, E.A. Siegbahn, J. Stepanek, J.-O. Gebbers, M. Jasmin, Jean A. Laissue, Hans Blattmann, Elke Bräuer-Krisch, Alberto Bravin, L. Zhang, Brauer-Krisch, E, Bravin, A, Zhang, L, Siegbahn, E, Stepanek, J, Blattmann, H, Slatkin, D, Gebbers, J, Jasmin, M, and Laissue, J
- Subjects
medicine.medical_specialty ,Materials science ,business.industry ,FIS/07 - FISICA APPLICATA (A BENI CULTURALI, AMBIENTALI, BIOLOGIA E MEDICINA) ,Synchrotron radiation ,chemistry.chemical_element ,tungsten collimator, microbeams, MRT ,Particle accelerator ,Collimator ,Microbeam ,Tungsten ,Collimated light ,law.invention ,Optics ,chemistry ,Beamline ,law ,medicine ,Medical physics ,Irradiation ,business ,Instrumentation - Abstract
Clinical microbeam radiation therapy (MRT) will require a multislit collimator with adjustable uniform slit widths to enable reliable Monte Carlo-based treatment planning. Such a collimator has been designed, fabricated of >99% tungsten [W] by Tecomet/Viasys (Woburn, Massachusetts, USA) and installed at the 6 GeV electron-wiggler-generated hard x-ray ID17 beamline of the European Synchrotron Radiation Facility. Its pair of 125 parallel, 8 mm deep, 0.100 mm wide radiolucent slits, 0.400 mm on center, are perfused with nitrogen gas [N2] to dissipate heat during irradiation. Major improvements in uniformity of microbeam widths and good peak/valley dose ratios combined with a very high dose rate in targeted tissues have been achieved.
- Published
- 2005
49. Sci-Sat AM: Brachy - 01: Evaluation of dose-volume metrics for microbeam radiation therapy.
- Author
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Anderson D, Siegbahn EA, Fallone BG, Serduc R, and Warkentin B
- Abstract
Microbeam radiation therapy (MRT) is an experimental technique delivering an array of high dose synchrotron X-ray microbeams. Development of metrics to predict the biological efficacy of MRT dose distributions is needed to guide further MRT research and for potential translation to human trials. The most commonly used metric is the peak-to-valley-dose ratio (PVDR) relating the dose at the microbeam center to that between two microbeams. We investigate three additional metrics that characterize dose distributions from a more volumetric perspective - the peak-to-mean-valley-dose ratio (PMVDR), mean dose, and percentage volume below a threshold. The metrics are evaluated for Monte Carlo simulations of dose distributions in three cubic head phantoms (2, 4 and 8 cm side lengths) for microbeam widths of 25, 50, and 75 μm and centre-to-centre spacings of 100, 200 and 400 μm. The ratio of the PMVDR to the PVDR varied from 0.24 to 0.80 for the different configurations, indicating a difference in the predicted geometric dependence of outcome for these two metrics. The mean dose was 102, 79, and 42 % of the mean skin dose for the 2, 8, and 16 cm head phantoms, respectively. The percentage volume below a 10% dose threshold was highly dependent on geometry, with ranges for the different collimation configurations of 2 - 87% and 33 - 96% for the 2 and 16 cm heads, respectively. Different dose-volume metrics exhibit different dependencies on MRT geometry parameters, suggesting that reliance on PVDR as a predictor of therapeutic outcome may be insufficient., (© 2012 American Association of Physicists in Medicine.)
- Published
- 2012
- Full Text
- View/download PDF
50. Effects of pulsed, spatially fractionated, microscopic synchrotron X-ray beams on normal and tumoral brain tissue.
- Author
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Bräuer-Krisch E, Serduc R, Siegbahn EA, Le Duc G, Prezado Y, Bravin A, Blattmann H, and Laissue JA
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- Animals, Blood Vessels radiation effects, Brain Neoplasms blood supply, Dose Fractionation, Radiation, History, 20th Century, History, 21st Century, Humans, Neoplasms blood supply, Radiometry, Radiotherapy instrumentation, Technology, Radiologic history, Brain radiation effects, Brain Neoplasms radiotherapy, Radiotherapy methods, Synchrotrons, Technology, Radiologic methods, X-Rays
- Abstract
Microbeam radiation therapy (MRT) uses highly collimated, quasi-parallel arrays of X-ray microbeams of 50-600keV, produced by third generation synchrotron sources, such as the European Synchrotron Radiation Facility (ESRF), in France. The main advantages of highly brilliant synchrotron sources are an extremely high dose rate and very small beam divergence. High dose rates are necessary to deliver therapeutic doses in microscopic volumes, to avoid spreading of the microbeams by cardiosynchronous movement of the tissues. The minimal beam divergence results in the advantage of steeper dose gradients delivered to a tumor target, thus achieving a higher dose deposition in the target volume in fractions of seconds, with a sharper penumbra than that produced in conventional radiotherapy. MRT research over the past 20 years has yielded many results from preclinical trials based on different animal models, including mice, rats, piglets and rabbits. Typically, MRT uses arrays of narrow ( approximately 25-100 microm wide) microplanar beams separated by wider (100-400 microm centre-to-centre) microplanar spaces. The height of these microbeams typically varies from 1 to 100 mm, depending on the target and the desired preselected field size to be irradiated. Peak entrance doses of several hundreds of Gy are surprisingly well tolerated by normal tissues, up to approximately 2 yr after irradiation, and at the same time show a preferential damage of malignant tumor tissues; these effects of MRT have now been extensively studied over nearly two decades. More recently, some biological in vivo effects of synchrotron X-ray beams in the millimeter range (0.68-0.95 mm, centre-to-centre distances 1.2-4 mm), which may differ to some extent from those of microscopic beams, have been followed up to approximately 7 months after irradiation. Comparisons between broad-beam irradiation and MRT indicate a higher tumor control for the same sparing of normal tissue in the latter, even if a substantial fraction of tumor cells are not receiving a radiotoxic level of radiation. The hypothesis of a selective radiovulnerability of the tumor vasculature versus normal blood vessels by MRT, and of the cellular and molecular mechanisms involved remains under investigation. The paper highlights the history of MRT including salient biological findings after microbeam irradiation with emphasis on the vascular components and the tolerance of the central nervous system. Details on experimental and theoretical dosimetry of microbeams, core issues and possible therapeutic applications of MRT are presented., (2010 Elsevier B.V. All rights reserved.)
- Published
- 2010
- Full Text
- View/download PDF
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