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Koksal Akbas C, Vurro F, Fiorino C, Cozzarini C, Cavaliere F, Milani P, Broggi S, Del Vecchio A, Di Muzio N, Tacchetti C, Enrico Spinelli A. Preclinical photon minibeam radiotherapy using a custom collimator: Dosimetry characterization and preliminary in-vivo results on a glioma model. Phys Med 2024; 124:103420. [PMID: 38970950 DOI: 10.1016/j.ejmp.2024.103420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 05/28/2024] [Accepted: 06/28/2024] [Indexed: 07/08/2024] Open
Abstract
PURPOSE The purpose of this study is to investigate the dosimetric characteristics of a collimator for minibeam radiotherapy (MBRT) with film dosimetry and Monte Carlo (MC) simulations. The outcome of MBRT with respect to conventional RT using a glioma preclinical model was also evaluated. METHODS A multi-slit collimator was designed to be used with commercial small animal irradiator. The collimator was built by aligning 0.6 mm wide and 5 mm thick parallel lead leaves at 0.4 mm intervals. Dosimetry characteristics were evaluated by Gafchromic (CG) films and TOPAS Monte Carlo (MC) code. An in vivo experiment was performed using a glioma preclinical model by injecting two million GL261cells subcutaneously and treating with 25 Gy, single fraction, with MBRT and conventional RT. Survival curves and acute radiation damage were measured to compare both treatments. RESULTS A satisfactory agreement between experimental results and MC simulations were obtained, the measured FWHM and distance between the peaks were respectively 0.431 and 1.098 mm. In vivo results show that MBRT can provide local tumor control for three weeks after RT treatment and a similar survival fraction of open beam radiotherapy. No severe acute effects were seen for the MBRT group. CONCLUSIONS We developed a minibeam collimator and presented its dosimetric features. Satisfactory agreement between MC and GC films was found with differences consistent with uncertainties due to fabrication and set-up errors. The survival curves of MBRT and open field RT are similar while atoxicity is dramatically lower with MBRT, preliminarily confirming the expected effect.
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Affiliation(s)
- Canan Koksal Akbas
- Experimental Imaging Center, IRCCS San Raffaele Scientific Institute, Milan, Italy; Medical Physics Department, Istanbul University Oncology Institute, Istanbul, Turkey
| | - Federica Vurro
- Experimental Imaging Center, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Claudio Fiorino
- Medical Physics Department, IRCCS San Raffaele Scientific Institute, Milan, Italy.
| | - Cesare Cozzarini
- Radiotherapy Department, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | | | - Paolo Milani
- Department of Physics, University of Milan, Milan, Italy
| | - Sara Broggi
- Medical Physics Department, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | | | - Nadia Di Muzio
- Radiotherapy Department, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Carlo Tacchetti
- Experimental Imaging Center, IRCCS San Raffaele Scientific Institute, Milan, Italy
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Kundapur V, Torlakovic E, Auer RN. The Story Behind the First Mini-BEAM Photon Radiation Treatment: What is the Mini-Beam and Why is it Such an Advance? Semin Radiat Oncol 2024; 34:337-343. [PMID: 38880542 DOI: 10.1016/j.semradonc.2024.04.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2024]
Abstract
Radiation treatment has been the cornerstone in cancer management. However, long term treatment-related morbidity always accompanies tumor control which has significant impact on quality of life of the patient who has survived the cancer. Spatially fractionated radiation has the potential to achieve both cure and to avoid dreaded long term sequelae. The first ever randomized study of mini-beam radiation treatment (MBRT) of canine brain tumor has clearly shown the ability to achieve this goal. Dogs have gyrencephalic brains functionally akin to human brain. We here report long term follow-up and final outcome of the dogs, revealing both tumor control and side effects on normal brain. The results augur potential for conducting human studies with MBRT.
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Affiliation(s)
- Vijayananda Kundapur
- Saskatoon Cancer Centre, Clinical Professor, College of Medicine, University of Saskatchewan, Saskatoon, SK S7N 4H4 Canada.
| | - Emina Torlakovic
- Department of Pathology, University of Saskatchewan, Royal University Hospital, Saskatoon, SK S7N 0W8 Canada
| | - Roland N Auer
- Department of Pathology, University of Saskatchewan, Royal University Hospital, Saskatoon, SK S7N 0W8 Canada
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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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Kundapur V, Mayer M, Auer RN, Alexander A, Weibe S, Pushie MJ, Cranmer-Sargison G. Is Mini Beam Ready for Human Trials? Results of Randomized Study of Treating De-Novo Brain Tumors in Canines Using Linear Accelerator Generated Mini Beams. Radiat Res 2022; 198:162-171. [PMID: 35536992 DOI: 10.1667/rade-21-00093.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 04/22/2022] [Indexed: 11/03/2022]
Abstract
The main challenge in treating malignant brain neoplasms lies in eradicating the tumor while minimizing treatment-related damage. Conventional radiation treatments are associated with considerable side effects. Synchrotron generated micro-beam radiation (SMBRT) has shown to preserve brain architecture while killing tumor cells, however physical characteristics and limited facility access restrict its use. We have created a new clinical device which produces mini beams on a linear accelerator, to provide a new type of treatment called mini-beam radiation therapy (MBRT). The objective of this study is to compare the treatment outcomes of linear accelerator based MBRT versus standard radiation treatment (SRT), to evaluate the tumor response and the treatment-related changes in the normal brain with respect to each treatment type. Pet dogs with de-novo brain tumors were accrued for treatment. Dogs were randomized between standard fractionated stereotactic (9 Gy in 3 fractions) radiation treatment vs. a single fraction of MBRT (26 Gy mean dose). Dogs were monitored after treatment for clinical assessment and imaging. When the dogs were euthanized, a veterinary pathologist assessed the radiation changes and tumor response. We accrued 16 dogs, 8 dogs in each treatment arm. In the MBRT arm, 71% dogs achieved complete pathological remission. The radiation-related changes were all confined to the target region. Structural damage was not observed in the beam path outside of the target region. In contrast, none of the dogs in control group achieved remission and the treatment related damage was more extensive. Therapeutic superiority was observed with MBRT, including both tumor control and the normal structural preservation. The MBRT findings are suggestive of an immune related mechanism which is absent in standard treatment. These findings together with the widespread availability of clinical linear accelerators make MBRT a promising research topic to explore further treatment and clinical trial opportunities.
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Affiliation(s)
- V Kundapur
- Radiation Oncology, Saskatchewan Cancer Agency, Saskatoon Cancer Centre, Saskatoon, SK Canada S7N4H4
| | - M Mayer
- Veterinary Radiation Oncology, Department of Small Animal clinical Sciences, University of Saskatchewan, Saskatoon, SK Canada S7N 0W8
| | - R N Auer
- Department of Pathology and Laboratory Medicine, University of Saskatchewan, Saskatoon, SK Canada S7N 0W8
| | - A Alexander
- Radiation Physics, Saskatchewan Cancer Agency, Saskatoon Cancer Centre, Saskatoon, SK Canada S7N4H4
| | - S Weibe
- Department of Clinical Imaging, University of Saskatchewan, Saskatoon, SK Canada S7N 0W8
| | - M J Pushie
- Department of Surgery, University of Saskatchewan, Saskatoon, SK Canada S7N 0W8
| | - G Cranmer-Sargison
- Radiation Physics, Saskatchewan Cancer Agency, Saskatoon Cancer Centre, Saskatoon, SK Canada S7N4H4
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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: 6] [Impact Index Per Article: 2.0] [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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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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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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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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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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Davis W, Crewson C, Alexander A, Kundapur V, Cranmer-Sargison G. Dosimetric characterization of an accessory mounted mini-beam collimator across clinically beam matched medical linear accelerators. Biomed Phys Eng Express 2017. [DOI: 10.1088/2057-1976/aa586d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Reynoso FJ, Tailor R, Wang CKC, Cho SH. Comparison of filtered x-ray spectra and depth doses derived from a hybrid Monte Carlo model of an orthovoltage x-ray unit with experimental measurements. Biomed Phys Eng Express 2016. [DOI: 10.1088/2057-1976/2/4/045011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Cranmer-Sargison G, Crewson C, Davis WM, Sidhu NP, Kundapur V. Medical linear accelerator mounted mini-beam collimator: design, fabrication and dosimetric characterization. Phys Med Biol 2015; 60:6991-7005. [PMID: 26305166 DOI: 10.1088/0031-9155/60/17/6991] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The goal of this work was to design, build and experimentally characterize a linear accelerator mounted mini-beam collimator for use at a nominal 6 MV beam energy. Monte Carlo simulation was used in the design and dosimetric characterization of a compact mini-beam collimator assembly mounted to a medical linear accelerator. After fabrication, experimental mini-beam dose profiles and central axis relative output were measured and the results used to validate the simulation data. The simulation data was then used to establish traceability back to an established dosimetric code of practice. The Monte Carlo simulation work revealed that changes in collimator blade width have a greater influence on the valley-to-peak dose ratio than do changes in blade height. There was good agreement between the modeled and measured profile data, with the exception of small differences on either side of the central peak dose. These differences were found to be systematic across all depths and result from limitations associated with the collimator fabrication. Experimental mini-beam relative output and simulation data agreed to better than ± 2.0%, which is well within the level of uncertainty required for dosimetric traceability of non-standard field geometries. A mini-beam collimator has now been designed, built and experimentally characterized for use with a commercial linear accelerator operated at a nominal 6 MV beam energy.
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Affiliation(s)
- G Cranmer-Sargison
- Department of Medical Physics, Saskatchewan Cancer Agency, Saskatoon, Saskatchewan, Canada. Division of Oncology, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
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Prezado Y, Deman P, Varlet P, Jouvion G, Gil S, Le Clec'H C, Bernard H, Le Duc G, Sarun S. Tolerance to Dose Escalation in Minibeam Radiation Therapy Applied to Normal Rat Brain: Long-Term Clinical, Radiological and Histopathological Analysis. Radiat Res 2015; 184:314-321. [DOI: 10.1667/rr14018.1] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
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