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Whitmore L, Mackay RI, van Herk M, Korysko P, Farabolini W, Malyzhenkov A, Corsini R, Jones RM. CERN-based experiments and Monte-Carlo studies on focused dose delivery with very high energy electron (VHEE) beams for radiotherapy applications. Sci Rep 2024; 14:11120. [PMID: 38750131 PMCID: PMC11096185 DOI: 10.1038/s41598-024-60997-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 04/30/2024] [Indexed: 05/18/2024] Open
Abstract
Very High Energy Electron (VHEE) beams are a promising alternative to conventional radiotherapy due to their highly penetrating nature and their applicability as a modality for FLASH (ultra-high dose-rate) radiotherapy. The dose distributions due to VHEE need to be optimised; one option is through the use of quadrupole magnets to focus the beam, reducing the dose to healthy tissue and allowing for targeted dose delivery at conventional or FLASH dose-rates. This paper presents an in depth exploration of the focusing achievable at the current CLEAR (CERN Linear Electron Accelerator for Research) facility, for beam energies >200 MeV. A shorter, more optimal quadrupole setup was also investigated using the TOPAS code in Monte Carlo simulations, with dimensions and beam parameters more appropriate to a clinical situation. This work provides insight into how a focused VHEE radiotherapy beam delivery system might be achieved.
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Affiliation(s)
- L Whitmore
- Department of Physics and Astronomy, University of Manchester, Manchester, M13 9PL, UK
- The Cockcroft Institute of Science and Technology, Daresbury, UK
- Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, USA
| | - R I Mackay
- Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
- Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester, UK
| | - M van Herk
- Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
- Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester, UK
| | - P Korysko
- Department of Physics, University of Oxford, Oxford, UK
- CERN, 1211, Geneva 23, Switzerland
| | | | | | | | - R M Jones
- Department of Physics and Astronomy, University of Manchester, Manchester, M13 9PL, UK.
- The Cockcroft Institute of Science and Technology, Daresbury, UK.
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Zurl B, Bayerl A, De Vries A, Geinitz H, Hawliczek R, Knocke-Abulesz TH, Lukas P, Pötter R, Raunik W, Scholz B, Schratter-Sehn A, Sedlmayer F, Seewald D, Selzer E, Kapp KS. ÖGRO survey on radiotherapy capacity in Austria : Status quo and estimation of future demands. Strahlenther Onkol 2017; 194:284-292. [PMID: 29222711 DOI: 10.1007/s00066-017-1240-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 11/15/2017] [Indexed: 11/26/2022]
Abstract
BACKGROUND A comprehensive evaluation of the current national and regional radiotherapy capacity in Austria with an estimation of demands for 2020 and 2030 was performed by the Austrian Society for Radiation Oncology, Radiobiology and Medical Radiophysics (ÖGRO). MATERIALS AND METHODS All Austrian centers provided data on the number of megavoltage (MV) units, treatment series, fractions, percentage of retreatments and complex treatment techniques as well as the daily operating hours for the year 2014. In addition, waiting times until the beginning of radiotherapy were prospectively recorded over the first quarter of 2015. National and international epidemiological prediction data were used to estimate future demands. RESULTS For a population of 8.51 million, 43 MV units were at disposal. In 14 radiooncological centers, a total of 19,940 series with a mean number of 464 patients per MV unit/year and a mean fraction number of 20 (range 16-24) per case were recorded. The average re-irradiation ratio was 14%. The survey on waiting times until start of treatment showed provision shortages in 40% of centers with a mean waiting time of 13.6 days (range 0.5-29.3 days) and a mean maximum waiting time of 98.2 days. Of all centers, 21% had no or only a limited ability to deliver complex treatment techniques. Predictions for 2020 and 2030 indicate an increased need in the overall number of MV units to a total of 63 and 71, respectively. CONCLUSION This ÖGRO survey revealed major regional differences in radiooncological capacity. Considering epidemiological developments, an aggravation of the situation can be expected shortly. This analysis serves as a basis for improved public regional health care planning.
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Affiliation(s)
- Brigitte Zurl
- Universitätsklinik für Strahlentherapie-Radioonkologie, Comprehensive Cancer Center Graz, Medizinische Universität Graz, Auenbruggerplatz 32, 8036, Graz, Austria.
| | - Anja Bayerl
- Klinische Abteilung für Strahlentherapie-Radioonkologie, Universitätsklinikum Krems, Krems, Austria
| | - Alexander De Vries
- Abteilung für Strahlentherapie-Radioonkologie, Landeskrankenhaus Feldkirch, Feldkirch, Austria
| | - Hans Geinitz
- Abteilung für Radio-Onkologie, Krankenhaus der Barmherzigen Schwestern Linz, Linz, Austria
| | - Robert Hawliczek
- Institut für Radioonkologie, SMZ-Ost Donauspital der Stadt Wien, Wien, Austria
| | | | - Peter Lukas
- Universitätsklinik für Strahlentherapie-Radioonkologie, Medizinische Universität Innsbruck, Innsbruck, Austria
| | - Richard Pötter
- Universitätsklinik für Strahlentherapie, Medizinische Universität Wien, Wien, Austria
| | - Wolfgang Raunik
- Institut für Strahlentherapie/Radioonkologie, Klinikum Klagenfurt, Klagenfurt, Austria
| | - Brigitte Scholz
- Institut für Radioonkologie, Wilhelminenspital der Stadt Wien, Wien, Austria
| | | | - Felix Sedlmayer
- Universitätsklinik für Radiotherapie und Radio-Onkologie, Universitätsklinikum Salzburg, Salzburg, Austria
| | - Dietmar Seewald
- Institut für Radioonkologie/Strahlentherapie, Salzkammergut-Klinikum Vöcklabruck, Vöcklabruck, Austria
| | - Edgar Selzer
- Institut für Radioonkologie u. Strahlentherapie, Landesklinikum Wiener Neustadt, Wiener Neustadt, Austria
| | - Karin S Kapp
- Universitätsklinik für Strahlentherapie-Radioonkologie, Comprehensive Cancer Center Graz, Medizinische Universität Graz, Auenbruggerplatz 32, 8036, Graz, Austria
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Sanz DE. Shielding Design for Adjacent, Underground Buildings of a Megavoltage Radiotherapy Facility. Health Phys 2016; 111:1-10. [PMID: 27218288 DOI: 10.1097/hp.0000000000000513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
In a radiotherapy facility, safety in areas next to the treatment room can be of concern when irradiating downward due to oblique x-ray transmission through the floor and/or walls, especially in areas immediately adjacent or underground. Even when there is no basement underneath, a usual conservative solution is to build a thick concrete slab as the base for the treatment room. Of course, this implies deeper soil excavation and higher associated costs. As a convenient alternative, the limiting walls can be buried a certain depth below floor level to shield oblique, downward irradiation. Besides, for space considerations, laminated barriers are usually employed, and some additional shielding to the floor may be required (L-shaped barriers). In this work, the author introduces an analytical method for calculating the required wall penetration below floor level or, alternatively, the additional floor shielding for L-shaped barriers, taking into account in either case the attenuation properties of the earth underneath the vault. Interestingly, the required penetration depth for a given wall barrier (primary or secondary), relative to a reference thickness, is only a function of basic attenuation data. Likewise, for a laminated, lead-concrete barrier, the required dimensions depend on the relative amount of lead used for the wall and on the corresponding attenuation data. The shielding design criteria developed in this work to protect underground nearby sites is conservative in nature, yet it yields optimal shield dimensions for wall footing and for wall-floor shielding, avoiding the need to construct oversized concrete slab floors.
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Affiliation(s)
- Darío Esteban Sanz
- *Fundación Escuela de Medicina Nuclear, Garibaldi 405, 5500 Mendoza, Argentina
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Abstract
Intensity modulated radiotherapy with high enengy photons (IMRT) and with charged particles (IMPT) refer to the most advanced development in conformal radiation therapy. Their general aim is to increase local tumor control rates while keeping the radiation induced complications below desired thresholds. IMRT is currently widely introduced in clinical practice. However, the more complicated IMPT is still under development. Especially, spot-scanning techniques integrated in rotating gantries that can deliver proton or light ion-beams to a radiation target from any direction will be available in the near future. We describe the basic concepts of intensity modulated particle therapy (IMPT). Starting from the potential advantages of hadron therapy inverse treatment planning strategies are discussed for various dose delivery techniques of IMPT. Of special interest are the techniques of distal edge tracking (DET) and 3D-scanning. After the introduction of these concepts a study of comparative inverse treatment planning is presented. The study aims to identify the potential advantages of achievable physical dose distributions with proton and carbon beams, if different dose delivery techniques are employed. Moreover, a comparison to standard photon IMRT is performed. The results of the study are summarized as: i) IMRT with photon beams is a strong competitor to intensity modulated radiotherapy with charged particles. The most obvious benefit observed for charged particles is the reduction of medium and low doses in organs at risk. ii) The 3D-scanning technique could not improve the dosimetric results achieved with DET, although 10–15 times more beam spots were employed for 3D-scanning than for DET. However, concerns may arise about the application of DET, if positioning errors of the patient or organ movements have to be accounted for. iii) Replacing protons with carbon ions leads to further improvements of the physical dose distributions. However, the additional degree of improvement due to carbon ions is modest. The main clinical potential of heavy ion beams is probably related to their radiobiological properties.
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Affiliation(s)
- U Oelfke
- Department of Medical Physics, Deutsches Krebsforschungszentrum (DKFZ), Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany.
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Israngkul-Na-Ayuthaya I, Suriyapee S, Pengvanich P. Evaluation of equivalent dose from neutrons and activation products from a 15-MV X-ray LINAC. J Radiat Res 2015; 56:919-26. [PMID: 26265661 PMCID: PMC4628218 DOI: 10.1093/jrr/rrv045] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Revised: 06/16/2015] [Accepted: 07/03/2015] [Indexed: 06/01/2023]
Abstract
A high-energy photon beam that is more than 10 MV can produce neutron contamination. Neutrons are generated by the [γ,n] reactions with a high-Z target material. The equivalent neutron dose and gamma dose from activation products have been estimated in a LINAC equipped with a 15-MV photon beam. A Monte Carlo simulation code was employed for neutron and photon dosimetry due to mixed beam. The neutron dose was also experimentally measured using the Optically Stimulated Luminescence (OSL) under various conditions to compare with the simulation. The activation products were measured by gamma spectrometer system. The average neutron energy was calculated to be 0.25 MeV. The equivalent neutron dose at the isocenter obtained from OSL measurement and MC calculation was 5.39 and 3.44 mSv/Gy, respectively. A gamma dose rate of 4.14 µSv/h was observed as a result of activations by neutron inside the treatment machine. The gamma spectrum analysis showed (28)Al, (24)Na, (54)Mn and (60)Co. The results confirm that neutrons and gamma rays are generated, and gamma rays remain inside the treatment room after the termination of X-ray irradiation. The source of neutrons is the product of the [γ,n] reactions in the machine head, whereas gamma rays are produced from the [n,γ] reactions (i.e. neutron activation) with materials inside the treatment room. The most activated nuclide is (28)Al, which has a half life of 2.245 min. In practice, it is recommended that staff should wait for a few minutes (several (28)Al half-lives) before entering the treatment room after the treatment finishes to minimize the dose received.
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Affiliation(s)
- Isra Israngkul-Na-Ayuthaya
- Department of Nuclear Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok, Thailand Division of Therapeutic Radiology and Oncology, Department of Radiology, King Chulalongkorn Memorial Hospital, Thailand
| | - Sivalee Suriyapee
- Division of Therapeutic Radiology and Oncology, Faculty of Medicine, Chulalongkorn University, Thailand
| | - Phongpheath Pengvanich
- Department of Nuclear Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok, Thailand
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Bräuer-Krisch E, Adam JF, Alagoz E, Bartzsch S, Crosbie J, DeWagter C, Dipuglia A, Donzelli M, Doran S, Fournier P, Kalef-Ezra J, Kock A, Lerch M, McErlean C, Oelfke U, Olko P, Petasecca M, Povoli M, Rosenfeld A, Siegbahn EA, Sporea D, Stugu B. Medical physics aspects of the synchrotron radiation therapies: Microbeam radiation therapy (MRT) and synchrotron stereotactic radiotherapy (SSRT). Phys Med 2015; 31:568-83. [PMID: 26043881 DOI: 10.1016/j.ejmp.2015.04.016] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 04/27/2015] [Accepted: 04/28/2015] [Indexed: 11/19/2022] Open
Abstract
Stereotactic Synchrotron Radiotherapy (SSRT) and Microbeam Radiation Therapy (MRT) are both novel approaches to treat brain tumor and potentially other tumors using synchrotron radiation. Although the techniques differ by their principles, SSRT and MRT share certain common aspects with the possibility of combining their advantages in the future. For MRT, the technique uses highly collimated, quasi-parallel arrays of X-ray microbeams between 50 and 600 keV. Important features of highly brilliant Synchrotron sources are a very small beam divergence and an extremely high dose rate. The minimal beam divergence allows the insertion of so called Multi Slit Collimators (MSC) to produce spatially fractionated beams of typically ∼25-75 micron-wide microplanar beams separated by wider (100-400 microns center-to-center(ctc)) spaces with a very sharp penumbra. Peak entrance doses of several hundreds of Gy are extremely well tolerated by normal tissues and at the same time provide a higher therapeutic index for various tumor models in rodents. The hypothesis of a selective radio-vulnerability of the tumor vasculature versus normal blood vessels by MRT was recently more solidified. SSRT (Synchrotron Stereotactic Radiotherapy) is based on a local drug uptake of high-Z elements in tumors followed by stereotactic irradiation with 80 keV photons to enhance the dose deposition only within the tumor. With SSRT already in its clinical trial stage at the ESRF, most medical physics problems are already solved and the implemented solutions are briefly described, while the medical physics aspects in MRT will be discussed in more detail in this paper.
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Affiliation(s)
- Elke Bräuer-Krisch
- ESRF-The European Synchrotron, 71, Avenue des Martyrs, Grenoble, France.
| | | | - Enver Alagoz
- University of Bergen Department of Physics and Technology, PB 7803 5020, Norway
| | - Stefan Bartzsch
- The Institute of Cancer Research, 15 Cotswold Rd, Sutton SM2 5NG, United Kingdom
| | - Jeff Crosbie
- RMIT University, Melbourne, VIC, 3001, Australia
| | | | - Andrew Dipuglia
- Centre for Medical Radiation Physics, University of Wollongong, Northfields Ave, NSW, Australia
| | - Mattia Donzelli
- ESRF-The European Synchrotron, 71, Avenue des Martyrs, Grenoble, France
| | - Simon Doran
- CRUK Cancer Imaging Centre, Institute of Cancer Research, 15 Cotswold Rd, Sutton Surrey, UK
| | - Pauline Fournier
- ESRF-The European Synchrotron, 71, Avenue des Martyrs, Grenoble, France; Centre for Medical Radiation Physics, University of Wollongong, Northfields Ave, NSW, Australia
| | - John Kalef-Ezra
- Medical Physics Laboratory, University of Ioannina, 451.10, Ioannina, Greece
| | - Angela Kock
- Sintef Minalab, Gaustadalléen 23C, 0373, Oslo, Norway
| | - Michael Lerch
- Centre for Medical Radiation Physics, University of Wollongong, Northfields Ave, NSW, Australia
| | - Ciara McErlean
- CRUK Cancer Imaging Centre, Institute of Cancer Research, 15 Cotswold Rd, Sutton Surrey, UK
| | - Uwe Oelfke
- The Institute of Cancer Research, 15 Cotswold Rd, Sutton SM2 5NG, United Kingdom
| | - Pawel Olko
- Institute of Nuclear Physics PAN, Radzikowskiego 152, 31-342, Krawkow, Poland
| | - Marco Petasecca
- Centre for Medical Radiation Physics, University of Wollongong, Northfields Ave, NSW, Australia
| | - Marco Povoli
- University of Oslo, Department of Physics, 0316, Oslo, Norway
| | - Anatoly Rosenfeld
- Centre for Medical Radiation Physics, University of Wollongong, Northfields Ave, NSW, Australia
| | - Erik A Siegbahn
- Department of Oncolgy-Pathology, Karolinska Institutet, S-177176, Stockholm, Sweden
| | - Dan Sporea
- National Institute for Laser, Plasma and Radiation Physics, Magurele, RO-077125, Romania
| | - Bjarne Stugu
- University of Bergen, Department of Physics and Technology, PB 7803, 5020, Bergen, Norway
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Wisotzky E, Fast MF, Oelfke U, Nill S. Automated marker tracking using noisy X-ray images degraded by the treatment beam. Z Med Phys 2015; 25:123-34. [PMID: 25280891 DOI: 10.1016/j.zemedi.2014.08.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Revised: 08/01/2014] [Accepted: 08/15/2014] [Indexed: 12/25/2022]
Abstract
This study demonstrates the feasibility of automated marker tracking for the real-time detection of intrafractional target motion using noisy kilovoltage (kV) X-ray images degraded by the megavoltage (MV) treatment beam. The authors previously introduced the in-line imaging geometry, in which the flat-panel detector (FPD) is mounted directly underneath the treatment head of the linear accelerator. They found that the 121 kVp image quality was severely compromised by the 6 MV beam passing through the FPD at the same time. Specific MV-induced artefacts present a considerable challenge for automated marker detection algorithms. For this study, the authors developed a new imaging geometry by re-positioning the FPD and the X-ray tube. This improved the contrast-to-noise-ratio between 40% and 72% at the 1.2 mAs/image exposure setting. The increase in image quality clearly facilitates the quick and stable detection of motion with the aid of a template matching algorithm. The setup was tested with an anthropomorphic lung phantom (including an artificial lung tumour). In the tumour one or three Calypso beacons were embedded to achieve better contrast during MV radiation. For a single beacon, image acquisition and automated marker detection typically took around 76 ± 6 ms. The success rate was found to be highly dependent on imaging dose and gantry angle. To eliminate possible false detections, the authors implemented a training phase prior to treatment beam irradiation and also introduced speed limits for motion between subsequent images.
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Affiliation(s)
- E Wisotzky
- Fraunhofer Institute for Production Systems and Design Technology (IPK), Pascalstraße 8-9, 10587 Berlin, Germany; German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.
| | - M F Fast
- Joint Department of Physics at The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London, SM2 5NG, UK
| | - U Oelfke
- Joint Department of Physics at The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London, SM2 5NG, UK; German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - S Nill
- Joint Department of Physics at The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London, SM2 5NG, UK.
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Yeo IJ, Teran A, Ghebremedhin A, Johnson M, Patyal B. Radiographic film dosimetry of proton beams for depth-dose constancy check and beam profile measurement. J Appl Clin Med Phys 2015; 16:5402. [PMID: 26103499 PMCID: PMC5690120 DOI: 10.1120/jacmp.v16i3.5402] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Revised: 01/28/2015] [Accepted: 12/21/2014] [Indexed: 11/23/2022] Open
Abstract
Radiographic film dosimetry suffers from its energy dependence in proton dosimetry. This study sought to develop a method of measuring proton beams by the film and to evaluate film response to proton beams for the constancy check of depth dose (DD). It also evaluated the film for profile measurements. To achieve this goal, from DDs measured by film and ion chamber (IC), calibration factors (ratios of dose measured by IC to film responses) as a function of depth in a phantom were obtained. These factors imply variable slopes (with proton energy and depth) of linear characteristic curves that relate film response to dose. We derived a calibration method that enables utilization of the factors for acquisition of dose from film density measured at later dates by adapting to a potentially altered processor condition. To test this model, the characteristic curve was obtained by using EDR2 film and in-phantom film dosimetry in parallel with a 149.65 MeV proton beam, using the method. An additional validation of the model was performed by concurrent film and IC measurement perpendicular to the beam at various depths. Beam profile measurements by the film were also evaluated at the center of beam modulation. In order to interpret and ascertain the film dosimetry, Monte Carlos simulation of the beam was performed, calculating the proton fluence spectrum along depths and off-axis distances. By multiplying respective stopping powers to the spectrum, doses to film and water were calculated. The ratio of film dose to water dose was evaluated. Results are as follows. The characteristic curve proved the assumed linearity. The measured DD approached that of IC, but near the end of the spread-out Bragg peak (SOBP), a spurious peak was observed due to the mismatch of distal edge between the calibration and measurement films. The width of SOBP and the proximal edge were both reproducible within a maximum of 5mm; the distal edge was reproducible within 1 mm. At 5 cm depth, the dose was reproducible within 10%. These large discrepancies were identified to have been contributed by film processor uncertainty across a layer of film and the misalignment of film edge to the frontal phantom surface. The deviations could drop from 5 to 2 mm in SOBP and from 10% to 4.5% at 5 cm depth in a well-controlled processor condition(i.e., warm up). In addition to the validation of the calibration method done by the DD measurements, the concurrent film and IC measurement independently validated the model by showing the constancy of depth-dependent calibration factors. For profile measurement, the film showed good agreement with ion chamber measurement. In agreement with the experimental findings, computationally obtained ratio of film dose to water dose assisted understanding of the trend of the film response by revealing relatively large and small variances of the response for DD and beam profile measurements, respectively. Conclusions are as follows. For proton beams, radiographic film proved to offer accurate beam profile measurements. The adaptive calibration method proposed in this study was validated. Using the method, film dosimetry could offer reasonably accurate DD constancy checks, when provided with a well-controlled processor condition. Although the processor warming up can promote a uniform processing across a single layer of the film, the processing remains as a challenge.
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Affiliation(s)
- D Jones
- Northwest Medical Physics Center, Lynnwood, Wash
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10
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Affiliation(s)
- C C Wang
- Department of Radiation Medicine, Massachusetts General Hospital Cancer Center, Boston
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11
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Wolkov HB. Intraoperative electron beam therapy in the community environment. Front Radiat Ther Oncol 2015; 25:322-9; discussion 330-3. [PMID: 1908423 DOI: 10.1159/000429602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- H B Wolkov
- Radiation Oncology Center, Sutter Community Hospitals, Sacramento, CA
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12
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Shimizu M, Morishita Y, Kato M, Tanaka T, Kurosawa T, Takata N, Saito N, Ramanathan G, Harty PD, Oliver C, Wright T, Butler DJ. Comparison of the NMIJ and the ARPANSA standards for absorbed dose to water in high-energy photon beams. Radiat Prot Dosimetry 2015; 164:181-186. [PMID: 25209996 DOI: 10.1093/rpd/ncu272] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 07/30/2014] [Indexed: 06/03/2023]
Abstract
The authors report the results of an indirect comparison of the standards of absorbed dose to water in high-energy photon beams from a clinical linac and (60)Co radiation beam performed between the National Metrology Institute of Japan (NMIJ) and the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA). Three ionisation chambers were calibrated by the NMIJ in April and June 2013 and by the ARPANSA in May 2013. The average ratios of the calibration coefficients for the three ionisation chambers obtained by the NMIJ to those obtained by the ARPANSA were 0.9994, 1.0040 and 1.0045 for 6-, 10- and 15-MV (18 MV at the ARPANSA) high-energy photon beams, respectively. The relative standard uncertainty of the value was 7.2 × 10(-3). The ratio for (60)Co radiation was 0.9986(66), which is consistent with the results published in the key comparison of BIPM.RI(I)-K4.
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Affiliation(s)
- M Shimizu
- National Metrology Institute of Japan, AIST, Tsukuba, Japan
| | - Y Morishita
- National Metrology Institute of Japan, AIST, Tsukuba, Japan
| | - M Kato
- National Metrology Institute of Japan, AIST, Tsukuba, Japan
| | - T Tanaka
- National Metrology Institute of Japan, AIST, Tsukuba, Japan
| | - T Kurosawa
- National Metrology Institute of Japan, AIST, Tsukuba, Japan
| | - N Takata
- National Metrology Institute of Japan, AIST, Tsukuba, Japan
| | - N Saito
- National Metrology Institute of Japan, AIST, Tsukuba, Japan
| | - G Ramanathan
- Australian Radiation Protection and Nuclear Safety Agency, Yallambie, Australia
| | - P D Harty
- Australian Radiation Protection and Nuclear Safety Agency, Yallambie, Australia
| | - C Oliver
- Australian Radiation Protection and Nuclear Safety Agency, Yallambie, Australia
| | - T Wright
- Australian Radiation Protection and Nuclear Safety Agency, Yallambie, Australia School of Chemistry and Physics, University of Adelaide, Adelaide, Australia
| | - D J Butler
- Australian Radiation Protection and Nuclear Safety Agency, Yallambie, Australia
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Al-Affan IAM, Hugtenburg RP, Bari DS, Al-Saleh WM, Piliero M, Evans S, Al-Hasan M, Al-Zughul B, Al-Kharouf S, Ghaith A. Dose reduction of scattered photons from concrete walls lined with lead: Implications for improvement in design of megavoltage radiation therapy facility mazes. Med Phys 2015; 42:606-614. [PMID: 25771559 DOI: 10.1118/1.4905100] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 12/02/2014] [Accepted: 12/11/2014] [Indexed: 11/07/2022] Open
Abstract
PURPOSE This study explores the possibility of using lead to cover part of the radiation therapy facility maze walls in order to absorb low energy photons and reduce the total dose at the maze entrance of radiation therapy rooms. METHODS Experiments and Monte Carlo simulations were utilized to establish the possibility of using high-Z materials to cover the concrete walls of the maze in order to reduce the dose of the scatteredphotons at the maze entrance. The dose of the backscatteredphotons from a concrete wall was measured for various scattering angles. The dose was also calculated by the FLUKA and EGSnrc Monte Carlo codes. The FLUKA code was also used to simulate an existing radiotherapy room to study the effect of multiple scattering when adding lead to cover the concrete walls of the maze. Monoenergetic photons were used to represent the main components of the x ray spectrum up to 10 MV. RESULTS It was observed that when the concrete wall was covered with just 2 mm of lead, the measured dose rate at all backscattering angles was reduced by 20% for photons of energy comparable to Co-60 emissions and 70% for Cs-137 emissions. The simulations with FLUKA and EGS showed that the reduction in the dose was potentially even higher when lead was added. One explanation for the reduction is the increased absorption of backscatteredphotons due to the photoelectric interaction in lead. The results also showed that adding 2 mm lead to the concrete walls and floor of the maze reduced the dose at the maze entrance by up to 90%. CONCLUSIONS This novel proposal of covering part or the entire maze walls with a few millimeters of lead would have a direct implication for the design of radiation therapy facilities and would assist in upgrading the design of some mazes, especially those in facilities with limited space where the maze length cannot be extended to sufficiently reduce the dose.
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Grotzer MA, Schültke E, Bräuer-Krisch E, Laissue JA. Microbeam radiation therapy: Clinical perspectives. Phys Med 2015; 31:564-7. [PMID: 25773883 DOI: 10.1016/j.ejmp.2015.02.011] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2014] [Revised: 02/12/2015] [Accepted: 02/16/2015] [Indexed: 11/19/2022] Open
Abstract
Microbeam radiation therapy (MRT), a novel form of spatially fractionated radiotherapy (RT), uses arrays of synchrotron-generated X-ray microbeams (MB). MRT has been identified as a promising treatment concept that might be applied to patients with malignant central nervous system (CNS) tumours for whom, at the current stage of development, no satisfactory therapy is available yet. Preclinical experimental studies have shown that the CNS of healthy rodents and piglets can tolerate much higher radiation doses delivered by spatially separated MBs than those delivered by a single, uninterrupted, macroscopically wide beam. High-dose, high-precision radiotherapies such as MRT with reduced probabilities of normal tissue complications offer prospects of improved therapeutic ratios, as extensively demonstrated by results of experiments published by many international groups in the last two decades. The significance of developing MRT as a new RT approach cannot be understated. Up to 50% of cancer patients receive conventional RT, and any new treatment that provides better tumour control whilst preserving healthy tissue is likely to significantly improve patient outcomes.
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Affiliation(s)
- M A Grotzer
- University Children's Hospital of Zurich, Steinwiesstrasse 75, CH-8032 Zurich, Switzerland.
| | - E Schültke
- Rostock University Medical Center, Department of Radiotherapy, Südring 75, 18059 Rostock, Germany
| | - E Bräuer-Krisch
- European Synchrotron Radiation Facility, 71 Avenue des Martyrs, F-38043 Grenoble Cedex 9, France
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15
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Fujita Y, Myojoyama A, Saitoh H. Bremsstrahlung and photoneutron production in a steel shield for 15-22-MeV clinical electron beams. Radiat Prot Dosimetry 2015; 163:148-159. [PMID: 24821930 DOI: 10.1093/rpd/ncu153] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The physical data regarding bremsstrahlung and neutrons produced in a steel shield by high-energy electron beams from a medical linear accelerator were investigated. These data are required to allow the accurate prediction of shielding performance for high-energy electron beams and in the design of radiotherapy facilities. A Monte Carlo code was used to develop Monte Carlo beam models for clinical electron beams and to directly simulate bremsstrahlung and secondary neutron production in a steel shield. The effective dose and dose equivalent of bremsstrahlung X rays and secondary neutrons outside a vault were determined using a realistic radiation source. The accuracy of Monte Carlo simulations was validated experimentally by comparing the measured and calculated physical quantities. In validating the Monte Carlo simulation, the measured and calculated values showed reasonable agreement, indicating that bremsstrahlung and photoneutron production and transport were simulated accurately. The bremsstrahlung X-ray dose was the main component of the total dose outside a vault. The secondary neutron dose was 1-20 % of the bremsstrahlung X-ray dose, but the neutron dose was also at a non-negligible level. The calculated neutron dose outside the vault differed from the McGinley's reported data. These results indicate that McGinley's method overestimates the neutron dose beyond the steel shield. The physical data used here will be useful in the accurate estimation of bremsstrahlung X-ray and neutron doses for high-energy electron beams.
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Affiliation(s)
- Yukio Fujita
- Department of Radiation Oncology, Tokai University School of Medicine, Isehara, Kanagawa 259-1193, Japan
| | - Atsushi Myojoyama
- Graduate School of Human Health Sciences, Tokyo Metropolitan University, Arakawa-ku, Tokyo 116-8551, Japan
| | - Hidetoshi Saitoh
- Graduate School of Human Health Sciences, Tokyo Metropolitan University, Arakawa-ku, Tokyo 116-8551, Japan
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16
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Tsuda S, Sato T, Watanabe R, Takada M. Radial dependence of lineal energy distribution of 290-MeV/u carbon and 500-MeV/u iron ion beams using a wall-less tissue-equivalent proportional counter. J Radiat Res 2015; 56:197-204. [PMID: 25210053 PMCID: PMC4572583 DOI: 10.1093/jrr/rru076] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 07/15/2014] [Accepted: 08/11/2014] [Indexed: 06/03/2023]
Abstract
Using a wall-less tissue-equivalent proportional counter for a 0.72-μm site in tissue, we measured the radial dependence of the lineal energy distribution, yf(y), of 290-MeV/u carbon ions and 500-MeV/u iron ion beams. The measured yf(y) distributions and the dose-mean of y, [Formula: see text], were compared with calculations performed with the track structure simulation code TRACION and the microdosimetric function of the Particle and Heavy Ion Transport code System (PHITS). The values of the measured [Formula: see text] were consistent with calculated results within an error of 2%, but differences in the shape of yf(y) were observed for iron ion irradiation. This result indicates that further improvement of the calculation model for yf(y) distribution in PHITS is needed for the analytical function that describes energy deposition by delta rays, particularly for primary ions having linear energy transfer in excess of a few hundred keV μm(-1).
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Affiliation(s)
- Shuichi Tsuda
- Research Group for Radiation Protection, Japan Atomic Energy Agency, 2-4, Shirakata-shirane, Tokai-mura, Naka-gun, Ibaraki 319-1195, Japan
| | - Tatsuhiko Sato
- Research Group for Radiation Protection, Japan Atomic Energy Agency, 2-4, Shirakata-shirane, Tokai-mura, Naka-gun, Ibaraki 319-1195, Japan
| | - Ritsuko Watanabe
- Research Group for Radiation Effect Analysis, Japan Atomic Energy Agency, 2-4, Shirakata-shirane, Tokai-mura, Naka-gun, Ibaraki 319-1195, Japan
| | - Masashi Takada
- Department of Technical Support and Development Fundamental Technology Center, National Institute of Radiological Sciences, 4-9-1, Anagawa, Inage-ku, Chiba 263-8555, Japan
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17
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Butler DJ, Ramanathan G, Oliver C, Cole A, Lye J, Harty PD, Wright T, Webb DV, Followill DS. Direct megavoltage photon calibration service in Australia. Australas Phys Eng Sci Med 2014; 37:753-61. [PMID: 25146559 PMCID: PMC4297255 DOI: 10.1007/s13246-014-0293-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Accepted: 08/12/2014] [Indexed: 10/24/2022]
Abstract
The Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) maintains the Australian primary standard of absorbed dose. Until recently, the standard was used to calibrate ionisation chambers only in (60)Co gamma rays. These chambers are then used by radiotherapy clinics to determine linac output, using a correction factor (k Q) to take into account the different spectra of (60)Co and the linac. Over the period 2010-2013, ARPANSA adapted the primary standard to work in megavoltage linac beams, and has developed a calibration service at three photon beams (6, 10 and 18 MV) from an Elekta Synergy linac. We describe the details of the new calibration service, the method validation and the use of the new calibration factors with the International Atomic Energy Agency's TRS-398 dosimetry Code of Practice. The expected changes in absorbed dose measurements in the clinic when shifting from (60)Co to the direct calibration are determined. For a Farmer chamber (model 2571), the measured chamber calibration coefficient is expected to be reduced by 0.4, 1.0 and 1.1 % respectively for these three beams when compared to the factor derived from (60)Co. These results are in overall agreement with international absorbed dose standards and calculations by Muir and Rogers in 2010 of k Q factors using Monte Carlo techniques. The reasons for and against moving to the new service are discussed in the light of the requirements of clinical dosimetry.
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Affiliation(s)
- D J Butler
- Australian Radiation Protection and Nuclear Safety Agency, 619 Lower Plenty Road, Yallambie, VIC, 3085, Australia,
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18
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Maslyuk VT, Megela IG, Okunieva TO, Pekar JM, Pekar VJ. Specific features of the influence of high-energy electron beams on the luminescent properties of undoped and Nb, Fe-doped Al₂O₃ crystals. Radiat Prot Dosimetry 2014; 162:34-37. [PMID: 25061130 DOI: 10.1093/rpd/ncu213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The influence of 10 MeV high-current electron beams accelerated by the M-30 microtron on the luminescent properties of the α-Al₂O₃, Al₂O₃:Nb and Al₂O₃:Fe crystals has been studied. The effect of the long-term phosphorescence at room temperature has been found that can be used to monitor electron and gamma accelerator beams.
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Affiliation(s)
- V T Maslyuk
- Institute of Electron Physics, Ukr. Nat. Acad. Sci., Universytetska St. 21, Uzhhorod 88000, Ukraine
| | - I G Megela
- Institute of Electron Physics, Ukr. Nat. Acad. Sci., Universytetska St. 21, Uzhhorod 88000, Ukraine
| | - T O Okunieva
- Institute of Electron Physics, Ukr. Nat. Acad. Sci., Universytetska St. 21, Uzhhorod 88000, Ukraine
| | - J M Pekar
- LLC 'Tehnocristal-Corund', Granitna St., 5a, Uzhhorod 88000, Ukraine
| | - V J Pekar
- LLC 'Tehnocristal-Corund', Granitna St., 5a, Uzhhorod 88000, Ukraine
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Yabuta K, Monzen H, Tamura M, Tsuruta T, Itou T, Nohtomi A, Nishimura Y. [Neutron Dosimetry System Using CR-39 for High-energy X-ray Radiation Therapy]. Igaku Butsuri 2014; 34:139-148. [PMID: 26288880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Neutrons are produced during radiation treatment by megavolt X-ray energies. However, it is difficult to measure neutron dose especially just during the irradiation. Therefore, we have developed a system for measuring neutrons with the solid state track detector CR-39, which is free from the influence of the X-ray beams. The energy spectrum of the neutrons was estimated by a Monte Carlo simulation method, and the estimated neutron dose was corrected by the contribution ratio of each energy. Pit formation rates of CR-39 ranged from 2.3 x 10(-3) to 8.2 x 10(-3) for each detector studied. According to the estimated neutron energy spectrum, the energy values for calibration were 144 keV and 515keV, and the contribution ratios were approximately 40:60 for 10 MV photons and 20:70 for photons over 15 MV. Neutron doses measured in the center of a high-energy X-ray field were 0.045 mSv/Gy for a 10 MV linear accelerator and 0.85 mSv/Gy for a 20 MV linear accelerator. We successfully developed the new neutron dose measurement system using the solid track detector, CR-39. This on-time neutron measurement system allows users to measure neutron doses produced in the radiation treatment room more easily.
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20
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Notake R, Kyuuma Y, Sasamori K, Sagawa M, Annaka Y, Saitoh H, Shibuya H. Experimental evaluations of head scatter factor calculation by use of a Gaussian function. Radiol Phys Technol 2013; 7:114-23. [PMID: 24323798 DOI: 10.1007/s12194-013-0251-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Revised: 10/31/2013] [Accepted: 11/03/2013] [Indexed: 11/25/2022]
Abstract
In external beam radiation therapy, it is important to calculate the output of the linear accelerator. The head scatter factor, S h, is one of the important factors for calculation of Monitor Unit, which changes with the size of the irradiation field. In irregular fields shaped by multileaf collimators (MLCs), it is difficult to calculate S h precisely. S h comprises backscatter from the upper and lower secondary collimators and scatter from the flattening filter. We measured the effect of backscatter on a monitor chamber (S b), and we modeled the scatter from a flattening filter using a Gaussian distribution. The modeled parameters used in this method are derived from measurements of square field sizes on the central axis. Furthermore, we divided an MLC irregular field in the shape of fans and integrated the scatter from a flattening filter by a method similar to Clarkson's sector integration. We were able to calculate S h with <1% error in comparison with measurements, even with a field setting with an error of >3% by the conventional method. This method requires no special measuring tools or software.
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Affiliation(s)
- Ryoichi Notake
- Head and Neck Reconstruction Division, Department of Diagnostic Radiology and Oncology, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyoku, Tokyo, 113-8519, Japan,
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21
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Takada M, Kosako K, Oishi K, Nakamura T, Sato K, Kamiyama T, Kiyanagi Y. Angular distributions of absorbed dose of Bremsstrahlung and secondary electrons induced by 18-, 28- and 38-MeV electron beams in thick targets. Radiat Prot Dosimetry 2013; 153:369-383. [PMID: 22761326 DOI: 10.1093/rpd/ncs114] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Angular distributions of absorbed dose of Bremsstrahlung photons and secondary electrons at a wide range of emission angles from 0 to 135°, were experimentally obtained using an ion chamber with a 0.6 cm(3) air volume covered with or without a build-up cap. The Bremsstrahlung photons and electrons were produced by 18-, 28- and 38-MeV electron beams bombarding tungsten, copper, aluminium and carbon targets. The absorbed doses were also calculated from simulated photon and electron energy spectra by multiplying simulated response functions of the ion chambers, simulated with the MCNPX code. Calculated-to-experimental (C/E) dose ratios obtained are from 0.70 to 1.57 for high-Z targets of W and Cu, from 15 to 135° and the C/E range from 0.6 to 1.4 at 0°; however, the values of C/E for low-Z targets of Al and C are from 0.5 to 1.8 from 0 to 135°. Angular distributions at the forward angles decrease with increasing angles; on the other hand, the angular distributions at the backward angles depend on the target species. The dependences of absorbed doses on electron energy and target thickness were compared between the measured and simulated results. The attenuation profiles of absorbed doses of Bremsstrahlung beams at 0, 30 and 135° were also measured.
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Affiliation(s)
- Masashi Takada
- National Institute of Radiological Sciences, Chiba 263-8555, Japan.
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22
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Zhu J, Chen S, Chen L, Liu X. Evaluations of absorbed dose ratio factor of Al2O3 dosemeter in radiotherapy photon beams using cavity theory. Radiat Prot Dosimetry 2012; 152:393-399. [PMID: 22562942 DOI: 10.1093/rpd/ncs061] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The aim of the work was to evaluate the absorbed dose ratio factor f(md) of an Al(2)O(3) dosemeter to water in photon radiotherapy beams using cavity theory. Burlin theory was used for calculating of this ratio. The effective mass attenuation coefficient β was obtained by comparing Monte Carlo simulations in monoenergetic photon beams. The evaluations of the absorbed dose ratio factor f(md) were studied for Al(2)O(3) dosemeters of different sizes, which were placed at various depths of the water phantom in different radiation field sizes of Mohan's 6, 10 and 15-MV X-rays. Beyond the build-up region, the variation of f(md) increases by 0.25 % as the depth increases from 4 to 10 cm. The maximum variation due to different dosemeter sizes is 8.3 %. The difference in the f(md) due to different radiation field sizes is 1.5 %. The effect of the dosemeter size cannot be neglected. The difference in the f(md) due to the radiation field sizes of different beams would increase as the dosemeter size increases.
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Affiliation(s)
- Jinhan Zhu
- School of Physics Science and Engineering, Sun Yat-Sen University, Guangzhou 510275, China
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23
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Lonski P, Taylor ML, Franich RD, Harty P, Kron T. Assessment of leakage doses around the treatment heads of different linear accelerators. Radiat Prot Dosimetry 2012; 152:304-312. [PMID: 22511732 DOI: 10.1093/rpd/ncs049] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Out-of-field doses to untargeted organs may have long-term detrimental health effects for patients treated with radiotherapy. It has been observed that equivalent treatments delivered to patients with different accelerators may result in significant differences in the out-of-field dose. In this work, the points of leakage dose are identified about the gantry of several treatment units. The origin of the observed higher doses is investigated. LiF:Mg,Cu,P thermoluminescent dosimetry has been employed to quantify the dose at a several points around the linac head of various linear accelerators (linacs): a Varian 600C, Varian 21-iX, Siemens Primus and Elekta Synergy-II. Comparisons are also made between different energy modes, collimator rotations and field sizes. Significant differences in leaked photon doses were identified when comparing the various linac models. The isocentric-waveguide 600C generally exhibits the lowest leakage directed towards the patient. The Siemens and Elekta models generally produce a greater leakage than the Varian models. The leakage 'hotspots' are evident on the gantry section housing the waveguide on the 21-iX. For all machines, there are significant differences in the x and y directions. Larger field sizes result in a greater leakage at the interface plate. There is a greater leakage around the waveguide when operating in a low-energy mode, but a greater leakage for the high-energy mode at the linac face. Of the vendors investigated, the Varian 600C showed the lowest average leakage dose. The Varian 21-iX showed double the dose of the 600C. The Elekta Synergy-II had on average four times the dose leakage than the 600C, and the Siemens Primus showed an average of five times that of the 600C. All vendors show strong differences in the x and y directions. The results offer the potential for patient-positioning strategies, linac choice and shielding strategies to reduce the leakage dose to patients.
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Affiliation(s)
- P Lonski
- School of Applied Sciences, RMIT University, GPO Box 2476, Melbourne 3000, Australia
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Alnawaf H, Butson M, Yu PKN. Measurement and effects of MOSKIN detectors on skin dose during high energy radiotherapy treatment. Australas Phys Eng Sci Med 2012; 35:321-8. [PMID: 22972481 DOI: 10.1007/s13246-012-0153-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2012] [Accepted: 06/28/2012] [Indexed: 12/01/2022]
Abstract
During in vivo dosimetry for megavoltage X-ray beams, detectors such as diodes, Thermo luminescent dosimeters (TLD's) and MOSFET devices are placed on the patient's skin. This of course will affect the skin dose delivered during that fraction of the treatment. Whilst the overall impact on increasing skin dose would be minimal, little has been quantified concerning the level of increase in absorbed dose, in vivo dosimeters produce when placed in the beams path. To this extent, measurements have been made and analysis performed on dose changes caused by MOSKIN, MOSFET, skin dose detectors. Maximum increases in skin dose were measured as 15 % for 6 MV X-rays and 10 % for 10 MV X-rays at the active crystal of the MOSKIN device which is the thickest part of the detector. This is compared to 32 and 26 % for a standard 1 mm thick LiF TLD at 10 × 10 cm(2) field size for 6 and 10 MV X-rays respectively. Radiochromic film, EBT2 has been shown to provide a high resolution 2 dimensional map of skin dose from these detectors and measures the effects of in vivo dosimeters used for radiotherapy dose assessment.
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Affiliation(s)
- Hani Alnawaf
- Centre for Medical Radiation Physics, Illawarra Health and Medical Research Institute, University of Wollongong, Northfields Ave, Gwynneville, NSW, Australia
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Iktueren B, Bilge H, Karacam S, Atkovar G. The peripheral dose outside the applicator in electron beams of Oncor linear accelerator. Radiat Prot Dosimetry 2012; 150:192-197. [PMID: 22025738 DOI: 10.1093/rpd/ncr392] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
In this study, the peripheral dose outside the applicator was measured using electron beams produced by an Oncor linear accelerator and compared with the data of the treatment planning system (TPS). The dose profiles have been measured, by using a water-equivalent slab phantom and a parallel plate ionisation chamber, at 6, 9 and 15 MeV energy levels in 5×5, 10×10, 15×15, 20×20 and 25×25 cm(2) applicators and at 0, 10 and 20° gantry angles; and at the surface, 0.2, 0.5, 1 cm and d(max) depth for each electron energy level. The peripheral dose has been determined with these profiles by normalisation at the field central beam axis (CAX). It has been noticed that, using a 10×10 cm(2) applicator, there is a 1.4 % dose peak on the surface 6 cm away from the field edge where the field CAX is at 100 %, at a gantry angle of 0° with 6 and 9 MeV electron beams; also for the 15 MeV electron beam there is a 2.3 % dose peak. It has been discovered that the peak dose approaches a minimum depending on the increase in depth and reaches 2.5-4 % depending on the growth of the field dimension. At gantry angles of 10 and 20°, 6 and 9 MeV electron beams created small peaks and a maximum dose could be reached at 0.2 and 1 cm depth. Electron beam of 15 MeV did not peak at depths of 0.2 and 1 cm at gantry angles of 10 and 20°. The measured peripheral dose outside the applicators has been compared with the data from a TPS's computer using the Pencil Beam algorithm; it has been stated that dose calculations can be made as far as 3 cm outside the field. In conclusion, the TPS is not sufficient to measure the peripheral dose outside the applicators, and this dose can only be determined by direct measurement.
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Affiliation(s)
- Basak Iktueren
- Radiation Oncology Department, Cerrahpasa Medical Faculty, Istanbul University, Istanbul, Turkey.
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Kaiser FJ, Bassler N, Tölli H, Jäkel O. Initial recombination in the track of heavy charged particles: numerical solution for air filled ionization chambers. Acta Oncol 2012; 51:368-75. [PMID: 22047061 DOI: 10.3109/0284186x.2011.626452] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
INTRODUCTION Modern particle therapy facilities enable sub-millimeter precision in dose deposition. Here, also ionization chambers (ICs) are used, which requires knowledge of the recombination effects. Up to now, recombination is corrected using phenomenological approaches for practical reasons. In this study the effect of the underlying dose distribution on columnar recombination, a quantitative model for initial recombination, is investigated. MATERIAL AND METHODS Jaffé's theory, formulated in 1913 quantifies initial recombination by elemental processes, providing an analytical (closed) solution. Here, we investigate the effect of the underlying charged carrier distribution around a carbon ion track. The fundamental partial differential equation, formulated by Jaffé, is solved numerically taking into account more realistic charge carrier distributions by the use of a computer program (Gascoigne 3D). The investigated charge carrier distributions are based on track structure models, which follow a 1/r(2) behavior at larger radii and show a constant value at small radii. The results of the calculations are compared to the initial formulation and to data obtained in experiments using carbon ion beams. RESULTS The comparison between the experimental data and the calculations shows that the initial approach made by Jaffé is able to reproduce the effects of initial recombination. The amorphous track structure based charge carrier distribution does not reproduce the experimental data well. A small additional correction in the assessment of the saturation current or charge is suggested by the data. CONCLUSION The established model of columnar recombination reproduces the experimental data well, whereas the extensions using track structure models do not show such an agreement. Additionally, the effect of initial recombination on the saturation curve (i.e. Jaffé plot) does not follow a linear behavior as suggested by current dosimetry protocols, therefore higher order corrections (such as the investigated ones) might be necessary.
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Fujibuchi T, Obara S, Yamaguchi I, Oyama M, Watanabe H, Sakae T, Katoh K. Induced radioactive nuclides of 10-MeV radiotherapy accelerators detected by using a portable HP-Ge survey meter. Radiat Prot Dosimetry 2012; 148:168-173. [PMID: 21317145 DOI: 10.1093/rpd/ncr005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The radioactivation of linear accelerator components for radiation therapy is interest for radiation protection in general, and particularly, when decommissioning these structures. The energy spectra of gamma rays emitted from the heads of two accelerator models, EXL-15SP and Clinac iX, after 10-MeV X-ray irradiation, were measured using a high-purity germanium semiconductor survey meter. After spectrum analyses, activities of (24)Na, (28)Al, (54)Mn, (56)Mn, (57)Ni, (58)Co, (60)Co, (64)Cu, (65)Zn, (122)Sb, (124)Sb, (181)W, (187)W, (196)Au, and (198)Au were detected. One centimetre deep dose-equivalent rate of the heads of the linear accelerator was measured using the survey meter. The dose rate decreased to ∼10 % of its initial rate after 1 week. Long-term activations were few, the radioactivity level was low, and a cooling time of several days was effective for reducing dose rate to an acceptable level for decommissioning.
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Affiliation(s)
- Toshioh Fujibuchi
- Department of Radiological Sciences, School of Health Sciences, Ibaraki Prefectural University of Health Science, 4669-2 Ami, Ami-machi, Inashiki-gun, Ibaraki 300-0394, Japan
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28
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Tsujii H. [History and current status of charged particle therapy in Japan]. Igaku Butsuri 2012; 32:98-103. [PMID: 24592678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Affiliation(s)
- Hirohiko Tsujii
- National Institute of Radiological Sciences, Inage-ku, Chiba 263-8555, Japan
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29
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Fukumura A, Mizuno H, Fukahori M, Sakata S. [Development of the 60Co gamma-ray standard field for therapy-level dosimeter calibration in terms of absorbed dose to water (N(D,w))]. Igaku Butsuri 2012; 32:182-188. [PMID: 24568023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A primary standard for the absorbed dose rate to water in a 60Co gamma-ray field was established at National Metrology Institute of Japan (NMIJ) in fiscal year 2011. Then, a 60Co gamma-ray standard field for therapy-level dosimeter calibration in terms of absorbed dose to water was developed at National Institute of Radiological Sciences (NIRS) as a secondary standard dosimetry laboratory (SSDL). The results of an IAEA/WHO TLD SSDL audit demonstrated that there was good agreement between NIRS stated absorbed dose to water and IAEA measurements. The IAEA guide based on the ISO standard was used to estimate the relative expanded uncertainty of the calibration factor for a therapy-level Farmer type ionization chamber in terms of absorbed dose to water (N(D,w)) with the new field. The uncertainty of N(D,w) was estimated to be 1.1% (k = 2), which corresponds to approximately one third of the value determined in the existing air kerma field. The dissemination of traceability of the calibration factor determined in the new field is expected to diminish the uncertainty of dose delivered to patients significantly.
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Affiliation(s)
| | | | - Mai Fukahori
- National Institute of Radiological Sciences, Chiba, Japan
| | - Suoh Sakata
- National Institute of Radiological Sciences, Chiba, Japan
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Abstract
Simulations based on the coupled relativistic equations of motion show that protons stemming from laser-plasma processes can be efficiently post-accelerated employing single and crossed pulsed laser beams focused to spot radii on the order of the laser wavelength. We demonstrate that the crossed beams produce quasi-monoenergetic accelerated protons with kinetic energies exceeding 200 MeV, small energy spreads of about 1% and high densities as required for hadron cancer therapy. To our knowledge, this is the first scheme allowing for this important application based on an all-optical set-up.
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Affiliation(s)
- Benjamin J Galow
- Max-Planck-Institut f¨ur Kernphysik, Saupfercheckweg 1, D-69029 Heidelberg, Germany
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31
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Johnson B. Planning for proton therapy. Health Estate 2010; 64:26-29. [PMID: 20839523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Bruce Johnson, senior vice-president at the Houston, Texas offices of internationally-recognised HKS Architects, examines the considerable physical challenge of accommodating sizeable proton external beam radiation therapy equipment into hospitals, drawing on work undertaken by the practice to date in designing hospitals to cater for such sizeable machinery.
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32
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Hu J, Tao J, Zhang Y, Zhang Y. [Some special problems and countermeasure about dose calibration of high-energy electron for linear accelerator]. Zhongguo Yi Liao Qi Xie Za Zhi 2010; 34:94-96. [PMID: 20540289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
This article presents and discusses some special problems about the dose calibration of high-energy elections for Linear Accelerator according to the practice of the authors. Thus the paper explain the issues of this work, and clarify the wrong understanding of real work for the aim of attaining the rules of quality assurance in radiotherapy by WHO.
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Affiliation(s)
- Jie Hu
- Department of Radiotherapy, Shanghai Tenth People's Hospital, Shanghai 200072.
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33
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Fassò A, Rokni S. Operational radiation protection in high-energy physics accelerators: implementation of ALARA in design and operation of accelerators. Radiat Prot Dosimetry 2009; 137:94-99. [PMID: 19783841 DOI: 10.1093/rpd/ncp189] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
This paper considers the historical evolution of the concept of optimisation of radiation exposures, as commonly expressed by the acronym ALARA, and discusses its application to various aspects of radiation protection at high-energy accelerators.
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Affiliation(s)
- A Fassò
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA.
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Abstract
An overview of operational radiation protection (RP) policies and practices at high-energy electron and proton accelerators used for physics research is presented. The different radiation fields and hazards typical of these facilities are described, as well as access control and radiation control systems. The implementation of an operational RP programme is illustrated, covering area and personnel classification and monitoring, radiation surveys, radiological environmental protection, management of induced radioactivity, radiological work planning and control, management of radioactive materials and wastes, facility dismantling and decommissioning, instrumentation and training.
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Affiliation(s)
- S H Rokni
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA.
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35
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Zabihzadeh M, Ay MR, Allahverdi M, Mesbahi A, Mahdavi SR, Shahriari M. Monte Carlo estimation of photoneutrons contamination from high-energy X-ray medical accelerators in treatment room and maze: a simplified model. Radiat Prot Dosimetry 2009; 135:21-32. [PMID: 19483207 DOI: 10.1093/rpd/ncp097] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Despite all advantages associated with high-energy radiotherapy to improve therapeutic gain, the production of photoneutron via interaction of high-energy photons with high atomic number (Z) materials increases undesired dose to the patient and staff. Owing to the limitation and complication of experimental neutron dosimetry in mixed beam environment, including photon and neutron, the Monte Carlo (MC) simulation is a gold standard method for calculation of photoneutron contaminations. On the other hand, the complexity of treatment head makes the MC simulation more difficult and time-consuming. In this study, the possibility of using a simplified MC model for the simulation of treatment head has been investigated using MCNP4C general purpose MC code. As a part of comparative assessment strategy, the fluence, average energy and dose equivalent of photoneutrons were estimated and compared with other studies for several fields and energies at different points in treatment room and maze. The mean energy of photoneutrons was 0.17, 0.19 and 0.2 MeV at the patient plan for 10, 15 and 18 MeV, respectively. The calculated values differed, respectively, by a factor of 1.4, 0.7 and 0.61 compared with the reported measured data for 10, 15 and 18 MeV. Our simulation results in the maze showed that the neutron dose equivalent is attenuated by a factor of 10 for every 4.6 m of maze length while the related factor from Kersey analytical method is 5 m. The neutron dose equivalent was 4.1 mSv Gy(-1) at the isocentre and decreased to 0.79 mSv Gy(-1) at a distance of 100 cm away from the isocentre for 40 x 40 cm(2). There is good agreement between the data calculated using simplified model in this study and measurements. Considering the reported high uncertainties (up to 50%) in experimental neutron dosimetry, it can be concluded that the simplified model can be used as a useful tool for estimation of photoneutron contamination associated with high-energy photon radiotherapy.
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Affiliation(s)
- Mansour Zabihzadeh
- Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran, Iran
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Abstract
Complex radiation therapy techniques require dosimetric verification of treatment planning and delivery. The authors investigated a liquid scintillator (LS) system for application for real-time high-energy photon beam dosimetry. The system was comprised of a transparent acrylic tank filled with liquid scintillating material, an opaque outer tank, and a CCD camera. A series of images was acquired when the tank with liquid scintillator was irradiated with a 6 MV photon beam, and the light data measured with the CCD camera were filtered to correct for scattering of the optical light inside the liquid scintillator. Depth-dose and lateral profiles as well as two-dimensional (2D) dose distributions were found to agree with results from the treatment planning system. Further, the corrected light output was found to be linear with dose, dose rate independent, and is robust for single or multiple acquisitions. The short time needed for image acquisition and processing could make this system ideal for fast verification of the beam characteristics of the treatment machine. This new detector system shows a potential usefulness of the LS for 2D QA.
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Affiliation(s)
- Falk Pönisch
- Department of Radiation Physics, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard., Unit 94, Houston, Texas 77030, USA
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Abstract
Spectral fluence of photoneutrons generated in the head of the radiotherapeutic linac Varian 2100 C/D was measured by means of the Bonner spheres spectrometer whose active detector of thermal neutrons was replaced by a track detector, i.e. a sandwich of four CR-39s with the boron radiator inserted between them. Measurements with different collimator settings showed that the fluence of photoneutrons was higher for the more open collimator.
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Affiliation(s)
- M Králík
- Inspectorate for Ionizing Radiation, Czech Metrology Institute, Radiová 1, CZ 102 00 Prague 10, Czech Republic.
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38
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Bilge H, Yondem S, Kucucuk H, Cakir A, Meral R. Effects of immobilization beds on the dose in the entrance and exit dose region for Co-60, 4, 6 and 15 MV photons. J BUON 2008; 13:385-390. [PMID: 18979554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
PURPOSE The aim of this study was to determine the effects of Styrofoam beds used for immobilization on build-up and exit dose regions for high energy photon beams. MATERIALS AND METHODS Build-up dose and exit dose measurements in central axis of Co-60 and 4, 6 and 15 MV photons at various field sizes and source to phantom distances were made in a water equivalent solid phantom with 2, 5 and 10 cm thick uniform Styrofoam beds at the surface. A Markus type plane-parallel ion chamber with fixed separation between collecting electrodes was used to measure the percent depth doses. RESULTS The surface dose increased almost linearly with field size for Co-60, 4, 6 and 15 MV X-ray beams. The effect of immobilization (Styrofoam beds) on the surface dose increased with the thickness and this effect was lower with higher energies. When a 2 cm thick Styrofoam bed was used for immobilization, the surface dose in a 10x10 cm field was higher (43.9, 36.8, 28.8 and 14.9% for Co-60, 4, 6 and 15 MV, respectively). CONCLUSION As the Styrofoam bed was thicker, the maximum dose point moved closer to the surface of the phantom for all energies. The exit surface dose was also enhanced with the presence of Styrofoam beds and similar to the effects on the surface dose. This enhancement was the maximum 5% for high energy photon beams and 6% for Co-60 beam. The introduction of Styrofoam beds in the radiation beam for the immobilization of the patient increases surface and exit doses to a considerable extent.
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Affiliation(s)
- H Bilge
- Istanbul University, Oncology Institute, Medical Physics Division, Radiation Oncology Department, Istanbul, Turkey
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39
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da Rosa LAR, Brito RRA, Gonçalves M, de Paiva E, Dovales ACM, Freire BLV, Giannoni RA, Di Prinzio R, Velasco AF, Castelo LHR, Oliveira RV. Dosimetric audits of photon beams in radiation therapy centres in Rio de Janeiro, Brazil. Radiat Prot Dosimetry 2008; 131:272-275. [PMID: 18503063 DOI: 10.1093/rpd/ncn169] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Data related to 11 y of high-energy photon radiotherapy beam dosimetry are presented and analysed. Dosimetric evaluations were carried out using water phantoms and thimble ionisation chambers and are part of the radiation protection regulatory licensing process for medicine facilities of Brazilian government. Measurements were done at reference conditions for a standard absorbed dose of 100 cGy [cGy (=1 rad)]. The absolute per cent deviation between the measured and presumed delivered doses should not exceed the tolerance level of +/-3%. The first dosimetry survey from 1996 to 1998 showed a situation that was an object of concern. Deviations of 22 and 18.7% could be measured, although small deviations were also obtained. After 1998, the improvement in dosimetry quality control by the radiotherapy centres became clear, with most of the deviations situated within the +/-3% range. The decrease in the measured deviations presents the effective success of the Institute of Radiation Protection and Dosimetry audit programme for the improvement in the control of radiotherapy photon beams in Rio de Janeiro. Also, it is possible to recommend to Brazilian regulatory organisation a decrease in the tolerance level for dosimetric deviations in order to achieve a more precise dose delivered to patients in radiotherapy centres.
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Affiliation(s)
- L A R da Rosa
- Instituto de Radioproteção e Dosimetria - IRD/CNEN, Av. Salvador Allende s/n, 22780-160 Rio de Janeiro, RJ, Brazil.
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40
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Abstract
Sequences of in situ gamma spectra, accompanied by continuous dose rate measurements, have been obtained at the isocenters of four different brands of high-energy medical linear accelerators shortly after beam-off in order to study the effects of radioactivation. Spectral analysis revealed up to 20 different radionuclides per machine, with a total of 21 found isotopes having half-lives between 2.3 min and 5.3 y. Important isotopes as judged from activity, dose rate, and half-life were Al, Mn, Mn, Ni, Co, Cu, Cu, Sb, W, and Au. Dose rates at isocenter calculated from the results of spectrum analysis ranged between 0.78 and 3.16 microSv h after beam-off, decaying to values between 0.18 and 0.54 microSv h within 30 min. Measured dose rates were systematically higher by up to a factor of 2, which is attributed mainly to the effect of beta radiation. No systematic dependence on machine properties or manufacturer could be identified. Assuming realistic working scenarios, absorbed dose values for the radiotherapy technologist staff range between 0.62 and 2.53 mSv y.
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Kitagawa A, Muramatsu M, Sasaki N, Takasugi W, Wakaisami S, Biri S, Drentje AG. Multiply charged carbon-ion production for medical application. Rev Sci Instrum 2008; 79:02C303. [PMID: 18315243 DOI: 10.1063/1.2832361] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Over 3000 cancer patients have already been treated by the heavy-ion medical accelerator in Chiba at the National Institute of Radiological Sciences since 1994. The clinical results have clearly verified the effectiveness and safety of heavy-ion radiotherapy. The most important result has been to establish that the carbon ion is one of the most effective radiations for radiotherapy. The ion source is required to realize a stable beam with the same conditions for daily operation. However, the deposition of carbon ions on the wall of the plasma chamber is normally unavoidable. This causes an "anti-wall-coating effect," i.e., a decreasing of the beam, especially for the higher charge-state ions due to the surface material of the wall. The ion source must be required to produce a sufficiently intense beam under the bad condition. Other problems were solved by improvements and maintenance, and thus we obtained enough reproducibility and stability along with decreased failures. We summarize our over 13 years of experience, and show the scope for further developments.
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Affiliation(s)
- A Kitagawa
- National Institute of Radiological Sciences, Inage, Chiba, Japan
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42
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Tinschert K, Iannucci R, Lang R. Electron cyclotron resonance ion sources in use for heavy ion cancer therapy. Rev Sci Instrum 2008; 79:02C505. [PMID: 18315248 DOI: 10.1063/1.2805226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The use of electron cyclotron resonance (ECR) ion sources for producing ion beams for heavy ion cancer therapy has been established for more than ten years. After the Heavy Ion Medical Accelerator (HIMAC) at Chiba, Japan started therapy of patients with carbon ions in 1994 the first carbon ion beam for patient treatment at the accelerator facility of GSI was delivered in 1997. ECR ion sources are the perfect tool for providing the required ion beams with good stability, high reliability, and easy maintenance after long operating periods. Various investigations were performed at GSI with different combinations of working gas and auxiliary gas to define the optimal beam conditions for an extended use of further ion species for the dedicated Heidelberg Ion Beam Therapy (HIT) facility installed at the Radiological University Hospital Heidelberg, Germany. Commercially available compact all permanent magnet ECR ion sources operated at 14.5 GHz were chosen for this facility. Besides for (12)C(4+) these ion sources are used to provide beams of (1)H(3)(1+), (3)He(1+), and (16)O(6+). The final commissioning at the HIT facility could be finished at the end of 2006.
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Affiliation(s)
- K Tinschert
- Gesellschaft für Schwerionenforschung (GSI), Planckstrasse 1, Darmstadt, Germany.
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Abstract
The PEFP has been developing a 100 MeV proton linear accelerator and user facilities for 20 and 100 MeV proton beams. At one end of the five 20 MeV proton beam lines, a proton microbeam construction was considered for an application in the fields of material, biological, and medical sciences. To develop the proton microbeam, realization of a few MeV proton beam with a few tens of microamperes in diameter of a beam spot was essentially required. In this report, the basic descriptions of the proton microbeam which is composed of an energy degrader, slits, magnetic lens, a target chamber, and detectors are presented including a consideration of unfavorable aspects concerning some specific characteristics of a linear accelerator, such as pulse mode operation and fixed energy. Some calculation results from a Monte Carlo simulation by using the SRIM2006 and the TURTLE codes are also included.
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Affiliation(s)
- Kye Ryung Kim
- Korea Atomic Energy Research Institute, Daejeon, Republic of Korea
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Winkelmann T, Cee R, Haberer T, Naas B, Peters A, Scheloske S, Spädtke P, Tinschert K. Electron cyclotron resonance ion source experience at the Heidelberg Ion Beam Therapy Center. Rev Sci Instrum 2008; 79:02A331. [PMID: 18315121 DOI: 10.1063/1.2823952] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Radiotherapy with heavy ions is an upcoming cancer treatment method with to date unparalleled precision. It associates higher control rates particularly for radiation resistant tumor species with reduced adverse effects compared to conventional photon therapy. The accelerator beam lines and structures of the Heidelberg Ion Beam Therapy Center (HIT) have been designed under the leadership of GSI, Darmstadt with contributions of the IAP Frankfurt. Currently, the accelerator is under commissioning, while the injector linac has been completed. When the patient treatment begins in 2008, HIT will be the first medical heavy ion accelerator in Europe. This presentation will provide an overview about the project, with special attention given to the 14.5 GHz electron cyclotron resonance (ECR) ion sources in operation with carbon, hydrogen, helium, and oxygen, and the experience of one year of continuous operation. It also displays examples for beam emittances, measured in the low energy beam transport. In addition to the outlook of further developments at the ECR ion sources for a continuously stable operation, this paper focuses on some of the technical processings of the past year.
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Affiliation(s)
- T Winkelmann
- Heidelberger Ionenstrahl-Therapie Centrum (HIT), Heidelberg, Germany
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45
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Konefal A, Polaczek-Grelik K, Zipper W. Undesirable nuclear reactions and induced radioactivity as a result of the use of the high-energy therapeutic beams generated by medical linacs. Radiat Prot Dosimetry 2008; 128:133-45. [PMID: 17569692 DOI: 10.1093/rpd/ncm318] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
In this paper, the problem of undesirable photonuclear, electronuclear and neutron capture reactions taking place in the treatment room during emission of the typical high-energy therapeutic beams from two different medical accelerators, i.e. Primus Siemens and Varian Clinac-2300, is presented. The radioisotopes (187)W, (56)Mn, (28)Al, (57)Ni, (38)Cl, (57)Co and (19)Au and the neutron activation of (1)H were identified as a consequence of these reactions. Moreover, the increased photon fluence rate behind the door of the accelerator bunker in the operator console room was observed during emission of the 20 MV X-rays from the Varian Clinac-2300 as well as in the case of the 15 MV X-ray beam from the Primus Siemens. No increased radiation was observed during the 6 MV X-ray beam emission. The performed measurements produced evidences on the presence of neutrons in the operator console room during emission of the 15 MV X-ray beam from the Primus Siemens as well as the 20 MV X-rays and the 22 MeV electrons from the Varian Clinac-2300 accelerator.
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Affiliation(s)
- Adam Konefal
- Department of Nuclear Physics and Its Application, Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice, Poland.
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46
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Hecksel D, Sandison GA, Farr JB, Edwards AC. Scattered neutron dose equivalent from an active scanning proton beam delivery system. Australas Phys Eng Sci Med 2007; 30:326-330. [PMID: 18274074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
A study of neutron production from a novel active scanning proton beam delivery system at the Midwest Proton Radiotherapy Institute (MPRI) has been performed. The neutron dose equivalent was determined using a neutron rem (roentgen equivalent in man) detector which has an upper energy limit of 10 MeV. Measurement were taken at 0, 45, and 90 degrees from the proton beam central axis and for various proton beam energies (127-208 MeV) and scanned field sizes (25-144 cm2). The maximum neutron dose observed was 0.43 mSv / (proton treatment Gy) at 90 degrees from the beam axis for a beam energy of 208.4 MeV and a scanned field size of 144 cm2. It is still possible to further mitigate this secondary neutron dose during treatment by optimizing parameters within the treatment nozzle and using shielding.
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Affiliation(s)
- Draik Hecksel
- School of Health Sciences, Purdue University, West Lafayette, Indiana, USA
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47
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Abstract
In three-dimensional irradiation with pencil beam scanning, an extra dose is inevitably delivered to the irradiated site due to the finite reaction times of the beam delivery system, and it causes a severe distortion of the dose distribution in the target region. Since the amount of the extra dose is proportional to the beam intensity, the dose uniformity deteriorates as the beam intensity is increased in order to shorten the treatment time. In order to overcome this problem and shorten the treatment time, we have developed an optimization method in which the extra dose is integrated into the optimization process of the best weighting matrix. The effectiveness and applicability of the optimization method for spot and raster scanning irradiation were confirmed with computer simulations and also confirmed using irradiation experiments for spot scanning irradiation. The treatment time could be shortened to about one sixth of the time needed without taking the extra dose into account while obtaining the same degree of dose homogeneity in the target volume. A typical treatment time with the proposed method is about 15 s for the irradiation of a spherical target with an 80 mm diameter at 3 GyE.
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Affiliation(s)
- Taku Inaniwa
- Medical Physics Research Group, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan.
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48
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Abstract
Proton therapy offers the potential for excellent dose conformity and reduction in integral dose. The superior dose distribution is, however, much more sensitive to changes in radiological depths along the beam path than for photon fields. Respiratory motion can cause such changes for treatments sites like lung, liver, and mediastinum and thus affect the proton dose distribution significantly. We have implemented and commissioned a respiratory-gated system for range-modulated treatment fields. The gating system was designed to ensure that each gate always contains complete modulation cycles so that for any beam segment the delivered dose has the planned depth-dose distribution. Measurements have been made to estimate the time delays for the various components of the system. The total delay between the actual motion and the beam on/off control is in the range of 65-195 ms. Time-resolved dose measurements and film tests were also conducted to examine the overall gating effect.
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Affiliation(s)
- Hsiao-Ming Lu
- Francis H. Burr Proton Therapy Center, Massachusetts General Hospital Harvard Medical School, Boston, Massachusetts 02214, USA.
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49
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Li Q, Dai Z, Yan Z, Jin X, Liu X, Xiao G. Heavy-ion conformal irradiation in the shallow-seated tumor therapy terminal at HIRFL. Med Biol Eng Comput 2007; 45:1037-43. [PMID: 17879104 DOI: 10.1007/s11517-007-0245-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2006] [Accepted: 08/20/2007] [Indexed: 10/22/2022]
Abstract
Basic research related to heavy-ion cancer therapy has been done at the Institute of Modern Physics (IMP), Chinese Academy of Sciences since 1995. Now a plan of clinical trial with heavy ions has been launched at IMP. First, superficially placed tumor treatment with heavy ions is expected in the therapy terminal at the Heavy Ion Research Facility in Lanzhou (HIRFL), where carbon ion beams with energy up to 100 MeV/u can be supplied. The shallow-seated tumor therapy terminal at HIRFL is equipped with a passive beam delivery system including two orthogonal dipole magnets, which continuously scan pencil beams laterally and generate a broad and uniform irradiation field, a motor-driven energy degrader and a multi-leaf collimator. Two different types of range modulator, ripple filter and ridge filter with which Guassian-shaped physical dose and uniform biological effective dose Bragg peaks can be shaped for therapeutic ion beams respectively, have been designed and manufactured. Therefore, two-dimensional and three-dimensional conformal irradiations to tumors can be performed with the passive beam delivery system at the earlier therapy terminal. Both the conformal irradiation methods have been verified experimentally and carbon-ion conformal irradiations to patients with superficially placed tumors have been carried out at HIRFL since November 2006.
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Affiliation(s)
- Qiang Li
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 730000, China.
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Kanematsu N, Torikoshi M, Mizota M, Kanai T. Secondary range shifting with range compensator for reduction of beam data library in heavy-ion radiotherapy. Med Phys 2007; 34:1907-10. [PMID: 17654892 DOI: 10.1118/1.2733812] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
We report our experience with extended usage of range compensators in heavy-ion radiotherapy with broad beams to lighten the management task of the beam data library, which is a collection of the standard beams to be referenced in treatment planning. Partly due to interference between lateral spreading and range shifting, as many as hundreds of beam entries may be necessary to cover all the possible clinical situations. We have introduced downstream secondary range shifting with a range compensator to reduce the interference and consequently to simplify the library. In our case, 30% reduction in beam entries is achieved without significantly degrading the beam quality nor increasing the material consumption by more than 3%, which is experimentally verified with carbon-ion beams or statistically estimated from the clinical records.
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Affiliation(s)
- Nobuyuki Kanematsu
- National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan.
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