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Sohrabi M. On Different Methods of Measuring Neutron Dose/Fluence Generated During Radiation Therapy with Megavoltage Beams. HEALTH PHYSICS 2020; 119:368-370. [PMID: 32740396 DOI: 10.1097/hp.0000000000001323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Affiliation(s)
- Mehdi Sohrabi
- Health Physics and Dosimetry Research Laboratory Department of Energy Engineering and Physics Amirkabir University of Technology Tehran, Iran
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Farhood B, Ghorbani M, Abdi Goushbolagh N, Najafi M, Geraily G. Different Methods of Measuring Neutron Dose/Fluence Generated During Radiation Therapy with Megavoltage Beams. HEALTH PHYSICS 2020; 118:65-74. [PMID: 31764421 DOI: 10.1097/hp.0000000000001130] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Medical linear accelerators (linacs) are the most frequently applied radiation therapy machines in the locoregional treatment of cancers by producing either high-energy electron or photon beams. However, with high-energy photons (>8 MeV), interaction of these photons with different high-Z nuclei of materials in components of the linac head unavoidably generates neutrons. On the other hand, the average energy of these generated neutrons has almost the highest radiation-weighting factor. Therefore, the produced neutrons should not be neglected. There are various tools for the measurement of neutron dose/fluence generated in a megavoltage linac, including thermoluminescent dosimeters, solid-state nuclear track detectors, bubble detectors, activation foils, Bonner sphere systems, and ionization chamber pairs. In this review article, each of the above-mentioned dosimetric methods will be described in detail.
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Affiliation(s)
- Bagher Farhood
- Department of Medical Physics and Radiology, Faculty of Paramedical Sciences, Kashan University of Medical Sciences, Kashan, Iran
| | - Mehdi Ghorbani
- Biomedical Engineering and Medical Physics Department, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Nouraddin Abdi Goushbolagh
- Medical Physics Department, Faculty of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
| | - Masoud Najafi
- Radiology and Nuclear Medicine Department, School of Paramedical Sciences, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Ghazale Geraily
- Medical Physics and Medical Engineering Department, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran
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Ghorbani M, Azizi M, Mowlavi AA, Azadegan B. Experimental study of the influence of dental restorations on thermal and fast photo-neutron production in radiotherapy with a high-energy photon beam. Appl Radiat Isot 2019; 147:113-120. [PMID: 30870764 DOI: 10.1016/j.apradiso.2019.03.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2018] [Revised: 02/01/2019] [Accepted: 03/04/2019] [Indexed: 10/27/2022]
Abstract
In head and neck radiation therapy, the presence of dental restorations can increase unwanted neutron dose to the patient. This study aimed at the measurement of secondary neutron production induced by irradiation of a healthy tooth, Amalgam, Ni-Cr alloy and Ceramco with a photon beam generated in the treatment head of a Siemens Primus linac at a voltage of 15 MV. The irradiation field amounted to 10 × 10 cm2. The measurements of thermal and fast-neutron equivalent doses were performed by means of CR-39 detectors positioned in various depths of a Perspex (polymethyl methacrylate) phantom as at open field as at presence of corresponding dental restorations. The general trend of thermal neutron as well as fast-neutron equivalent dose behind the denture samples reveals their reduction with increasing depth. The maximum values of thermal-neutron dose related to Amalgam, Ceramco and Ni-Cr alloy amount to 1.45 mSv/100 MU, 1.38 mSv/100 MU and 1.32 mSv/100 MU, whereas the corresponding maximum values of fast-neutron dose at the depth of 1.8 cm amount to 0.19 mSv/100 MU, 1.04 mSv/100 MU and 0.97 mSv/100 MU, respectively. The present study investigates the neutron dose accompanied with radiotherapy. It is recommended that attempts have to be made to ensure that dental restorations are not in the path of the primary high-energy photon beam. Considering treatment planning, the guidelines of radiation protection should be improved.
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Affiliation(s)
- Mahdi Ghorbani
- Medical Physics Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Mona Azizi
- Physics Department, School of Sciences, Hakim Sabzevari University, Sabzevar, Iran.
| | - Ali Asghar Mowlavi
- Physics Department, School of Sciences, Hakim Sabzevari University, Sabzevar, Iran; Associate Federation Scheme, Medical Physics Field, International Centre for Theoretical Physics (ICTP), Trieste, Italy
| | - Behnam Azadegan
- Physics Department, School of Sciences, Hakim Sabzevari University, Sabzevar, Iran
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Sánchez-Nieto B, Romero-Expósito M, Terrón JA, Irazola L, Paiusco M, Cagni E, Ghetti C, Filice S, Sánchez-Doblado F. Intensity-modulated radiation therapy and volumetric modulated arc therapy versus conventional conformal techniques at high energy: Dose assessment and impact on second primary cancer in the out-of-field region. Rep Pract Oncol Radiother 2018; 23:251-259. [PMID: 29991929 PMCID: PMC6035902 DOI: 10.1016/j.rpor.2018.04.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2017] [Revised: 01/19/2018] [Accepted: 04/12/2018] [Indexed: 12/22/2022] Open
Abstract
The aim of this work was to estimate peripheral neutron and photon doses associated with the conventional 3D conformal radiotherapy techniques in comparison to modern ones such as Intensity modulated radiation therapy and volumetric modulated arc therapy. Assessment in terms of second cancer incidence ought to peripheral doses was also considered. For that, a dosimetric methodology proposed by the authors has been applied beyond the region where there is no CT information and, thus, treatment planning systems do not calculate and where, nonetheless, about one third of second primary cancers occurs.
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Affiliation(s)
- Beatriz Sánchez-Nieto
- Instituto de Física, Pontificia Universidad Católica de Chile, Santiago, Chile
- Center UC Investigation in Oncology at Pontificia Universidad Católica de Chile, Pontificia Universidad Católica de Chile, Santiago, Chile
| | | | - José Antonio Terrón
- Servicio de Radiofísica, Hospital Universitario Virgen Macarena, Sevilla, Spain
| | - Leticia Irazola
- Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Sevilla, Spain
| | - Marta Paiusco
- Veneto Institute of Oncology IOV – IRCCS, Padua, Italy
| | | | - Caterina Ghetti
- Servizio di Fisica Sanitaria, Azienda Ospedaliera Universitaria di Parma, Italy
| | - Silvano Filice
- Servizio di Fisica Sanitaria, Azienda Ospedaliera Universitaria di Parma, Italy
| | - Francisco Sánchez-Doblado
- Servicio de Radiofísica, Hospital Universitario Virgen Macarena, Sevilla, Spain
- Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Sevilla, Spain
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Kry SF, Bednarz B, Howell RM, Dauer L, Followill D, Klein E, Paganetti H, Wang B, Wuu CS, George Xu X. AAPM TG 158: Measurement and calculation of doses outside the treated volume from external-beam radiation therapy. Med Phys 2017; 44:e391-e429. [DOI: 10.1002/mp.12462] [Citation(s) in RCA: 164] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 05/17/2017] [Accepted: 05/25/2017] [Indexed: 12/14/2022] Open
Affiliation(s)
- Stephen F. Kry
- Department of Radiation Physics; MD Anderson Cancer Center; Houston TX 77054 USA
| | - Bryan Bednarz
- Department of Medical Physics; University of Wisconsin; Madison WI 53705 USA
| | - Rebecca M. Howell
- Department of Radiation Physics; MD Anderson Cancer Center; Houston TX 77054 USA
| | - Larry Dauer
- Departments of Medical Physics/Radiology; Memorial Sloan-Kettering Cancer Center; New York NY 10065 USA
| | - David Followill
- Department of Radiation Physics; MD Anderson Cancer Center; Houston TX 77054 USA
| | - Eric Klein
- Department of Radiation Oncology; Washington University; Saint Louis MO 63110 USA
| | - Harald Paganetti
- Department of Radiation Oncology; Massachusetts General Hospital and Harvard Medical School; Boston MA 02114 USA
| | - Brian Wang
- Department of Radiation Oncology; University of Louisville; Louisville KY 40202 USA
| | - Cheng-Shie Wuu
- Department of Radiation Oncology; Columbia University; New York NY 10032 USA
| | - X. George Xu
- Department of Mechanical, Aerospace, and Nuclear Engineering; Rensselaer Polytechnic Institute; Troy NY 12180 USA
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Sánchez-Nieto B, Romero-Expósito M, Terrón JA, Sánchez-Doblado F. Uncomplicated and Cancer-Free Control Probability (UCFCP): A new integral approach to treatment plan optimization in photon radiation therapy. Phys Med 2017; 42:277-284. [PMID: 28392313 DOI: 10.1016/j.ejmp.2017.03.025] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Revised: 03/24/2017] [Accepted: 03/29/2017] [Indexed: 12/25/2022] Open
Abstract
PURPOSE Biological treatment plan evaluation does not currently consider second cancer induction from peripheral doses associated to photon radiotherapy. The aim is to propose a methodology to characterize the therapeutic window by means of an integral radiobiological approach, which considers not only Tumour Control Probability (TCP) and Normal Tissue Complication Probability (NTCP) but also Secondary Cancer Probability (SCP). METHODS Uncomplicated and Cancer-Free Control Probability (UCFCP) function has been proposed assuming a statistically uncorrelated response for tumour and normal tissues. The Poisson's and Lyman's models were chosen for TCP and NTCP calculations, respectively. SCP was modelled as the summation of risks associated to photon and neutron irradiation of radiosensitive organs. For the medium (>4Gy) and low dose regions, mechanistic and linear secondary cancer risks models were used, respectively. Two conformal and intensity-modulated prostate plans at 15MV (same prescription dose) were selected to illustrate the UCFCP features. RESULTS UCFCP exhibits a bell-shaped behaviour with its maximum inside the therapeutic window. SCP values were not different for the plans analysed (∼2.4%) and agreed with published epidemiological results. Therefore, main differences in UCFCP came from differences in rectal NTCP (18% vs 9% for 3D-CRT and IMRT, respectively). According to UCFCP values, the evaluated IMRT plan ranked first. CONCLUSIONS The level of SCP was found to be similar to that of NTCP complications which reinforces the importance of considering second cancer risks as part of the possible late sequelae due to treatment. Previous concerns about the effect of peripheral radiation, especially neutrons, in the induction of secondary cancers can be evaluated by quantifying the UCFCP.
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Affiliation(s)
- Beatriz Sánchez-Nieto
- Instituto de Física, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4880, Macul, Santiago, Chile.
| | - Maite Romero-Expósito
- Departament de Física, Universitat Autònoma de Barcelona, Edifici C, Campus UAB E-08193, Bellaterra, Spain.
| | - José A Terrón
- Servicio de Radiofísica, Hospital Universitario Virgen Macarena, Av. Doctor Fedriani, 3, 41009 Sevilla, Spain.
| | - Francisco Sánchez-Doblado
- Servicio de Radiofísica, Hospital Universitario Virgen Macarena, Av. Doctor Fedriani, 3, 41009 Sevilla, Spain; Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Av. Doctor Fedriani S/N, 41009 Sevilla, Spain.
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Sohrabi M, Hakimi A. Novel 6MV X-ray photoneutron detection and dosimetry of medical accelerators. Phys Med 2017; 36:103-109. [PMID: 28410678 DOI: 10.1016/j.ejmp.2017.03.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2016] [Revised: 03/17/2017] [Accepted: 03/20/2017] [Indexed: 10/19/2022] Open
Abstract
PURPOSE Dosimetry of fast, epithermal and thermal photoneutrons in 6MV X-ray beams of two medical accelerators were studied by novel dosimetry methods. METHODS A Siemens ONCOR and an Elekta COMPACT medical accelerators were used. Fast, epithermal and thermal photoneutron dose equivalents in 10cm×10cm 6MV X-rays fields were determined in air and on surface of a polyethylene phantom in X and Y directions. Polycarbonate dosimeters as bare or with enriched 10B convertors (with or without cadmium covers) were used applying a 50Hz-HV electrochemical etching method. RESULTS Fast, epithermal and thermal photoneutron dose equivalents were efficiently determined respectively as ∼1145.8, ∼45.3 and ∼170.6μSv in air and ∼1888.5, ∼96.1 and ∼640.6μSv on phantom per 100Gy X-rays at the isocenter of Siemens ONCOR accelerator in air. The dose equivalent is maximum at the isocenter which decreases as distance from it increases reaching a constant level. Tissue-to-air ratios are constants up to 15cm from the isocenter. No photoneutrons was detected in the Elekta COMPACT accelerator. CONCLUSIONS Fast, epithermal and thermal photoneutron dosimetry of 6MV X-rays were made by novel dosimetry methods in a Siemens ONCOR accelerator with sum dose equivalent per Gy of ∼0.0014% μSv with ∼0.21MeV mean energy at the isocenter; i.e. ∼150 times smaller than that of 18MV X-rays. This observation assures clinical safety of 6MV X-rays in particular in single-mode machines like Elekta COMPACT producing no photoneutrons due to no "beryllium exit window" in the head structure.
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Affiliation(s)
- Mehdi Sohrabi
- Health Physics and Dosimetry Research Laboratory, Department of Energy Engineering, and Physics, Amirkabir University of Technology, Tehran, Iran.
| | - Amir Hakimi
- Health Physics and Dosimetry Research Laboratory, Department of Energy Engineering, and Physics, Amirkabir University of Technology, Tehran, Iran
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Arbor N, Higueret S, Elazhar H, Combe R, Meyer P, Dehaynin N, Taupin F, Husson D. Real-time detection of fast and thermal neutrons in radiotherapy with CMOS sensors. Phys Med Biol 2017; 62:1920-1934. [PMID: 28192285 DOI: 10.1088/1361-6560/aa5bc9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The peripheral dose distribution is a growing concern for the improvement of new external radiation modalities. Secondary particles, especially photo-neutrons produced by the accelerator, irradiate the patient more than tens of centimeters away from the tumor volume. However the out-of-field dose is still not estimated accurately by the treatment planning softwares. This study demonstrates the possibility of using a specially designed CMOS sensor for fast and thermal neutron monitoring in radiotherapy. The 14 microns-thick sensitive layer and the integrated electronic chain of the CMOS are particularly suitable for real-time measurements in γ/n mixed fields. An experimental field size dependency of the fast neutron production rate, supported by Monte Carlo simulations and CR-39 data, has been observed. This dependency points out the potential benefits of a real-time monitoring of fast and thermal neutron during beam intensity modulated radiation therapies.
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Affiliation(s)
- Nicolas Arbor
- Université de Strasbourg, IPHC, 23 rue du Loess 67037 Strasbourg, France. CNRS, UMR7178, 67037 Strasbourg, France
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Irazola L, Terrón JA, Bedogni R, Pola A, Lorenzoli M, Jimenez-Ortega E, Barbeiro AR, Sánchez-Nieto B, Sánchez-Doblado F. Neutron measurements in radiotherapy: A method to correct neutron sensitive devices for parasitic photon response. Appl Radiat Isot 2017; 123:32-35. [PMID: 28214683 DOI: 10.1016/j.apradiso.2016.12.060] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2016] [Revised: 09/29/2016] [Accepted: 12/28/2016] [Indexed: 11/20/2022]
Abstract
One of the major causes of secondary malignancies after radiotherapy treatments are peripheral doses, known to increase for some newer techniques (such as IMRT or VMAT). For accelerators operating above 10MV, neutrons can represent important contribution to peripheral doses. This neutron contamination can be measured using different passive or active techniques, available in the literature. As far as active (or direct-reading) procedures are concerned, a major issue is represented by their parasitic photon sensitivity, which can significantly affect the measurement when the point of test is located near to the field-edge. This work proposes a simple method to estimate the unwanted photon contribution to these neutrons. As a relevant case study, the use of a recently neutron sensor for "in-phantom" measurements in high-energy machines was considered. The method, called "Dual Energy Photon Subtraction" (DEPS), requires pairs of measurements performed for the same treatment, in low-energy (6MV) and high energy (e.g. 15MV) fields. It assumes that the peripheral photon dose (PPD) at a fixed point in a phantom, normalized to the unit photon dose at the isocenter, does not depend on the treatment energy. Measurements with ionization chamber and Monte Carlo simulations were used to evaluate the validity of this hypothesis. DEPS method was compared to already published correction methods, such as the use of neutron absorber materials. In addition to its simplicity, an advantage of DEPs procedure is that it can be applied to any radiotherapy machine.
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Affiliation(s)
- L Irazola
- Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Spain; Servicio de Radiofísica, Hospital Universitario Virgen Macarena, Sevilla, Spain.
| | - J A Terrón
- Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Spain; Servicio de Radiofísica, Hospital Universitario Virgen Macarena, Sevilla, Spain
| | - R Bedogni
- Politecnico di Milano, Dipartimento di Ingegneria Nuclear, Milano, Italy
| | - A Pola
- Laboratori Nazionali di Frascati, Istituto Nazionale di Fisica Nucleare (INFN), Italy
| | - M Lorenzoli
- Laboratori Nazionali di Frascati, Istituto Nazionale di Fisica Nucleare (INFN), Italy
| | - E Jimenez-Ortega
- Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Spain
| | - A R Barbeiro
- Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Spain
| | - B Sánchez-Nieto
- Instituto de Física, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - F Sánchez-Doblado
- Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Spain; Servicio de Radiofísica, Hospital Universitario Virgen Macarena, Sevilla, Spain
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Improving the neutron-to-photon discrimination capability of detectors used for neutron dosimetry in high energy photon beam radiotherapy. Appl Radiat Isot 2016; 115:49-54. [DOI: 10.1016/j.apradiso.2016.06.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 06/08/2016] [Accepted: 06/08/2016] [Indexed: 11/17/2022]
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Kron T, Lehmann J, Greer PB. Dosimetry of ionising radiation in modern radiation oncology. Phys Med Biol 2016; 61:R167-205. [DOI: 10.1088/0031-9155/61/14/r167] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Sohrabi M, Hakimi A, Mahdavi SR. A novel position-sensitive mega-size dosimeter for photoneutrons in high-energy X-ray medical accelerators. Phys Med 2016; 32:778-86. [PMID: 27174443 DOI: 10.1016/j.ejmp.2016.05.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Revised: 05/03/2016] [Accepted: 05/05/2016] [Indexed: 11/15/2022] Open
Abstract
PURPOSE A novel position-sensitive mega-size polycarbonate (MSPC) dosimeter is introduced. It provides photoneutron (PN) dose equivalent matrix of positions in and out of a beam of a high energy X-ray medical accelerator under a single exposure. METHODS A novel position-sensitive MSPC dosimeter was developed and applied. It has an effective etched area of 50×50cm(2), as used in this study, processed in a mega-size electrochemical etching chamber to amplify PN-induced-recoil tracks to a point viewed by the unaided eyes. Using such dosimeters, PN dose equivalents, dose equivalent profiles and isodose equivalent distribution of positions in and out of beams for different X-ray doses and field sizes were determined in a Siemens ONCOR Linac. RESULTS The PN dose equivalent at each position versus X-ray dose was linear up to 20Gy studied. As the field size increased, the PN dose equivalent in the beam was also increased but it remained constant at positions out of the beam up to 20cm away from the beam edge. The jaws and MLCs due to material differences and locations relative to the target produce different PN contributions. CONCLUSIONS The MSPC dosimeter introduced in this study is a perfect candidate for PN dosimetry with unique characteristics such as simplicity, efficiency, dose equivalent response, large size, flexibility to be bent, resembling the patient's skin, highly position-sensitive with high spatial resolution, highly insensitive to X-rays, continuity in measurements and need to a single dosimeter to obtain PN dose equivalent matrix data under a single X-ray exposure.
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Affiliation(s)
- Mehdi Sohrabi
- Health Physics and Dosimetry Research Laboratory, Department of Energy Engineering and Physics, Amirkabir University of Technology, Tehran, Iran.
| | - Amir Hakimi
- Health Physics and Dosimetry Research Laboratory, Department of Energy Engineering and Physics, Amirkabir University of Technology, Tehran, Iran
| | - Seyed Rabi Mahdavi
- Department of Medical Physics, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran
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Irazola L, Praena J, Fernández B, Macías M, Bedogni R, Terrón JA, Sánchez-Nieto B, Arias de Saavedra F, Porras I, Sánchez-Doblado F. Using a Tandem Pelletron accelerator to produce a thermal neutron beam for detector testing purposes. Appl Radiat Isot 2015; 107:330-334. [PMID: 26595777 DOI: 10.1016/j.apradiso.2015.11.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Revised: 11/03/2015] [Accepted: 11/10/2015] [Indexed: 11/25/2022]
Abstract
Active thermal neutron detectors are used in a wide range of measuring devices in medicine, industry and research. For many applications, the long-term stability of these devices is crucial, so that very well controlled neutron fields are needed to perform calibrations and repeatability tests. A way to achieve such reference neutron fields, relying on a 3 MV Tandem Pelletron accelerator available at the CNA (Seville, Spain), is reported here. This paper shows thermal neutron field production and reproducibility characteristics over few days.
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Affiliation(s)
- L Irazola
- Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Spain; Servicio de Radiofísica, Hospital Universitario Virgen Macarena, Sevilla, Spain.
| | - J Praena
- Departamento de Física Atómica, Molecular y Nuclear, Universidad de Granada, Spain; Centro Nacional de Aceleradores (US-JA-CSIC), Sevilla, Spain
| | - B Fernández
- Departamento de Física Atómica, Molecular y Nuclear, Universidad de Granada, Spain
| | - M Macías
- Departamento de Física Atómica, Molecular y Nuclear, Universidad de Granada, Spain
| | - R Bedogni
- Istituto Nazionale di Fisica Nucleare (INFN), Frascati, Italy
| | - J A Terrón
- Servicio de Radiofísica, Hospital Universitario Virgen Macarena, Sevilla, Spain; Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Spain
| | - B Sánchez-Nieto
- Instituto de Física, Pontificia Universidad Católica de Chile, Santiago, Chile
| | | | - I Porras
- Centro Nacional de Aceleradores (US-JA-CSIC), Sevilla, Spain
| | - F Sánchez-Doblado
- Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Spain; Servicio de Radiofísica, Hospital Universitario Virgen Macarena, Sevilla, Spain
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Sánchez-Nieto B, El-far R, Irazola L, Romero-Expósito M, Lagares JI, Mateo JC, Terrón JA, Doblado FS. Analytical model for photon peripheral dose estimation in radiotherapy treatments. Biomed Phys Eng Express 2015. [DOI: 10.1088/2057-1976/1/4/045205] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Romero-Expósito M, Sánchez-Nieto B, Terrón JA, Lopes MC, Ferreira BC, Grishchuk D, Sandín C, Moral-Sánchez S, Melchor M, Domingo C, Gómez F, Sánchez-Doblado F. Commissioning the neutron production of a Linac: Development of a simple tool for second cancer risk estimation. Med Phys 2014; 42:276-81. [DOI: 10.1118/1.4903525] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Li G, Xu J, Zhang J. Estimation of low-level neutron dose-equivalent rate by using extrapolation method for a curie level Am-Be neutron source. Appl Radiat Isot 2014; 95:122-128. [PMID: 25464188 DOI: 10.1016/j.apradiso.2014.10.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 09/29/2014] [Accepted: 10/11/2014] [Indexed: 11/29/2022]
Abstract
Neutron radiation protection is an important research area because of the strong radiation biological effect of neutron field. The radiation dose of neutron is closely related to the neutron energy, and the connected relationship is a complex function of energy. For the low-level neutron radiation field (e.g. the Am-Be source), the commonly used commercial neutron dosimeter cannot always reflect the low-level dose rate, which is restricted by its own sensitivity limit and measuring range. In this paper, the intensity distribution of neutron field caused by a curie level Am-Be neutron source was investigated by measuring the count rates obtained through a 3He proportional counter at different locations around the source. The results indicate that the count rates outside of the source room are negligible compared with the count rates measured in the source room. In the source room, 3He proportional counter and neutron dosimeter were used to measure the count rates and dose rates respectively at different distances to the source. The results indicate that both the count rates and dose rates decrease exponentially with the increasing distance, and the dose rates measured by a commercial dosimeter are in good agreement with the results calculated by the Geant4 simulation within the inherent errors recommended by ICRP and IEC. Further studies presented in this paper indicate that the low-level neutron dose equivalent rates in the source room increase exponentially with the increasing low-energy neutron count rates when the source is lifted from the shield with different radiation intensities. Based on this relationship as well as the count rates measured at larger distance to the source, the dose rates can be calculated approximately by the extrapolation method. This principle can be used to estimate the low level neutron dose values in the source room which cannot be measured directly by a commercial dosimeter.
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Affiliation(s)
- Gang Li
- Department of Nuclear Engineering and Technology, College of Physical Science and Technology, Sichuan University, Chengdu 610064, Sichuan Province, China.
| | - Jiayun Xu
- Key Laboratory for Neutron Physics, Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621999, Sichuan Province, China.
| | - Jie Zhang
- Key Laboratory for Neutron Physics, Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621999, Sichuan Province, China
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Irazola L, Lorenzoli M, Bedogni R, Pola A, Terrón JA, Sanchez-Nieto B, Expósito MR, Lagares JI, Sansaloni F, Sanchez-Doblado F. A new online detector for estimation of peripheral neutron equivalent dose in organ. Med Phys 2014; 41:112105. [DOI: 10.1118/1.4898591] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Hernandez-Davila VM, Soto-Bernal TG, Vega-Carrillo HR. Determination of neutron fluence-to-dose conversion coefficients by means of artificial neural networks. Appl Radiat Isot 2014; 83 Pt C:249-51. [DOI: 10.1016/j.apradiso.2013.04.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Revised: 04/05/2013] [Accepted: 04/11/2013] [Indexed: 11/28/2022]
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20
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Bahreyni Toossi MT, Behmadi M, Ghorbani M, Gholamhosseinian H. A Monte Carlo study on electron and neutron contamination caused by the presence of hip prosthesis in photon mode of a 15 MV Siemens PRIMUS linac. J Appl Clin Med Phys 2013; 14:52-67. [PMID: 24036859 PMCID: PMC5714559 DOI: 10.1120/jacmp.v14i5.4253] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Revised: 06/01/2013] [Accepted: 05/27/2013] [Indexed: 12/05/2022] Open
Abstract
Several investigators have pointed out that electron and neutron contamination from high‐energy photon beams are clinically important. The aim of this study is to assess electron and neutron contamination production by various prostheses in a high‐energy photon beam of a medical linac. A 15 MV Siemens PRIMUS linac was simulated by MCNPX Monte Carlo (MC) code and the results of percentage depth dose (PDD) and dose profile values were compared with the measured data. Electron and neutron contaminations were calculated on the beam's central axis for Co‐Cr‐Mo, stainless steel, Ti‐alloy, and Ti hip prostheses through MC simulations. Dose increase factor (DIF) was calculated as the ratio of electron (neutron) dose at a point for 10×10 cm2 field size in presence of prosthesis to that at the same point in absence of prosthesis. DIF was estimated at different depths in a water phantom. Our MC‐calculated PDD and dose profile data are in good agreement with the corresponding measured values. Maximum dose increase factor for electron contamination for Co‐Cr‐Mo, stainless steel, Ti‐alloy, and Ti prostheses were equal to 1.18, 1.16, 1.16, and 1.14, respectively. The corresponding values for neutron contamination were respectively equal to: 184.55, 137.33, 40.66, and 43.17. Titanium‐based prostheses are recommended for the orthopedic practice of hip junction replacement. When treatment planning for a patient with hip prosthesis is performed for a high‐energy photon beam, attempt should be made to ensure that the prosthesis is not exposed to primary photons. PACS numbers: 87.56.bd, 87.55.kh, 87.55.Gh
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Expósito MR, Sánchez-Nieto B, Terrón JA, Domingo C, Gómez F, Sánchez-Doblado F. Neutron contamination in radiotherapy: Estimation of second cancers based on measurements in 1377 patients. Radiother Oncol 2013; 107:234-41. [DOI: 10.1016/j.radonc.2013.03.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2012] [Revised: 02/27/2013] [Accepted: 03/09/2013] [Indexed: 11/28/2022]
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Guardiola C, Gómez F, Fleta C, Rodríguez J, Quirion D, Pellegrini G, Lousa A, Martínez-de-Olcoz L, Pombar M, Lozano M. Neutron measurements with ultra-thin 3D silicon sensors in a radiotherapy treatment room using a Siemens PRIMUS linac. Phys Med Biol 2013; 58:3227-42. [PMID: 23611848 DOI: 10.1088/0031-9155/58/10/3227] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The accurate detection and dosimetry of neutrons in mixed and pulsed radiation fields is a demanding instrumental issue with great interest both for the industrial and medical communities. In recent studies of neutron contamination around medical linacs, there is a growing concern about the secondary cancer risk for radiotherapy patients undergoing treatment in photon modalities at energies greater than 6 MV. In this work we present a promising alternative to standard detectors with an active method to measure neutrons around a medical linac using a novel ultra-thin silicon detector with 3D electrodes adapted for neutron detection. The active volume of this planar device is only 10 µm thick, allowing a high gamma rejection, which is necessary to discriminate the neutron signal in the radiotherapy peripheral radiation field with a high gamma background. Different tests have been performed in a clinical facility using a Siemens PRIMUS linac at 6 and 15 MV. The results show a good thermal neutron detection efficiency around 2% and a high gamma rejection factor.
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Affiliation(s)
- C Guardiola
- Instituto de Microelectrónica de Barcelona (IMB-CNM, CSIC), E-08193 Bellaterra, Barcelona, Spain.
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Sánchez-Doblado F, Domingo C, Gómez F, Sánchez-Nieto B, Muñiz JL, García-Fusté MJ, Expósito MR, Barquero R, Hartmann G, Terrón JA, Pena J, Méndez R, Gutiérrez F, Guerre FX, Roselló J, Núñez L, Brualla-González L, Manchado F, Lorente A, Gallego E, Capote R, Planes D, Lagares JI, González-Soto X, Sansaloni F, Colmenares R, Amgarou K, Morales E, Bedogni R, Cano JP, Fernández F. Estimation of neutron-equivalent dose in organs of patients undergoing radiotherapy by the use of a novel online digital detector. Phys Med Biol 2012; 57:6167-91. [DOI: 10.1088/0031-9155/57/19/6167] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Domingo C, García-Fusté M, Morales E, Amgarou K, Terrón J, Roselló J, Brualla L, Nuñez L, Colmenares R, Gómez F, Hartmann G, Sánchez-Doblado F, Fernández F. Neutron spectrometry and determination of neutron ambient dose equivalents in different LINAC radiotherapy rooms. RADIAT MEAS 2010. [DOI: 10.1016/j.radmeas.2010.05.023] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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