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ABSTRACT: A realistic knowledge of the energy spectrum is very important in Quality Control (QC) of X-ray tubes in order to reduce dose to patients. However, due to the implicit difficulties to measure the X-ray spectrum accurately, it is not normally obtained in routine QC. Instead, some parameters are measured and/or calculated. PENELOPE and MCNP5 codes, based on the Monte Carlo method, can be used as complementary tools to verify parameters measured in QC. These codes allow estimating Bremsstrahlung and characteristic lines from the anode taking into account specific characteristics of equipment. They have been applied to simulate an X-ray spectrum. Results are compared with theoretical IPEM 78 spectrum. A sensitivity analysis has been developed to estimate the influence on simulated spectra of important parameters used in simulation codes. With this analysis it has been obtained that the FORCE factor is the most important parameter in PENELOPE simulations. FORCE factor, which is a variance reduction method, improves the simulation but produces hard increases of computer time. The value of FORCE should be optimized so that a good agreement of simulated and theoretical spectra is reached, but with a reduction of computer time. Quality parameters such as Half Value Layer (HVL) can be obtained with the PENELOPE model developed, but FORCE takes such a high value that computer time is hardly increased. On the other hand, depth dose assessment can be achieved with acceptable results for small values of FORCE.
Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 08/2012; 2012:5777-80.
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ABSTRACT: An accurate knowledge of the photonic spectra emitted by X-ray tubes in radiodiagnostics is essential to better estimate the imparted dose to patients and to improve the image quality obtained with these devices. In this work, several X-ray spectra have been simulated using the MCNP5 code to simulate X-ray production in a commercial device. To validate the Monte Carlo results, simulated spectra have been compared to those extracted from the IPEM 78 database. The uncertainty associated to some geometrical features of the tube and its effect on the simulated spectra has been analyzed using the Noether-Wilks formula. This analysis has been focused on the thickness of collimators, filters, shielding and barrel shutter. Furthermore, results show that the uncertainty due to geometrical parameters (0.98% in terms of Root Mean Squared) is higher than the statistical uncertainty associated to the MCNP5 calculations.
Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 08/2011; 2011:389-92.
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ABSTRACT: The Monte Carlo (MC) method can be applied to simulate brachytherapy treatment planning. The MCNP5 code gives, together with results, a statistical uncertainty associated with them. However, the latter is not the only existing uncertainty related to the simulation and other uncertainties must be taken into account. A complete analysis of all sources of uncertainty having some influence on results of the simulation of brachytherapy treatment is presented in this paper. This analysis has been based on the recommendations of the American Association for Physicist in Medicine (AAPM) and of the International Standard Organisation (ISO).
Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine 02/2011; 69(8):1108-11. · 1.09 Impact Factor
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4th International Conference on Biomedical Engineering and Informatics, BMEI 2011, Shanghai, China, October 15-17, 2011; 01/2011
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ABSTRACT: The image quality obtained by a radiographic equipment is very useful to characterize the physical properties of the image radiographic chain, in a quality control of the radiographic equipment. In the radiographic technique it is necessary that the evaluation of the image can guarantee the constancy of its quality to carry out a suitable diagnosis. In this work we have designed some radiographic phantoms for different radiographic digital devices, as dental, conventional, equipments with computed radiography (phosphor plate) and direct radiography (sensor) technology. Additionally, we have developed a software to analyse the image obtained by the radiographic equipment with digital processing techniques, as edge detector, morphological operators, statistical test for the detected combinations.. The design of these phantoms let the evaluation of a wide range of operating conditions of voltage, current and time of the digital equipments. Moreover, the image quality analysis by the automatic software, let study it with objective parameters.
Engineering in Medicine and Biology Society (EMBC), 2010 Annual International Conference of the IEEE; 10/2010
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ABSTRACT: A thorough knowledge of the primary spectrum is very important for Quality Control (QC) of X-ray tubes. A methodology to assess primary spectrum using a Compton spectrometer has been simulated with the MCNP5 code based on the Monte Carlo (MC) method. The Pulse Height Distribution (PHD) recorded in the detector is related with the primary X-ray spectrum by means of a Response matrix. Tikhonov and Modified Truncated Singular Values Decomposition (MTSVD) unfolding methods have been applied to the Response matrix to assess the primary spectrum. Both methods are tested comparing unfolded results with theoretical spectra from IPEM-78 catalogue.
Engineering in Medicine and Biology Society (EMBC), 2010 Annual International Conference of the IEEE; 10/2010
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ABSTRACT: The modified truncated singular value decomposition (MTSVD) unfolding method is applied to obtain primary spectra for X-ray tubes in radiodiagnostic. Three parameters - voltage, anode angle and filter thickness - of the tube are tested. Unfolded spectra are compared with theoretical extracted from IPEM-78 catalogue. A 2σ error criterion is applied to assess the minimum variations in tested parameters that permits distinguishing between close spectra.
Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine 10/2010; 69(8):1112-7. · 1.09 Impact Factor
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ABSTRACT: BWR control rods are activated by neutron reactions in the reactor. The dose produced by this activity can affect workers in the area surrounding the storage pool, where activated rods are stored. Monte Carlo (MC) models for neutron activation and dose assessment around the storage pool have been developed and validated. In this work, the MC models are applied to verify the expected reduction of dose when the irradiated control rod is hanged in an inverted position into the pool.
Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine 10/2010; 69(8):1104-7. · 1.09 Impact Factor
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ABSTRACT: The aim of the present work is to describe the main results produced using the thermal-hydraulic code TRACE5, in the frame of OECD/NEA ROSA Project Test 6.1 (SB-PV-9 in JAEA) with the purpose of testing the behavior of the code for this transient. The experiment 6.1 of the OECD/NEA ROSA (SB-PV-9 in JAEA) project was performed in the Large Scale Test Facility (LSTF) of the Japanese Atomic Energy Agency (JAEA). The LSTF simulates a PWR reactor, Westinghouse type, of four loops and 3423 MW of thermal power, scaled to 1/48 in volume and two loops. The experiment simulates an SBLOCA in the upper head of the vessel of a Pressurize Water Reactor (PWR) of four loops. The size of the break is equivalent to 1.9% of the diameter of the cold leg. Three different versions of TRACE5 have been used in the simulation of this transient: TRACE V5.0 RC3 (Release Candidate 3), TRACE V5.0 and TRACE V5.0 patch 01. The same input has been run in each case, obtaining slight differences. The goal of this work is provide a general description of the differences implemented in every version of the code and their effects in the simulation, comparing the results with the experimental ones.
Nuclear & Renewable Energy Conference (INREC), 2010 1st International; 04/2010
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ABSTRACT: A thorough knowledge of the primary spectrum is very important for Quality Control (QC) of X-ray tubes. A methodology to assess primary spectrum using a Compton spectrometer has been simulated with the MCNP5 code based on the Monte Carlo (MC) method. The Pulse Height Distribution (PHD) recorded in the detector is related with the primary X-ray spectrum by means of a Response matrix. Tikhonov and Modified Truncated Singular Values Decomposition (MTSVD) unfolding methods have been applied to the Response matrix to assess the primary spectrum. Both methods are tested comparing unfolded results with theoretical spectra from IPEM-78 catalogue.
Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 01/2010; 2010:536-9.
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[show abstract]
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ABSTRACT: The image quality obtained by a radiographic equipment is very useful to characterize the physical properties of the image radiographic chain, in a quality control of the radiographic equipment. In the radiographic technique it is necessary that the evaluation of the image can guarantee the constancy of its quality to carry out a suitable diagnosis. In this work we have designed some radiographic phantoms for different radiographic digital devices, as dental, conventional, equipments with computed radiography (phosphor plate) and direct radiography (sensor) technology. Additionally, we have developed a software to analyse the image obtained by the radiographic equipment with digital processing techniques, as edge detector, morphological operators, statistical test for the detected combinations‥ The design of these phantoms let the evaluation of a wide range of operating conditions of voltage, current and time of the digital equipments. Moreover, the image quality analysis by the automatic software, let study it with objective parameters.
Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 01/2010; 2010:3174-7.
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ABSTRACT: Brachytherapy is a radiotherapy treatment where encapsulated radioactive sources are introduced permanently (interstitial
seeds) or temporally (interstitial or intracavitary devices) within a patient. When high dose rate sources (HDR) are used
in intracavitary treatments, high doses can be locally imparted within the patient body. In multiple types of gynecological
cancer, intracavitary brachytherapy can be used combined with other therapy treatment to give an additional local dose to
the tumor. In these cases, different types of applicators can be used in order to increase the dose imparted to the tumor
while the effect on healthy tissues is restricted. In order to control both source characteristics and treatment planning
evaluation, an independent system must be used by the physicist consisting in experimental devices and/or simulation techniques
(i.e. the Monte Carlo method). The aim of this work is to model both applicator and source in order to evaluate the dose distribution
and some source characteristics (i.e. air kerma strength). The MCNP5 code based on the Monte Carlo method has been used for
the simulation. A gynecological applicator, consisting of a metallic intra-uterine tube with a plastic vaginal applicator
and a Microselectron HDR Ir-192 source has been simulated to evaluate the dose distribution. A solid phantom (PMMA) has been
designed to perform measurements around the applicator with radiochromic films (type Gafchromic EBT). The dose profile obtained
with the F4MESH tally of MCNP5 has been compared with measurements done with radiochromic films and simulation with a treatment
planning system.
Keywordsbrachytherapy-Monte Carlo method-treatment planning-dose assessment-Quality control
12/2009: pages 188-191;
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ABSTRACT: The Valencian Breast Cancer Early Detection Program (VBCEDP) started in the Valencian Community (Spain) in 1992. Up to now, 24 mammographic units have been installed all over the region. Mammography is used to aid in the diagnosis of breast cancer diseases in women. There is a health risk in the studied women due to ionising radiation that has to be estimated and controlled. A methodology to calculate approximately the radiological detriment in the VBCEDP has been developed based on Monte Carlo techniques. It has been used, as qualitative parameter, the average mean glandular dose from representative sample populations undergoing screening mammography (digital or screenfilm) from each of the twenty-four units in operation. The American College of Radiology Imaging Network reached to conclusion that digital mammography performed significantly better than film for pre and perimenopausal women younger than 50. Women who are undergoing the program are between 45 and 69. This fact allows us to study premenopausic women. Our group uses the software SCREENRISK to estimate induction and mortality rates in order to corroborate American conclusions in an European region. The obtained results confirm the American results about the application of digital mammography in pre and perimenopausal women younger than 50 years.
Engineering in Medicine and Biology Society, 2009. EMBC 2009. Annual International Conference of the IEEE; 10/2009
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ABSTRACT: A gynaecological applicator consisting of a metallic intra-uterine tube with a plastic vaginal applicator and an HDR Ir-192 source have been simulated with MCNP5 (Monte Carlo code). A solid phantom has been designed to perform measurements around the applicator with radiochromic films. The isodose curves obtained are compared with curves calculated with the F4MESH tally of MCNP5 with a good agreement. A pinpoint ionization chamber has been used to evaluate dose at some reference points.
Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine 10/2009; 68(4-5):735-7. · 1.09 Impact Factor
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ABSTRACT: BWR control rods become activated by neutron reactions into the reactor. Therefore, when they are withdrawn from the reactor, they must be stored into the storage pool for irradiated fuel at a certain depth under water. Dose rates on the pool surface and the area surrounding the pool should be lower than limits for workers. The MCNP code based on the Monte Carlo method has been applied to model this situation and to calculate dose rates at points of interest.
Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine 09/2009; 68(4-5):909-12. · 1.09 Impact Factor
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ABSTRACT: Brachytherapy is an advanced cancer treatment that is minimally invasive, minimising radiation exposure to the surrounding healthy tissues. Microselectron© Nucletron devices with 192Ir source can be used for gynaecological brachytherapy, in patients with vaginal or uterine cancer. Measurements of isodose curves have been performed in a PMMA phantom and compared with Monte Carlo calculations and TPS (Plato software of Nucletron BPS 14.2) evaluation. The isodose measurements have been performed with radiochromic films (Gafchromic EBT©). The dose matrix has been obtained after digitalisation and use of a dose calibration curve obtained with a 6 MV photon beam provided by a medical linear accelerator. A comparison between the calculated and the measured matrix has been performed. The calculated dose matrix is obtained with a simulation using the MCNP5 Monte Carlo code (F4MESH tally).
Radiation Effects and Defects in Solids 05/2009; 164(5-6):319-324. · 0.40 Impact Factor
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ABSTRACT: Quality Control (QC) parameters for an X-ray tube such as Half Value Layer (HVL), homogeneity factor and mean photon energy, can be obtained from the primary beam spectrum. A direct Monte Carlo (MC) simulation has been used to obtain this spectrum. Indirect spectrometry procedures such as Compton scattering have been also experimentally utilized since direct spectrometry causes a pile-up effect in detectors. As well the Compton spectrometry has been simulated with the MC method. In both cases unfolding techniques shall be applied to obtain the primary spectrum. Two unfolding methods (TSVD and Spectro-X) have been analyzed. Results are compared each other and with reference values taken from IPEM Report 78 catalogue. Direct MC simulation is a good approximation to obtain the primary spectrum and hence the QC parameters. TSVD is a better unfolding method for the scattered spectrum than the Spectro-X code. An improvement of the methodology to obtain QC parameters is important in Biomedical Engineering (BME) applications due to the wide use of X-ray tubes.
Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 01/2009; 2009:1367-70.
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ABSTRACT: The Valencian Breast Cancer Early Detection Program (VBCEDP) started in the Valencian Community (Spain) in 1992. Up to now, 24 mammographic units have been installed all over the region. Mammography is used to aid in the diagnosis of breast cancer diseases in women. There is a health risk in the studied women due to ionising radiation that has to be estimated and controlled. A methodology to calculate approximately the radiological detriment in the VBCEDP has been developed based on Monte Carlo techniques. It has been used, as qualitative parameter, the average mean glandular dose from representative sample populations undergoing screening mammography (digital or screenfilm) from each of the twenty-four units in operation. The American College of Radiology Imaging Network reached to conclusion that digital mammography performed significantly better than film for pre and perimenopausal women younger than 50. Women who are undergoing the program are between 45 and 69. This fact allows us to study premenopausic women. Our group uses the software SCREENRISK to estimate induction and mortality rates in order to corroborate American conclusions in an European region. The obtained results confirm the American results about the application of digital mammography in pre and perimenopausal women younger than 50 years.
Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 01/2009; 2009:900-2.
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ABSTRACT: Brachytherapy is a radiotherapy treatment where encapsulated radioactive sources are introduced within a patient. Depending on the technique used, such sources can produce high, medium or low local dose rates. The Monte Carlo method is a powerful tool to simulate sources and devices in order to help physicists in treatment planning. In multiple types of gynaecological cancer, intracavitary brachytherapy (HDR Ir-192 source) is used combined with other therapy treatment to give an additional local dose to the tumour. Different types of applicators are used in order to increase the dose imparted to the tumour and to limit the effect on healthy surrounding tissues. The aim of this work is to model both applicator and HDR source in order to evaluate the dose at a reference point as well as the effect of the materials constituting the applicators on the near field dose. The MCNP5 code based on the Monte Carlo method has been used for the simulation. Dose calculations have been performed with *F8 energy deposition tally, taking into account photons and electrons. Results from simulation have been compared with experimental in-phantom dose measurements. Differences between calculations and measurements are lower than 5%.The importance of the source position has been underlined.
Journal of Physics Conference Series 04/2008; 102(1):012012.
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ABSTRACT: The main goal of the present paper is to quantify, in homogeneous and heterogeneous phantoms, the differences between experimentally measured dose distributions inside it, and those calculated by the simulation of different transport models using the Monte Carlo computer code MCNP. This objective has been achieved simulating the electron and photon transport in a water phantom irradiated by a Theratron 780 (MDS Nordion) <sup>60</sup>Co radiotherapy unit, which has been realistically modeled, considering field sizes from 5 cmtimes5 cm to 20 cmtimes20 cm. The source description and characteristics of the incident beam have been slightly modified in order to study the results variations of these models. Different methodologies have also been applied to speed up the calculations with the aim of applying MCNP efficiently in radiotherapy treatment planning
IEEE Transactions on Nuclear Science 01/2007; · 1.45 Impact Factor
