Neutron spectra and H*(10) around an 18 MV LINAC by ANNs

Neutron spectra and ambient dose equivalent H*(10) were calculated for a radiotherapy room in 16 point-like detectors, 15 located inside the vault room and 1 located outside the bunker. The calculation was carried out using Monte Carlo Methods with the MCNP5 code for a generic radiotherapy room model operating with a 18 MV Linac, obtaining 16 neutron spectra with 47 energy bins, the H*(10) values were calculated from the neutron spectra by the use of the fluence-dose conversion factors. An Artificial Neural Network (ANN) were designed and trained to determine the neutron H*(10) in 15 different locations inside the vault room from the H*(10) dose calculated for the detector located outside the room, using the calculated dose values as training set, using the scaled conjugated gradient training algorithm The mean squared error (mse) set for the network training was 1E(-14), adjusting the data in 99.992 %. In the treatment hall, as the distance respect to the isocenter is increased, the amount of neutrons and the H*(10) are reduced, neutrons in the high-energy region are shifted to lower region peaking around 0.1 MeV, however the epithermal and thermal neutrons remain constant due to the room-return effect. In the maze the spectra are dominated by epithermal and thermal neutrons that contributes to produce activation and the production of prompt gamma-rays. The results shows the using this Artificial Intelligence technic as a useful tool for the neutron spectrometry and dosimetry by the simplification on the neutronic fields characterization inside radiotherapy rooms avoiding the use of traditional spectrometric systems. And once the H*(10) doses have been calculated, to take the appropriated actions to reduce or prevent the patient and working staff exposure to this undesirable neutron radiatio

Neutron area monitor with passive detector

Using Monte Carlo methods the responses of a passive neutron monitor area has been calculated. To detect thermal neutrons the monitor has a gold foil that is located at the center of a polyethylene cylinder. Impinging neutrons are moderated by polyethylene nuclei reaching the gold foil with the energy to induce activation through the reaction 197Au (n,γ) 198Au. The198Au decays emitting 0.411 MeV gamma rays with a half life of 2.7 days. The induced activity is intended to be measured with a gamma-ray spectrometer with a 3”Ø×3” NaI(Tl) scintillator and the saturation activity is correlated to the ambient dose equivalent. The response was calculated for 47 monoenergetic neutron sources ranging from 1×10−9 to 20 MeV. Calculated fluence response was compared with the response of neutron monitor area LB 6411. = Se utilizó el método de Monte Carlo para calcular las respuestas de un monitor de neutrones pasivo. Para detectar los neutrones térmicos el monitor tiene una lámina de oro que se encuentra en el centro de un cilindro de polietileno. Los neutrones que inciden son moderados por los núcleos de polietileno que llega a la lámina de oro con la energía para inducir la activación a través de la 197Au reacción (n,γ)198 Au. El 197Au decae emitiendo rayos gamma de 0.411 MeV con una vida media de 2.7 días. La actividad inducida se destina a medir con un espectrómetro de rayos gamma con un detector de centelleo de 3”Ø×3” NaI (Tl) y la actividad de saturación se correlaciona con la dosis equivalente ambiental. La respuesta se calculó para 47 fuentes de neutrones monoenergéticos desde 1×10−9 a 20 MeV. La respuesta a la fluencia se comparó con la respuesta del monitor de área LB 6411

Passive neutron area monitor with TLD pairs

The response of a passive neutron area monitor with pairs of thermoluminescent dosimeters has been calculated using the Monte Carlo code MCNP5. The response was calculated for one TLD 600 located at the center of a polyethylene moderator. The response was calculated for 47 monoenergetic neutron sources ranging from 1E(-9) to 20 MeV. Response was calculated using two irradiation geometries, one with an upper source and another with a lateral source. For both irradiation schemes the response was calculated with the TLD in two positions, one parallel to the source and another perpendicular to the source. The advantage of this passive neutron monitor area is that can be used in locations with intense, pulsed and mixed radiation fields like those in radiotherapy vault rooms with linear accelerators. La respuesta de un monitor de área pasivo para neutrones con pares de dosímetros termoluminiscentes TLDs ha sido calculada mediante métodos Montecarlo con el código MCNP5. La respuesta fue calculada para un TLD 600 localizado en el centro del moderador cilíndrico de polietileno. La respuesta se calculó para 47 fuentes mono energéticas de neutrones con energías de 1E (-9) a 20 MeV. La respuesta se calculó para dos geometrías de irradiación, una con una fuente superior y la otra con una fuente lateral, para ambas geometrías la respuesta se obtuvo con el TLD en dos posiciones respecto a la fuente, una perpendicular y la otra paralela. La ventaja del monitor pasivo es que puede ser usado en instalaciones con campos de radiación intensos, pulsados y mixtos como los que se producen en los bunkers de radioterapia con aceleradores lineales

Neutron spectra and H*(10) of photoneutrons inside the vault room of an 18 MV LINAC

Neutron spectra and the ambient dose equivalent were estimated inside the radiotherapy hall with an 18 MV linac. Estimations were carried out using Monte Carlo methods where a realist hall was modeled including a phantom made of equivalent tissue. The source term for photoneutrons was calculated using the Tosi et al. function that account for evaporation and knock-on neutrons. The spectra were estimated using two different energy distributions. Detectors were located in several sites inside the hall including the maze and outside the hall door, all detectors were located at the plane were the isocenter is located. In the treatment hall, as the distance respect to the isocenter is increased, the amount of neutrons and the H*(10) are reduced, neutrons in the high-energy region are shifted to lower region peaking around 0.1 MeV, however the epithermal and thermal neutrons remain constant due to the room-return effect. In the maze the spectra are dominated by epithermal and thermal neutrons that contributes to produce activation and the production of prompt gamma-rays.El espectro de neutrones y el equivalente de dosis ambiental fueron estimados dentro de una sala de radioterapia con un Linac de 18 MV. Las estimaciones se llevaron a cabo utilizando m´etodos Monte Carlo donde una sala realista fue modelada incluyendo un fantoma de tejido equivalente. El t´ermino fuente para neutrones fue calculado usando la funci´on de Tosi et al, la cual contabiliza los neutrones de evaporaci´on y reacci´on directa. El espectro fue estimado usando dos diferentes distribuciones de energ´ıa. Los detectores fueron colocados en el plano donde se encuentra el isocentro. Dentro de la sala de tratamiento, como la distancia respecto al isocentro aumenta, la cantidad de neutrones y H*(10) se reduce, los neutrones dentro de la regi´on de alta energ´ıa son desplazados a una regi´on de menor energ´ıa de alrededor de 0.1 MeV. Sin embargo, los neutrones epit´ermicos y t´ermicos permanecen constantes debido al efecto de room-return. En el laberinto el espectro es dominado peor neutrones t´ermicos y epit´ermicos los cuales contribuyen a la producci´on de activaci´on y a la producci´on de rayos gamma prontos

Response of a neutron monitor area with TLDs pairs

The response of a passive neutron monitor area has been calculated using the Monte Carlo code MCNP5. The response was the amount of n(6Li, T) reactions occurring in a TLD600 located at the center of a cylindrical polyethylene moderator. Fluence, (n, a) and H*(10) responses were calculated for 47 monoenergetic neutron sources. The H*(10) relative response was compared with responses of commercially available neutron monitors being alike. Due to 6Li cross section (n, ) reactions are mainly produced by thermal neutrons, however TLD600 is sensitive to gamma-rays; to eliminate the signal due to photons monitor area was built to hold 2 pairs of TLD600 and 2 pairs of TLD700, thus from the difference between TLD600 and TLD700 readouts the net signal due to neutrons is obtained. The monitor area was calibrated at the Universidad Politecnica de Madrid using a 241AmBe neutron source; net TLD readout was compared with the H*(10) measured with a Berthold LB6411. Performance of the neutron monitor area was determined through two independent experiments, in both cases the H*(10) was statistically equal to H*(10) measured with a Berthold LB6411. Neutron monitor area with TLDs pairs can be used in working areas with intense, mixed and pulsed radiation fields

Neutron absorbed dose in a pacemaker CMOS

The neutron spectrum and the absorbed dose in a Complementary Metal Oxide Semiconductor, has been estimated using Monte Carlo methods. Eventually a person with a pacemaker becomes an oncology patient that must be treated in a linear accelerator. Pacemaker has integrated circuits as CMOS that are sensitive to intense and pulsed radiation fields. Above 7 MV therapeutic beam is contaminated with photoneutrons that could damage the CMOS. Here, the neutron spectrum and the absorbed dose in a CMOS cell was calculated, also the spectra were calculated in two point-like detectors in the room. Neutron spectrum in the CMOS cell shows a small peak between 0.1 to 1 MeV and a larger peak in the thermal region, joined by epithermal neutrons, same features were observed in the point-like detectors. The absorbed dose in the CMOS was 1:522 £ 10¡17 Gy per neutron emitted by the source.El espectro y la dosis absorbida, debida a neutrones, por un Semiconductor de O´ xido Meta´lico Complementario ha sido estimada utilizando m´etodos Monte Carlo. Eventualmente, una persona con marcapasos se convierte en un paciente oncol´ogico que debe ser tratado en un acelerador lineal. El marcapasos contiene circuitos integrados como los CMOS que son sensibles a los campos de radiaci ´on intensos y pulsados. El haz terap´eutico de un LINAC operando a voltajes mayores a 7 MV est´a contaminado con fotoneutrones que pueden da˜nar el CMOS. En este trabajo se estim´o el espectro de neutrones y la dosis absorbida por un CMOS; adem´as, se calcularon los espectros de neutrones en dos detectores puntuales ubicados dentro de la sala. El espectro de neutrones en el CMOS tiene un pico entre 0.1 y 1 MeV y otro en la regi´on de los t´ermicos, conectados mediante neutrones epit´ermicos. Estas mismas caracter´ısticas se observan en los otros detectores. La dosis absorbida por el CMOS es 1:522 £ 10¡17 Gy por cada neutr´on emitido por el t´ermino fuente

Territorial Intelligence through the application of Business and Competitive intelligence: The case of Guadalupe, Zacatecas (Mexico)

The competitiveness it is a quality demanded by organizations, independently of its nature, size, or position in the value chain, public administrations also do this. Public administrations, on its side, have decided to bet for the development of initiatives that prompt the development of a single knowledge, which allows to improve the activities between agents installed in its action zones and, thus, enhancing its competitiveness in a coordinated manner, fulfilling its most immediate needs, and building a trustful environment. With this intention, public administrations require formal studies that identify and measure each one of the elements that compose competitiveness of the organizations, and allows each person involved to analyze and make decisions for adequate economic planning, sustainable development of the region, the enhancement of the life quality, and the perception of an environment of opportunities. For this reason, the city council of the municipality of Guadalupe, Zacatecas (Mexico) in collaboration with the National Institute of Geography and Statistics (INEGI, by its acronym in Spanish) have launched an initiative for identifying, finding, and cataloging, 100% of the active businesses in the territory comprised in an intelligence and geolocalization system, that was named “Inteligencia Competitiva del Comercio, Guadalupe, Zacatecas (ICCGZ)” that roughly translates to “Competitive Commerce Intelligence, Guadalupe, Zacatecas”. This initiative allows to know rapidly the current status of the local commerce and establishes strategies for strengthening and growing up it, through the intelligent use of the data and information