Out-of-field patient doses in proton therapy are dominated by neutrons. Currently, they are not taken into account by treatment planning systems. There is an increasing need to include out-of-field doses in the dose calculation, especially when treating children, pregnant patients, and patients with implants. In response to this demand, this work presents the first steps towards a tool for the prediction of out-of-field neutron doses in pencil beam scanning proton therapy facilities. As a first step, a general Monte Carlo radiation transport model for simulation of out-of-field neutron doses was set up and successfully verified by comparison of simulated and measured ambient neutron dose equivalent and neutron fluence energy spectra around a solid water phantom irradiated with a variation of different treatment plan parameters. Simulations with the verified model enabled a detailed study of the variation of the neutron ambient dose equivalent with field size, range, modulation width, use of a range shifter, and position inside the treatment room. For future work, it is planned to use this verified model to simulate out-of-field neutron doses inside the phantom and to verify the simulation results by comparison with previous in-phantom measurement campaigns. Eventually, these verified simulations will be used to build a library and a corresponding tool to allow assessment of out-of-field neutron doses at pencil beam scanning proton therapy facilities.
- Publikační typ
- časopisecké články MeSH
Purpose: This study aims to characterize the neutron radiation field inside a scanning proton therapy treatment room including the impact of different pediatric patient sizes. Materials and Methods: Working Group 9 of the European Radiation Dosimetry Group (EURADOS) has performed a comprehensive measurement campaign to measure neutron ambient dose equivalent, H*(10), at eight different positions around 1-, 5-, and 10-year-old pediatric anthropomorphic phantoms irradiated with a simulated brain tumor treatment. Several active detector systems were used. Results: The neutron dose mapping within the gantry room showed that H*(10) values significantly decreased with distance and angular deviation with respect to the beam axis. A maximum value of about 19.5 μSv/Gy was measured along the beam axis at 1 m from the isocenter for a 10-year-old pediatric phantom at 270° gantry angle. A minimum value of 0.1 μSv/Gy was measured at a distance of 2.25 m perpendicular to the beam axis for a 1-year-old pediatric phantom at 140° gantry angle.The H*(10) dependence on the size of the pediatric patient was observed. At 270° gantry position, the measured neutron H*(10) values for the 10-year-old pediatric phantom were up to 20% higher than those measured for the 5-year-old and up to 410% higher than for the 1-year-old phantom, respectively. Conclusions: Using active neutron detectors, secondary neutron mapping was performed to characterize the neutron field generated during proton therapy of pediatric patients. It is shown that the neutron ambient dose equivalent H*(10) significantly decreases with distance and angle with respect to the beam axis. It is reported that the total neutron exposure of a person staying at a position perpendicular to the beam axis at a distance greater than 2 m from the isocenter remains well below the dose limit of 1 mSv per year for the general public (recommended by the International Commission on Radiological Protection) during the entire treatment course with a target dose of up to 60 Gy. This comprehensive analysis is key for general neutron shielding issues, for example, the safe operation of anesthetic equipment. However, it also enables the evaluation of whether it is safe for parents to remain near their children during treatment to bring them comfort. Currently, radiation protection protocols prohibit the occupancy of the treatment room during beam delivery.
- Publikační typ
- časopisecké články MeSH
Neutron detection using nuclear emulsions can offer an alternative in personal dosimetry. The production of emulsions and their quality have to be well controlled with respect to their application in dosimetry. Nuclear emulsions consist mainly of gelatin and silver halide. Gelatin contains a significant amount of hydrogen, which can be used for fast neutron detection. The addition of B-10 in the emulsion is convenient for thermal neutron detection. In this paper, standard nuclear emulsions BR-2 and nuclear emulsions BR-2 enriched with boron produced at the Slavich Company, Russia, were applied for evaluation of fast and thermal neutron fluences. The results were obtained by calculation from the presumed emulsion composition without prior calibration. Evidence that nuclear emulsions used in the experiment are suitable for neutron dosimetry is provided.
- MeSH
- bor chemie MeSH
- bromidy chemie MeSH
- emulze * MeSH
- fantomy radiodiagnostické MeSH
- helium analýza MeSH
- kalibrace MeSH
- lithium analýza MeSH
- neutrony * MeSH
- počítačové zpracování obrazu MeSH
- radiometrie přístrojové vybavení metody MeSH
- rychlé neutrony * MeSH
- sloučeniny stříbra chemie MeSH
- vodík chemie MeSH
- želatina chemie MeSH
- Publikační typ
- časopisecké články MeSH
Monitoring of exposures of aircrew members of airline operators registered in the Czech Republic has been performed since 1998. The individual effective doses are calculated using the computer code CARI annually. The calculations are based on information about participation of aircrew members on the specific flights and on the parameters describing the typical flight profiles of the flights; the latter is regularly verified with control measurements performed onboard aircraft. The results show that (1) the average annual effective doses in the period from 1998 to 2017 range from 1.3 to 2.1 mSv, (2) the maximum effective dose of a crew member is 5.7 mSv and (3) the annual collective effective doses range from 1.3 to 4.1 manSv. Combined relative uncertainty of the results is ~25%.
- MeSH
- dávka záření MeSH
- kalibrace MeSH
- kosmické záření * MeSH
- letadla MeSH
- letecké a kosmické lékařství metody MeSH
- letectví * MeSH
- lidé MeSH
- monitorování radiace metody normy MeSH
- pracovní expozice analýza MeSH
- radiační ochrana metody MeSH
- reprodukovatelnost výsledků MeSH
- sluneční aktivita MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Česká republika MeSH
Long-term measurements using silicon radiation spectrometer Liulin on board commercial aircraft have been performed since 2001; results were put into a new database, which covers more than 4500 flights with more than 130 000 measurements. Methodology and tools were developed to normalize the data with respect to latitude and altitude and thus enable comparison with other radiation detectors and with model calculations. This capability is demonstrated using data from the neutron monitor at Lomnický štít. Instead of providing data files for individual measurement period, two software solutions are delivered. First is a web-based user interface for visualizing and downloading arbitrary time window of interest from the database hosted at http://cr10.odz.ujf.cas.cz. The second is a set of interactive Python notebooks available at GitHub. Those implement the calibration, normalization and visualization methods-so the outputs can be tailored to user needs. The software and data are provided under GNU/CC license.
- MeSH
- databáze faktografické MeSH
- dávka záření MeSH
- internet MeSH
- kalibrace MeSH
- kosmické záření * MeSH
- křemík chemie MeSH
- letadla * MeSH
- letecké a kosmické lékařství MeSH
- letectví MeSH
- monitorování radiace statistika a číselné údaje MeSH
- nadmořská výška * MeSH
- neutrony * MeSH
- radiační expozice MeSH
- sluneční aktivita MeSH
- software MeSH
- zeměpis MeSH
- Publikační typ
- časopisecké články MeSH
Aircrew members and passengers are exposed to increased rates of cosmic radiation on-board commercial jet aircraft. The annual effective doses of crew members often exceed limits for public, thus it is recommended to monitor them. In general, the doses are estimated via various computer codes and in some countries also verified by measurements. This paper describes a comparison of three cosmic rays detectors, namely of the (a) HAWK Tissue Equivalent Proportional Counter; (b) Liulin semiconductor energy deposit spectrometer and (c) TIMEPIX silicon semiconductor pixel detector, exposed to radiation fields on-board commercial Czech Airlines company jet aircraft. Measurements were performed during passenger flights from Prague to Madrid, Oslo, Tbilisi, Yekaterinburg and Almaty, and back in July and August 2011. For all flights, energy deposit spectra and absorbed doses are presented. Measured absorbed dose and dose equivalent are compared with the EPCARD code calculations. Finally, the advantages and disadvantages of all detectors are discussed.
- MeSH
- absorpce radiace MeSH
- design vybavení MeSH
- kosmické záření * MeSH
- letadla přístrojové vybavení MeSH
- lidé MeSH
- monitorování radiace přístrojové vybavení MeSH
- polovodiče MeSH
- pracovní expozice analýza normy MeSH
- radiační expozice MeSH
- sluneční aktivita MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
Active mobile dosimetry unit (Liulin), passive plastic nuclear track detectors (PNTD) and thermoluminescent detectors (TLD) were exposed in a C290 MeV/n beam at HIMAC-BIO (NIRS, Japan). Two different types of beam configuration were used--monoenergetic beam (MONO) and spread-out Bragg peak (SOBP); the detectors were placed at several depths from the entrance up to the depths behind the Bragg peak. Relative response of TLDs in beams has been studied as a function of the depth, and it was re-proved that it can depend on the linear energy transfer (LET). Liulin measures energy deposition in Si; the spectra of energy deposited in Si can be transformed to the spectra of lineal energy or LET. PNTDs are able to determine the LET of registered particles directly. The limitation of both methods is in the range in which they can determine the LET-Liulin is able to measure perpendicularly incident charged particles up to ∼35 keV/µm (in water), PNTD can measure from ∼7 to 400 keV/µm, independently of the registration angle. The results from both methods are compared and combined for both beams' configuration, and a good agreement is observed.
- MeSH
- analýza selhání vybavení MeSH
- částice - urychlovače přístrojové vybavení MeSH
- design vybavení MeSH
- lineární přenos energie MeSH
- radiometrie přístrojové vybavení MeSH
- radioterapie těžkými ionty MeSH
- těžké ionty MeSH
- Publikační typ
- časopisecké články MeSH
- hodnotící studie MeSH
- srovnávací studie MeSH
- Geografické názvy
- Japonsko MeSH
A widely discussed question is how much a nuclear power plant really contributes to irradiation of the people living in its vicinity. A number of laboratory and in situ measurements were performed in the area surrounding NPP Temelin, on the basis of which we can specify the irradiation of this area from various sources. The evaluation includes the contributions from natural sources, such as radon, terrestrial radiation and cosmic radiation, together with the contribution from inhalation and ingestion of radionuclides. Medical irradiation and nuclear fallout are also included.
- MeSH
- jaderné elektrárny statistika a číselné údaje MeSH
- lidé MeSH
- monitorování radiace statistika a číselné údaje MeSH
- obsah radioaktivních látek v organizmu MeSH
- radiační pozadí MeSH
- vystavení vlivu životního prostředí analýza MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Česká republika MeSH
The neutron contribution to the spacecraft crew exposure could represent an important part of the total dose equivalent value. The determination of this contribution represents a rather complex and difficult task, both through experimental and theoretical estimation. This paper will present an attempt to determine the neutron contribution onboard the International Space Station and Foton capsule using the data measured by means of a Si-diode based energy deposition spectrometer. As such a spectrometer, the MDU-Liulin equipment, developed in one of our laboratories was used. The equipment allows the data accumulated during the passage in or out of the South Atlantic Anomaly (SAA). In this paper, only the data obtained out of the SAA were analysed, assuming that the neutron spectra are similar to those onboard aircraft and/or at the CERF high-energy radiation field. The excess of deposited energy in the region above 1 MeV, when comparing with the aircraft field, was expected to represent the primary high-energy charged particles. Total dosimetry characteristics obtained in this way are in reasonable agreement with other data, neutron contribution representing approximately 40% of the total dose equivalent for the flight duration outside of the SAA.
- MeSH
- analýza selhání vybavení MeSH
- dávka záření MeSH
- design vybavení MeSH
- kosmické záření MeSH
- kosmický let MeSH
- monitorování radiace metody přístrojové vybavení MeSH
- neutrony MeSH
- pracovní expozice analýza MeSH
- radiační ochrana metody přístrojové vybavení MeSH
- reprodukovatelnost výsledků MeSH
- senzitivita a specificita MeSH
ICRP Publication 60 recommended that the radiation exposure due to the cosmic component at high altitudes be considered when appropriate as part of occupational exposure to the radiation. The recommendation was incorporated to the Czech regulation in 1997, and the studies on how to perform individual dosimetry of Czech companies aircraft crew started immediately. The individual monitoring values were calculated using the Transport code CARI. The results obtained since the beginning have been recalculated, now with the version 6. The information on the flight schedules and the participation of aircraft crew in the flight were received from the air company. Routine individual dosimetry had started in 1998. Main results for the period 1998-2003 are as follows: both relative frequencies, as well as, average annual effective doses vary with the company and with the year, without any evident general tendency; the average annual values of E were between 1.5 and 2 mSv; and collective effective dose increased regularly, from approximately 1.5 manSv to >2.2 manSv. More detailed analysis is presented, including the verification of the procedure by a series of onboard experimental measurements.
- MeSH
- analýza selhání vybavení MeSH
- dávka záření MeSH
- design vybavení MeSH
- financování organizované MeSH
- internacionalita MeSH
- kosmické záření MeSH
- letectví MeSH
- monitorování radiace metody MeSH
- pracovní expozice analýza MeSH
- radiační ochrana metody MeSH
- reprodukovatelnost výsledků MeSH
- senzitivita a specificita MeSH
- Geografické názvy
- Česká republika MeSH
