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Rodríguez-Oliver P, Corbacho JA, Caballero JM. Design and development of a detector system and software tool installed on a mobile laboratory to provide both radiological characterisation of large areas and a simple tool for localising radioactive sources. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2023; 43:032501. [PMID: 37619553 DOI: 10.1088/1361-6498/acf385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 08/24/2023] [Indexed: 08/26/2023]
Abstract
In emergency situations where an immediate response is required to make appropriate decisions by the competent authorities, it is essential to have measurement tools that provide results as accurate as possible in real-time. This paper presents the description of the upgrade of the mobile laboratory of the Radiological Alert Network of Extremadura, focusing on the characterisation of radioactive-contaminated land during emergency situations and the detection of radioactive sources. The detector system is based on two scintillation detectors and a car-borne dose rate monitor. Additionally, a software tool has been developed to collect information from the different devices involved (detectors, GPS, etc) and display it in an intuitive manner. This system has been tested in an area of a former phosphate facility where soils remain contaminated to varying degrees with radionuclides of TE-NORM origin.
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Affiliation(s)
- P Rodríguez-Oliver
- Universidad de Extremadura, Laboratorio de Radiactividad Ambiental. Servicio de apoyo a la investigación, Cáceres, Spain
| | - J A Corbacho
- Departamento de Física Aplicada, Centro Universitario de Mérida. Universidad de Extremadura, 06800 Mérida (Badajoz), Spain
| | - J M Caballero
- Universidad de Extremadura, Laboratorio de Radiactividad Ambiental. Servicio de apoyo a la investigación, Cáceres, Spain
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Bukartas A, Wallin J, Finck R, Rääf C. Accuracy of a Bayesian technique to estimate position and activity of orphan gamma-ray sources by mobile gamma spectrometry: Influence of imprecisions in positioning systems and computational approximations. PLoS One 2022; 17:e0268556. [PMID: 35731746 PMCID: PMC9216606 DOI: 10.1371/journal.pone.0268556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 05/02/2022] [Indexed: 11/19/2022] Open
Abstract
The purpose of this study was to investigate the effects of experimental data on performance of a developed Bayesian algorithm tailored for orphan source search, estimating which parameters affect the accuracy of the algorithm. The algorithm can estimate the position and activity of a gamma-ray point source from experimental mobile gamma spectrometry data. Bayesian estimates were made for source position and activity using mobile gamma spectrometry data obtained from one 123% HPGe detector and two 4-l NaI(Tl) detectors, considering angular variations in counting efficiency for each detector. The data were obtained while driving at 50 km/h speed past the sources using 1 s acquisition interval in the detectors. It was found that deviations in the recorded coordinates of the measurements can potentially increase the uncertainty in the position of the source 2 to 3 times and slightly decrease the activity estimations by about 7%. Due to the various sources of uncertainty affecting the experimental data, the maximum predicted relative deviations of the activity and position of the source remained about 30% regardless of the signal-to-noise ratio of the data. It was also found for the used vehicle speed of 50 km/h and 1 s acquisition time, that if the distance to the source is greater than the distance travelled by the detector during the acquisition time, it is possible to use point approximations of the count-rate function in the Bayesian likelihood with minimal deviations from the integrated estimates of the count-rate function. This approximation reduces the computational demands of the algorithm increasing the potential for applying this method in real-time orphan source search missions.
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Affiliation(s)
- Antanas Bukartas
- Medical Radiation Physics, Lund University, Lund, Sweden
- * E-mail:
| | - Jonas Wallin
- Department of Statistics, Lund University, Lund, Sweden
| | - Robert Finck
- Medical Radiation Physics, Lund University, Lund, Sweden
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Bukartas A, Wallin J, Finck R, Rääf C. Bayesian algorithm to estimate position and activity of an orphan gamma source utilizing multiple detectors in a mobile gamma spectrometry system. PLoS One 2021; 16:e0245440. [PMID: 33481856 PMCID: PMC7822251 DOI: 10.1371/journal.pone.0245440] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Accepted: 12/31/2020] [Indexed: 11/24/2022] Open
Abstract
To avoid harm to the public and the environment, lost ionizing radiation sources must be found and brought back under the regulatory control as soon as possible. Usually, mobile gamma spectrometry systems are used in such search missions. It is possible to estimate the position and activity of point gamma sources by performing Bayesian inference on the measurement data. The aim of this study was to theoretically investigate the improvements in the Bayesian estimations of the position and activity of a point gamma source due to introduction of data from multiple detectors with angular variations of efficiency. Three detector combinations were tested—a single 123% HPGe detector, single 4l NaI (Tl) detector and a 123% HPGe with 2x4l NaI (Tl) detector combination—with and without angular efficiency variations for each combination resulting in six different variants of the Bayesian algorithm. It was found that introduction of angular efficiency variations of the detectors did improve the accuracy of activity estimation slightly, while introduction of data from additional detectors lowered the signal-to-noise ratio threshold of the system significantly, increasing the stability and accuracy of the estimated source position and activity, for a given signal-to-noise ratio.
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Affiliation(s)
- Antanas Bukartas
- Medical Radiation Physics, Lund University, Lund, Sweden
- * E-mail:
| | - Jonas Wallin
- Department of Statistics, Lund University, Lund, Sweden
| | - Robert Finck
- Medical Radiation Physics, Lund University, Lund, Sweden
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Bukartas A, Finck R, Wallin J, Rääf CL. A Bayesian method to localize lost gamma sources. Appl Radiat Isot 2019; 145:142-147. [PMID: 30612009 DOI: 10.1016/j.apradiso.2018.11.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 11/19/2018] [Accepted: 11/19/2018] [Indexed: 11/30/2022]
Affiliation(s)
- A Bukartas
- Medical Radiation Physics, Lund University, Sweden.
| | - R Finck
- Medical Radiation Physics, Lund University, Sweden
| | - J Wallin
- Department of Statistics, Lund University, Sweden
| | - C L Rääf
- Medical Radiation Physics, Lund University, Sweden
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Nilsson JMC, Finck RR, Rääf CL. A rotating-slit-collimator-based gamma radiation mapper. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2017; 177:225-232. [PMID: 28711774 DOI: 10.1016/j.jenvrad.2017.07.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 07/04/2017] [Accepted: 07/05/2017] [Indexed: 06/07/2023]
Abstract
For situations with radioactive material out of control where it may be physically difficult or prohibited to access areas close to the source, measurements from distance may be the only way to assess the radiation environment. Using collimated detectors will provide means to locate the direction of the radiation from the source. To investigate the possibilities of mapping gamma emitting radioactive material in a closed non-enterable area, a tentative system for mapping radioactive materials from a distance was built. The system used a computer controlled cylindrical rotating slit collimator with a high purity germanium detector placed in the cylinder. The system could be placed on a car-towed trailer, with the centre of the detector about 1.4 m above ground. Mapping was accomplished by the use of a specially developed image reconstruction algorithm that requires measurements from two or more locations around the area to be investigated. The imaging capability of the system was tested by mapping an area, 25 by 25 m2, containing three 330 MBq 137Cs point sources. Using four locations outside the area with about 20 min measuring time in each location and applying the image reconstruction algorithm on the deconvoluted data, the system indicated the three source locations with an uncertainty of 1-3 m. The results demonstrated the potential of using collimated mobile gamma radiometry combined with image reconstruction to localize gamma sources inside non-accessible areas.
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Affiliation(s)
- Jonas M C Nilsson
- Medical Radiation Physics, Department of Translational Medicine, Lund University, Skåne, University Hospital, S-205 02 Malmö, Sweden
| | - Robert R Finck
- Medical Radiation Physics, Department of Translational Medicine, Lund University, Skåne, University Hospital, S-205 02 Malmö, Sweden
| | - Christopher L Rääf
- Medical Radiation Physics, Department of Translational Medicine, Lund University, Skåne, University Hospital, S-205 02 Malmö, Sweden.
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Albéri M, Baldoncini M, Bottardi C, Chiarelli E, Fiorentini G, Raptis KGC, Realini E, Reguzzoni M, Rossi L, Sampietro D, Strati V, Mantovani F. Accuracy of Flight Altitude Measured with Low-Cost GNSS, Radar and Barometer Sensors: Implications for Airborne Radiometric Surveys. SENSORS 2017; 17:s17081889. [PMID: 28813023 PMCID: PMC5579878 DOI: 10.3390/s17081889] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 08/10/2017] [Accepted: 08/13/2017] [Indexed: 11/16/2022]
Abstract
Flight height is a fundamental parameter for correcting the gamma signal produced by terrestrial radionuclides measured during airborne surveys. The frontiers of radiometric measurements with UAV require light and accurate altimeters flying at some 10 m from the ground. We equipped an aircraft with seven altimetric sensors (three low-cost GNSS receivers, one inertial measurement unit, one radar altimeter and two barometers) and analyzed ~3 h of data collected over the sea in the (35–2194) m altitude range. At low altitudes (H < 70 m) radar and barometric altimeters provide the best performances, while GNSS data are used only for barometer calibration as they are affected by a large noise due to the multipath from the sea. The ~1 m median standard deviation at 50 m altitude affects the estimation of the ground radioisotope abundances with an uncertainty less than 1.3%. The GNSS double-difference post-processing enhanced significantly the data quality for H > 80 m in terms of both altitude median standard deviation and agreement between the reconstructed and measured GPS antennas distances. Flying at 100 m the estimated uncertainty on the ground total activity due to the uncertainty on the flight height is of the order of 2%.
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Affiliation(s)
- Matteo Albéri
- Department of Physics and Earth Sciences, University of Ferrara, Via Saragat, 1, 44122 Ferrara, Italy.
- Ferrara Section of the National Institute of Nuclear Physics, Via Saragat, 1, 44122 Ferrara, Italy.
| | - Marica Baldoncini
- Department of Physics and Earth Sciences, University of Ferrara, Via Saragat, 1, 44122 Ferrara, Italy.
- Ferrara Section of the National Institute of Nuclear Physics, Via Saragat, 1, 44122 Ferrara, Italy.
| | - Carlo Bottardi
- Department of Physics and Earth Sciences, University of Ferrara, Via Saragat, 1, 44122 Ferrara, Italy.
- Ferrara Section of the National Institute of Nuclear Physics, Via Saragat, 1, 44122 Ferrara, Italy.
| | - Enrico Chiarelli
- Legnaro National Laboratory, National Institute of Nuclear Physics, Via dell'Università 2, 35020 Legnaro (Padova), Italy.
| | - Giovanni Fiorentini
- Department of Physics and Earth Sciences, University of Ferrara, Via Saragat, 1, 44122 Ferrara, Italy.
- Ferrara Section of the National Institute of Nuclear Physics, Via Saragat, 1, 44122 Ferrara, Italy.
| | | | - Eugenio Realini
- Geomatics Research & Development (GReD) srl, Via Cavour 2, 22074 Lomazzo (Como), Italy.
| | - Mirko Reguzzoni
- Department of Civil and Environmental Engineering (DICA), Polytechnic of Milan, Piazza Leonardo da Vinci 32, 20133 Milano, Italy.
| | - Lorenzo Rossi
- Department of Civil and Environmental Engineering (DICA), Polytechnic of Milan, Piazza Leonardo da Vinci 32, 20133 Milano, Italy.
| | - Daniele Sampietro
- Geomatics Research & Development (GReD) srl, Via Cavour 2, 22074 Lomazzo (Como), Italy.
| | - Virginia Strati
- Legnaro National Laboratory, National Institute of Nuclear Physics, Via dell'Università 2, 35020 Legnaro (Padova), Italy.
| | - Fabio Mantovani
- Department of Physics and Earth Sciences, University of Ferrara, Via Saragat, 1, 44122 Ferrara, Italy.
- Ferrara Section of the National Institute of Nuclear Physics, Via Saragat, 1, 44122 Ferrara, Italy.
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