ABSTRACT
The objective of this work is to obtain fluence to effective dose conversion coefficients for neutron point sources, using the GEANT4 toolkit. These calculations aim to investigate the aspects of neutron transport in the human body through Monte Carlo simulation using the International Commission on Radiological Protection (ICRP) voxel phantoms, described in its publication 110. A benchmarking of the code was made for the case of monoenergetic plane parallel neutron beam in the antero-posterior (AP) irradiation geometry and organ absorbed dose conversion coefficients were compared with those found in the ICRP publication 116. The results showed good agreement with ICRP results in the studied energy range. Conversion coefficients were presented for specific conditions with 241Am-Be and 252Cf point neutron sources 1 m away from the phantom in the AP geometry.
Subject(s)
Models, Biological , Neutrons , Phantoms, Imaging , Radiation Protection/methods , Radiometry/methods , Whole-Body Counting/methods , Americium/analysis , Anthropometry , Body Burden , Californium/analysis , Computer Simulation , Humans , Radiation Dosage , Relative Biological EffectivenessABSTRACT
Brazil has about 300 nuclear medicine services (NMS), 44 of them located in the state of Rio de Janeiro (RJ). Most nuclear medicine staff are routinely monitored for external dose. This paper makes a statistical analysis of all the RJ NMS annual external occupational doses in year 2005. Around 100 professionals of RJ NMS received annual doses >4.0 mSv, considering only external doses, but no one receives doses higher than the mean annual dose limit of 20 mSv. Extremities dosemeters are used by about 10 % of the staff. In some cases, these doses are more than 10 times higher than the dose in thorax. The maximum ratio of extremity dose/thorax dose, in 2005, was 72. This study shows the importance to improve radiation protection procedures in nuclear medicine, mainly because the number of occupational individuals in nuclear medicine and their external doses are increasing.
Subject(s)
Nuclear Medicine , Occupational Exposure/prevention & control , Occupational Medicine/standards , Radiation Monitoring/methods , Radiometry/methods , Brazil , Humans , Nuclear Medicine/methods , Occupational Medicine/methods , Photons , Positron-Emission Tomography/methods , Radiation Dosage , Radiation Protection/methods , Radiopharmaceuticals/analysis , Thorax/radiation effects , Tomography, Emission-Computed, Single-Photon/methods , WorkforceABSTRACT
Brazil, a large country, with more than 120,000 workers under individual monitoring for ionising radiation, developed, more than 20 y ago, a centralised data bank for external occupational dose. This old database, however, presented some problems and does not satisfy any more Brazilian present needs, not allowing dose analysis reports, for example. Therefore, a new system that reduces manual tasks, provides system communication support, manages reports and improves data storage management is being developed. This paper describes this new web-based information system, named Brazilian External Occupational Dose Management database system--GDOSE.
Subject(s)
Occupational Exposure/prevention & control , Radiation Monitoring/methods , Radiation Protection/methods , Radiation, Ionizing , Radiometry/methods , Brazil , Computer Systems , Databases, Factual , Humans , Information Storage and Retrieval , Internet , RegistriesABSTRACT
Instituto de Radioproteção e Dosimetria, a Brazilian government research institute, provides individual monitoring services since 1972. Its dosemeters are: film-based thorax for whole body photons, thermoluminescence dosimetry (TLD) albedo for whole body neutrons and TLD ring for extremity photons. About 6000 radiation workers are currently being monitored with film dosemeters in 256 different facilities in Brazil, most of them working in health-related activities. Around 400 Brazilian radiation workers are monitored with TLD albedo neutron monitor and about 500 workers use TLD rings. This paper describes the monitoring systems used, presents the results obtained in internal quality programs and in intercomparison exercises and analyses the measured dose values from 1985 to 2009.