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[en] Human beings are continuously exposed to ionising radiation originating from natural or artificial sources. Uranium-238 and Thorium-232 found in building materials are important sources of radon and thoron in the indoor environment. The concentration levels of radon, thoron and thoron progeny were measured in mud-walled, metallic or iron sheet-walled and stone-walled modern houses in Kilimambogo region, Kenya for 3 months. Radon and thoron concentration levels were measured using passive radon–thoron discriminative monitors (RADUET), while thoron progeny concentrations as the equilibrium equivalent thoron concentration (EETC) were measured using thoron progeny monitors. The mean radon concentration levels in mud, metallic and stone-walled dwellings were 67 ± 11, 60 ± 10 and 75 ± 10 Bq m⁻³, respectively. The mean thoron concentration levels in the corresponding dwellings were 195 ± 36, 71 ± 24 and 161 ± 31 Bq m⁻³, respectively, while EETCs were 12 ± 2, 3 ± 1 and 7 ± 1 Bq m⁻³, respectively. The annual effective doses for radon were 1.3 ± 0.2, 1.1 ± 0.1 and 1.4 ± 0.2 mSv y⁻¹ in mud, metallic and stone-walled houses while those from thoron estimated from EETC were 2.4 ± 0.4, 0.5 ± 0.1 and 1.5 ± 0.2 mSv y⁻¹ in the corresponding houses, respectively. (author)

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[en] In 2007, the European Commission (EC) commissioned a group of experts to undertake the revision of Report Radiation Protection (RP) 91, written in 1997, on 'Criteria for acceptability of radiological (including radiotherapy) and nuclear medicine installations' The revised draft report was submitted to the EC. Before publication, the EC issued this document for public consultation and has commissioned the same group of experts to consider the comments of the public consultation in further improving the revised report. The EC intends to publish the final report under its Radiation Report Series with the number RP 162. This paper introduces the project and presents the methodology adopted to devise the criteria of acceptability/suspension levels for nuclear medicine equipment. (authors)

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[en] In the author's clinical affiliation in Helsinki, Finland, multiple positron emission tomography (PET) procedures with approximately 10 different fluorine-18 or Ga-68-tracers are carried out. Because of the location, there are also patients who cross national borders or who go to the airports, where they may trigger highly sensitive radiation monitors at security check points. Therefore, a certificate is automatically given for administered radioactivity even for PET tracers; if possible security checks are going to take place on the same day. A 57-year-old man was administered with 326 MBq (8.81 mCi) fluoro-18-methylcholine (FCH) at 12:50 p.m. for a whole-body PET/computed tomography study. The next morning at 7:00 a.m. when he entered his work place at a nuclear power plant, all alarms sounded. His radioactivity level was measured to be 0.35 MBq (9.5 μCi) i.e. approximately of 1/930 original activity. The nuclear power plant was informed about the origin of the activity, and all later measurements demonstrated kBq. Radiation safety measurements are extremely sensitive in nuclear power plants, and the person did not have a certificate because the radiation safety check should have happened on the following day. The physical half-life (t_1_/_2) of fluorine-18 is 110 minutes, and the time difference between these activity measurements was 18.2 hours, i.e. 9.73 half-lives. The measured activity was very close with that of physical decay indicating that the activity measured on the next morning might have been overestimated. FCH has urinary excretion and also biological half-life is essential part of effective half-life, especially because this person did not have any sites of pathologic uptakes. This event demonstrates that extremely low radioactivity, <10 μCi, can be detected, in this case for supersensitive nuclear safety reasons. Nuclear medicine community has to keep this in mind while handling in a daily routine 1000- to 10?000-fold activity levels as compared with the levels that can be detected by radiation monitors at check points. (authors)

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[en] This special issue of Radiation Protection Dosimetry constitutes the proceedings of the 'First National Conference on Radiation Awareness and Detection in Natural Environment' (RADNET-1), organised by the Departments of Physics and Chemistry, HNB Garhwal University, Badshahi Thaul Campus, Tehri Garhwal and Govt. P.G. College, New Tehri, Tehri Garhwal, held at HNB Garhwal University, Badshahi Thaul Campus, Tehri Garhwal, India, during June 15-17, 2015. This national conference attracted 121 participants both from India and abroad. A series of invited lectures were delivered from the dignitaries from India and abroad. There were 17 invited talks, 24 oral and 52 poster presentations on Natural Sources of Radiation and Detection Methodologies. The aim of the conference was to bring together the researchers from all over the country, to share the knowledge on radiation awareness and detection; to identify the importance, challenges and issues in the area of natural radioactivity and its measurement techniques; and to work together to discover feasible solutions for the associated problems from various viewpoints such as improvements in measurement techniques, dosimetry, its impact on radon epidemiology and/or regulations. The conference covered all the key topics of natural radioactivity with special focus on the awareness, detection and effects of the presence of radiation in the human environment. Special attention was on new techniques, radon and thoron decay products measurements, soil radioactivity, radon in drinking water, heavy metals in river basins, high natural background radiation areas in India, building material characterisation, inhalation dosimetry, importance of thoron and its decay product measurements etc. This special issue contains 24 peer reviewed research papers selected from the body of the contributions presented at the conference. Some work-in-progress presentations are not included in the proceedings and are expected to lead to independent papers later. (authors)