Calcium has been electrochemically inserted from a 1:2(v/v) mixed solution of ethylene carbonate and methylethyl carbonate containing 0.5mol dm−3 Ca(ClO4)2 into graphite, and the calcium isotope fractionation accompanying the insertion was observed. The lighter isotope, 40Ca, was preferentially fractionated into graphite. The single-stage separation coefficient for the 48Ca/40Ca isotopic pair ranged from 1.0×10−3 to 7.2×10−3 at 50°C. These experimental results were qualitatively consistent with the estimation of the equilibrium constant of the calcium isotope exchange reaction between the calcium ion in the electrolyte solution and the calcium atom in graphite based on molecular orbital calculations of the reduced partition function ratios of the calcium species involved in the equilibrium.
The concentrations of naturally occurring radionuclides (226Ra, 228Ra, 228Th, and 40K) in ashes of papers such as magazines and newspapers were determined from the nuclide concentrations in the papers and the ash contents of the papers. The average 226Ra, 228Ra, 228Th, and 40K concentrations in the 34 ashes were respectively 27, 68, 75, and 75Bq kg−1. The radium equivalent activities of the ashes were calculated to evaluate the hazard of &gannma;-ray radiation from the ashes in the environment. A copying paper sample showed a high radium equivalent activity of 602Bq kg−1. However, the average radium equivalent activity was 140Bq kg−1 and was lower than the level that causes an environmental health problem.
A questionnaire survey on safety of nuclear medicine studies was conducted under the subcommittee for radionuclide imaging and nuclear medicine technology of Japan Radioisotope Association to promote patient safety. Questionnaires sheets were sent to 1288 hospitals and 14 clinical laboratories in Japan with valid responses from 1016 facilities (78.0%). The total number of workers in nuclear medicine facilities was 5894 composed of 1468 women (24.9%) and 1207 workers (20.5%) in the 6th decade. The numbers of workers in hospitals and clinics was 5664 including 1326 women (23.4%). There were 1169 workers in the 6th decade, showing increased age of the workers. Proportions of physicians and pharmacists in hospitals increased to 21.3%, 3.1% respectively. The number of workers engaged in in-vitro studies further declined to 287(4.9%). The number of Anger cameras was 1267 with reduction by 69. SPECT system composed of 98.4% of all the cameras, in which 2-detecter system was prevailing (79.8%) with decrease in single or 3-detecter systems. The number of SPECT/CT systems increased to 95 with a six-fold increase compared to 2004. Facilities having dose meters decreased to 61.4%. Composite PET/CT system increased to occupy 75.8% of the PET camera systems. Establishment of maintenance plan, daily test, maintenance by venders were performed in 63.3%, 87.4%, 92.1% of the 2-detecter systems, and 80.6%, 95.8% and 98.6% of the PET/CT systems, respectively. Mean operating period of the cameras increased by 2 years. Filmless systems were operating in 77.0% of the all facilities, with the maximum of 81.2% in public facilities and the minimum of 60.3% of facilities of the National Hospital Organization of Japan. The survey revealed both favorable changes for promotion of safety including increase in pharmacists and unfavorable changes including decrease in the number of dose meters, elongation operating period of cameras. Steady increase in SPECT/CT systems and filmless systems were also revealed by the survey.