BACKGROUND:The information on the results of the survey of collective effective dose SE to children in the Czech Republic (CR) due to nuclear medicine examinations performed during the one-year period July 1995-June 1996.METHODS:The estimate of SE was based on the annual frequency of nuclear medicine procedures and the type and amount of administered radiopharmaceuticals provided by the General Health Insurance Company covering 75% of the CR population.RESULTS:In the period considered, 15,281 examinations of children younger than 18 years were performed, which represented 7.5% of total nuclear medicine examinations in the CR. The annual SE 43.8 man Sv formed 5.1% of the collective effective dose to all patients examined by nuclear medicine procedures in the CR. The contributions of procedures in various body systems of children to the annual SE: urinary tract 32.8%, bone 30.4%, brain 12.8 %, cardiovascular 6.4%, GIT 6.0%, thyroid 4.4%, lungs 3.0%, other 4.2%. In comparison with a similar survey performed in the CR in 1987 (based on a questionnaire) there was an increase in SE to children younger than 15 years by a factor of 2.8, mainly due to the expansion of kidney and bone investigations.CONCLUSIONS:The mean effective dose per exam to children younger than 15 years was 60% of that for adults, which was in agreement with the requirement that the radiation burden of children should not exceed that of adults. The use of data from the Insurance Company for regular conducting of such surveys appeared to be not as cumbersome and time-consuming as questionnaire surveys.

Consistent with the worldwide development of nuclear medicine, in the Czech Republic in 1987 to 1996 partly the spectrum of used radiopharmaceutical preparations and their ratio changed. In the majority of radiopharmaceutical preparations the mean administered activity increased by 20 to 80% and the range of activities administered in different departments diminished somewhat. Adherence to principles of radiation protection of patients is assisted by guidelines of administered activities of radiopharmaceutical preparations laid down in new regulations on radiation protection valid in the CR from the middle of 1997. The radiation burden associated with the majority of examinations in nuclear medicine expressed as the effective dose is comparable with the radiation burden of radiodiagnostic examinations, only after administration of preparations with 131I, 201Tl, 67Ga and 111In it is markedly higher. Based on knowledge of the effective dose it may be concluded that the lifetime extra risk of a fatal tumour due to administration of radiopharmaceutical preparations is by two to three orders lower than the lifetime risk of spontaneous development of fatal tumours. A special feature of radiation risk is its hypothetical character--it is frequently projected into the distant future of human life, contrary to immediate non-radiation risks of some medical procedures and risks in the living environment which frequently are higher. Any examination using ionising radiation can be made only if the expected health benefit for the patient is significantly greater than the radiation risk. Excessive fear of radiation risk should not lead to refusal of justified examinations with possible subsequent serious health damage for the patient.

The paper deals with the problem of the outpatient administration of186Re-HEDP and153Sm-EDTMP for palliative therapy of bone metastases. The subsequent 6 hours stay of the treated patients in a department of nuclear medicine appears to be in compliance with regulations proposed in the Czech Republic as well as with ICRP recommendations.

Our modification of a method for the absolute quantification of gallium-67 uptake in lungs with a scintillation camera and computer is described. The uptake of 67Ga in lungs, expressed in percentage of administered radioactivity, was determined by the transmission-emission method. We proved theoretically and experimentally that a 67Ga planar source could be replaced with a 57Co planar source. The performance of lung perfusion scans allows a more accurate delineation of the regions of interest on gallium scans. The method was applied to control subjects (n = 27) and to patients (n = 114) suffering from biopsy-proven pulmonary sarcoidosis (28 with inactive and 86 with active disease). The obtained results were compared with chest X-ray findings, the percentage of lymphocytes in the bronchoalveolar fluid (BAF-ly%), and serum angiotensin-converting enzyme (SACE) values. The method seems suitable for the assessment of disease activity in sarcoidosis. It is more accurate in detecting parenchymal involvement in lung sarcoidosis than the commonly used X-ray criteria. No correlation was found between 67Ga uptake and the BAF-ly% and SACE values.

Attention is drawn to some erroneous and incomplete pieces of information on 99Mo-99mTc generator kinetics published in the literature. The assumption that 99mTc is eluted completely from the generator leads to the incorrect 99mTc activity-time curve plotted in some papers. It is shown that the time at which 99mTc activity in the generator reaches the maximum value depends on the efficiency of 99mTc separation. The expression derived by authors allows the prediction of 99mTc activity available in the second separation performed several hours after the previous separation.

Using the specific absorbed fractions reported by Smith and Warner, the radiation doses absorbed by the embryo in early pregnancy were calculated for various radiopharmaceuticals used in the diagnostic procedures of nuclear medicine. Radiopharmaceuticals are considered which are excreted predominantly through urine and cause the doses to the embryo to be 40%–90% higher than gonad doses. Also discussed are large differences of doses reported by various authors to the embryo by 99mTcpertechnetate.