Emission rates of alpha particles from supports with different surface conditions in direct deposition sources.

Direct deposition is the only method that can be utilised for the standardisation of radioactive solutions because there is no deposition loss on a support. The present study investigated how much the roughness of the support influences the emission rate of alpha particles for direct deposition sources from the practical viewpoint of use of the method. A number of samples were prepared by evaporating a 0.1-ml aliquot of a dilute nitric acid aqueous solution that contained (241)Am on stainless steel supports with four different surface conditions; untreated supports were either polished (using metal abrasives available commercially) or not polished, and buffed supports (grid size of #400) were either polished or not polished. Alpha spectrometry of the samples revealed that the detection efficiency was significantly different between the non-polished and polished supports; the former was lower by 3 % than the latter for both the untreated and buffed supports. Microscopic observations clarified that the counting loss was attributed to irregular flaws or polishing lines on the non-polished supports, most of which were found to be in the order of submicron in depth and were diminished on the polished supports. One may usually assume that a direct deposition source offers no counting loss if its entire energy spectrum is seen above a low-energy discrimination limit of the spectrometer. However, this should be experimentally confirmed using a solution with known activity. It was difficult to identify the counting loss for the buffed supports without polishing because their energy spectra showed little degradation.

Dietary iodine and bromine intakes in Ukrainian subjects.

Dietary iodine and bromine intakes in Ukrainian subjects were estimated in relation to the health effects on inhabitants after the Chernobyl accident. Two hundred and eighty-six total diets were collected from twenty-five regions for Ukrainians by a duplicate portion study. Iodine and bromine were rapidly determined by inductively coupled plasma mass spectrometry after chemical separation. The range, median, and geometric mean of iodine intakes were 2.86-698, 44.7, and 48.1 microg per person per day, respectively. Those of bromine were 0.627-16.9, 2.97, and 2.92 mg per person per day, respectively. Daily intakes of both elements in Ukrainians were lower than previously reported values. The iodine intake in areas contaminated by the Chernobyl accident was lower than that in non-contaminated areas. The low iodine intake in both areas would be related to the high prevalence of goiters throughout the whole country. The low bromine intakes indicated Ukrainians were not exposed to bromine-containing foods.

Method for reducing noise in X-ray images by averaging pixels based on the normalized difference with the relevant pixel.

A real-time digital filter for noise reduction in X-ray images is proposed. The filter is based on averaging of only similar pixels (pixels that differ only little) rather than neighboring pixels, which are averaged in conventional linear low-pass filters. The effectiveness of the filter was evaluated by computer simulation, where original images that were acquired by X-ray exposure were processed in accordance with the filter algorithm. The resulting images were evaluated in terms of the pre-sampled modulation transfer function (MTF), the noise power spectrum (NPS), and the lag. Comparison of the filtered and original images revealed that the NPS was reduced for the full range of spatial frequencies in the filtered image, resulting in a reduction of total noise power to about 1/9 the level in the original image with no degradation in the MTF or lag. The usefulness of the filter was demonstrated in fluoroscopic, digital subtraction angiography (DSA) and mammographic phantom studies. The filter was found to have the potential to reduce the patient dose by reducing the noise in dynamic as well as static X-ray images.

Dietary iodine intake in residents of northwestern regions of ukraine contaminated by the chernobyl accident.

Daily iodine intake in Ukrainian subjects of northwestern regions was estimated in relation to the health effects on inhabitants after the Chernobyl accident. Total diets were collected from 106 locations for children and adult males by a duplicate portion study. Iodine was rapidly determined by inductively coupled plasma mass spectrometry after chemical separation. Iodine concentration on a dry basis for Ukrainians was 0.11 microg g(-1) and the daily iodine intake was in the range of 2.80-372 microg per person. The median, geometric mean, and standard deviation were 28.1, 32.7, and 2.51 microg, respectively. The yearly trend of the intake had almost no change. Regional differences would be expected to exist among the 10 areas of the Ukraine, but no clear differences appeared in the present findings. Daily iodine intake in Ukrainians was lower than the recommended dietary intake (RDI) allowance (150 microg), and its lack would be related to the high prevalence of goiter in the country.

Dose effect for Japanese due to 232Th and 238U in imported drinking water.

The consumption rate of bottled mineral water in Japan has increased due to changes in eating habits and contamination of water sources. Radioactivity levels of 238U and 232Th in imported mineral water were checked from the viewpoint of internal radiation for Japanese subjects. Concentration ranges of 238U and 232Th in imported bottled mineral water, domestic bottled mineral water, domestic tap water, and domestic soft drinks were as follows: for U, N.D to 7.48 x 10(3), 1.07 to 344, 0.66 to 104, and 3.04 to 46.2 ng dm (ppt); for Th, 0.60 to 5.12, 0.65 to 22.4, 0.64 to 22.1, and 11.0 to 48.5 ng dm, respectively. In some brands of imported bottled mineral water, U concentration was sometimes much higher than domestic bottled mineral water and domestic tap water. The annual effective dose (1.5 x 10(-3) mSv y(-1) estimated from intake of 238U was approximately 7 times higher than that through dietary intake in Japanese. However, the internal dose added by drinking the imported portable water is negligible compared with total annual internal dose. Concentrations of non-radioactive elements were also compared between imported and domestic bottled water. Geometric means of cobalt, arsenic, strontium, cesium, phosphorous, and calcium in imported bottled water were higher compared with those of domestic bottled mineral water and domestic tap water. Maximum values of 11 elements (arsenic, rubidium, strontium, cesium, barium, sodium, magnesium, potassium, calcium, and manganese) were also found in imported bottled water.

Uranium concentration in typical Pakistani diet.

To strengthen the radiation protection infrastructure in Pakistan, the uranium concentration in daily diet was measured and its associated radiation risks were estimated for the adult population. Food samples were collected from major cities and districts of the country by the market basket method, from which daily diets were prepared. These diet samples were analyzed using inductively coupled plasma mass spectrometry (ICP-MS) at the National Institute of Radiological Sciences, Japan, the regional Central Reference Laboratory of the Reference Asian Man Project. The measured values of the uranium content were found to vary from 2.3 ng (g dry)(-1) to 11 ng (g dry)(-1). The geometric mean concentration and geometric standard deviation were 4.5 x//1.7 ng (g dry)(-1). This leads to a daily dietary intake of 2.6 x// 1.7 microg d(-1) or 33 x// 1.7 mBq d(-1), which is approximately 40% higher than the ICRP value. The measured value, i.e. 33 mBq d(-1), contributes 12 Bq y(-1) to annual intake of 238U activity and 0.54 microSv to the committed effective dose to the adult population. This is a very small fraction of the ICRP annual effective dose limit of 1 mSv for the general public. Therefore, it would pose no significant health hazard.

Estimation of daily micronutrient intake of Filipinos.

The Fourth National Nutrition Survey of the Food and Nutrition Research Institute conducted in 1993 showed an increasing prevalence of micronutrient-related diseases in various age groups. Hence, the daily diet consumed by the average Filipino was examined for its nutrient content. A total of 19 regional diet samples were collected and analyzed for phosphorous, iron, zinc, magnesium, manganese, calcium, potassium, and sodium by using inductively coupled plasma atomic emission spectrometry (ICP-AES). Iodine was determined by inductively coupled plasma mass spectrometry (ICP-MS). Benchmark data for the abovementioned micronutrients showed decreased intake values as compared to the recommended dietary allowance established in 1989. The information will be useful in assessing the existing nutritional status so that appropriate nutrient interventions can possibly be put in place.

Dose estimation by ESR on tooth enamel from two workers exposed to radiation due to the JCO accident.

ESR dosimetry is useful to estimate the external dose for the general population as well as for occupational workers in a nuclear emergency. Three teeth were extracted from two exposed workers (A and B) related to the JCO criticality accident. Tooth enamel was carefully separated from other tooth parts and subjected to ESR dosimetry. Doses equivalent to the gamma-ray dose of 60Co were estimated as follows: for worker A, the buccal and lingual sides of the eighth tooth in the upper right side, 11.8 +/- 3.6 and 12.0 +/- 3.6 Gy, respectively; for worker B, the buccal and lingual sides of the fourth tooth in the upper right side and the fifth tooth in the upper left side, 11.3 +/- 3.4 and 10.8 +/- 3.3 Gy, 11.7 +/- 3.5 and 11.4 +/- 3.4 Gy, respectively. The estimated doses were found to be similar and not dependent on the tooth positions, whether the buccal or lingual sides in each tooth.