[en] The scale of drainage equipment for liquid radioactive waste disposal is affected remarkably by maximum permissible concentration (MPCw) and physical half-life (HL) of radionuclides contained in waste water. Iodine 125 (¹²⁵I) has the widest use in the field of clinical in-vitro tests using radioactive nuclides and it has the lowest MPCw value and the longest HL. So the nuclide tends to lead to the expansion of the drainage equipment, and the increase in the use of ¹²⁵I raises a serious problem in hospital management. A new apparatus for the effective pre-treatment of liquid ¹²⁵I has been developed in the present study. By using the apparatus along with strage tanks, it is possible to reduce the scale of drainage equipment by the factor of 10 because 99 % of ¹²⁵I contained in liquid waste can safely be decontaminated. This results in economical improvement for the hospital management. (author)

[en] Radiation doses of medical workers in Japan between 1976 and 1979 were analysed based on the data provided by a film badge servicing company. Average annual radiation doses between April, 1978 and March, 1979 were 129 mrems for 2556 doctors, 108 mrems for 2074 radiographers, and 60 mrems for 1915 nurses. It was also suggested that the log-normal distribution could provide a good fit to the frequency distribution of radiation doses of these medical staffs. Time series data of monthly average doses during the period between April, 1976 and March, 1979 were analysed using a computer code named EPA that had been developed by the Japanese Economic Planning Agency. The EPA code separated the original time series data into three components, i.e., the trend and cycle factor, the seasonal factor and the irregular factor based on a multiplicative model. The results of analyses strongly suggested that there existed a significant common pattern among the trend factors of doctors, radiographers and nurses. The similar phenomenon was also observed about the seasonal factors. Some specific cases of medical workers who received considerably high radiation doses were studied, and it was pointed out that, in order to lower the doses of medical workers, the factors which are peculiar to each medical facility must be precisely examined in addition to the strengthening of general radiological protective measures. (author)

No abstract available

[en] From 1985 to 2006, six children underwent surgical management for a cyst at the base of the tongue. Their ages ranged from 3 months to 13 years old. A 3-month-old infant was complaining of inspiratory stridor. Another five children were complaining of abnormal sensation in the pharynx or had no symptoms. Four children underwent total resection of the outer portion of the cystic walls by oral approach. In two of four cases, children have shown cyst recurrence, and one underwent complete removal of the cyst wall by suprahyoid surgical approach. Two children underwent total removal of the cyst by suprahyoid surgical approach. No recurrence has been observed in these two cases. (author)

[en] Recently radioisotopes and radiations have been used for various medical purposes in Japan. A series of investigations into the radiation protection measures for patients and medical workers have been carried out. The present report deals with the estimation of internal radiation doses as the result of a medical use 9 3mCi (=111MBq) of Ga-67 administered for the diagnosis of parotitis. A radiation worker whose accumulated dose over 23 years was 3.2 mGy has been regarded as the subject. Internal radiation dose, on the other hand, was estimated to be about 6 mGy for total body and 150 mGy for liver, which suggested that more effort is expected to be for minimizing radiation doses further but the problem is that medical use of radioisotopes is according to the basic philosophy developed in the recommendation of the International Commission on Radiological Protection. (author)

[en] Today, radioactive pharmaceuticals are widely used for the purpose of diagnosis in the field of nuclear medicine, bringing many bits of useful information. On the other hand, radiation is known to be bionegative, having possibility of inducing stochastic effects such as cancers and genetic effects even in the relatively low dose region together with non-stochastic effects which could result from radiation exposure higher than threshold value. The authors have published a series of papers with regard to the estimation of radiation exposures for medical use based on three principles for radiation protection stated in the ICRP publication 26, i.e., the principles of justification, optimization and limitation. In this paper, radiation dose by a radiation worker due to ²⁰¹Tl administration for the diagnosis of acardiac disease was evaluated based on the measurement of concentration of radioactive isotope excreted in urine over 1 month. Internal radiation dose due to the administration of 3 mCi (1.11x10⁸ Bq) of ²⁰¹Tl was estimated to be 610 mrem (6.1 mSv) which agreed well with the result reported by H.L. Atkins (1977) and far exceeded the occupational exposure (approximately 60 mrem over 12 years). The authors suggested the importance of reducing medical exposure. (author)

[en] We compared the differences in absolute speed of four screen-film systems in seven institutions. Four different screens (HR-4, Fuji; Lanex Medium, Kodak; Lanex 250, Kodak; and HR-12, Fuji) combined with super HRS-30 (Fuji) film and a beam quality of 80 kV tube voltage with a 20 mm aluminum filter were employed. Absolute speeds of the HR-4, Lanex Medium, Lanex 250, and HR-12 in combination with super HRS-30 were 1.83 mR^-1, 2.72 mR^-1, 2.79 mR^-1, and 5.35 mR^-1 (average of seven institutions), respectively. The variation in speed was about ±10% for the seven institutions. Two factors (film processor and densitometer) affecting absolute speed were analyzed. The absolute speed measured in seven institutions varied ±14% depending on the film processor (development conditions) and ±3% depending on the densitometer employed in each institution. (author)

[en] A 66-year-old man with Thorotrast liver disease underwent a partial hepatectomy for a small tumor of the liver, which was demonstrated by digital subtraction angiography. The resected specimen was grossly a sharply circumscribed, gray-yellow nodule, 7.5 mm in diameter. Microscopically, the nodule was an ill-defined hepatic cell mass, which was divided by fine fibrous septa irregularly and incompletely. Central veins and Glisson's capsules were not observed inside the nodule. Bile duct proliferation and infiltration of lymphocytes were found in the fibrous septa. There were Thorotrast depositions within the fibrous tissues around the nodule. Because a typical fibrous boundary and central scar were not found, we have termed this condition a focal nodular hyperplasia-like lesion. A relationship between focal nodular, hyperplasia as a precancerous state and Thorotrast liver disease was suggested. (author)

[en] We report the physical imaging properties of a flat panel detector (FPD) designed for radiographic imaging applications (Revolution XQ/i digital chest imaging system, G.E. Medical Systems). The imaging properties of the detector were evaluated through measurements of the characteristic curve, modulation transfer function (MTF), and Wiener spectrum. The digital characteristic curves of the FPD system were measured for the two tube voltages (80 kV and 120 kV). They showed that the correlation between the pixel values of FPD and the incident exposure to the FPD was a linear correlation. The dynamic range of characteristic curves had a range from about 0.003 to 2μC/kg at the exposure. The presampling MTFs for different tube voltage were almost the same, when we measured the MTFs at 80 kV and 120 kV. And also, there was no significant difference between the MTFs measured with the slit in the direction parallel to the horizontal direction and with the slit in the perpendicular direction. The relative resolution of the FPD system was a 46% higher than that of ST-V imaging plate of FCR (Fuji Computed Radiography) system at 2 cycles/mm. The digital Wiener spectrum of the FPD system was about 1/10 lower than that of the CR system. Thus the FPD system can provide superior imaging performance due to both high resolution and low noise. (author)