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Organobismuth compounds have been used in various areas of science, like biology and organic synthesis, because they are normally nontoxic and exhibit unique properties. Bismuth induces metallothionein production and is known to exhibit thiophilicity. However, few reports on the reactions between bismuth and sulfur compounds exist. This article reviews studies on the reactivity of bismuth (III and V) with sulfur compounds. A simple approach for the reaction of azole-2-thiones, which contains a heterocyclic ring, with triaryl bismuthines in the presence of a copper catalyst affords the S-arylated coupling product. When a palladium catalyst is used instead of a copper catalyst, desulfinative C-C bond formation occurs. These reactions indicate that trivalent bismuth compounds can be used as novel aryl sources. Triphenylbismuth dichloride, an organobismuth (V) reagent, successfully promotes the cyclodesulfurization of thioureas within short reaction times under mild conditions. The reaction affords N-substituted benzoxazol-2-amines in excellent yields. Tafamidis, a drug used to treat transthyretin amyloidosis, can be synthesized using this reaction.

Objective: The purpose of this study was to assess the dose reduction and the image quality using bismuth sheets during the computed tomography fluoroscopy (CTF)., Materials and Methods: The bismuth sheets of 1-mm thick were put on the upper mylar ring to reduce the frontal X-ray. The dose rates of an operator were measured using a torso phantom in the patient position during the CTF. The torso phantom was set on the gantry rotation center (center) and the lower position from the center (off-center). The image quality of the CTF image was assessed using an original phantom that mimics the normal liver parenchyma and the low attenuation lesions. The image contrast and contrast-to-noise ratio (CNR) were compared with and without the bismuth sheets., Results: The bismuth sheets reduced the dose rate of the operator, regardless of whether the torso phantom was set at the center or the off-center. The reduction rate of exposure at the center and the off-center were 42.3% and 34.5%, respectively. There were no significant differences in the image contrast and the CNR, although the bismuth sheets increased the CT values of the liver parenchyma and the low attenuation lesions., Conclusion: The bismuth sheets were effective for the reduction of exposure to the operator without degrading the image quality of CTF images.

In order to determine trace amounts of lead in copper gluconate by atomic absorption spectrometry (AAS), the authors investigated a separation and pre-concentration procedure using a co-precipitation technique with bismuth. After ashing 2.0 g of the sample by means of a dry process, the ash was dissolved in (1→100) nitric acid and 75 μg of bismuth was added. Lead was co-precipitated by using an ammonium solution controlled to pH 9.5-10.5. The precipitate was left at room temperature for over 15 minutes to age, and then washed with a (3→100) ammonium solution three times. The precipitate was dissolved in (1→100) nitric acid and then analyzed by AAS. The quantification limit of this method was 0.5 mg/kg, and the trueness, repeatability and intermediate precision were 99.6%, 4.2% and 4.2% at the spiked concentration of 0.5 mg/kg, and 94.4%, 2.8% and 4.0% at the spiked concentration of 5.0 mg/kg, respectively. Thus, the present method for trace analysis of lead in copper gluconate was validated.

We evaluated the effectiveness of metallic shields that were used for reduction of the breast dose in thoracic computed tomography(CT). For the evaluation, we measured breast surface dose and image standard deviation(SD)in the lung area. The metallic shields were made from bismuth, zinc, copper, and iron. The bismuth shield has been marketed and used for dose reduction. The other three metallic shields were chosen because they have lower atomic numbers and a lower yield of characteristic X-rays. As a result, use of the metallic shields showed a lower breast dose than the decrement of the tube current in the same image SD. The insertion of a thin aluminum sheet between the shield and a phantom was also effective in reducing breast surface dose. We calculated the dose reduction rate to evaluate the effectiveness of these metallic shields. This dose reduction rate was defined as the ratio of the decrease in breast surface dose by metallic shields to the breast surface dose measured with the tube current decrement in the same image SD. The maximum dose reduction rate was 6.4% for the bismuth shield, and 12.0-13.3% for the other shields. These results indicate that the shields made from zinc, copper, and iron are more effective for dose reduction than the shield made form bismuth. The best dose reduction rate, 13.3%, has been achieved when the zinc shield placed 20 mm apart from a phantom with 0.2 mm aluminum was used.

In connection with low-level gamma-ray counting of natural samples, background due to 220Rn- and 222Rn-daughters was monitored. The results obtained for 4 months showed that the background gamma-ray from 222Rn-daughters was more variable than that of 220Rn-daughters. An efficient air-conditioning was helpful to keep the background stable. It was practically equivalent to the use of N2-gas. Radiometric data for dust samples filtered from the laboratory air suggested that Rn-daughters tended to be removed by air-conditioning.

Since lead contains more or less 210Pb, the selection for lead materials has to be done before construction of the low level radiation shield. In this paper, a method for determination of 210Pb is based on radioanalytical separation such as DDTC (sodium diethyl dithio carbamate) extraction followed by beta ray counting of 210Bi. Fourteen commercial lead samples and three old lead samples were analysed for 210Pb. The concentration for 210Pb in commercial samples was found to range from 0.063 to 11 Bq/g (1.7 to 300 pCi/g) and in old samples was less than 0.01 Bq/g (0.3 pCi/g). These results will be useful to the selection of shielding material. The detection limit and the time required for 210Pb determination was 0.003 Bq/g (0.1 pCi/g) and 5.5 hours, respectively.

Observation of gamma-ray background has been done by using a Ge(Li) semiconductor detector when it was placed inside the lead shielding material. With the aid of a very simple model calculation, the concentration of 210Pb radioisotope embedded in the lead material has been estimated to be 0.1-0.4 (Bq/Pb-g) (3-12 (pCi/Pb-g). The origin of Pb-KX-ray emission, the highest peak in the background spectrum, has been investigated by comparing the 210Pb-47 keV gamma-ray and Pb-KX-ray peak counts. As the results, about 50 +/- 30% of Pb-KX-ray production is estimated to be due to the Pb-K shell photoionization which is induced by the bremsstrahlung of 210Bi beta-ray.