[en] Absorbed doses parotid gland, cervical vertebrae and thyroid gland were measured with various exposure settings of the tube voltage and tube current during use of a rotational panoramic radiographs, Veraview (J. Morita Corp., Kyoto, Japan) and PM 2002 CC (Planmeca Oy, Helsinki, Finland) using Rando phantom and thermoluminescence dosimeters. The magnitude of each absorbed dose was greatest in the parotid gland, followed in order by the cervical vertebrae and thyroid gland and was proportional to tube current. The increase of the thyroid gland absorbed dose with increasing tube voltage was steeper than were the increases in the absorbed doses in either the parotid gland or the cervical vertebrae. (author)

[en] Sliced exposures which restrict the exposed area and adjust the region of diagnosis are possible using a sector selector system which is installed in the rotational panoramic radiograph, PM 2002 CC (Planmeca Oy, Helsinki, Finland). The effects of altering the horizontal and vertical sector selector system on thyroid gland dose were measured using Rando phantom and thermoluminescence dosimeters. The horizontal sector selector system clarified that the most of the thyroid gland dose was delivered from exposure of the mandibular region. The vertical sector selector system clarified that scattered x-rays which originated from primary x-rays curved at the incisor and canine, premolar and molar, and ramus regions contributed equally to the thyroid gland dose. (author)

[en] This report describes the radiation dosage reduction possible in the general dental practice with two CCD (charge-coupled device)-based intraoral radiographic systems; the RVG-S (Trophy Radiologie, Vincennes, France) and the Sens-A-Ray (Regam Medical Systems, Sundsvall, Sweden). Radiation dosages (air-kerma; Gy) necessary for obtaining clinically acceptable images were measured at the cone tip using an ionization chamber type 660-1 (Nuclear Associates, Victoreen, Inc., Carle Place, New York, USA). When the RVG-S was used with an Oramatic 70 (Trophy Radiologie) X-ray generator, dosages at the cone tip ranged from 322 to 612 μGy. These corresponded to 40-60% of the dosages necessary when using Ektaspeed dental X-ray film (Eastman Kodak, Rochester, New York, USA) with a Heliodent 70 (Siemens, Erlangen, Germany) X-ray generator. At 60 kVp, the Sens-A-Ray reduced the dosage in the order of 30% compared with Ektaspeed dental X-ray film. Reduction in radiation dosage is one of the benefits of digital intraoral radiographic systems in general dental clinics. The RVG-S provides greater dose savings than does the Sens-A-Ray. (author)

[en] Ten teeth from patients involved in a radioactive accident in Goiania, Brazil, were analysed for ¹³⁷Cs content. Most of the ¹³⁷Cs was on the external root surface of the tooth. Teeth with the highest values were from patients with high whole body content of radiation. (author)

[en] The image contrast of X-ray CT systems depends on the properties of the imaging system, the number of grey scales used in the digital sampling process, and the addition or otherwise of a contrast medium. The effect of contrast medium is often emphasized in the peripheral rim of pathologic masses. In this study, a special hexagonal test object made of acrylic phosphate and a cylindrical container were employed. When the contrast medium IOPAMIRON 300 was used to fill the space between the test object and its cylindrical container, a contrast-enhanced peripheral rim with or without signal of defect was observed. Visual perceptibility was examined from the signals resulting from varying contrast by use of contrast medium and adjusting the grey scale by image processing. Threshold contrast influenced by window width was recorded in each instance using statistical analyses. While window width was inversely proportional to image contrast, different ranges of window width and image contrast provided better visual perceptibility for each concentration of the contrast medium. The range of window width for obtaining the best visual perceptibility was determined for a contrast-enhanced image. (author)