Usefulness of the newly developed artificial denture plaque for practical denture care training.

OBJECTIVES: The aim of this study was to investigate whether the newly developed artificial dental plaque (A-DP) is useful as an educational tool for denture care of dental hygienist that compared it with conventional artificial dental plaque from the viewpoint of practical skills. MATERIAL AND METHODS: The 125 dental hygienist school students and 26 dental hygienists who had clinical experience were subjected a practical training of denture plaque control using the conventional denture plaque (C-DP) and the A-DP. The questionnaires based on the semantic differential method were used to survey whether the A-DP is similar to the real denture plaque (R-DP). Factor analysis by rotation of promax was carried out. RESULTS: In the results of the factor analysis, the two factors could be detected in students and three factors in dental hygienists. The total score of each denture plaque was calculated for each factor, and correlation coefficient was examined. There was significant correlation between the A-DP and the R-DP at the first factors, both students and dental hygienists. C-DP was not similar to R-DP in all factors. CONCLUSIONS: These results suggested that A-DP resembles R-DP better than C-DP. It was concluded that the A-DP was similar to the R-DP and could be a potent educational tool for practical denture care.

Muscle IGF-I Ea, MGF, and myostatin mRNA expressions after compensatory overload in hypophysectomized rats.

To determine whether IGF-I Ea, MGF, and myostatin mRNAs are related to GH-independent overload-induced muscle growth, we examined the expressions of IGF-I Ea and MGF mRNAs in the plantaris muscle after compensatory overload in hypophysectomized rats. The muscles were divided into four groups: normal-control, normal-overloaded, hypophysectomized-control, and hypophysectomized-overloaded. The weights of the plantaris muscle in the normal-overloaded were significantly higher than those of the normal-control. The weights of the hypophysectomized-overloaded were also significantly higher than those of the hypophysectomized-control. IGF-I Ea and MGF mRNAs in normal-overloaded and hypophysectomized-overloaded 3 days after overload were significantly higher than those of normal-control and hypophysectomized-control, respectively. Myostatin mRNAs in normal-overloaded and hypophysectomized-overloaded 3 days after the overload were significantly lower than those of normal-control and hypophysectomized-control, respectively. Thus, it was shown that IGF-I Ea, MGF, and myostatin mRNAs were expressed in association with muscle enlargement after compensatory overload independently of pituitary state. These observations suggest that the expression of IGF-I Ea, MGF, and myostatin mRNAs due to compensatory overload would be associated in a growth-hormone-independent manner.

[New method of estimating effective energy for X-ray CT scanners].

Because the exposure dose in X-ray computed tomography examinations is sometimes difficult to determine, it is important to be able to estimate the dose for these examinations. The effective energy of the X-ray CT scanner is required to estimate exposure dose. Although the half-value-layer (HVL) method has been used to calculate effective energy, it is not an easy method. This paper proposes a technique by which effective energy can be easily calculated. Certain details were found to cause change in effective energy, and the ratio (inner-metal center-air ratio: IMCAR) between air dose and dose in fixing the metallic pipe in the isocenter of an X-ray CT scanner was necessary. The IMCAR from a different X-ray CT scanner was required, and, when effective energy was calculated, it showed an error of less than 0.7% for the half-value-layer method. The effect of this error on dose estimation was slight (0.4%). This technique is useful, because effective energy can easily be calculated with a high degree of accuracy.

[Measurement of the humeral retroversion angle using a simple X-ray pictorial image].

The semi-axial-view method is used to measure humeral retroversion angles by a single x-ray exposure. We examined the clinical utility of this method using a humerus model and normal volunteers. In an experiment with a humerus model, humeral retroversion angles were measured at various positioning angles by the semi-axial-view method, and compared with the angles measured by the CT method, which is considered the standard, and the best position was determined. The upper arms of three volunteers were photographed by the semi-axial-view method in the most suitable position, and humeral retroversion angles were compared with those obtained by the CT method. As a result of examination with a humerus model, the best positioning angles were 20 degrees of shoulder abduction angle, 90 degrees of shoulder flexion angle, and 90 degrees of elbow flexion angle. There were no significant differences between the humeral retroversion angles of the CT and semi-axial-view methods with the best position determined in volunteers. In conclusion, the semi-axial-view method is a useful, easy method for measuring the humeral retroversion angle. This method will be a great asset in researching large numbers of samples.

[Effect of the respiratory movements on the intensity of FDG accumulation in PET inspection image].

PURPOSE: With chest PET examination, expansion of an image showing a small accumulation and reduction in the radiation count due to breathing movements are anticipated. The purpose of this paper is to analyze movement in the chest region when breathing and to clarify effects of the movement on expansion of the image of a small accumulation and intensity of the radiation count. METHODS: Movements around the hilum of the lung under resting respiration are analyzed in X-rays, CT images and MR images. Based on results of the analysis, breathing movements are reproduced by means of a phantom of our own design. The phantom is adjusted to the PET apparatus so as to change in accordance with the magnitude and movement of a small accumulation to obtain expansion of the image of this part and the intensity of the radiation count. RESULTS: It was found that movements around the hilum of the lung under resting respiration are of a reciprocative kind in the cranio-caudal direction which can be approximated by the fundamental wave. The extent of the image with average amplitude (8.2 +/- 2.8 mm, n = 30) was 6 mm in the cranio-caudal direction. The average amplitude of the radiation count was lowered 38% at 3 mm phi and 22% at 6 mm phi. CONCLUSIONS: It is considered that breathing movement results in a reduction in the radiation count in small accumulations and this may cause underestimation of SUV.

[Evaluation of efficiency of a semiconductor gamma camera].

We evaluation basic characteristics of a compact type semiconductor gamma camera (eZ-SCOPE AN) of Cadmium Zinc Telluride (CdZnTe). This new compact gamma camera has 256 semiconductors representing the same number of pixels. Each semiconductor is 2 mm square and is located in 16 lines and rows on the surface of the detector. The specific performance characteristics were evaluated in the study referring to NEMA standards; intrinsic energy resolution, intrinsic count rate performance, integral uniformity, system planar sensitivity, system spatial resolusion, and noise to the neighboring pixels. The intrinsic energy resolution measured 5.7% as FWHM. The intrinsic count rete performance ranging from 17 kcps to 1,285 kcps was evaluated, but the highest intrinsic count rate was not observed. Twenty percents count loss was recognized at 1,021 kcps. The integral uniformity was 1.3% with high sensitivity collimator. The system planar sensitivity was 33,330 cpm/MBq with high resolution collimator and 766,767 cpm/MBq with high sensitivity collimator. The system spatial resolution (FWHM) was 2.0 mm and 2.2 mm when the distance between source and collimator was 0 cm and 3 cm respectively.