A pilot study of half-value layer measurements using a semiconductor dosimeter for intraoral radiography.

Purpose: This pilot study was conducted to evaluate half-value layer (HVL) measurements obtained using a semiconductor dosimeter for intraoral radiography. Materials and Methods: This study included 8 aluminum plates, 4 of which were low-purity (less than 99.9%) and 4 high-purity (greater than 99.9%). Intraoral radiography was performed using an intraoral X-ray unit in accordance with the dental protocol at the authors' affiliated hospital: tube voltage, 60 kVp and 70 kVp; tube current, 7 mA; and exposure time, 0.10 s. The accuracy of HVL measurements for intraoral radiography was assessed using a semiconductor dosimeter. A simple regression analysis was performed to compare the aluminum plate thickness and HVL in relation to the tube voltage (60 kVp and 70 kVp) and aluminum purity (low and high). Results: For the low-purity aluminum plates, the HVL at 60 kVp (Y) and 70 kVp (Y) was significantly correlated with the thickness of the aluminum plate (X), with Y = 1.708 + 0.415X (r=0.999, P<0.05) and Y = 1.980 + 0.484X (r=0.999, P<0.05), respectively. Similarly, for the high-purity aluminum plates, the HVL at 60 kVp (Y) and 70 kVp (Y) was significantly correlated with the plate thickness (X), with Y = 1.696 + 0.454X (r=0.999, P<0.05) and Y = 1.968 + 0.515X (r=0.998, P<0.05), respectively. Conclusion: This pilot study examined the relationship between aluminum plate thickness and HVL measurements using a semiconductor dosimeter for intraoral radiography. Semiconductor dosimeters may prove useful in HVL measurement for purposes such as quality assurance in dental X-ray imaging.

Accuracy of non-contact semiconductor X-ray analyzer for quality assurance in intraoral radiography: a comparison with ionization chamber dosimeter.

OBJECTIVES: The aim of the present study was to evaluate the accuracy of a non-contact semiconductor X-ray analyzer for quality assurance in intraoral radiography, especially a comparison with an ionization chamber dosimeter. METHODS: Intraoral radiography was performed with intraoral X-ray unit using the dental protocol at our hospital: tube voltage, 70 kV; tube current, 7 mA. Accuracy of dose and half-value layer (HVL) measurements was analyzed with a non-contact semiconductor X-ray analyzer and an ionization chamber dosimeter. Stability of the semiconductor sensor, effect of scattered radiation, and comparison of measured HVL between the ionization chamber and the semiconductor sensor were analyzed in this study. RESULTS: The values with the semiconductor sensor were tube voltage: 70.3 ± 0.2 kVp (degree of variability: 0.28%), dose: 454.1 ± 12.3 µGy (degree of variability: 2.7%), and HVL: 1.91 ± 0.02 mmAl (degree of variability: 1.0%). With collimator, the dose with the semiconductor sensor and the ionization chamber decreased by 2.3 µ Gy and 5.2 µ Gy, respectively. The measured HVL of the semiconductor dosimeter was more than that of ionization chamber, and the semiconductor dosimeter was less than ionization chamber in variation of between without and with collimator. CONCLUSION: This study indicated the accuracy of a non-contact semiconductor X-ray analyzer for quality assurance in intraoral radiography, especially a comparison with an ionization chamber dosimeter. The semiconductor sensor can be useful for quality assurance in intraoral radiography.