Recently, patient dose management has become an important topic in the X-ray based diagnosis. This is because dose exposure has become increasingly precise during diagnosis. The relevance between the exposure dose and the quality of an obtained medical image should be managed through the measured exposure dose. In fact currently, the exposure dose is estimated by the air-kerma measurement using an ionization chamber, and the methodology to calculate the exposure dose has been established [1-3]. In this method, the contribution of scattered X-rays is estimated...

The proposed irradiation system is presented in Fig. 3. In order to achieve a small irradiation field, the detection region was covered with phantoms having thicknesses of “t”. Here, the size of the irradiation field (S×S) was defined as S = R + 10 mm + R, where R was range of secondary electrons. Figure 4 shows the properties of the Monte-Carlo simulation. In the present study, EGS5 (electron gamma shower ver.5) code [15,16] was used. The number of photons used was 108, the energy...

When calculating the irradiation field, it was found that phantom thicknesses of 1 mm, 5 mm, and 10 mm were necessary to achieve electron equilibration for 100-300 keV, 400-1000 keV, and 1500-2000 keV photons, respectively. Figure 8 shows the results of the consistency check for D and Kcol. The vertical axis shows that D/Kcol, so D/Kcol=1 is the ideal value. The corresponding values of “Air/Air” (blue) and “PMMA/PMMA” (green) deviate within the range of 1±0.05. On the other hand, thecorresponding value of “Air/PMMA” (red) is...

In conclusion, we proposed a new irradiation system in order to evaluate the basic properties of the nanoDot OSL dosimeter in a simulation study. In the method, the detection region was totally covered with phantoms having thicknesses of 1-15 mm which enables the establishment of small irradiation fields. We evaluated the accuracy of our system by comparing an absorbed dose and collision kerma. As a result, we found that they agree with an accuracy of 10%. The calculation efficiency was greatly improved. The fractions of...

Hiroki Okino Graduate School of Health Sciences, Tokushima University, Japan

[1] Grosswendt B: Backscatter factors for x-rays generated at voltages between 10 and 100 keV, Physics in Medical and Biology 29(5), 579-591, 1984. [2] Klevenhagen SC: Experimentally determined backscatter factors for x-rays generated at voltages between 16 and 140 kV, Physics in Medical and Biology 34(12), 1871-1882, 1989. [3] Grosswendt B: Dependences of the photon backscatter factor for water on source-to-phantom distance and irradiation field size, Physics in Medical and Biology 35(9), 1233-1245, 1990. [4] Jursinic PA: Characterization of optically stimulated luminescent dosimeters, OSLDs, for...