• Journal of radiological science and technology
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• v.35 no.3
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• pp.265-273
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• 2012

Aquisition of accurate beam data is very important to calculate a reliable dose distribution of the treatment planning system for small radiation fields in intensity-modulated radiation therapy(IMRT) and stereotactic radiosurgery(SRS). For the measurement of small fields, the choice of a suitable detector is important due to the shape gradient in profile penumbra, the lack of lateral electronic equilibrium, and the effect of effective detector volume. Therefore, this study was to analyze the dosimetric characteristics of various detectors in measurement of beam data for small fields of linear accelerator. 0.01cc and 0.13cc ion chambers (CC01 and CC13) and a stereotactic diode detector(SFD) were used for measurement of small fields. The beam data, including the percent depth dose, output factor, and beam profile were acquired under 6 MV and 15 MV photon beams. Measurements were performed with the field size ranging from $2{\times}2cm^2$ to $5{\times}5cm^2$. For $2{\times}2cm^2$ field size, the differences of the ratios of $PDD_{20}$ and $PDD_{10}$ measured by CC01 and SFD detectors were 1.02% and 0.12% for 6 MV and 15 MV photon beams, respectively. For field sizes larger than $3{\times}3cm^2$, the differences of values of $PDD_{20}/PDD_{10}$ obtained from each detector were 1.15% and 0.71% for 6 MV and 15 MV photon beams, respectively. The output factors obtained from CC01 and SFD for $2{\times}2cm^2$ field size were within 0.5% and 1.5% for 6 MV and 15 MV, respectively. The differences in output factor of three detectors for $3{\times}3cm^2$ to $5{\times}5cm^2$ field sizes were within 0.5%. Profile penumbras measured by the SFD, CC01, and CC13 detectors at three depths were average 2.7 mm and 3.5 mm, 3.4 mm and 4.3 mm, and 5.2 mm and 6.1 mm for 6 MV and 15 MV photon beams, respectively. In conclusion, it could be possible to use of the CC01 and SFD detectors for the measurement of percent depth dose and output factor for $2{\times}2cm^2$ field size, and to use of three detectors for $3{\times}3cm^2$ to $5{\times}5cm^2$ field sizes. CC01 and SFD detectors, consider ably smaller than the radiation field, should be used in order to accurately measure the profile penumbra for small field sizes.

• Korean Journal of Agricultural Science
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• v.20 no.1
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• pp.56-67
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• 1993

To applying of genetic markers of milk proteins as dairy cow registration and selection aids for genetic improvement, genopypes controlling the 4 milk protein loci, ${\alpha}S1$-casein (${\alpha}S1$-CN), ${\beta}$-casein(${\beta}$-CN), ${\kappa}$-casein(${\kappa}$-CN), and ${\beta}$-lactoglobulin(${\beta}$-LG), from a total of 159 Holstein lactating cows reared at National Animal Breeding Station in 1992 were detected by polyacrylamide gel(PAGE) electrophoresis, and associations between genetic polymorphisms of milk proteins and milk compositions were analyzed. The observed distribution of phenotypes for ${\alpha}S1$-CN, ${\beta}$-CN, ${\kappa}$-CN and ${\beta}$-LG were agreement with those expected under the assumption of genetic equilibrium. The observed genotypic frequencies of the ${\alpha}S1$-CN BB, ${\beta}$-CN AA, ${\kappa}$-CN AA and ${\beta}$-LG AB genotypes were founded to be very high as 79.87%, 84.28%, 71.70% and 49.10%, respectively. Gene frequencies were 0.899 and 0.101 for ${\alpha}S1-CN^B$ and ${\alpha}S1-CN^C$, 0.921 and 0.079 for ${\beta}-CN^A$ and ${\beta}-CN^B$, 0.837 and 0.163 for ${\kappa}-CN^A$ and ${\kappa}-CN^B$, 0.378 and 0.622 for ${\beta}-LG^A$ and ${\beta}-CN^B$. According to the results of analysis of variance, the genotypes of the ${\alpha}S1-CN$, ${\beta}-CN$, ${\kappa}-CN$ and ${\beta}-LG$ were significantly difference for fat, protein and total solid percentage in milk compositions. On milk compositions, the ${\kappa}$-CN BB genotype was very high fat and protein percentage more than ${\kappa}$-CN AA and AB genotypes, and ${\beta}$-LG AA genotype was very high fat percentage more than ${\beta}$-LG AB and BB genotype at 5% level of significant difference, respectively. As a consequence, the fat and protein percentage may be improved to select to ${\kappa}$-CN BB and ${\beta}$-LG AA genotypes.