• Progress in Medical Physics
• /
• v.23 no.2
• /
• pp.114-122
• /
• 2012

For the determination of absorbed dose to water from a linear accelerator photon beams, it needs a exposure calibration factor $N_x$ or air kerma calibration factor $N_k$ of air ionization chamber. We used the exposure calibration factor $N_x$ to find the absorbed dose calibration factors of water in a reference source through the TG-21 and TRS-277 protocol. TG-21 used for determine the absorbed dose in accuracy, but it required complex calculations including the chamber dependent factors. The authors obtained the absorbed dose calibration factor $N_{dw}{^{Co-60}}$ for reduce the complex calculations with unknown $N_{dw}$ only with $N_x$ or $N_k$ calibration factor in a TM31010 (S/N 1055, 1057) ionization chambers. The results showed the uncertainty of calculated $N_{dw}$ of IC-15 which was known the $N_x$ and $N_{dw}$ is within -0.6% in TG-21, but 1.0% in TRS-277. and TM31010 was compared the $N_{dw}$ of SSDL to that of PSDL as shown the 0.4%, -2.8% uncertainty, respectively. The authors experimented with good agreement the calculated $N_{dw}$ is reliable for cross check the discrepancy of the calibration factor with unknown that of TM31010 and IC-15 chamber.

• Progress in Medical Physics
• /
• v.22 no.2
• /
• pp.92-98
• /
• 2011

This study is to keep the accuracy and stability of the output dose evaluations for linear accelerator photon beams by using the air ionization chambers (TM31010, 0.125 cc, PTW) through the Task Group 51 protocol. The absorbed dose to water calibration factor $N_{dw}{^{Co-60}}$ was delivered from the air kerma calibration factor $N_k$ which was provided from manufacture through SSDL calibration for determination of output factor. The ionization chamber of TM31010 series was reviewed the calibration factor and other parameters for reduce the uncertainty within ${\pm}2%$ discrepancy and we found the supplied $N_{dw}{^{Co-60}}$ which was derived from Nk has shown a -2.8% uncertainty compare to that of PSDL. The authors provided the program to perform the output dosimetry with TG-51 protocol as it is composed same screen of TG-51 worksheets. The evaluated dose by determination of output factor delivered to postal TLD block for comparison the output dose to that of MDACC (RPC) in postal monitoring program. The results have shown the $1.001{\pm}0.013$ for 6 MV and $0.997{\pm}0.012$ discrepancy for 15 MV X rays for 5 years followed. This study shows the evaluated outputs for linear accelerate photon beams are very close to that of international output monitor with small discrepancy of ${\pm}1.3%$ with high reliability and showing the gradually stability after 2010.

• Korean Journal of Environmental Agriculture
• /
• v.22 no.3
• /
• pp.233-235
• /
• 2003

Heavy metal contents in commercial horticultural growing media were investigated Fifty-three samples were collected nationwide during 2000 to 2001 and heavy metals in the samples were analyzed by ICP-OES after acid digestion and 0.1N HCl extraction. Average contents of total Cd, Cr, Co, Ni, Pb, and Zn by acid digestion in the growing media were 0.69, 35.7, 14.9, 15.5, 12.7, and 54.8 mg/kg DW, respectively. The ranges of heavy metal in the growing media were $0{\sim}1.82$, $0{\sim}259.8$, $1.6{\sim}69.5$, $0{\sim}60.7$, $0{\sim}36.5$, $12.9{\sim}124.0\;mg/kg$ DW for Cd, Cr, Co, Ni, Pb, and Zn, respectively. Heavy metal contents in the commercial horticultural growing media were showed lower levels than the permitted levels for quality control described by Korean Standard Analytical Method for Growing Media. Average contents and ranges of 0.1 N HCl extractable heavy metals were 0.08 and $0{\sim}0.20$ for Cd, 0.38 and $0{\sim}2.10$ for Cr, 1.45 and $0{\sim}4.03$ for Cu, 0.85 and $0{\sim}3.31$ for Ni, 0.84 and $0{\sim}2.21$ for Pb, and 30.68 and $0.18{\sim}88.45\;mg/kg$ DW for Zn, respectively. These concentrations by 0.1 N HCl extraction showed much less levels than those of total heavy metals by acid digestion.