• Progress in Medical Physics
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• v.19 no.2
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• pp.131-138
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• 2008

We evaluated on the calculation accuracy of treatment planning system (TPS) with phantom having convex and concave surface. The TPS is Eclipse (Varian, USA) using both algorithms AAA and PBC for photon dose calculations. PBC algorithms have three corrections of Batho, modified Batho (M-Batho), and equivalent TAR (E-TAR). The field sizes were $10{\times}10\;cm^2$ and $20{\times}20\;cm^2$, and MLC-shaped fields for these fields. We measured doses at three depths 5, 10 and 15cm in phantom of SSD=90cm in the condition of inserted farmer chamber. For given conditions, we have calculated dose with these algorithms and compared them with measured doses. In AAA the calculated doses (dose/MU) were agreed to measured doses within ${\pm}1%$ in flat and convex surface and were under estimated with -1.9% maximum in concave surface. In PBC the calculated doses were over estimated with +1.7% and +4.1% respectively in flat and convex surface and the differences were from -3.1% to +2.1% in concave surface. In comparison of criteria from AAPM and IAEA reports, and statistical analysis for these results, it is found that the AAA's results are in good agreement with measured values and the M-Batho's results are generally good agreed with measured values among PBC algorithms.

• Journal of Radiation Protection and Research
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• v.39 no.4
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• pp.213-217
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• 2014

Medical operations and diagnosis using interventional radiology techniques have been increased. The management and monitoring of occupational radiation exposure to the staff of interventional radiology become important, specially because they stand in close proximity to the patient. The operational radiation protection quantity, Hp(10) which can be obtained from personal dosimeter do not always represent the effective dose to the staff. So, in this study, to estimate the critical organ doses to the staff of interventional radiology, Monte Carlo calculations with mathematical human phantom and dose measurements with personal dosimeters were carried out for the major interventional radiology procedures using C-arm. Results showed that the values of Hp(10) measured by personal dosimeters were higher than critical organ doses which were calculated. And the calculated dose to thyroids was much higher than those of other critical organ doses. For the proper radiation protection of the medical staff of interventional radiology, additional radiation protection for thyroids as well as for whole body shielding like wearing a lead apron should be considered.

• Progress in Medical Physics
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• v.19 no.4
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• pp.231-240
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• 2008

We developed a user-friendly program to independently verify monitor units (MUs) calculated by radiation treatment planning systems (RTPS), as well as to manage beam database in clinic. The off-axis factor, beam hardening effect, inhomogeneity correction, and the different depth correction were incorporated into the program algorithm to improve the accuracy in calculated MUs. A beam database in the program was supposed to use measured data from routine quality assurance (QA) processes for timely update. To enhance user's convenience, a graphic user interface (GUI) was developed by using Visual Basic for Application. In order to evaluate the accuracy of the program for various treatment conditions, the MU comparisons were made for 213 cases of phantom and for 108 cases of 17 patients treated by 3D conformal radiation therapy. The MUs calculated by the program and calculated by the RTPS showed a fair agreement within ${\pm}3%$ for the phantom and ${\pm}5%$ for the patient, except for the cases of extreme inhomogeneity. By using Visual Basic for Application and Microsoft Excel worksheet interface, the program can automatically generate beam data book for clinical reference and the comparison template for the beam data management. The program developed in this study can be used to verify the accuracy of RTPS for various treatment conditions and thus can be used as a tool of routine RTPS QA, as well as independent MU checks. In addition, its beam database management interface can update beam data periodically and thus can be used to monitor multiple beam databases efficiently.

• Nuclear Medicine and Molecular Imaging
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• v.42 no.6
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• pp.464-468
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• 2008

Purpose: Effective half life of I-131 ($T_{eff}$) in patients with differentiated thyroid cancer treated by I-131 is must-know value for dose calculation and determination of release time from isolation room. There has been no report about $T_{eff}$ in Koreans. Thus, author tried to measure dose rate without radiation exposure to faculty members and calculated $T_{eff}$. Methods: Probe of radiation survey meter was fixed at the wall of isolation room, and body of survey meter was placed outside the room. With this simple arrangement, author could measure radiation frequently without radiation exposure to faculty members in 68 patient (F=55, M=13, age=$47{\pm}13.7$) treated by I-131 ($3.7{\sim}7.4\;GBq$) for differentiated thyroid cancer from Jan 2006 to Dec 2006. From this data, $T_{eff}$, 48 hr retention rate, and the time necessary to whole body retention of I-131 become less than 1.1 GBq were calculated. Serum creatinine levels were measured before and after thyroid hormone withdrawal. Results: $T_{eff}$ was $15.4{\pm}4.3\;hr$ ($9.4{\sim}32.5\;hr$). There was a loose correlation between $T_{eff}$ and serum creatinine concentration (r=0.45). 48hr retention was $4.9{\pm}4.2%$ ($1{\sim}23%$). Time necessary to whole body retention of I-131 become less than 1.1 GBq was calculated as $47.1{\pm}13.2\;hr$ for 9.25 GBq, $42.1{\pm}11.9\;hr$ for 7.4 GBq, $35.7{\pm}10.0\;hr$ for 5.55 GBq, and $26.7{\pm}7.5\;hr$ for 3.7 GBq dose of I-131. Conclusion: Author successfully measured radiation dose rates in isolated patients treated by high dose of I-131 without radiation exposure to the faculty members with simple arrangement of survey meter probe. Using those data, $T_{eff}$ and some other indices were calculated.

• Proceedings of the Korean Nuclear Society Conference
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• 2001.05a
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• pp.444.1-444
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• 2001

• Proceedings of the Korean Society of Radiological Science
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• 2002.06b
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• pp.34.1-34.1
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• 2002

• Proceedings of the Korean Nuclear Society Conference
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• 1998.10a
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• pp.333-333
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• 1998

• Proceedings of the Korean Nuclear Society Conference
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• 2004.05a
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• pp.387.2-387.2
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• 2004

• Proceedings of the Korean Nuclear Society Conference
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• 2002.05a
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• pp.395.1-395
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• 2002

• Journal of The Korean Radiological Technologist Association
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• v.28 no.1
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• pp.247-247
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• 2002