• Radiation Oncology Journal
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• v.5 no.2
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• pp.149-155
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• 1987

The success of radioation therapy depends on exact treatment of the tumor with significant high dose for maximizing local control and excluding the normal tissues for minimizing unwanted complications. To achieve these goals, correct estimation of target volume in three dimension, exact dose distribution in tumor and normal critical structures and correction of tissue inhomogeneity are required. The effect of therapy oriented CT (plannng CT) were compared with conventional simulation method in necessity of planning change, set dose, and proper distribution of tumor dose. Of 365 new patients examined, planning CT was performed in 104 patients $(28\%)$. Treatment planning was changed in $47\%$ of head and neck tumor, $79\%$ of intrathoracic tumor and $63\%$ of abdmonial tumor. in breast cancer and musculoskeletal tumors, planning CT was recommended for selection of adequate energy and calculation of exact dose to critical structures such as kidney or spinal cord. The average difference of tumor doses between CT planning and conventional simulation was $10\%$ in intrathoracic and intra-abdominal tumors but $20\%$ in head and neck tumors which suggested that tumor dose may be overestimated in conventional simulation Although some limitations and disadvantages including the cost and irradiation during CT are still criticizing, our study showed that CT Planning is very helpful in radiotherapy Planning.

• The Journal of Korean Society for Radiation Therapy
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• v.24 no.1
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• pp.11-14
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• 2012

Purpose: Anisotropic Analytical Algorithm (AAA) provides more accurate dose calculation regarding impact on scatter and tissue inhomogeneity in comparison to Pencil Beam Convolution (PBC) algorithm. This study tries to analyze the difference of dose distribution according to PBC algorithm and dose calculation algorithm of AAA on breast cancer tangential plan. Materials and Methods: Computerized medical care plan using Eclipse treatment planning system (version 8.9, VARIAN, USA) has been established for the 10 breast cancer patients using 6 MV energy of Linac (CL-6EX, VARIAN, USA). After treatment plan of Conventional Radiation Therapy plan (Conventional plan) and Field-in-Field Intensity Modulated Radiation Therapy plan (FiF plan) using PBC algorithm has been established, MU has been fixed, implemented dose calculation after changing it to AAA, and compared and analyzed treatment plan using Dose Volume Histogram (DVH). Results: Firstly, as a result of evaluating PBC algorithm of Conventional plan and the difference according to AAA, the average difference of CI value on target volume has been highly estimated by 0.295 on PBC algorithm and as a result of evaluating dose of lung, $V_{47Gy}$ and $V_{45Gy}$ has been highly evaluated by 5.83% and 4.04% each, Mean dose, $V_{20Gy}$, $V_{5Gy}$, $V_{3Gy}$ has been highly evaluated 0.6%, 0.29%, 6.35%, 10.23% each on AAA. Secondly, in case of FiF plan, the average difference of CI value on target volume has been highly evaluated on PBC algorithm by 0.165, and dose on ipsilateral lung, $V_{47Gy}$, $V_{45Gy}$, Mean dose has been highly evaluated 6.17%, 3.80%, 0.15% each on PBC algorithm, $V_{20Gy}$, $V_{5Gy}$, $V_{3Gy}$ has been highly evaluated 0.14%, 4.07%, 4.35% each on AAA. Conclusion: When calculating with AAA on breast cancer tangential plan, compared to PBC algorithm, Conformity on target volume of Conventional plan, FiF plan has been less evaluated by 0.295, 0.165 each. For the reason that dose of high dose region of ipsilateral lung has been showed little amount, and dose of low dose region has been showed much amount, features according to dose calculation algorithm need to be considered when we evaluate dose for the lungs.

• Progress in Medical Physics
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• v.19 no.1
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• pp.9-13
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• 2008

The purpose of this study was to measure the skin dose using the glass dosimeter and diode and to compare those measurements to the planned skin dose from the treatment planning system. For the reproducibility of the glass dosimeter (ASAHI TECHNO GLASS CIRPORATION, Japan), the same dose was irradiated to 40 glass dosimeters three times, among which 28 with the reproducibility within 3% were selected for the use of this study. For each of 27 breast cancer patients, the glass dosimeters and diodes were attached to 4 different locations on the skin to measure the dose during treatment. All the patients received one fraction of 180 cGy each. The maximum difference of measurements between the glass dosimeter and diode at the same location was 3.2%. Comparing with the planned skin dose from the treatment planning system (Eclipse v6.5, Varian, USA), the dose measured by the glass dosimeter and the diodeshowed on an average 3.4% and 2.3% difference, respectively. The measured doses were always less than the planned skin dose. This may be due to the specific errors of both detectors. Also, the difference may be caused by the fact that since the skin where the detectors were attached is pretty moveable, it was not fix the detectors on the skin.

• Progress in Medical Physics
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• v.11 no.2
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• pp.109-116
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• 2000

One consideration of radiation delivery in cervical cancer is the complication of critical organs, e.g., bladder and rectum. The absorbed dose of bladder and rectum in HDR intracavitary brachytherapy is measured indirectly with TLD dosimetry A method for the complication reduction of bladder and rectum is suggested. For two-hundred cervical cancer patients, follow-up MRI images were reviewed and distances from cervical central axis to bladder and rectum and vaginal wall thickness were measured. The sealed TLDs were placed upon the gauze packing of the ovoids and the distances to the TLDs from the ovoid center were measured in the simulation film and actual doses of bladder and rectum were calculated. From published data, maximal tolerance doses of bladder and rectum were derived and based on the permissible doses per fraction in HDR brachytherapy the packing thicknesses were determined in both directions. The required minimal packing thicknesses for bladder and rectum were 0.43 and 0.92 cm, respectively. The results were compared with computer calculation using the Meisberger polynomial approach. It is our hope this study can be used for a guideline for users in clinic in estimating critical organ dose in bladder and rectum in HDR brachytherapy in vivo dosimetry.

• Radiation Oncology Journal
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• v.20 no.3
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• pp.274-282
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• 2002

Purpose : Measurement of transmission dose is useful for in vivo dosimetry. In this study, the algorithm for estimating the transmission dose for open radiation fields was modified for application to partially blocked radiation fields. Materials and Methods : The beam data was measured with a flat solid phantom with various blocked fields. A new correction algorithm for partially blocked radiation field was developed from the measured data. This algorithm was tested in some settings simulating clinical treatment with an irregular field shape. Results : The correction algorithm for the beam block could accurately reflect the effect of the beam block, with an error within ${\pm}1.0\%$, with both square fields and irregularly shaped fields. Conclusion : This algorithm can accurately estimate the transmission dose in most radiation treatment settings, including irregularly shaped field.

• Analytical Science and Technology
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• v.20 no.6
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• pp.460-467
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• 2007

Dose rate conversion factor was calculated to estimate the absorbed effective annual doses for soils for the beta-rays and gamma-rays, which were emitted from $^{238,235}U$, $^{232}Th$, and $^{40}K$ isotopes. The most recent data of the emitted energies per decay, half-lifes, and branching ratios, which were obtained from National Nuclear Data Center, were used. When this factor and the effective annual doses for the beta-rays and the gamma-rays of natural radioisotopes were compared with those of Aitken, these of $^{238}U$, $^{232}Th$ and $^{40}K$ are estimated to have good agreements but a large difference is shown in this for $^{235}U$. Through the calculations of effective annual doses by using these factor and the measurements of gamma-ray spectra for soils, which were extracted from prehistoric remains (Mansuri) on Osong, Chungchengbuk-do, The annual effective doses were obtained to be 3.8~5.9 mGy/yr. Also, when these doses including decay elements upper Rn were compared with those on all isotopes, the differences within 9~30 % were obtained. The analysis method of the annual effective doses for the beta-rays and the gamma-rays of the natural isotopes of soils was established by this dose rate conversion factor.

• Journal of Radiation Protection and Research
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• v.10 no.2
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• pp.155-159
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• 1985

In general, dose rates for a monoenergetic gamma emitter uniformly distributed in an infinite cloud have been calulated by using the monoenergetic point-isotorpic source kernel technique. The most serious limitation on use of the kernel technique is subjected to the fact that it estimates the dose only at the surface of body. As a result, an alternative method is presented in which estimates of dose rate for immersion in a radioactive cloud are resulted from the scattered photon spectra incident on the surface of body. The results are in excellent agreement with other's. Work is currently in progress to apply these results to immersion dose problems associated with absorbed dose distribution in the MIRD phatom.

• 대한방사선방어학회:학술대회논문집
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• 2010.04a
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• pp.220-221
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• 2010

• Journal of Radiation Protection and Research
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• v.21 no.1
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• pp.41-50
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• 1996

In this study, the theoretical calculation of the air kerma-to-dose equivalent conversion factors was performed with a Monte Carlo N-Particle transport code for the two types of extremity phantom of the ANSI and the KAERI, respectively. Considering the distribution of absorbed dose due to the interaction of homogeneous Parallel broad beam of monoenergetic primary photons in the range between 15keV and 1.5MeV, the air kerma-to-dose equivalent conversion factors based on the kerma approximation were calculated. It is showed that all the theoretical conversion factors of the two types of the extremity phantom for the ANSI and the KAERI agree well with the experimental values of the ANSI N13.32 draft(1995) for each energy within 5.7%, maximum difference ratio, except for 13.6%, difference ratio in the case for the energy of less than 40keV. It is due to uncertainties of experiment occurred in the low X-ray energy range and geometry considered in the MCNP code.

• Journal of Radiation Protection and Research
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• v.38 no.1
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• pp.22-28
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• 2013

The skyshine effect is an essential and important phenomenon in the shielding design of the high energy accelerator. In this study, a new estimation method of neutron skyshine was proposed and was verified by comparison with existing methods. The effective dose of secondary neutrons and photons at the locations that was far away from high-energy electron accelerator was calculated using FLUKA and PHITS Monte Carlo code. The transport paths of secondary radiations to reach a long distance were classified as skyshine, direct, groundshine and multiple-shine. The contribution of each classified component to the total effective dose was evaluated. The neutrons produced from the thick copper target irradiated by 10 GeV electron beam was applied as a source term of this transport. In order to evaluate a groundshine effect, the composition of soil on the PAL-XFEL site was considered. At a relatively short distance less than 50 m from the accelerator tunnel, the direct and groundshine components mostly contributed to the total effective dose. The skyshine component was important at a long distance. The evaluated dose of neutron skyshine agreed better with the results using Rindi's formula, which was based on the experimental results at high energy electron accelerator. That also agreed with the estimated dose using the simple evaluation code, SHINE3, within about 20%. The total effective dose, including all components, was 10 times larger than the estimated doses using other methods for this comparison. The influence of multiple-shine path in this evaluation of the estimation method was investigated to be bigger than one of pure skyshine path.