• Journal of Radiation Protection and Research
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• v.17 no.2
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• pp.1-13
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• 1992

The purpose of this study is to develop an algorithm of TLD dose evaluation to meet all requirements stated in ANSI N13. 11-1983. It made the PB-3 TLD of Teledyne Isotopes an object of the development. Personal dosimetry performance testings of the development algorithm have been performed twice through the Atlan-Tech, INC. in accordance with the criteria of testing described in ANSI N13. 11-1983. As ,a result, it is assured that the developed algorithm has complied with all requirements stated in ANSI N13. 11-1983.

• Journal of Radiation Protection and Research
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• v.33 no.4
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• pp.151-160
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• 2008

In Korean nuclear power plants (NPPs), two thermoluminescent dosimeters (TLD) were provided to workers who work in an inhomogeneous radiation field; one on the chest and the other on the head. In this way, the effective dose for radiation workers at NPPs was determined by the high deep dose between two radiation dose from these TLDs. This represented a conservative method of evaluating the degree of exposure to radiation. In this study, to prevent the overestimation of the effective dose, field application experiments were implemented using two-dosimeter algorithms developed by several international institutes for the selection of an optimal algorithm. The algorithms used by the Canadian Ontario Power Generation (OPG) and American ANSI HPS N13.41, NCRP (55/50), NCRP (70/30), EPRI (NRC), Lakslumanan, and Kim (Texas A&M University) were extensively analyzed as two-dosimeter algorithms. In particular, three additional TLDs were provided to radiation workers who wore them on the head, chest, and back during maintenance periods, and the measured value were analyzed. The results found no significant differences among the calculated effective doses, apart from Lakshmanan's algorithm. Thus, this paper recommends the NCRP(55/50) algorithm as an optimal two-dosimeter algorithm in consideration of the solid technical background of NCRP and the convenience of radiation works. In addition, it was determined that a two-dosimeter is provided to a single task which is expected to produce a dose rate of more than 1 mSv/hr, a difference of dose rates depending on specific parts of the body of more than 30%, and an exposure dose of more than 2 mSv.

• 대한방사선방어학회:학술대회논문집
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• 2011.11a
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• pp.372-373
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• 2011

• 대한방사선방어학회:학술대회논문집
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• 2009.04a
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• pp.216-217
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• 2009

• 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.

• Journal of the Korean Society of Radiology
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• v.17 no.5
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• pp.633-640
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• 2023

With the recent development of static and dynamic modulated brachytherapy methods in brachytherapy, which use radiation shielding to modulate the dose distribution to deliver the dose, the amount of parameters and data required for dose calculation in inverse treatment planning and treatment plan optimization algorithms suitable for new directional beam intensity modulated brachytherapy is increasing. Although intensity-modulated brachytherapy enables accurate dose delivery of radiation, the increased amount of parameters and data increases the elapsed time required for dose calculation. In this study, a GPU-based CUDA-accelerated dose calculation algorithm was constructed to reduce the increase in dose calculation elapsed time. The acceleration of the calculation process was achieved by parallelizing the calculation of the system matrix of the volume of interest and the dose calculation. The developed algorithms were all performed in the same computing environment with an Intel (3.7 GHz, 6-core) CPU and a single NVIDIA GTX 1080ti graphics card, and the dose calculation time was evaluated by measuring only the dose calculation time, excluding the additional time required for loading data from disk and preprocessing operations. The results showed that the accelerated algorithm reduced the dose calculation time by about 30 times compared to the CPU-only calculation. The accelerated dose calculation algorithm can be expected to speed up treatment planning when new treatment plans need to be created to account for daily variations in applicator movement, such as in adaptive radiotherapy, or when dose calculation needs to account for changing parameters, such as in dynamically modulated brachytherapy.

• Journal of Radiation Protection and Research
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• v.22 no.3
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• pp.207-218
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• 1997

Purpose: The objective of this study is to develop an algorithm for estimation of tumor dose using measured transmission dose as a part of the development of on-line dosimetry system. Materials and Methods: Data of transmission dose were measured under various FS, Tp and PCD with a special water phantom for 6 MV and 10 MV X-ray. SCD (source-chamber distance) was set to 150 cm. Measurements were conducted with a 0.125 cc ion chamber. Results: Using measured data and regression analysis, two algorithms were developed for estimation of expected reading for measured data. Algorithm 1 consisted of the quadratic function of PCD and the tertiary function of AlP (area-perimeter ratio). Algorithm 2 consisted of the tertiary function of log(A/P)and the tertiary function of PCD. Algorithm 2 required less data set and was more accurate in comparing expected and observed dose. Conclusion: Using the algorithm developed, transmission dose can be estimated for any exposure condition, i.e. any given Tp, PCD and FS with high accuracy. To complete this algorithm, further developments are needed regarding the beam modifying device, the tissue inhomogeneity and the irregular body surface.

• Progress in Medical Physics
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• v.10 no.2
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• pp.103-114
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• 1999

In this study, as a preliminary study for developing a full 3D photon dose calculation algorithm, We developed 2.5D photon dose calculation algorithm by extending 2D calculation algorithm to allow non-coplanar configurations of photon beams. For this purpose, we defined the 3d patient coordinate system and the 3d beam coordinate system, which are appropriate to 3d treatment planning and dose calculation. and then, calculate a transformation matrix between them. For dose calculation, we extended 2d "Clarkson-Cunningham" model to 3d one, which can calculate wedge fields as well as regular and irregular fields on arbitrary plane. The simple Batho's power-law method was implemented as an inhomogeneity correction. We evaluated the accuracy of our dose model following procedures of AAPM TG#23; radiation treatment planning dosimetry verifications for 4MV of Varian Clinac-4. As results, PDDs (percent depth dose) of cubic fields, the accuracy of calculation are within 1% except buildup region, and $\pm$3% for irregular fields and wedge fields. And for 45$^{\circ}$ oblique incident beam, the deviations between measurements and calculations are within $\pm$4%. In the case of inhomogeneity correction, the calculation underestimate 7% at the lung/water boundary and overestimate 3% at the bone/water boundary. At the conclusions, we found out our model can predict dose with 5% accuracy at the general condition. we expect our model can be used as a tool for educational and research purpose.. purpose..

• Journal of the Korean Society of Radiology
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• v.13 no.3
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• pp.481-487
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• 2019

Based on the scan conditions and algorithms that are generally applied during examinations during head CT examinations, the results of dose reduction through the application of algorithm changes were investigated through experiments. As a result, the dose reduction effect was more meaningful for the change of perfusion than for the tube voltage, and the quality evaluation using the brain phantom was relatively less reduced when the dose was reduced after the application of the Bone algorithm, especially for the application of the Bone algorithm, and the deviation of the mean CT number or Pixel value was measured relatively significantly. In other words, the conditions under which dose was reduced and quality was maintained to reduce the patient's exposure dose and obtain images of the same quality were obtained with the application of the Smooth algorithm and the resulting values of 120 kVp, 160 mA. At this point, doses were reduced by about 28%, and the mean CT number or Pixel value was also measured with relatively little error. If the results are applied to patients who visit the hospital for examination or follow-up after applying various algorithms and follow up scan conditions, the results are considered to be very useful in reducing patient exposure dose.

• Progress in Medical Physics
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• v.6 no.2
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• pp.35-40
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• 1995

Purpose: We have developed new film dosimetry algorithm for personal dosimetry and examined its characteristics. Materials and methods: Agfagaevart personal monitoring 2/10 films are used. Films which are in the film badges filtered with Cu 0.3mm, plastic 1.5mm, Aluminum 0.6mm and tin 0.8mm, were exposed by standard dosimetry laboratory. Irradiated energy categories are ANSI N13.1l Category III, and IV. Manual type film precessor and X-rite film densitometor was used. Filtered densities to energy relations and does to transformed densities relations can be obtained ofter transformation of H＆D curves to linear shape by polynomal fitting. Reults : Personal dose be determined within 25％ error for category m and 15％ for category IV. And we are able to evaluate the exposed energy. Conclusion : New algorithm developed in this study is good for personal dosimetry within 30％ error range for catergory III and IV. It is expectd to be complete personal dosimetry algorithm with further study for categrory, I, Dand II V.