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Feasibility Study of Beam Angle Optimization for Proton Treatment Planning Using a Genetic Algorithm
Seo Jaehyeon,Jo Yunhui,Moon Sunyoung,Yoon Myonggeun,안성환,Lee Boram,Chung Kwangzoo,Jeong Seonghoon 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.77 No.4
This study describes a method that uses a genetic algorithm to select optimal beam angles in proton therapy and evaluates the effectiveness of the proposed algorithm in actual patients. In the use of the genetic algorithm to select the optimal angle, a gene represents the angle of each field and a chromosome represents the combination of beam angles. The fitness of the genetic algorithm, which represents the suitability of the chromosome to the solution, was quantified by using the dose distribution. The weighting factors of the organs used for fitness were obtained from clinical data through logistic regression, reflecting the dose characteristics of actual patients. Genetic operations, such as selection, crossover, mutation, and replacement, were used to modify the population and were repeated until an evaluation based on fitness reached the termination criterion. The proposed genetic algorithm was tested by assessing its ability to select optimal beam angles in three patients with liver cancer. The optimal results for fitness, planning target volume (PTV), normal liver, and skin in the population were compared with the clinical treatment plans, a process that took an average of 36.8 minutes. The dose-volume histograms (DVHs) and the fitness of the genetic algorithm plans did not differ significantly from the actual treatment plans. These findings indicate that the proposed genetic algorithm can automatically generate proton treatment plans with the same quality as actual clinical treatment plans.
Park, Soojeong,Seo, Yeonju,Kim, Myung Soo,Lee, Seonghoon Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.3
The photoanode electrode of $TiO_2$ nanotubes (NTs) anchored with ZnS/CdSSe/CdS quantum dots (QDs) was prepared by anodization of Ti metal and successive ionic layer adsorption and reaction (SILAR) procedure. The tuning of the band gap of CdSSe was done with controlled composition of Cd, S, or Se during the SILAR. A ladder-like energy structure suitable for carrier transfer was attained with the photoanode electrode. The power conversion efficiency (PCE) of our solar cell fabricated with the regular array of $TiO_2$ NTs anchored with CdSSe/CdS or CdSe/CdS QDs [i.e., (CdSSe/CdS/$TiO_2NTs$) or (CdSe/CdS/$TiO_2NTs$)] was PCE = 3.49% and 2.81% under the illumination at 100 mW/$cm^2$, respectively. To protect the photocorrosion of our solar cell from the electrolyte and to suppress carrier recombination, ZnS was introduced onto CdSSe/CdS. The PCE of our solar cell with the structure of a photoanode electrode, (ZnS/CdSSe/CdS/$TiO_2$ NTs/Ti) was 4.67% under illumination at 100 mW/$cm^2$.
정민규(Jung Minkyu),서경우(Seo Kyoungwoo),김성훈(Kim Seonghoon) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11
A decay tank is installed to decrease the N-16 radioactivity in PCS (Primary Cooling System) of research reactor. As the flow velocity is sharply decreased by huge volume of the decay tank, the flow of primary coolant is delayed inside the tank. The N-16 activity is rapidly decreased by passing through the tank, since the half-time of N-16 activity is only 7.13 seconds. For the cooling system design of research reactor, the accident scenario of pipe break should be considered to secure the safe shutdown of the reactor. The loss of coolant or air inflow conditions could be occurred at the break position in accordance with the system design. For the air inflow accident, the coolant flow of air volume fraction over certain level could give rise to serious problems for pumps. And, the air inflow of reactor core could cause the structural problems of nuclear fuels. Therefore, in the present system design, a study on the role of trapping the air inside the decay tank is performed by using the numerical methods. As the air inflows inside the tank, the air-water stratification phenomenon is observed by the density difference of two fluids. The efficiency of trapping the air is evaluated by the estimation of air volume fraction inside the tank when the air is leaved the tank. And, the trapping efficiency comparison is also performed according to the decay tank types.