• 대한핵의학회:학술대회논문집
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• 2003.11a
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• pp.28.2-28.2
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• 2003

• The Journal of Korean Society for Radiation Therapy
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• v.28 no.1
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• pp.65-75
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• 2016

Purpose : By analyzing seroma volume changes in the patients who underwent Partial breast radiation therapy after breast conserving surgery, we try to contribute to the improvement of radiotherapy effect. Materials and Methods : Enrolled 20 patients who underwent partial breast radiation therapy by ViewRay MRIdian System were subject. After seeking for the size of the removed sample in the patients during surgery and obtained seroma volume changes on a weekly basis. On the Basis of acquired volume, it was compared with age, term from start of the first treatment after surgery, BMI (body mass index) and the extracted sample size during surgery. And using the ViewRay MRIdian RTP System, the figure was analyzed by PTV(=seroma volume + margin) to obtain a specific volume of the Partial breast radiation therapy. Results : The changes of seroma volume from MR simulation to the first treatment (a week) is 0~5% in 8, 5~10% in 3, 10 to 15% in 2, and 20% or more in 5 people. Two patients(A, B patient) among subjects showed the biggest change. The A patient's 100% of the prescribed dose volume is 213.08 cc, PTV is 181.93 cc, seroma volume is 15.3 cc in initial plan. However, while seroma volume decreased 65.36% to 5.3 cc, 100% of the prescribed dose volume was reduced to 3.4% to 102.43 cc and PTV also did 43.6% to 102.54 cc. In the case of the B patient, seroma volume decreased 42.57% from 20.2 cc to 11.6 cc. Because of that, 100% of the prescribed dose volume decreased 8.1% and PTV also did to 40%. Conclusion : As the period between the first therapy and surgery is shorter, the patient is elder and the size of sample is smaller than 100 cc, the change grow bigger. It is desirable to establish an adaptive plan according to each patient's changes of seroma volume through continuous observation. Because partial breast patients is more sensitive than WBRT patients about dose conformity in accordance with the volume change.

• Journal of Radiation Protection and Research
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• v.33 no.4
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• pp.167-172
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• 2008

Recently a high-quality voxel model of a Korean adult male was constructed at Hanyang University by using very high resolution serially-sectioned anatomical images of a cadaver, which was provided by the Korean Institute of Science and Technology Information (KISTI). Most existing voxel phantoms are developed based on an individual in the supine posture. This study converted the HDRK-Man voxel model into surface model and adjusted the flattened back of the HDRK-Man to a normal shape in the upright posture using 3D graphic softwares such as $3D-DOCTOR^{TM}$, $Rapidform^{(R)}$2006, $Rhinoceros^{(R)}$4.0, $MAYA^{(R)}$8.5. The effective doses of adjusted model were compared with those of unadjusted model for some standard irradiation geometries (i.e., AP, PA, LLAT, RLAT). In general, the differences were not very large and, among those, the largest difference was found for the PA radiation geometry, as expected. These methodologies can be used for the development of various deformed posture models of HDRK-Man in the later stage of this project.

• Journal of radiological science and technology
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• v.45 no.3
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• pp.241-248
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• 2022

In this study, a recovery coefficient (RC) calculation was conducted that can correct the underestimation of the standardized uptake value (SUV) due to the partial volume effect (PVE) through phantom measurements and formulas. The experiment was conducted using a dynamic phantom capable of implement cranio-caudal movement at a respiratory rate of 15 times per minute along with the measured phantom experiment of the stopped state, and the RC of the moving state is calculated and compared. Ingenuity TF (Philips Healthcare, Netherland) was used as a positron emission tomography/computed tomography (PET/CT) device. PET-CT Phantom (Biodex Medical System, USA) was used as a phantom for measurement. A phantom image in a stationary state was acquired, and a moving phantom image was acquired using the AZ-733V Respiratory Phantom (Anzai Medical Co, Japan) capable of breathing movement in the cranio-caudal direction under the same acquisition parameters. For RC calculation, the sphere maximum radioactivity concentration and the background mean radioactivity concentration of the acquired images were measured, and the initially determined sphere and background radioactivity concentrations were calculated. The calculated RC was 0.08 to 0.72. The size of sphere smaller, it was confirmed that the RC reduced. And the RC in the moving state reduced than in the stationary state. As a result of this study, the change of the RC was confirmed according to the size of spheres and the phantom moving. Using the RC derived by implement movement of breathing with the respiratory phantom, it is possible to considering correction of underestimated SUV by the partial volume effect of PET images and the patient movements.

• The Korean Journal of Nuclear Medicine Technology
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• v.15 no.1
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• pp.10-16
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• 2011

Purpose: The partial volume effect occurs because of limit of the spatial resolution. It makes partial loss of intensity and causes SUV to be lower than it should actually be. So the purpose of this study is to calculate recovery coefficient for correcting PVE from phantom study and to compare before and after SUV correction applying to PET/CT examination. Materials and Methods: The flangeless Esser PET phantom consisting of four hot cylinders was used for this study. All of the hot cylinders were filled with FDG solution of 20.72 MBq per 1000 ml, and the phantom background was filled with FDG solution of different concentrations (33.30, 22.20, 16.65 MBq per 6440 ml) to yield H/B ratios of around 4:1, 6:1 and 8:1. Using the Biograph Truepoint 40(SIEMENS, Germany), we applied recovery coefficient method to 30 patients who were diagnosed with lung cancer after PET/CT exam. And then we analyzed and compared SUV before and after correcting partial volume effect. Results: The smaller the diameter of hot cylinder becomes, the more recovery coefficient decreased. When we applied recovery coefficient to clinical patients and compared SUV before and after correcting PVE, before the correction all lesions gave an average max SUV of 7.83. And after the correction, the average max SUV increases to 10.31. The differences in the max SUV between before and after correction were analyzed by paired t test. As a result, there were statistically significant differences (t=7.21, p=0.000). Conclusion: The SUV for quantification should be measured precisely to give consistent information of tumor uptake. But PVE is one of factors that causes SUV to be lower and to be underestimated. We can correct this PVE and calculate corrected SUV using the recovery coefficient from phantom study. And if we apply this correction method to clinical patients, we can finally assess and provide quantitative analysis more accurately.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2009.04a
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• pp.246-248
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• 2009

기존의 항공사진 및 위성사진을 활용한 원격탐사방법은 기상조건에 따른 제약과 3차원적 수직구조 관한 정보 수집에 한계가 있다. 따라서 보다 정확하고 신속한 산림자원 정보를 획득하기 위해서는 새로운 기술적 접근이 필요하다. 3차원 측정이 가능한 LiDAR의 특성을 이용하면 기존 방법의 부정확성과 비효율성을 상당부분 극복 할 수 있다. 본 연구에서는 지상 Laser Scanner 와 항공 LiDAR를 이용하여 개체목의 3차원 구조를 예측하여 수고, 지하고, 수관면적, 수관체적을 추정하고 결과를 비교하였다. 지상 Laser Scanner에 의한 측정치를 참조자료로 하여 항공 LiDAR의 개체목 측정 정확성을 향상 시킬 수 있는 보정식을 최종적으로 개발하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.4B
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• pp.375-381
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• 2008

In this research, a physics based grid-multi layer distributed flood runoff model was developed to analyze discharge for the Namgang Dam Watershed ($2,293km^2$) and applied for sensitivity analysis for estimation of parameters, mainly initial soil moisture condition and saturate infiltration coefficient, which have a strong influence on discharge. Capability of the model was evaluated using VER and QER from the results of rainfall-runoff analysis and showed enhanced results of 6% compared to parameters before calibration. As the result with the sensitivity analysis of parameters, the part of the most influence on the runoff was the infiltration coefficient and ratio of layer partition. The total discharge and peak time showed comparatively precise runoff results without the initial calibration of the parameters.