• Title/Summary/Keyword: 호형

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Fractionated Stereotactic Radiotherapy (FSRT) Using Gold Markers : A Comparison of the Isocenter between Multiple Arcs and Static Conformal Beams (금속표지자를 이용한 다중호형 정위방사선치료와 입체조형 정위방사선치료의 회전중심점 비교)

  • 장지영;김기환;김재성;김준상;송창준;김선환;조문준
    • Progress in Medical Physics
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    • v.14 no.1
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    • pp.28-33
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    • 2003
  • The aim of the study was to assess the isocenter deviation between multiple arcs and conformal beams in frameless FSRT. Forty seven patients received single isocenter radiosurgery or therapy (SRS/T) using available framelss FSRT system from Aug. 1997 to Dec. 2m. In choosing multiple arc FSRT or conformal FSRT, we had considered one of two techniques with respect to tumor size and tumor shape. In multiple arc FSRT, the average and standard deviation (SD) of the isocenter deviation was 0.2 mm (SD 0.2 mm), 0.2 mm (SD 0.2) and 0.3 mm (SD 0.2 mm)in the lateral (x), anterior-posterior (y) and cranio-caudal directions (z). In conformal FSRT, the average deviation and SD of the isocenter deviation was 0.2 mm (SD 0.2 mm), 0.3 mm(0.2 mm) and 0.4 mm (SD 0.2 mm) in the x, y and z directions. The average spacial deviation ($\Delta$r) was 0.41 mm and 0.54 mm in multiple arcs and conformal beams, respectively. The isocenter deviation using frameless FSRT system was similar value between multiple arcs and conformal beams. In practice, we believed we can select the appropriate treatment technique according to tumor shape and size.

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Application of Weight Function Method to Elliptical Arc Through Cracks at Mechanical Fastener Holes (기계적 체결홀에 존재하는 타원호형 관통균열에 대한 가중함수법의 적용)

  • Heo, Sung-Pil;Yang, Won-Ho;Chung, Ki-Hyun;Hyun, Cheol-Seung
    • Proceedings of the KSME Conference
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    • 2001.11a
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    • pp.304-310
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    • 2001
  • Cracks at mechanical fastener holes usually nucleate as elliptical comer cracks at the faying surface of the mechanical joints and grow as elliptical arc through cracks after penetrating the opposite surface. In this study mode I, II and III stress intensity factors at two surface points of elliptical arc through cracks at mechanical fastener holes are analyzed by applying weight function method. The weight function method for two dimensional mixed-mode problem is extended to three dimensional one and it is verified.

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Field Observation of Morphological Response to Storm Waves and Sensitivity Analysis of XBeach Model at Beach and Crescentic Bar (폭풍파랑에 따른 해빈과 호형 사주 지형변화 현장 관측 및 XBeach 모델 민감도 분석)

  • Jin, Hyeok;Do, Kideok;Chang, Sungyeol;Kim, In Ho
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.32 no.6
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    • pp.446-457
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    • 2020
  • Crescentic sand bar in the coastal zone of eastern Korea is a common morphological feature and the rhythmic patterns exist constantly except for high wave energy events. However, four consecutive typhoons that directly and indirectly affected the East Sea of Korea from September to October in 2019 impacted the formation of longshore uniform sand bar and overall shoreline retreats (approx. 2 m) although repetitive erosion and accretion patterns exist near the shoreline. Widely used XBeach to predict storm erosions in the beach is utilized to investigate the morphological response to a series of storms and each storm impact (NE-E wave incidence). Several calibration processes for improved XBeach modeling are conducted by recently reported calibration methods and the optimal calibration set obtained is applied to the numerical simulation. Using observed wave, tide, and pre & post-storm bathymetries data with optimal calibration set for XBeach input, XBeach successfully reproduces erosion and accretion patterns near MSL (BSS = 0.77 (Erosion profile), 0.87 (Accretion profile)) and observed the formation of the longshore uniform sandbar. As a result of analysis of simulated total sediment transport vectors and bed level changes at each storm peak Hs, the incident wave direction contributes considerable impact to the behavior of crescentic sandbar. Moreover, not only the wave height but also storm duration affects the magnitude of the sediment transport. However, model results suggest that additional calibration processes are needed to predict the exact crest position of bar and bed level changes across the inner surfzone.

Stress Intensity Factor Analysis of Elliptical Arc Through Cracks at Mechanical Fastener Holes by Weight Function Method ( I ) - Development of Weight Function Method - (가중함수법에 의한 기계적 체결홀에 존재하는 타원호형 관통균열의 음력확대계수 해석 ( I ) - 가중함수법의 전개 -)

  • Heo, Seong-Pil;Yang, Won-Ho;Hyeon, Cheol-Seung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.10
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    • pp.1659-1670
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    • 2001
  • It has been reported that cracks at mechanical fastener holes usually nucleate as elliptical corner cracks at the faying surface of the mechanical joints and grow as elliptical arc through cracks after penetrating the opposite surface. The weight function method is an efficient technique to calculate the stress intensity factors fur elliptical cracks using uncracked stress field. In this study the weight function method for three dimensional mixed-mode problem applied to elliptical comer cracks Is modified for elliptical arc through cracks and the stress intensity factors at two surface points of elliptical arc through cracks at mechanical fastener holes are analyzed by the weight function method. This study consists of two parts and in part I , the weight function method for elliptical arc through cracks is developed and verified.

Stress Intensity Factor Analysis of Elliptical Arc Through Cracks at Mechanical Fastener Holes by Weight Function Method (II) - Mixed-Mode Stress Intensity Factor Analysis - (가중함수법에 의한 기계적 체결홀에 존재하는 타원호형: 관통균열의 음력확대계수 해석 (II) - 혼합모드 음력확대계수 해석 -)

  • Heo, Seong-Pil;Yang, Won-Ho;Ryu, Myeong-Hae
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.10
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    • pp.1671-1677
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    • 2001
  • Cracks at mechanical fastener holes usually nucleate as elliptical comer cracks at the faying surface of the mechanical joints and grow as elliptical arc through cracks. The weight function method for elliptical arc through cracks at mechanical fastener holes has been developed and verified in the part I of this study. In part H, applying the weight function method, the effects of the amount of clearance on the mixed-mode stress intensity (actors are investigated and the change of crack shape is predicted from the analysis for various crack shapes. The stress intensity factors leer inclined crack are analyzed and critical angle at which mode I stress intensity factor becomes maximum is determined.

The taxonomic implication of leaf anatomy in tribe Sorbarieae (Spiraeoideae: Rosaceae) (쉬땅나무족(Sorbarieae Rydb., 장미과) 잎의 해부학적 형질 및 분류학적 유용성)

  • Song, Jun-Ho;Hong, Suk-Pyo
    • Korean Journal of Plant Taxonomy
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    • v.44 no.2
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    • pp.119-131
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    • 2014
  • A comparative study of leaf anatomy in tribe Sorbarieae (Adenostoma, Chamaebatiaria, Sorbaria, Spiraeanthus) including one related genus Lyonothamnus was carried out using light microscopy. Anatomical characteristics of the leaf blade and midrib were described and taxonomically evaluated. The anatomical characters which described in this study are as follows: thickness of leaf midrib, blade in cross section, cuticle, epidermal cell, stoma, trichome, mesophyll, crystal, main vasculature type. All features were compared and the vascular patterns of midrib were distinguished two types. - Type 1: Trace tripartite (Adenostoma), Type 2: Trace continuous, subtype 2A: flat arc (Chamaebatiaria, Spiraeanthus), subtype 2B: U-shape arc (Lyonothamnus, Sorbaria). In conclusion, some of leaf anatomical characters (e.g., cuticle, epidermal cell, trichome, mesophyll, main vasculature type) can be useful for diagnostic features. Hypostomatic type, dorsiventral mesophyll, Ushape vasculature type would constitute a major characters for genus Sorbaria in Sorbarieae. The detailed anatomical description of studied taxa is provided, and its systematic importance is also briefly discussed.

Examination of Dose Change at the Junction at the Time of Treatment Using Multi-Isocenter Volumetric Modulated Arc Therapy (용적조절호형방사선치료(VMAT)의 다중치료중심(Multi- Isocenter)을 이용한 치료 시, 접합부(Junction)의 선량 변화에 대한 고찰)

  • Jung, Dong Min;Park, Kwang Soon;Ahn, Hyuk Jin;Choi, Yoon Won;Park, Byul Nim;Kwon, Yong Jae;Moon, Sung Gong;Lee, Jong Oon;Jeong, Tae Sik;Park, Ryeong Hwang;Kim, Se young;Kim, Mi Jung;Baek, Jong Geol;Cho, Jeong Hee
    • The Journal of Korean Society for Radiation Therapy
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    • v.33
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    • pp.9-14
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    • 2021
  • This study examined dose change depending on the reposition error of the junction at the time of treatment with multi-isocenter volumetric modulated arc therapy. This study selected a random treatment region in the Arccheck Phantom and established the treatment plan for multi-isocenter volumetric modulated arc therapy. Then, after setting the error of the junction at 0 ~ 4 mm in the X (left), Y (upper), and Z (inner and outer) directions, the area was irradiated using a linear accelerator; the point doses and gamma indexes obtained through the Phantom were subsequently analyzed. It was found that when errors of 2 and 4 mm took place in the X and Y directions, the gamma pass rates (point doses) were 99.3% (2.085) and 98% (2.079 Gy) in the former direction and 98.5% (2.088) and 95.5% (2.093 Gy) in the latter direction, respectively. In addition, when errors of 1, 2, and 4 mm occurred in the inner and outer parts of the Z direction, the gamma pass rates (point doses) were found to be 94.8% (2.131), 82.6% (2.164), and 72.8% (2.22 Gy) in the former part and 93.4% (2.069), 90.6% (2.047), and 79.7% (1.962 Gy) in the latter part, respectively. In the X and Y directions, errors up to 4 mm were tolerable; however, in the Z direction, error values exceeding 1 mm were beyond the tolerance level. This suggests that for high and low dose areas, errors in the direction same as the progress direction in the treatment region have a more sensitive dose distribution. If the guidelines for set-up errors are established at the institutional level through continuous research in the future, it will be possible to provide good quality treatment using junctions.

Comparative anatomy of petiole in Forsythieae, Fontanesieae and Myxopyrum (Oleaceae) and its systematic implication (개나리족, 향선나무족, Myxopyrum속(물푸레나무과) 엽병의 해부학적 형질 및 분류학적 유용성)

  • Song, Jun-Ho;Hong, Suk-Pyo
    • Korean Journal of Plant Taxonomy
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    • v.42 no.1
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    • pp.50-63
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    • 2012
  • A comparative study of the petiole anatomy in the tribes Forsythieae (Abeliophyllum, Forsythia) and Fontanesieae (Fontanesia), including one related genus Myxopyrum belonging to Myxopyreae, was carried out using light microscopy. The anatomical characteristics of the distal, medial and proximal parts of the petiole were studied to document any differences. We are described in detail based on their quantitative and qualitative characteristics. Three crystal types (acicular, druse, and prismatic crystals) were found in both Fontanesia and Myxopyrum within all of the studied taxa. Uni-cellular non-glandular trichomes were found in Abeliophyllum and three Forsythia taxa (F. europaea, F. giraldiana, and F. japonica). All features were compared and the vascular patterns of the petiole were distinguished in two types: Type 1A: Trace continuous arc - without crystals (Abeliophyllum, Forsythia), 1B: with crystals (Myxopyrum), Type 2: Trace invaginating at ends with crystals (Fontanesia). A detailed anatomical description of the studied taxa is provided, and its systematic importance is also briefly discussed. In conclusion, some petiole anatomical characteristics (e.g., the main vascular patterns, the presence/absence of crystals) can be useful for diagnostic features as well as partly for supporting the recently proposed molecular phylogeny.

Radiation Dose Accuracy 81 the Isocenter : Standard Stereotactic Radiosurgery Technique Developed at Seoul National University Hospital (서울대학교병원형 방사선수술 표준기법의 중심점 선량의 오차)

  • Shin Seong Soo;Kim Il Han;Ha Sung Whan;Park Charn Il;Kang Wee-Saing;Hur Sun Nyung
    • Radiation Oncology Journal
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    • v.20 no.4
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    • pp.391-395
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    • 2002
  • Purpose : To confirm the accuracy of the radiation dose at the isocenter by the standard linear accelerator-based stereotactic radiosurgery technique which was developed at Seoul National University Hospital. Materials and Methods : Radiation dosimetry was undertaken during standard 5-arc radiosurgery using 6 MV X-ray beam from CL2100C linac. The treatment head was attached with circular tertiary collimators of 10 and 20 mm diameter. We measured the absorbed dose at the isocenter of a multi-purpose phantom using two kinds of detector : a 0.125 co ionization chamber and a silicon diode detector. Results : The dose differences at each arc plane between the planned dose and the measured dose at the isocenter raged from $-0.73\%\;to\;-2.69\%$ with the 0.125 cc ion chamber, and from $-1.29\%\;to\;-2.91\%$ with the diode detector during radiosurgery with the tertiary collimator of 20 mm diameter. Those with the 10-mm tertiary collimator ranged from $-2.39\%\;to\;-4.25\%$ with the diode. Conclusion : The dose accuracy at the isocenter was ${\pm}3\%$. Therefore, further efforts such ws modification in processing of the archived image through DICOM3.0 format are required to lessen the dose difference.

The Effect of MLC Leaf Motion Constraints on Plan Quality and Delivery Accuracy in VMAT (체적조절호형방사선치료 시 갠트리 회전과 다엽콜리메이터의 이동 속도에 따른 선량분포 평가)

  • Kim, Yon-Lae;Chung, Jin-Beom;Lee, Jeong-woo;Shin, Young-Joo;Kang, Dong-Jin;Jung, Jae-Yong
    • Journal of radiological science and technology
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    • v.42 no.3
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    • pp.217-222
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    • 2019
  • The purpose of this study is to evaluate the dose distribution by gantry rotation and MLC moving speed on treatment planning system(TPS) and linear accelerator. The dose analyzer phantom(Delta 4) was scanned by CT simulator for treatment planning. The planning target volumes(PTVs) of prostate and pancreas was prescribed 6,500 cGy, 5,000 cGy on VMAT(Volumetric Modulated Arc Therapy) by TPS while MLC speed changed. The analyzer phantom was irradiated linear accelerator using by planned parameters. Dose distribution of PTVs were evaluated by the homogeneity index, conformity index, dose volume histogram of organ at risk(rectum, bladder, spinal cord, kidney). And irradiated dose analysis were evaluated dose distribution and conformity by gamma index. The PTV dose of pancreas was 4,993 cGy during 0.1 cm/deg leaf and gantry that was the most closest prescribed dose(5,000 cGy). The dose of spinal cord, left kidney, and right kidney were accessed the lowest during 0.1 cm/deg, 1.5 cm/deg, 0.3 cm/deg. The PTV dose of prostate was 6,466 cGy during 0.1 cm/deg leaf and gantry that was the most closest prescribed dose(6,500 cGy). The dose of bladder and rectum were accessed the lowest during 0.3 cm/deg, 2.0 cm/deg. For gamma index, pancreas and prostate were analyzed the lowest error 100% at 0.8, 1.0 cm/deg and 99.6% at 0.3, 0.5 cm/deg. We should used the optimal leaf speed according to the gantry rotation if the treatment cases are performed VMAT.