• Title/Summary/Keyword: 계산 복잡성

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Radio-isotope Red Cell Survival Studies Recommended by ICSH (방사성동위원소(放射性同位元素)를 이용(利用)한 적혈구수명측정법(赤血球壽命測定法)(ICSH추천(推薦)))

  • The Korea Society of Nuclear Medicine The Korea Society of Nuclear Medicine
    • The Korean Journal of Nuclear Medicine
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    • v.5 no.1
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    • pp.1-10
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    • 1971
  • 혈액질환(血液疾患), 특히 용혈성빈혈(溶血性貧血)을 수반(隨伴)한 경우(境遇)에 적혈구(赤血球)의 생성(生成) 및 파괴과정(破壞過程)을 정확(正確)히 파악(把握)하는 것은 중요(重要)하여 특히 적혈구수명측정(赤血球壽命測定)은 빈혈(貧血)의 본능(本能) 및 발생기전(發生機轉)을 이해(理解)하는데는 물론 병인적(病因的) 치료(治療) 및 예후(豫後)를 결정(決定)하는데 대단(犬端)히 유용(有用)하다. 적혈구수명측정(赤血球壽命測定)에는 1919년(年) Ashby가 개발(開發)한 differential agglutination법(法)이 이용(利用)되어 왔으나 수혈(輸血)에 따른 위험(危險)이 있고 방법(方法)이 복잡(複雜)하다는 단점(短點)을 가져 새로운 적혈구수명측정법(赤血球壽命測定法)이 연구(硏究)되어 왔다. 최근(最近)에 $^{51}Cr$이나, $^{32}DFP$같은 방사성동위원소(放射性同位元素)를 이용(利用)한 방법(方法)이 도입(導入)된 이래(以來) 임상적(臨床的)으로 적혈구수명측정(赤血球壽命測定)이 많이 시행(施行)되고 있지만 아직까지도 그 방법(方法)이나 결과(結果)의 해석(解釋)에 표준화(標準化)가 안되어 있다. 현재(現在) 임상영역(臨床領域)에서 가장 널리 이용(利用)되고 있는 적혈구수명측정법(赤血球壽命測定法)은 방사성(放射性) chromium($^{51}Cr$)법(法)으로 1950년(年) Gray와 Sterling에 의(依)해 창안(創案)된 이래(以來) 많은 학자(學者)들에 의(依)해 여러 가지 변법(變法)이 고안(考案)되어 왔는데, 이의 가장 큰 이유(理由)는 $^{51}Cr$이 적혈구표지(赤血球標識)에 가장 이상적(理想的)인 것만은 아니고 그 결과(結果)에 많은 요인(要因)들이 영향(影響)을 미치기 때문이다. 또 이런 변법(變法)의 사용(使用)은 각(各) 검사(檢査)에서 계산(計算)된 측정치(測定値)에 차이(差異)가 있어 그 결과(結果)의 해석(解釋) 및 비교(比較) 검토(檢討)에 적지않은 난점(難點)이 생겨 표준화(標準化)된 공통적(共通的)인 방법(方法)의 사용(使用)이 중요(重要)하다는 사실(事實)이 인식(認識)되게 되었다. 1966년(年) 호주(濠洲)의 Sydney에서 개최(開催)되었든 제11차(第11次) 국제혈액학회(國際血學會)때 열린 제4차(第4次) International Committee for Standardization in Haematology(ICSH)에서 Diagnostic Applications of Radioisotopes in Haematology에 관(關)한 expert panel을 갖을것을 의결(議決)하여 다음과 같은 12명(名)의 위원(委員)이 결정(決定)되었으며 위원회(委員會)의 의장(議長)에 Dr. Szur, 총무(總務)에 Dr. Glass가 각각(各各) 선임(選任)되었다. 그간(間) 1967년(年) 영경(英京) London에서 첫 회합(會合)이 있은후(後) New York, Vienna(IAEA후원(後援)) Brthesda(NIH후원(後援))에서 전문위원회(專門委員會)를 갖고 적혈구수명측정법(赤血球壽命測定法)에 관(關)한 의견(意見)의 일치(一致)를 보았다. ICSH와 국제혈액학회(國際血學會)에서는 이번에 결정(決定)된 적혈구수명측정법(赤血球壽命測定法)을 널리 소개(紹介)하며, 측정법(測定法)과 얻어진 결과(結果)의 해석(解釋)에 표준화(標準化)를 기(期)할 목적(目的)으로 이에 연관성(聯關性)있는 전문지(專門誌)에 게재(揭載)할 것을 요청(要請) 받었기에 이에 전문(全文)을 소개(紹介)하는 바이다. 이들은 방사성(放射性) chromium 법(法)의 모든 세부적(細部的)인 면(面)을 표준화(標準化)하고 있으며 그간(間) 가장 논란(論難)의 대상(對象)이 되었던, $^{51}Cr$-표지방법(標識方法)에 있어서의 세가지 변법(變法), 즉 ACD법(法), Citrate-wash법(法), ACD/ascorbic acid법(法)을 모두 인정(認定)하고 있다. 또한, DFP($DF^{32}P$ 또는 $^3H-DFP$) 표지법(標識法)의 표준방법(標準方法)도 기술(記述)하고 있으며, 더욱 중요(重要)한 것은 적혈구수명측정법(赤血球壽命測定法)으로서 현재(現在)까지 대부분(大部分)의 학자(學者)가 사용(使用)하여 왔던 지표(指標)인 $T_{50}Cr$ 대신(代身)에 mean red cell life span을 사용(使用)할 것을 권(勸)하고 있다.

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A Study on Shape Optimization of Plane Truss Structures (평면(平面) 트러스 구조물(構造物)의 형상최적화(形狀最適化)에 관한 구연(究研))

  • Lee, Gyu won;Byun, Keun Joo;Hwang, Hak Joo
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.5 no.3
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    • pp.49-59
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    • 1985
  • Formulation of the geometric optimization for truss structures based on the elasticity theory turn out to be the nonlinear programming problem which has to deal with the Cross sectional area of the member and the coordinates of its nodes simultaneously. A few techniques have been proposed and adopted for the analysis of this nonlinear programming problem for the time being. These techniques, however, bear some limitations on truss shapes loading conditions and design criteria for the practical application to real structures. A generalized algorithm for the geometric optimization of the truss structures which can eliminate the above mentioned limitations, is developed in this study. The algorithm developed utilizes the two-phases technique. In the first phase, the cross sectional area of the truss member is optimized by transforming the nonlinear problem into SUMT, and solving SUMT utilizing the modified Newton-Raphson method. In the second phase, the geometric shape is optimized utilizing the unidirctional search technique of the Rosenbrock method which make it possible to minimize only the objective function. The algorithm developed in this study is numerically tested for several truss structures with various shapes, loading conditions and design criteria, and compared with the results of the other algorithms to examme its applicability and stability. The numerical comparisons show that the two-phases algorithm developed in this study is safely applicable to any design criteria, and the convergency rate is very fast and stable compared with other iteration methods for the geometric optimization of truss structures.

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Evaluating the Dosimetric Characteristics of Radiation Therapies according to Head Elevation Angle for Head and Neck Tumors (두 경부 종양 치료 시 거상각도에 따른 치료기법 별 선량특성 평가)

  • Cheon, Geum-Seong;Kang, Seong-Hee;Kim, Dong-Su;Kim, Tae-Ho;Suh, Tae-Suk
    • Progress in Medical Physics
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    • v.27 no.1
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    • pp.14-24
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    • 2016
  • Since the head and neck region is densely located with organs at risk (OAR), OAR-sparing is an important issue in the treatment of head and neck cancers. This study-in which different treatment plans were performed varying the head tilt angle on brain tumor patients-investigates the optimal head elevation angle for sparing normal organs (e.g. the hippocampus) and further compares the dosimetric characteristics of different types of radiation equipment. we performed 3D conformal radiation therapy (3D-CRT), intensity-modulated radiation therapy (IMRT), and tomotherapy on 10 patients with brain tumors in the frontal lobe while varying the head tilt angle of patients to analyze the dosimetric characteristics of different therapy methods. In each treatment plan, 95% of the tumor volume was irradiated with a dose of 40 Gy in 10 fractions. The step and shoot technique with nine beams was used for IMRT, and the same prescription dose was delivered to the tumor volume for the 3D-CRT and tomotherapy plans. The homogeneity index, conformity index, and normal tissue complication probability (NTCP) were calculated. At a head elevation angle of $30^{\circ}$, conformity of the isodose curve to the target increased on average by 53%, 8%, and 5.4%. In 3D-CRT, the maximum dose received by the brain stem decreased at $15^{\circ}$, $30^{\circ}$, and $40^{\circ}$, compared to that observed at $0^{\circ}$. The NTCP value of the hippocampus observed in each modality was the highest at a head and neck angle of $0^{\circ}$ and the lowest at $30^{\circ}$. This study demonstrates that the elevation of the patients' head tilt angle in radiation therapy improves the target region's homogeneity of dose distribution by increasing the tumor control rate and conformity of the isodose curve to the target. Moreover, the study shows that the elevation of the head tilt angle lowers the NTCP by separating the tumor volume from the normal tissues, which helps spare OARs and reduce the delivered dose to the hippocampus.

The Statistical Identification of Airmass Characteristics during the Manna Loa Observatory Photochemistry Experiment (Mauna Loa (Hawaii)에서 관측된 대기질 특성의 통계적 분석)

  • Lee, Gang-Woong;Barry J. Huebert
    • Journal of Korean Society for Atmospheric Environment
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    • v.10 no.E
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    • pp.332-342
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    • 1994
  • Hierarchical cluster and factor analyses were used to identify various influences on free tropospheric air samples at Mauna Loa Observatory in Hawaii during MLOPEX. The cluster analysis separated thirteen chemical and meteorological variables into three characteristic groups (1)clean air, (2)anthropogenically influenced air, (3)marine and volcanic influenced air. The cluster analysis results compared well with those of factor analysis. Six independent components were identified in factor analysis. We have related these components to (1)volcano influenced air, (2)stratosphere-like air, (3)boundary-layer air with recent anthropogenic influence, (4)photochemical haze, (5)marine boundary- layer air, and (6)modified marine tropospheric air. Excluding local influence, we could calculate the nighttime free tropospheric values for $O_3$(41$\pm$10 ppbv), HN $O_3$(94$\pm$45 pptv), N $O_3$$^{[-10]}$ (16$\pm$10 ppbv), S $O_4$$^{[-10]}$ (60$\pm$0 pptv), N $H_4$$^{+}$(71$\pm$6 pptv), N $a^{+}$(5$\pm$1 pptv), PAN(13$\pm$9 pptv), MeN $O_3$(3.5$\pm$1.5 pptv), 2-butyl N $O_3$(0.6$\pm$0.1 pptv), $H_2O$$_2$(1015$\pm$44 pptv), $C_2$C $l_4$(3.3$\pm$0.1 pptv), condensation nuclei(249$\pm$13c $m^{-3}$), and dew point(-8.5$\pm$5.3$^{\circ}C$) during this experiment..

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Development of Correction Formulas for KMA AAOS Soil Moisture Observation Data (기상청 농업기상관측망 토양수분 관측자료 보정식 개발)

  • Choi, Sung-Won;Park, Juhan;Kang, Minseok;Kim, Jongho;Sohn, Seungwon;Cho, Sungsik;Chun, Hyenchung;Jung, Ki-Yuol
    • Korean Journal of Agricultural and Forest Meteorology
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    • v.24 no.1
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    • pp.13-34
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    • 2022
  • Soil moisture data have been collected at 11 agrometeorological stations operated by The Korea Meteorological Administration (KMA). This study aimed to verify the accuracy of soil moisture data of KMA and develop a correction formula to be applied to improve their quality. The soil of the observation field was sampled to analyze its physical properties that affect soil water content. Soil texture was classified to be sandy loam and loamy sand at most sites. The bulk density of the soil samples was about 1.5 g/cm3 on average. The content of silt and clay was also closely related to bulk density and water holding capacity. The EnviroSCAN model, which was used as a reference sensor, was calibrated using the self-manufactured "reference soil moisture observation system". Comparison between the calibrated reference sensor and the field sensor of KMA was conducted at least three times at each of the 11 sites. Overall, the trend of fluctuations over time in the measured values of the two sensors appeared similar. Still, there were sites where the latter had relatively lower soil moisture values than the former. A linear correction formula was derived for each site and depth using the range and average of the observed data for the given period. This correction formula resulted in an improvement in agreement between sensor values at the Suwon site. In addition, the detailed approach was developed to estimate the correction value for the period in which a correction formula was not calculated. In summary, the correction of soil moisture data at a regular time interval, e.g., twice a year, would be recommended for all observation sites to improve the quality of soil moisture observation data.

Estimation of Fractional Urban Tree Canopy Cover through Machine Learning Using Optical Satellite Images (기계학습을 이용한 광학 위성 영상 기반의 도시 내 수목 피복률 추정)

  • Sejeong Bae ;Bokyung Son ;Taejun Sung ;Yeonsu Lee ;Jungho Im ;Yoojin Kang
    • Korean Journal of Remote Sensing
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    • v.39 no.5_3
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    • pp.1009-1029
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    • 2023
  • Urban trees play a vital role in urban ecosystems,significantly reducing impervious surfaces and impacting carbon cycling within the city. Although previous research has demonstrated the efficacy of employing artificial intelligence in conjunction with airborne light detection and ranging (LiDAR) data to generate urban tree information, the availability and cost constraints associated with LiDAR data pose limitations. Consequently, this study employed freely accessible, high-resolution multispectral satellite imagery (i.e., Sentinel-2 data) to estimate fractional tree canopy cover (FTC) within the urban confines of Suwon, South Korea, employing machine learning techniques. This study leveraged a median composite image derived from a time series of Sentinel-2 images. In order to account for the diverse land cover found in urban areas, the model incorporated three types of input variables: average (mean) and standard deviation (std) values within a 30-meter grid from 10 m resolution of optical indices from Sentinel-2, and fractional coverage for distinct land cover classes within 30 m grids from the existing level 3 land cover map. Four schemes with different combinations of input variables were compared. Notably, when all three factors (i.e., mean, std, and fractional cover) were used to consider the variation of landcover in urban areas(Scheme 4, S4), the machine learning model exhibited improved performance compared to using only the mean of optical indices (Scheme 1). Of the various models proposed, the random forest (RF) model with S4 demonstrated the most remarkable performance, achieving R2 of 0.8196, and mean absolute error (MAE) of 0.0749, and a root mean squared error (RMSE) of 0.1022. The std variable exhibited the highest impact on model outputs within the heterogeneous land covers based on the variable importance analysis. This trained RF model with S4 was then applied to the entire Suwon region, consistently delivering robust results with an R2 of 0.8702, MAE of 0.0873, and RMSE of 0.1335. The FTC estimation method developed in this study is expected to offer advantages for application in various regions, providing fundamental data for a better understanding of carbon dynamics in urban ecosystems in the future.

Korean Sentence Generation Using Phoneme-Level LSTM Language Model (한국어 음소 단위 LSTM 언어모델을 이용한 문장 생성)

  • Ahn, SungMahn;Chung, Yeojin;Lee, Jaejoon;Yang, Jiheon
    • Journal of Intelligence and Information Systems
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    • v.23 no.2
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    • pp.71-88
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    • 2017
  • Language models were originally developed for speech recognition and language processing. Using a set of example sentences, a language model predicts the next word or character based on sequential input data. N-gram models have been widely used but this model cannot model the correlation between the input units efficiently since it is a probabilistic model which are based on the frequency of each unit in the training set. Recently, as the deep learning algorithm has been developed, a recurrent neural network (RNN) model and a long short-term memory (LSTM) model have been widely used for the neural language model (Ahn, 2016; Kim et al., 2016; Lee et al., 2016). These models can reflect dependency between the objects that are entered sequentially into the model (Gers and Schmidhuber, 2001; Mikolov et al., 2010; Sundermeyer et al., 2012). In order to learning the neural language model, texts need to be decomposed into words or morphemes. Since, however, a training set of sentences includes a huge number of words or morphemes in general, the size of dictionary is very large and so it increases model complexity. In addition, word-level or morpheme-level models are able to generate vocabularies only which are contained in the training set. Furthermore, with highly morphological languages such as Turkish, Hungarian, Russian, Finnish or Korean, morpheme analyzers have more chance to cause errors in decomposition process (Lankinen et al., 2016). Therefore, this paper proposes a phoneme-level language model for Korean language based on LSTM models. A phoneme such as a vowel or a consonant is the smallest unit that comprises Korean texts. We construct the language model using three or four LSTM layers. Each model was trained using Stochastic Gradient Algorithm and more advanced optimization algorithms such as Adagrad, RMSprop, Adadelta, Adam, Adamax, and Nadam. Simulation study was done with Old Testament texts using a deep learning package Keras based the Theano. After pre-processing the texts, the dataset included 74 of unique characters including vowels, consonants, and punctuation marks. Then we constructed an input vector with 20 consecutive characters and an output with a following 21st character. Finally, total 1,023,411 sets of input-output vectors were included in the dataset and we divided them into training, validation, testsets with proportion 70:15:15. All the simulation were conducted on a system equipped with an Intel Xeon CPU (16 cores) and a NVIDIA GeForce GTX 1080 GPU. We compared the loss function evaluated for the validation set, the perplexity evaluated for the test set, and the time to be taken for training each model. As a result, all the optimization algorithms but the stochastic gradient algorithm showed similar validation loss and perplexity, which are clearly superior to those of the stochastic gradient algorithm. The stochastic gradient algorithm took the longest time to be trained for both 3- and 4-LSTM models. On average, the 4-LSTM layer model took 69% longer training time than the 3-LSTM layer model. However, the validation loss and perplexity were not improved significantly or became even worse for specific conditions. On the other hand, when comparing the automatically generated sentences, the 4-LSTM layer model tended to generate the sentences which are closer to the natural language than the 3-LSTM model. Although there were slight differences in the completeness of the generated sentences between the models, the sentence generation performance was quite satisfactory in any simulation conditions: they generated only legitimate Korean letters and the use of postposition and the conjugation of verbs were almost perfect in the sense of grammar. The results of this study are expected to be widely used for the processing of Korean language in the field of language processing and speech recognition, which are the basis of artificial intelligence systems.

Geoacoustic characteristics of Quaternary stratigraphic sequences in the mid-eastern Yellow Sea (황해 중동부 제4기 퇴적층의 지음향 특성)

  • Jin, Jae-Hwa;Jang, Seong-Hyeong;Kim, Seong-Pil;Kim, Hyeon-Tae;Lee, Chi-Won;Chang, Jeong-Hae;Choi, Jin-Hyeok;Ryang, Woo-Heon
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.6 no.2
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    • pp.81-92
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    • 2001
  • According to analyses of high-resolution seismic profiles (air gun, sparker, and SBP) and a deep-drill core(YSDP 105) in the mid-eastern Yellow Sea, stratigraphic and geoacoustic models have been established and seismo-acoustic modeling has been fulfilled using ray tracing of finite element method. Stratigraphic model reflects seismo-, litho-, and chrono-stratigraphic sequences formed under a significant influence of Quaternary glacio-eustatic sea-level fluctuations. Each sequence consists of terrestrial to very-shallow-marine coarse-grained lowstand systems tract and tidal fine-grained transgressive to highstand systems tract. Based on mean grain-size data (121 samples) of the drill core, bulk density and P-wave velocity of depositional units have been inferred and extrapolated down to a depth of the recovery using the Hamilton's regression equations. As goo-acoustic parameters, the 121 pairs of bulk density and P-wave velocity have been averaged on each unit of the stratigraphic model. As a result of computer ray-tracing simulation of the subsurface strata, we have found that there are complex ray paths and many acoustic-shadow zones owing to the presence of irregular layer boundaries and low-velocity layers.

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Internal Waves and Surface Mixing Observed by CTD and Echo Sounder in the mid-eastern Yellow Sea (황해 중동부해역에서 CTD와 음향탐지기로 관측한 내부파와 표층 혼합)

  • Lee, Sang-Ho;Choi, Byoung-Ju;Jeong, Woo Jin
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.18 no.1
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    • pp.1-12
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    • 2013
  • Acoustic backscatter profiles were measured by Eco-sounder along an east-west section in the mid-eastern Yellow Sea and at an anchoring station in the low salinity region off the Keum River estuary in September 2012, with observing physical water property structure by CTD. Tidal front was established around the sand ridge developed in 50 m depth region. Internal waves measured by Eco-sounder during low tide period in the eastern side of the sand ridge were nonlinear depression waves with wave height of 15 m and mean wavelength of 500 m. These waves were interpreted into tidal internal waves that were produced by tidal current flowing over the sand ridge to the southeast. When weakly non-linear soliton model was applied, propagation speed and period of these internal depression wave were 50 m/s and 16~18 min. Red tides by Dinoflagelates Cochlodinium were observed in the sea surface where strong acoustic scattering layer was raised up to 7 m. Hourly CTD profiles taken at the anchoring station off the Keum River estuary showed the halocline depth change by tidal current and land-sea breeze. When tidal current flowed strongly to the northeast during flood period and land-breeze of 7 m/s blew to the west, the halocline was temporally raised up as much as 2 m and acoustic profile images showed a complex structure in the surface layer within 5-m depth: in tens of seconds the declined acoustic structure of strong and weak scattering signals alternatively appeared with entrainment and intrusion shape. These acoustic profile structures in the surface mixed layer were observed for the first time in the coastal sea of the mid-eastern Yellow Sea. The acoustic profile images and turbidity data suggest that relatively transparent low-layer water be intruded or entrained into the turbid upper-layer water by vertical shear between flood current and land breeze-induced surface current.

Quality Assurance of Patients for Intensity Modulated Radiation Therapy (세기조절방사선치료(IMRT) 환자의 QA)

  • Yoon Sang Min;Yi Byong Yong;Choi Eun Kyung;Kim Jong Hoon;Ahn Seung Do;Lee Sang-Wook
    • Radiation Oncology Journal
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    • v.20 no.1
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    • pp.81-90
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    • 2002
  • Purpose : To establish and verify the proper and the practical IMRT (Intensity--modulated radiation therapy) patient QA (Quality Assurance). Materials and Methods : An IMRT QA which consists of 3 steps and 16 items were designed and examined the validity of the program by applying to 9 patients, 12 IMRT cases of various sites. The three step OA program consists of RTP related QA, treatment information flow QA, and a treatment delivery QA procedure. The evaluation of organ constraints, the validity of the point dose, and the dose distribution are major issues in the RTP related QA procedure. The leaf sequence file generation, the evaluation of the MLC control file, the comparison of the dry run film, and the IMRT field simulate image were included in the treatment information flow procedure QA. The patient setup QA, the verification of the IMRT treatment fields to the patients, and the examination of the data in the Record & Verify system make up the treatment delivery QA procedure. Results : The point dose measurement results of 10 cases showed good agreement with the RTP calculation within $3\%$. One case showed more than a $3\%$ difference and the other case showed more than $5\%$, which was out side the tolerance level. We could not find any differences of more than 2 mm between the RTP leaf sequence and the dry run film. Film dosimetry and the dose distribution from the phantom plan showed the same tendency, but quantitative analysis was not possible because of the film dosimetry nature. No error had been found from the MLC control file and one mis-registration case was found before treatment. Conclusion : This study shows the usefulness and the necessity of the IMRT patient QA program. The whole procedure of this program should be peformed, especially by institutions that have just started to accumulate experience. But, the program is too complex and time consuming. Therefore, we propose practical and essential QA items for institutions in which the IMRT is performed as a routine procedure.