• Title, Summary, Keyword: dose calculation

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Dose Computational Time Reduction For Monte Carlo Treatment Planning

  • Park, Chang-Hyun;Park, Dahl;Park, Dong-Hyun;Park, Sung-Yong;Shin, Kyung-Hwan;Kim, Dae-Yong;Cho, Kwan-Ho
    • Proceedings of the Korean Society of Medical Physics Conference
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    • pp.116-118
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    • 2002
  • It has been noted that Monte Carlo simulations are the most accurate method to calculate dose distributions in any material and geometry. Monte Carlo transport algorithms determine the absorbed dose by following the path of representative particles as they travel through the medium. Accurate Monte Carlo dose calculations rely on detailed modeling of the radiation source. We modeled the effects of beam modifiers such as collimators, blocks, wedges, etc. of our accelerator, Varian Clinac 600C/D to ensure accurate representation of the radiation source using the EGSnrc based BEAM code. These were used in the EGSnrc based DOSXYZ code for the simulation of particles transport through a voxel based Cartesian coordinate system. Because Monte Carlo methods use particle-by-particle methods to simulate a radiation transport, more particle histories yield the better representation of the actual dose. But the prohibitively long time required to get high resolution and accuracy calculations has prevented the use of Monte Carlo methods in the actual clinical spots. Our ultimate aim is to develop a Monte Carlo dose calculation system designed specifically for radiation therapy planning, which is distinguished from current dose calculation methods. The purpose of this study in the present phase was to get dose calculation results corresponding to measurements within practical time limit. We used parallel processing and some variance reduction techniques, therefore reduced the computational time, preserving a good agreement between calculations of depth dose distributions and measurements within 5% deviations.

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조영제 사용 전${\cdot}$후 불균질 조직 보정 알고리즘에 따른 선량변화에 대한 연구

  • Kim, Ju-Ho;Jo, Jeong-Hui;Lee, Seok;Jeon, Byeong-Cheol;Park, Jae-Il
    • The Journal of Korean Society for Radiation Therapy
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    • v.13 no.1
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    • pp.38-46
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    • 2001
  • Purpose : The aim of this study is to investigate the effect of tissue inhomogeneities when appling to contrast medium among Homogeneous, Batho and ETAR dose calculation method in RTP system. Method and Material : We made customized heterogeneous phantom it filled with water or contrast medium slab. Phantom scan data have taken PQ 5000 (CT scanner, Marconi, USA) and then dose was calculated in 3D RTP (AcQ-Plan, Marconi, USA) depends on dose calculation algorithm (Homogeneous, Batho, ETAR). The dose comparisons were described in terms of 2D isodose distribution, percent depth dose data, effective path length and monitor unit. Also dose distributions were calculated with homogeneous and inhomogeneous correction algorithm, Batho and ETAR, in each patients with different clinical sites. Results : Result indicated that Batho and ETAR method gave rise to percent depth dose deviation $1.5{\sim}2.7\%,\;2.3{\sim}3.5\%$ (6MV, field size $10{\times}10cm^2$) in each status with and without contrast medium. Also show that effective path lengths were more increase in contrast status (23.14 cm) than Non-contrast (22.07 cm) about $4.9\%$ or 10.7 mm (In case Hounsfield Unit 270) and these results were similary showned in each patient with different clinical site that was lung. prostate, liver and brain region. Concliusion : In conclusion we shown that the use of inhomogeneity correction algorithm for dose calculation in status of injected contrast medium can not represent exact dose at GTV region. These results mean that patients will be more irradiated photon beam during radiation therapy.

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Implications of using a 50-μm-thick skin target layer in skin dose coefficient calculation for photons, protons, and helium ions

  • Yeom, Yeon Soo;Nguyen, Thang Tat;Choi, Chansoo;Han, Min Cheol;Lee, Hanjin;Han, Haegin;Kim, Chan Hyeong
    • Nuclear Engineering and Technology
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    • v.49 no.7
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    • pp.1495-1504
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    • 2017
  • In a previous study, a set of polygon-mesh (PM)-based skin models including a $50-{\mu}m-thick$ radiosensitive target layer were constructed and used to calculate skin dose coefficients (DCs) for idealized external beams of electrons. The results showed that the calculated skin DCs were significantly different from the International Commission on Radiological Protection (ICRP) Publication 116 skin DCs calculated using voxel-type ICRP reference phantoms that do not include the thin target layer. The difference was as large as 7,700 times for electron energies less than 1 MeV, which raises a significant issue that should be addressed subsequently. In the present study, therefore, as an extension of the initial, previous study, skin DCs for three other particles (photons, protons, and helium ions) were calculated by using the PM-based skin models and the calculated values were compared with the ICRP-116 skin DCs. The analysis of our results showed that for the photon exposures, the calculated values were generally in good agreement with the ICRP-116 values. For the charged particles, by contrast, there was a significant difference between the PM-model-calculated skin DCs and the ICRP-116 values. Specifically, the ICRP-116 skin DCs were smaller than those calculated by the PM models-which is to say that they were under-estimated-by up to ~16 times for both protons and helium ions. These differences in skin dose also significantly affected the calculation of the effective dose (E) values, which is reasonable, considering that the skin dose is the major factor determining effective dose calculation for charged particles. The results of the current study generally show that the ICRP-116 DCs for skin dose and effective dose are not reliable for charged particles.

An Experimental Dosimetry of Irregularly-Shaped-Field Using Therapeutic Planning Computer (치료계획용 콤퓨터를 이용한 부정형 조사면의 선량분포에 관한 실험)

  • Park, Joo-Sun;Lee, Gui-Won;Han, Yong-Moon;Kwon, Hyoung-Cheol;Yoon, Sei-Chul
    • The Journal of Korean Society for Radiation Therapy
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    • v.2 no.1
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    • pp.87-92
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    • 1987
  • The authors have intended to measure intrinsic dose distribution by Farmer dosimeter in irregularly shaped fields such as L, M, T,-shape model in order to determine dose inhomogeneity in those models. We made 2 off-axis points in each model and measured the depth dose at 1.5,5, and 9cm below surface. The results showed $1-3\%$ dose discrepancy between 2 points. We also measured the depth dose by geometric approximation and computer calculation in those models, and came to the conclusion that computer calculation using Clarkson's principle is simpler and the measurements are to the ideal data obtained by the experiment in those three models of irregularly shaped fields than those of geometric approximation method.

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An Experimental Dosimetry of Irregularly Shaped Fields Using Therapeutic Planning Computer (치료계획용 컴퓨터를 이용한 부정형조사면의 선량분포에 관한 실험)

  • Kwon Hyoung Cheol;Oh Yoon Kyeong;Yoon Sei Chul;Bahk Young Whee
    • Radiation Oncology Journal
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    • v.2 no.2
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    • pp.281-285
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    • 1984
  • The authors have intended to measure intrinsic dose distribution by Farmer dosimeter in irregularly shaped fields such as L.M and T shape models in order to determine dose inhomogeneity in those models. We made 2 off·axis points in each model and measured the depth dose at 1.5, 5 and 9cm below surface. The results showed $l\~3\%$ dose discrepancy between 2 points. We also measured the depth dose by geometric approximation and computer calculation in those models, and came to the conclusion that computer calculation using Clarkson's principle is simpler and the measurements are closer to the ideal data obtained by the experiment in three models of irregularly shaped fields than those of geometric approximation method.

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Convergence Study on the Drug Dose Calculations and Confidence of Nursing Students (간호 학생의 약물 용량 계산과 자신감에 관한 융합적 연구)

  • Jung, In-Sook
    • Journal of Convergence for Information Technology
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    • v.7 no.4
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    • pp.45-51
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    • 2017
  • The purpose of this study is to find the level of drug dose calculations and confidence of nursing students who completed fundamental nursing. After receiving informed consent, questionnaires and drug dose calculation paper of 152 subjects were collected. The data were analyzed using SPSS 19.0. The $mean{\pm}SD$ of drug dose calculations was $7.46{\pm}1.97$ on a scale of 10, the mean score of male students was higher than female's(t=3.64, p=.001), and the mean score of science was higher than vocational's according to high school departments(F=5.11, p=.007). In the score of confidence, the $mean{\pm}SD$ was $4.12{\pm}1.12$ on a scale of 6, the mean score of male students was higher than female's(t=8.94, p=.001), and the science was higher than humanity or vocational(F=6.28, p=.002). There was a positive correlation between drug dose calculation and confidence scores(r= .32, p=.001), and explanation rate of confidence on drug dose calculation was 10.2%(p=0.001) in regression analysis. This suggests that nursing students need to improve drug dose calculation ability by strengthening confidence.

Development of Reference Korean Organ and Effective Dose Calculation Online System (웹 기반 표준한국인 장기 흡수선량 및 유효선량 평가 시스템 개발)

  • Park, Sooyeun;Yeom, Yeon Soo;Kim, Jae Hyeon;Lee, Hyun Su;Han, Min Cheol;Jeong, Jong Hwi;Kim, Chan Hyeong
    • Journal of Radiation Protection and Research
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    • v.39 no.1
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    • pp.30-37
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    • 2014
  • Recently High-Definition Reference Korean-Man (HDRK-Man) and High-Definition Reference Korean-Woman (HDRK-Woman) were constructed in Korea. The HDRK phantoms were designed to represent respectively reference Korean male and female to calculate effective doses for Korean by performing Monte Carlo dose calculation. However, the Monte Carlo dose calculation requires detailed knowledge on computational human phantoms and Monte Carlo simulation technique which regular researchers in radiation protection dosimetry and practicing health physicists do not have. Recently the UFPE (Federal University of Pernambuco) research group has developed, and opened to public, an online Monte Carlo dose calculation system called CALDOSE_X(www.caldose.org). By using the CALDOSE_X, one can easily perform Monte Carlo dose calculations. However, the CALDOSE_X used caucasian phantoms to calculate organ doses or effective doses which are limited for Korean. The present study developed an online reference Korean dose calculation system which can be used to calculate effective doses for Korean.

Convergence Study on Ability and Accuracy in Drug Dose Calculations of Nursing Students (간호학생의 약물용량계산능력과 정확도에 관한 융합적 연구)

  • Jung, In-Sook
    • Journal of the Korea Convergence Society
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    • v.8 no.3
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    • pp.123-131
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    • 2017
  • This study is to find the weaknesses in drug dose calculations of nursing students by analyzing their general characteristics, confidence(C), performances in classes(PC) and exam sheets of drug dose calculations. The data were analyzed using SPSS 19.0. There was no significant difference between male and female students in simple calculation ability(SCA), but male students' mean scores were higher in applied calculation ability(ACA) and accuracy on calculation(AC). There were no significant differences in calculation abilities according to high school departments. And students were weak in questions which are needed ACA. The explanation rate of C on PC and PC on AC were 4.2% and 3.2% respectively, so there were weak positive effects from C to PC, and PC to AC. This study suggests that there is a need to develop and implement an intervention program according to students' abilities to increase AC, C, and PC by studying math on an ongoing basis. This study needs to be cautious in generalizing, because the data set was limited to nursing students from one university.

COMPUTATIONAL ANTHROPOMORPHIC PHANTOMS FOR RADIATION PROTECTION DOSIMETRY: EVOLUTION AND PROSPECTS

  • Lee, Choon-Sik;Lee, Jai-Ki
    • Nuclear Engineering and Technology
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    • v.38 no.3
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    • pp.239-250
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    • 2006
  • Computational anthropomorphic phantoms are computer models of human anatomy used in the calculation of radiation dose distribution in the human body upon exposure to a radiation source. Depending on the manner to represent human anatomy, they are categorized into two classes: stylized and tomographic phantoms. Stylized phantoms, which have mainly been developed at the Oak Ridge National Laboratory (ORNL), describe human anatomy by using simple mathematical equations of analytical geometry. Several improved stylized phantoms such as male and female adults, pediatric series, and enhanced organ models have been developed following the first hermaphrodite adult stylized phantom, Medical Internal Radiation Dose (MIRD)-5 phantom. Although stylized phantoms have significantly contributed to dosimetry calculation, they provide only approximations of the true anatomical features of the human body and the resulting organ dose distribution. An alternative class of computational phantom, the tomographic phantom, is based upon three-dimensional imaging techniques such as magnetic resonance (MR) imaging and computed tomography (CT). The tomographic phantoms represent the human anatomy with a large number of voxels that are assigned tissue type and organ identity. To date, a total of around 30 tomographic phantoms including male and female adults, pediatric phantoms, and even a pregnant female, have been developed and utilized for realistic radiation dosimetry calculation. They are based on MRI/CT images or sectional color photos from patients, volunteers or cadavers. Several investigators have compared tomographic phantoms with stylized phantoms, and demonstrated the superiority of tomographic phantoms in terms of realistic anatomy and dosimetry calculation. This paper summarizes the history and current status of both stylized and tomographic phantoms, including Korean computational phantoms. Advantages, limitations, and future prospects are also discussed.

A Comparison of Dose in Changed Technique Factor Using X-ray Imaging System (X-선 장치의 기술적 인자의 변화에 따른 선량 비교 평가)

  • Han, Dong-Kyoon;Ko, Shin-Gwan;Seon, Jong-Ryul;Yoon, Seok-Hwan;Jung, Jae-Eun
    • Korean Journal of Digital Imaging in Medicine
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    • v.11 no.2
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    • pp.101-107
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    • 2009
  • With the recent development of diagnosis using radiation and increasing demand of the medical treatment, we need to minimize radiation exposure dose. So, This is the method which reduce patient dose by measuring surface dose of radiographic change factor and by comparing theoretical and actual dose, when we take an X-ray which is generally used. By changing the factor of kV, mAs, FSD, whose range is 60 to 120 kV, 20 to 100 mAs, 80 to 180 cm, we compared theoretical surface dose with actual surface dose calculated by the simple calculation program, Bit system, and NDD-M method As a result, when kV and mAs were higher, theoretical surface dose and actual surface dose were more increased. but the higher FSD was, the more decreased surface dose was. According to this, the error were measured about 0.1 to 0.2 mGy in low dose part and about 0.7 to 1.5 mGy in high dose part. Therefore, this shows that theoretical surface dose calculation method is more correct in low dose part than in high dose part. In conclusion, we will have to make constant efforts which can reduce patient and radiographer's exposure dose, studying methods which can predict patient's radiation exposure dose more exactly.

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