중입자 가속기-꿈의 암 치료센터 방사선방어 연구

금오연 대한방사선방어학회 2014 대한방사선방어학회 학술발표회 논문요약집 Vol.2014 No.04

Development of easy-to-use interface for nuclear transmutation computing, VCINDER code

금오연 한국원자력학회 2018 Nuclear Engineering and Technology Vol.50 No.1

The CINDER code has about 60 years of development history, and is thus one of the world's besttransmutation computing codes to date. Unfortunately, it is complex and cumbersome to use. Preparingauxiliary input files for activation computation from MCNPX output and executing them using Perl script(activation script) is the first difficulty, and separation of gamma source computing script (gamma script),which analyzes the spectra files produced by CINDER code and creates source definition format forMCNPX code, is the second difficulty. In addition, for highly nonlinear problems, multiple human interventionsmay increase the possibility of errors. Postprocessing such as making plots with large textoutputs is also time consuming. One way to improve these limitations is to make a graphical userinterface wrapper that includes all codes, such as MCNPX and CINDER, and all scripts with a visualC#.NET tool. The graphical user interface merges all the codes and provides easy postprocessing ofgraphics data and Microsoft office tools, such as Excel sheets, which make the CINDER code easy to use. This study describes the VCINDER code (with visual C#.NET) and gives a typical application example.

A Customized Cancer Radiation Treatment Planning Simulation (ccRTPs) System via Web and Network

금오연,Khm, O-Yeon Korean Society of Medical Physics 2006 의학물리 Vol.17 No.3

네트워크기술을 이용한 서버-클라이언트 원격의료기술은 특히 의료시설이 낙후된 지방도시의 의료기관에 질 높은 의료서비스를 제공할 수 있는 기술이다. 이러한 기술은 중앙 집중 방식으로 진단과 검사용으로 사용되는 대형 컴퓨터 하드웨어와 소프트웨어를 매우 효율적이고 경제적으로 관리할 수 있게 하게 때문에 궁극적으로는 의료수가를 감소시키는데도 기여할 것이다. 각 환자에 대해 환자 맞춤형 방사선 치료계획은 매우 효율적인 암 치료를 가능하게 하기 때문에 환자와 의사 모두에게 매우 유익한 방법이다. 치료계획전문가들은 환자에게 너무 적은 선량을 주면 암이 계속 재발할 확률이 높고 너무 많은 선량을 주면 환자를 다치게 할 수도 있다는 것을 잘 이해한다. 최고의 해법은 가장 정확한 선량을 주는 것인데 이것은 각 환자의 CT 자료를 기반으로 정확한 선량계획 시뮬레이션 시스템을 사용하는 것이다. 우리는 네트워크 기반과 웹 기반을 이용한 환자 맞춤형 치료계획 시뮬레이션 시스템개발을 위해 관련된 4가지 컴퓨터 프로그램을 개발하고 있다. 환자의 CT자료를 이용하여 각 환자의 표적 자료를 만드는 프로그램, 이 표적자료를 바탕으로 방사선 선량 시뮬레이션을 하는 병렬 몬테카를로 프로그램, 선량주사변수들을 최적화시키는 프로그램, 그리고 계산결과를 시각화하는 프로그램들이다. 모든 소프트웨어는 약 100-200개의 개인컴퓨터로 구성된 클러스터에서 병렬모드로 운영이 된다. 이와 같이 방대한 하드웨어와 소프트웨어의 효과적인 관리를 각 병원에 맡기는 것은 효율적이지 못하기 때문에 이를 중앙에서 관리하면서 각 병원에서는 네트워크나 웹을 통하여 마치 모든 것이 자기 병원에 있는 것과 같이 편리하게 쓸 수 있게 하는 시스템으로 의사와의 계속적인 의사소통은 클라이언트-서버 시스템의 메신저 기능을 이용한다. The telemedicine using independent client-server system via networks can provide high quality normalized services to many hospitals, specifically to local/rural area hospitals. This will eventually lead to a decreased medical cost because the centralized institute can handle big computer hardware systems and complicated software systems efficiently and economically, Customized cancer radiation treatment planning for each patient Is very useful for both a patient and a doctor because it makes possible for the most effective treatment with the least possible dose to patient. Radiation planners know that too small a dose to the tumor can result in recurrence of the cancer, while too large a dose to healthy tissue can cause complications or even death. The best solution is to build an accurate planning simulation system to provide better treatment strategies based on each patient's computerized tomography (CT) image. We are developing a web-based and a network-based customized cancer radiation therapy simulation system consisting of four Important computer codes; a CT managing code for preparing the patients target data from their CT image files, a parallel Monte Carlo high-energy beam code (PMCEPT code) for calculating doses against the target generated from the patient CT image, a parallel linear programming code for optimizing the treatment plan, and scientific data visualization code for efficient pre/post evaluation of the results. The whole softwares will run on a high performance Beowulf PC cluster of about 100-200 CPUs. Efficient management of the hardware and software systems is not an easy task for a hospital. Therefore, we integrated our system into the client-sewer system via network or web and provide high quality normalized services to many hospitals. Seamless communication with doctors is maintained via messenger function of the server-client system.

Semantic Web-Based PMCEPT Monte Carlo Code Simulations in Medical Physics

금오연,박길흠,Youngyih Han 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.5

PMCEPT is a three-dimensional parallel Monte Carlo electron and photon transport code based on the standard message passing interface. It has been intensively validated for use in diverse medical physics applications such as radiotherapy, dosimetry, nuclear medicine, X-ray diagnostics, and radiation protection calculations. Despite extensive validation, the Monte Carlo code may not be an easy tool to pick up for a user working in medical areas because it requires some advanced knowledge of information technologies. To overcome this difficulty, we developed a function web based on recent semantic web technology. Recent developments of the semantic web make it possible to understand and satisfy various requests of people and machines to intelligently use web contents or even control other machines. This paper describes a specific functional web (including shell scripts) to run the PMCEPT code through a network and verifies the overall dosimetric accuracy of PMCEPT physics algorithms with a 6-MV beam model of the Siemens Primus linear accelerator. A medical professional with relatively little information technology experience can take advantage of the Monte Carlo simulation via the functional web running on our dedicated server with his or her PC (client). We compare calculations with measurements in water and poly methyl methacrylate (PMMA) phantoms for 6-MV Siemens Primus photon beams. The target geometry of a PMMA head and neck phantom was derived from the CT data (DICOM format). Maximum discrepancies were lesser than 2 % in the tail parts of the lateral dose distributions. This study also suggests that our functional web may have a wide range of scientific applications because it is able to control any computer code running on physically separate machines via the Internet. PMCEPT is a three-dimensional parallel Monte Carlo electron and photon transport code based on the standard message passing interface. It has been intensively validated for use in diverse medical physics applications such as radiotherapy, dosimetry, nuclear medicine, X-ray diagnostics, and radiation protection calculations. Despite extensive validation, the Monte Carlo code may not be an easy tool to pick up for a user working in medical areas because it requires some advanced knowledge of information technologies. To overcome this difficulty, we developed a function web based on recent semantic web technology. Recent developments of the semantic web make it possible to understand and satisfy various requests of people and machines to intelligently use web contents or even control other machines. This paper describes a specific functional web (including shell scripts) to run the PMCEPT code through a network and verifies the overall dosimetric accuracy of PMCEPT physics algorithms with a 6-MV beam model of the Siemens Primus linear accelerator. A medical professional with relatively little information technology experience can take advantage of the Monte Carlo simulation via the functional web running on our dedicated server with his or her PC (client). We compare calculations with measurements in water and poly methyl methacrylate (PMMA) phantoms for 6-MV Siemens Primus photon beams. The target geometry of a PMMA head and neck phantom was derived from the CT data (DICOM format). Maximum discrepancies were lesser than 2 % in the tail parts of the lateral dose distributions. This study also suggests that our functional web may have a wide range of scientific applications because it is able to control any computer code running on physically separate machines via the Internet.

Verification of the PMCEPT Monte Carlo dose Calculation Code for Simulations in Medical Physics

금오연,Kum, O-Yeon Korean Society of Medical Physics 2008 의학물리 Vol.19 No.1

환자의 CT자료를 기반으로 만들어진 3차원상의 표적물질에 전자 및 광자의 전달 현상을 계산하는 몬테카를로(MC) 도즈계산용 병렬프로그램 (PMCEPT 코드)을 개발하여 베어울프 PC 클러스터에 탑제하였다. 시뮬레이션에서 오차를 최소화하고 코드를 더욱 발전시키기 위해서는 현재의 MC 코드의 한계를 아는 것이 매우 유익하다. 이러한 관점에서 저자는 PMCEPT코드를 이용하여 이질 혹은 동질의 표적물질에서 표준화된 깊이 도즈를 계산하여 잘 알려진 다른 코드들, MCNP5, EGS4, DPM, GEANT4 및 실험결과와 비교를 하였다. PMCEPT결과는 이질 혹은 동질의 표적에서 다른 코드들과 $1{\sim}3%$ 오차 범위 안에서 잘 일치하였다. 계산시간 비교에 있어서도 PMCEPT 코드가 MCNP5 보다는 약 20배, GEANT4코드보다는 약 3배정도 빨랐다. 이러한 결과를 종합하면, PMCEPT코드는 의학물리분야의 시뮬레이션 코드로 사용하기에 매우 좋은 것으로 사료된다. The parallel Monte Carlo electron and photon transport (PMCEPT) code [Kum and Lee, J. Korean Phys. Soc. 47, 716 (2006)] for calculating electron and photon beam doses has been developed based on the three dimensional geometry defined by computed tomography (CT) images and implemented on the Beowulf PC cluster. Understanding the limitations of Monte Carlo codes is useful in order to avoid systematic errors in simulations and to suggest further improvement of the codes. We evaluated the PMCEPT code by comparing its normalized depth doses for electron and photon beams with those of MCNP5, EGS4, DPM, and GEANT4 codes, and with measurements. The PMCEPT results agreed well with others in homogeneous and heterogeneous media within an error of $1{\sim}3%$ of the dose maximum. The computing time benchmark has also been performed for two cases, showing that the PMCEPT code was approximately twenty times faster than the MCNP5 for 20-MeV electron beams irradiated on the water phantom. For the 18-MV photon beams irradiated on the water phantom, the PMCEPT was three times faster than the GEANT4. Thus, the results suggest that the PMCEPT code is indeed appropriate for both fast and accurate simulations.

Development of Parallel Monte Carlo Electron and Photon Transport (PMCEPT) Code III: Applications to Medical Radiation Physics

금오연,한영이,Hae Sun Jeong 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.60 No.9

Minimizing the differences between dose distributions calculated at the treatment planning stage and those delivered to the patient is an essential requirement for successful radiotheraphy. Accurate calculation of dose distributions in the treatment planning process is important and can be done only by using a Monte Carlo calculation of particle transport. In this paper, we perform a further validation of our previously developed parallel Monte Carlo electron and photon transport (PMCEPT) code [Kum and Lee, J. Korean Phys. Soc. <b>47</b>, 716 (2005) and Kim and Kum, J. Korean Phys. Soc. <b>49</b>, 1640 (2006)] for applications to clinical radiation problems. A linear accelerator, Siemens?Primus 6 MV, was modeled and commissioned. A thorough validation includes both small fields, closely related to the intensity modulated radiation treatment (IMRT), and large fields. Two-dimensional comparisons with film measurements were also performed. The PMCEPT results, in general, agreed well with the measured data within a maximum error of about 2%. However, considering the experimental errors, the PMCEPT results can provide the gold standard of dose distributions for radiotherapy. The computing time was also much faster, compared to that needed for experiments, although it is still a bottleneck for direct applications to the daily routine treatment planning procedure.

Novel Spatio-temporal Parallel Molecular Dynamics Algorithms for Advanced Nanoscale (Semiconductor) Fabrication Technologies

금오연 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.1

We developed novel spatio-temporal parallel molecular dynamics models for advanced nanofabrication technologies relevant to semiconductors. The models enable three-dimensional atomistic simulations on micron and millisecond scales in space and time, respectively, with full atomistic resolution with increased computational power. Preliminary calculations for the dynamic and the static properties of crystals, as well as hydrocarbon pyrolysis and self-assembly of synthetic foldamer, were performed using large-scale and long-time-scale models, respectively. We developed novel spatio-temporal parallel molecular dynamics models for advanced nanofabrication technologies relevant to semiconductors. The models enable three-dimensional atomistic simulations on micron and millisecond scales in space and time, respectively, with full atomistic resolution with increased computational power. Preliminary calculations for the dynamic and the static properties of crystals, as well as hydrocarbon pyrolysis and self-assembly of synthetic foldamer, were performed using large-scale and long-time-scale models, respectively.

Photon Beam Dosimetry with EBT3 Film in Heterogeneous Regions: Application to the Evaluation of Dose-calculation Algorithms

정현욱,금오연,한영이,박병도,정광호 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.65 No.11

For a better understanding of the accuracy of state-of-the-art-radiation therapies, 2-dimensionaldosimetry in a patient-like environment will be helpful. Therefore, the dosimetry of EBT3 filmsin non-water-equivalent tissues was investigated, and the accuracy of commercially-used dosecalculationalgorithms was evaluated with EBT3 measurement. Dose distributions were measuredwith EBT3 films for an in-house-designed phantom that contained a lung or a bone substitute,i.e., an air cavity (3 × 3 × 3 cm3) or teflon (2 × 2 × 2 cm3 or 3 × 3 × 3 cm3), respectively. The phantom was irradiated with 6-MV X-rays with field sizes of 2 × 2, 3 × 3, and 5 × 5 cm2. The accuracy of EBT3 dosimetry was evaluated by comparing the measured dose with the doseobtained from Monte Carlo (MC) simulations. A dose-to-bone-equivalent material was obtained bymultiplying the EBT3 measurements by the stopping power ratio (SPR). The EBT3 measurementswere then compared with the predictions from four algorithms: Monte Carlo (MC) in iPlan, acurosXB (AXB), analytical anisotropic algorithm (AAA) in Eclipse, and superposition-convolution (SC)in Pinnacle. For the air cavity, the EBT3 measurements agreed with the MC calculation to within2% on average. For teflon, the EBT3 measurements differed by 9.297% (±0.9229%) on averagefrom the Monte Carlo calculation before dose conversion, and by 0.717% (±0.6546%) after applyingthe SPR. The doses calculated by using the MC, AXB, AAA, and SC algorithms for the air cavitydiffered from the EBT3 measurements on average by 2.174, 2.863, 18.01, and 8.391%, respectively;for teflon, the average differences were 3.447, 4.113, 7.589, and 5.102%. The EBT3 measurementscorrected with the SPR agreed with 2% on average both within and beyond the heterogeneitieswith MC results, thereby indicating that EBT3 dosimetry can be used in heterogeneous media. The MC and the AXB dose calculation algorithms exhibited clinically-acceptable accuracy (<5%)in heterogeneities.

새로운 CT 이미지 분석 방법 연구

김혜경,금오연,조광호 한국물리학회 2006 새물리 Vol.53 No.6

n this paper, we introduce a new CT segmentation algorithm and its results. For accurate segmentation, we used a 3-step procedure: edge-preserving statistical noise reduction, a watershed algorithm based on immersion process, and fast nearest-neighbor region merging. As a merging algorithm, the region adjacent graph (RAG) was used to represent the image partitions and was combined with a newly introduced nearest neighbor-merging graph (NNMG) to accelerate the region-merging process. Compared to the RAG-based merging algorithm, the NNMG algorithm showed a remarkable acceleration of the merging process. Two-dimensional CT segmentations are presented as examples. This study is essential for accurate diagnosis, radiation-treatment planning simulations, and non-invasive surgery. 최근에 개발한 컴퓨터 단층 촬영(CT: computed tomography) 분할(segmentation) 알고리즘과 초기적용 결과들을 소개하고자 한다. CT 이미지를 정확하게 분석하기 위해서 다음의 3 단계의 알고리즘을 동시에사용한다. 첫 번째 단계로 잡음소거(noise reduction) 알고리즘을이용하여 원시(original) CT가 가지고 있는 잡음을 최소화 한 후, 두번째 단계로 유역(watershed)알고리즘을 적용하여 이미지 분할을수행하고, 세 번째 단계에서 그래프 합병알고리즘을 적용하여 이미지분할을 마무리 한다. 그래프 합병알고리즘으로는 최근 이미지 분할에사용된 영역 인접그래프(RAG: region adjacent graph) 알고리즘을 더욱발전시켜 원래의 합병 알고리즘 보다 더 빠른 알고리즘으로 개발하였다. 이러한 CT분할은 병의 진단에도 사용되지만, 방사선 치료계획, 로봇을이용한 원격수술과 비 침범성(non-invasive) 수술 등 새로운 의료기술분야에 이용되는 필수적이고 핵심적인 기술의 하나이다.

방사선 조사에 대한 세포손상 모델 연구

조광호,김혜경,금오연 한국물리학회 2006 새물리 Vol.53 No.6

In this paper, we established a primitive analytical survivability model to explain irradiation experiments on gastrointestinal tracks at the DNA level. We observed the number of serotonin cells as a function of irradiation in eight different parts of the gastrointestinal track of C57BL/6 mice. The eight different parts were divided into two groups according to the number of serotonin cells in the normal state. We tried to explain the observed results analytically by using our direct and indirect damage models. Even though we were not very successful with our model and could not confirm the radiosensitivity of the serotonin cell with the present experimental results, we have developed an efficient method for analyzing irradiation effects when we have supplemental experimental results are available. 본 논문에서는 쥐의 위장 관에 방사선을 조사할 때 세로토린(serotonin)세포수가 흡수된 선량에 따라 급격히 감소하는 실험 결과를 디옥시리보 핵산(DNA) 단위에서 정량적으로 설명하는 모형을 소개한다. 쥐의 위장 관을 위 저부에서부터 직장에 이르기 까지 여덟 부위로 나누어 선량의 함수로 세로토린 세포 수의 변화를 관찰하였다. 쥐의 위장 관 여덟 부위를 세로토닌 세포 수에 따라 두 개의 대상 그룹으로 나누었다. 이 두 그룹의 대표 결과를 이용하여 방사선 입자가 DNA에 직접 혹은 간접적으로 손상을 주는 모델을 만들어 실험결과를 보다 쉽고 논리적으로 이해하려고 노력하였다. 또한 세라토린 세포의 방사선 민감도도 예측하였다. 본 연구를 통해서, 현재 실험결과만으로 이러한 모델을 충실하게 만들기는 어렵고, 또 예측된 세로토린 세포의 방사선 민감도를 확인할 방법은 없었지만, 실험 자료를 보강함으로써 방사선이 생명체에 미치는 영향을 정량적으로 이해 할 수 있는 모델을 만들 수 있다는 것을 알게 되었다.