Proton Accelerator, Proton Therpay

Youngyih Han 대한방사선방어학회 2014 대한방사선방어학회 학술발표회 논문요약집 Vol.2014 No.04

Current status of proton therapy techniques for lung cancer

Youngyih Han 대한방사선종양학회 2019 Radiation Oncology Journal Vol.37 No.4

Proton beams have been used for cancer treatment for more than 28 years, and several technological advancements have been made to achieve improved clinical outcomes by delivering more accurate and conformal doses to the target cancer cells while minimizing the dose to normal tissues. The state-of-the-art intensity modulated proton therapy is now prevailing as a major treatment technique in proton facilities worldwide, but still faces many challenges in being applied to the lung. Thus, in this article, the current status of proton therapy technique is reviewed and issues regarding the relevant uncertainty in proton therapy in the lung are summarized.

Independent Verification Program for High-Dose-Rate Brachytherapy Treatment Plans

한영이(Youngyih Han),추성실(Sung Sil Chu),허승재(Seung Jae Huh),서창옥(Chang-Ok Suh) 대한방사선종양학회 2003 Radiation Oncology Journal Vol.21 No.3

목 적 : 개별화되어 가는 고 선 량률 근접치료계획의 추세에 따라, 고성량률 근접치료계획의 절대적선량과 상대적인 선량분포를 독립적으로 계산하여 환자의 해부영상 위에 겹쳐 표시할 수 있는 품질보증용컴퓨터프로그램을 개발한다. 대상 및 방법: 컴퓨터 프로그램은 먼저, 환자의 치료계획에서 계산된 선원의 위치,각 위치에서의 조사시간, reference point에 서 의 선량, 치료계획이 실시된 날짜 등의 자료입력을 필요로 한다.ICWG 권고 수식과 선원의 비등방성 표를 이용하여 10×10×12 (cm3)의 공간에서 선량분포가 계산된 후 reference point에서의 선량이 자동적으로 치료계획의 결과와 비교된다. 모의치료의 영상이나 자기공명 (Magnetic Resonance) 영상을 입력하고 사용자가 선택한 점을 수직으로 교차하는 3개의 평면에서 등선량곡선을 겹쳐서 보여준다. Gamma Med사의 Gammadot(MDS Nordion, Germany)에서 표준 치료계획을 실행하여 정확성을 확인하였으며, Plato (Nucletron Cor-poration, The Netherlands)에서 실행된9명의 환자치료계획과 비교하였다. 결 과: 3개의 표준 치료계획에서 절대선량은 2.8% 내에서 일치하였으며 등선량분포도 좋은일치를 보였다. 9명의 환자에 대하여 시행된 치료계획과의 비교에서는 평균 3.4%의 오차를 보였다. 결 론: 개발된 컴퓨터 프로그램은 정확하고 신속하게 고선량률 치료환자의 치료계획의 정확성을 확인할 수 있게 해주며, 등선량 곡선을 환자의 해부적 영상에 결합할 수 있는 기능은 치료계획의 질을 높이는데 기여할 수 있을 것으로 기대된다. Purpose: The planning of High-Dose-Rate (HDR) brachytherapy treatments are becoming individualized and more dependent on the treatment planning system. Therefore, computer software has been developed to perform independent point dose calculations with the integration ofanisodose distribution curve display into the patient anatomy images. Materials and Methods As primary input data, the program takes patients' planning data including the source dwell positions, dwell times and the doses at reference points, computed by an HDR treatment planning system (TPS). Dosimetric calculations were performed in a 10 × 12 × 10 cm 3 grid space using the Interstitial Collaborative Working Group (ICWG) formalism and an anisotropy table for the HDR Iridium-192 source. The computed doses at the reference points w e re automatically compared with the relevant results of the TPS . T he MR and simulation film images were then imported and the isodose distributions on the axial, sagittal and coronal planes intersecting the point selected by a user were superimposed on the imported images and then displayed. The accuracy of the software was tested in three benchmark plans performed by Gamma-Med 12i TPS (MDS Nordion, Germany) . Nine patients' plans generated by Plato (Nucletron Corporation, The Netherlands) were verified by the developed software . Results The absolute doses computed by the developed software agreed with the commercial TPS results within an accuracy of 2.8% in the benchmark plans. The isodose distribution plots showed excellent agreements w ith the exception of the tip region of the source's longitudinal axis where a slight deviation was observed. Inclinica lplans, the secondary dose calculations had , on average, about a 3. 4% deviation from the TPS plans. Conclusion The accurate validation of complicate treatment plans is possible with the developed software and the quality of the HDR treatment plan can be improved with the isodose display integrated into the patient anatomy information.

Dosimetry in an IMRT phantom designed for a remote monitoring program : IMRT phantom for a remote monitoring program

Han, Youngyih,Shin, Eun Hyuk,Lim, Chunil,Kang, Se-Kwon,Park, Sung Ho,Lah, Jeong-Eun,Suh, Tae-suk,Yoon, Myonggeun,Lee, Se Byeong,Cho, Sang Hyun,Ibbott, Geoffrey S.,Ju, Sang Gyu,Ahn, Yong Chan Wiley (John WileySons) 2008 Medical physics Vol.35 No.6

<P>An accurate delivery of prescribed dose is essential to ensure the most successful outcome from advanced radiation treatments such as intensity modulated radiation therapy (IMRT). An anthropomorphic phantom was designed and constructed to conduct a remote-audit program for IMRT treatments. The accuracy of the dosimetry in the phantom was assessed by comparing the results obtained from different detectors with those from Monte Carlo calculations. The developed phantom has a shape of a cylinder with one target and three organs at risk (OARs) inside the unit. The target and OARs were shaped similar to those of nasopharyngeal cancer patients, and manufactured for their identification during computed tomography imaging. The phantom was designed with thermoluminescent dosimeter (TLD) holders that were inserted inside the target and the OARs for the measurements of absolute dose. In addition, the phantom allowed measurements with ionization chambers placed at the TLD locations. As a result, an inter-comparison between the two types of dosimeters was possible. For the measurement of the relative dose distribution across the target and OARs, two film slots were orthogonally placed near the center of the phantom, which also enabled the insertion of inhomogeneities near the target. Measurements with TLDs, provided by Korea Food and Drug Administration and Radiological Physics Center, and measurements with an ionization chamber (IC) were performed in four cases. The first case was one anterior field of 6 MV x rays delivered to the phantom; the second case used the same anterior field, but with inhomogeneities inserted into the phantom. The third case was three fields of 6 MV beams at an equi-gantry angle for the homogeneous phantom, and the fourth case was IMRT delivery to the phantom without inhomogeneities. For each case, measurements with both TLDs and IC were performed. For cases 1-3, theoretical predictions were obtained by using the Monte Carlo (MC) codes (BEAMnrc and DOSXYZnrc6.0). The TLD measurements were larger than the IC readings by 2.2% (1.3-2.5%), 2.2% (1.2-2.9%), and 2.1% (0-3.3%) on average for case 1, case 2 and case 3, respectively. The average deviation between TLDs and MC results was 0.97% (-0.13-2.07%) for the first case, 1.27% (0.34-2.18%) for the second case, and 1.13% (0.31-1.94%) for the third case. The IC reading was less than the MC results; the average deviations were -1.2% (-2.44--0.43%), -0.96% (-1.74 - -0.54%) and -0.94% (-1.53-0.27%) for the first, second, and third cases, respectively. For the IMRT case, the average deviation between IC readings and TLD measurements was 0.5% (-7.0-3.9%). In conclusion, the TLD measurements in the developed phantom agreed with IC and MC results with less than 3% of an average difference. The developed phantom with TLD dosimeters should be useful for remote monitoring of IMRT.</P>

Current status of proton therapy techniques for lung cancer

Han, Youngyih The Korean Society for Radiation Oncology 2019 Radiation Oncology Journal Vol.37 No.4

Proton beams have been used for cancer treatment for more than 28 years, and several technological advancements have been made to achieve improved clinical outcomes by delivering more accurate and conformal doses to the target cancer cells while minimizing the dose to normal tissues. The state-of-the-art intensity modulated proton therapy is now prevailing as a major treatment technique in proton facilities worldwide, but still faces many challenges in being applied to the lung. Thus, in this article, the current status of proton therapy technique is reviewed and issues regarding the relevant uncertainty in proton therapy in the lung are summarized.

원격 품질 보증 시스템을 사용한 세기변조 방사선치료의 예비 모니터링 결과

한영이(Youngyih Han),신은혁(Eun Hyuk Shin),임천일(Chunil Lim),강세권(Se-Kwon Kang),박성호(Sung Ho Park),라정은(Jeong-Eun Lah),서태석(Tae-Suk Suh),윤명근(Myonggeun Yoon),이세병(Se Byeong Lee),주상규(Sang Gyu Ju),안용찬(Yong Chan Ahn) 대한방사선종양학회 2007 Radiation Oncology Journal Vol.25 No.4

목 적: 국내에서 시행되고 있는 세기변조 방사선 치료(IMRT)의 품질 향상을 위하여, 우편으로 시행하는 원격 품질 보증 시스템을 개발하고, 이 시스템의 정확성 확인에 이어서, 국내 의료기관에서 타당성을 검증한다. 대상 및 방법: 원격 품질 보증 시스템은 두경부 팬톰과 IMRT 의 치료계획 지침을 포함하는 사용자 설명서로 구성되어 있다. 두경부 용 팬톰은 내부에 CT 영상에서 분별이 가능한 모사 치료표적(target)과 3개의 위험장기(좌, 우 이하선, 척추)를 포함하고 있으며, 각 모사 장기의 중심에서 열형광 소자(TLD)를 삽입하여 흡수 선량을 측정하도록 구성되어있다. 또한 2차원상의 선량분포를 확인 가능하도록 Gafchromic@EBT 필름을 2개의 평면에 삽입하도록 고안하였다. 고안된 팬톰과 사용자 설명서를 국내의 4개 기관에 보내어, 팬톰에 대한 IMRT 치료계획을 수행하고 치료를 시행하였다. 치료계획 시 예측된 치료표적과 위험장기 내의 각 TLD에서 예측되는 절대 선량과 TLD의 측정값을 비교하였고, 횡단면에서 면의 중심을 지나는 2개의 직교하는 수평선과 수직선상에서 예측되는 상대적인 선량분포 값과 실제 측정값을 비교하였다. 결 과: 치료 표적에서의 선량측정 값은 모두 치료계획시의 예측값과 3% 오차 안에서 일치하였으나(평균오차,1.5%), 좌우 이하선에 해당하는 위험장기에서는 최소 3.3% 최대 19.8%의 차이를 보였다. 척추에 해당하는 위험장기에서의 오차의 범위는 0.7∼14.8%였다. 2차원 선량분포는 3개 기관에 대한 자료를 분석하였는데, 직선상에서 예측 값과 5% 이상의 차이를 보이는 비율이 수평선상에서는 7∼27%, 수직선상에서는 7∼14%였다. 결 론: 본 연구에서 개발한 IMRT치료의 원격 품질보증 시스템과 사용자 설명서는 국내 시행이 가능한 상태로 판단된다. 그러나, 시행 시에 치료표적에서의 오차는 크지 않을 것으로 예상이 되지만, 위험장기에서의 오차는 클 것으로 예상되며, 이에 대한 방안이 마련돼야 할 것이며, 또한 임상의 중요성과 연관해 의미 있는 2차원 선량분포의 기준 마련이 요구된다. Purpose: In order to enhance the quality of IMRT as employed in Korea, we developed a remote monitoring system. The feasibility of the system was evaluated by conducting a pilot study. Materials and Methods: The remote monitoring system consisted of a head and neck phantom and a user manual. The phantom contains a target and three OARs (organs at risk) that can be detected on CT images. TLD capsules were inserted at the center of the target and at the OARs. Two film slits for GafchromicEBT film were located on the axial and saggital planes. The user manual contained an IMRT planning guide and instructions for IMRT planning and the delivery process. After the manual and phantom were sent to four institutions, IMRT was planed and delivered. Predicted doses were compared with measured doses. Dose distribution along the two straight lines that intersected at the center of the axial film was measured and compared with the profiles predicted by the plan. Results: The measurements at the target agreed with the predicted dose within a 3% deviation. Doses at the OARs that represented the thyroid glands showed larger deviations (minimum 3.3% and maximum 19.8%). The deviation at OARs that represented the spiral cord was 0.7∼14.8%. The percentage of dose distributions that showed more than a 5% of deviation on the lines was 7∼27% and 7∼14% along the horizontal and vertical lines, respectively. Conculsion: Remote monitoring of IMRT using the developed system was feasible. With remote monitoring, the deviation at the target is expected to be small while the deviation at the OARs can be very large. Therefore, a method that is able to investigate the cause of a large deviation needs to be developed. In addition, a more clinically relevant measure for the two-dimensional dose comparison and pass/fail criteria need to be further developed.

Improved Breast Irradiation Techniques Using Multistatic Fields or Three Dimensional Universal Compensators

한영이(Youngyih Han),조재호(Jae Ho Cho),박희철(Hee Chul Park),추성실(Sung Sil Chu),서창옥 (Chang-Ok Suh) 대한방사선종양학회 2002 Radiation Oncology Journal Vol.20 No.1

목적: 유방보존 수술 후 행하는 방사선치료인 2문 대칭조사(two tangential field technique)시 나타나는 선량분포의 불균일성을 효과적으로 개선하기 위하여, multistatic fields의 사용법과 공용보상체 사용법을 제시하고 평가하였다. 대상 및 방법: 1) multistatic fields 방법: 3차원의 치료계획용 software (RTP)를 이용하여, wedge를 사용한 2문 대칭조사의 최적의 치료계획을 시행한 후 beam's eye view상에서 과조사가 일어나는 부분을 가리워 주도록 blocked field를 설계하고, 그 beam에 대칭되는 beam을 만들었다. 기존의 2개의 tangentiall fields와 추가된 field의 weighting을 최적의 선량분포를 갖도록 조절하였다. 2) 공용보상체 사용법: 1999와 2000년에 본원에서 whole-breast radiotherapy를 받은 환자 20명의 유방의 크기를 측정하고 평균하여 표준 유방 모델을 만들었다. 이 모델에 대하여 공용보상체를 설계하고, 설계된 공용보상체의 geometry를 RTP에 입력한 후 환자의 치료 계획을 수행하였다. 2문 대칭조사 치료 계획과 ,multistatic fields의 경우 그리고 공용 보상체를 사용한 경우의 치료계획에서의 불 균일도(DII: 처방선량의 95-105%를 벗어나는 PTV의 부피의 백분율), 최대선량 값(Dmax) 그리고 등가선량 곡선을 각각 비교하였다. 결과: Multistatic fields 방법은 DII의 평균값을 14.6% (p value<0.000) 낮추고 Dmax를 4.7% (p value<0.000) 낮춤으로써, 전통적인 2문 대칭 조사법보다 우수한 방법으로 확인되었다. 반면에 공용보상체의 사용은 평균 DII를 3.7% 낮추지만(p value=0.260) 평균 Dmax는 거의 동일하여 (0.3% 감소, p value=0.867), 전통적인 방법보다 우수성이 크게는 없는 것으로 평가되었다. 그러나 환자의 체곡선이 보상체와 잘 일치하는 경우에는 DII가 18%까지 감소하였다. 결론: Multistatic fields 방법은 모든 환자에 대하여 선량분포의 균일성을 전반적으로 향상시키는 효과적인 방법으로 평가되는 반면 공용보상체의 사용은 보상체의 크기가 환자의 체 윤곽과 잘 일치하는 경우만 효과적으로, 적용의 범위에는 한계가 있는 방법으로 평가되었다. Purpose: In order to improve dose homogeneity and to reduce acute toxicity in tangential whole breast radiotherapy, we evaluated two treatment techniques using multiple static fields or universal compensators. Materials and Methods: 1) Multistatic field technique: Using a three dimensional radiation treatment planning system, Adac Pinnacle 4.0, we accomplished a conventional wedged tangential plan. Examining the isodose distributions, a third field which blocked overdose regions was designed and an opposing field was created by using an automatic function of RTPS. Weighting of the beams was tuned until an ideal dose distribution was obtained. Another pair of beams were added when the dose homogeneity was not satisfactory. 2) Universal compensator technique: The breast shapes and sizes were obtained from the CT images of 20 patients who received whole breast radiation therapy at our institution. The data obtained were averaged and a pair of universal physical compensators were designed for the averaged data. DII (dose Inhomogeneity Index: percentage volume of PTV outside 95~105% of the prescribed dose), Dmax(the maximum point dose in the PTV) and isodose distributions for each technique were compared. Results: The multistatic field technique was found to be superior to the conventional technique, reducing the mean value of DII by 14.6% (p value<0.000) and the Dmax by 4.7% (p value<0.000). The universal compensator was not significantly superior to the conventional technique since it decreased Dmax by 0.3% (p value=0.867) and reduced DII by 3.7%( p value=0.260). However, it decreased the value of DII by maximum 18% when patients' breast shapes fitted in with the compensator geometry. Conclusion: Multistatic field technique is effective for improving dose homogeneity for whole breast radiation therapy and is applicable to all patients, whereas the use of universal compensators is effective only in patients whose breast shapes fit inwith the universal compensator geometry, and thus has limited applicability.

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.

The first private-hospital based proton therapy center in Korea

Kwangzoo Chung,Youngyih Han,Jinsung Kim,Sung Hwan Ahn,Sang Gyu Ju,Sang Hoon Jung,Yoonsun Chung,Sungkoo Cho,Kwanghyun Jo,Eun Hyuk Shin,Chae-Seon Hong,Jung Suk Shin,Seyjoon Park,Dae-Hyun Kim,Hye Young K 대한방사선종양학회 2015 Radiation Oncology Journal Vol.33 No.4

Purpose: The purpose of this report is to describe the proton therapy system at Samsung Medical Center (SMC-PTS) including the proton beam generator, irradiation system, patient positioning system, patient position verification system, respiratory gating system, and operating and safety control system, and review the current status of the SMC-PTS. Materials and Methods: The SMC-PTS has a cyclotron (230 MeV) and two treatment rooms: one treatment room is equipped with a multi-purpose nozzle and the other treatment room is equipped with a dedicated pencil beam scanning nozzle. The proton beam generator including the cyclotron and the energy selection system can lower the energy of protons down to 70 MeV from the maximum 230 MeV. Results: The multi-purpose nozzle can deliver both wobbling proton beam and active scanning proton beam, and a multi-leaf collimator has been installed in the downstream of the nozzle. The dedicated scanning nozzle can deliver active scanning proton beam with a helium gas filled pipe minimizing unnecessary interactions with the air in the beam path. The equipment was provided by Sumitomo Heavy Industries Ltd., RayStation from RaySearch Laboratories AB is the selected treatment planning system, and data management will be handled by the MOSAIQ system from Elekta AB. Conclusion: The SMC-PTS located in Seoul, Korea, is scheduled to begin treating cancer patients in 2015.

세기변조 방사선치료의 환자 치료 전 선량보증에 대한 고찰

한영이,Han, Youngyih 한국의학물리학회 2013 의학물리 Vol.24 No.4

본 논문은 현재 세기변조 방사선 치료를 시행 시에 일반적으로 사용 되고 있는 환자 치료 전 품질보증의 방법 중, 2차원 선량분포를 측정하여 품질을 보증하는 방법들에 관한 이슈들을 최근 3~4년 간 발표된 논문들을 중심으로 살펴보고, 향후 품질보증 방법의 개선방향에 대하여 조명해 보고자 하였다. This review paper deals with the current statues of pre-treatment quality assurance conducted for Intensity modulated radiation therapy. Focusing on the issues relevant to two-dimensional verification of absorbed dose distribution, review was made for the papers published during the last 3~4 years. Lastly, the future development direction was projected.