Monte Carlo modeling of uniform scanning beam in proton therapy using GEANT4

Seyjoon Park,Dae-Hyun Kim,Jungwook Shin,Se Byeong Lee 대한방사선방어학회 2011 대한방사선방어학회 학술발표회 논문요약집 Vol.2011 No.11

양성자 치료계획에서 fiducial marker의 density override 방법에 따른 선량변화 비교 : Planning study

성두영,박세준,박지현,박용철,박희철,최병기,Sung, Doo Young,Park, Seyjoon,Park, Ji Hyun,Park, Yong Chul,Park, Hee Chul,Choi, Byoung Ki 대한방사선치료학회 2017 대한방사선치료학회지 Vol.29 No.1

목 적: 양성자 치료계획에서 metal 재질의 fiducial marker에 의한 선량 계산오차를 최소화하려면 density override의 적용은 매우 중요하다. 하지만 실제 metal 재질로 density override을 할 경우 정확한 contouring 및 range compensator 제작에 어려움이 있기에 본 연구에서는 fiducial marker의 주변 재질로 density override를 시행하고 fiducial marker의 위치, 재질, beam의 개수에 따른 선량분포를 비교, 분석하여 평가하고자 한다. 대상 및 방법: Water phantom을 이용하여 fiducial marker의 위치를 proton beam의 최대 비정 끝에서부터 1.5, 2.5, 4.0, 6.0 cm로 설정하고 재질로는 gold, steel, titanium으로 설정하여 실제 metal 재질 및 주변 재질로 density override를 적용한 치료계획을 세웠다. 또한 본원에서 양성자치료를 받은 간암 환자 1명을 선정하여 proton beam의 최대 비정 끝에서부터 0, 1.5, 3.5 cm로 설정하고 재질로는 gold, steel, titanium으로 설정하여 치료계획을 세웠다. Fiducial marker의 재질, 위치 및 beam의 개수에 따른 PTV 내에 Homogeneity Index(HI), Conformity Index(CI), 종양에 가장 근접한 Organ At Risk(OAR)인 Esophagus의 maximum dose을 평가 지표로 설정하고 비교 분석하였다. 결 과: Water phantom 및 간암 환자를 대상으로 한 치료계획에서 fiducial marker의 위치에 따른 Homogeneity Index를 분석한 결과 실제 metal 재질로 density override 했을 때보다 주변 재질로 density override했을 때 Homogeneity Index가 감소했으며 주변 재질의 density override에서 하나의 beam에 대해서는 최대 비정 끝에서 멀리 위치할수록, 두 개 이상의 beam에서는 isocenter에 가까이 위치할수록 Homogeneity Index가 증가하였다. Fiducial marker의 위치에 따른 Conformity Index 및 종양 주위 OAR의 maximum dose를 분석한 결과 주변 재질로 density override 했을 때 Conformity Index는 1에 가까웠으며 OAR의 maximum dose는 크게 감소했다. 결 론: 일반적으로 임상에서 사용하는 작은 fiducial marker에 대해서 실제 metal 재질이 아닌 주변 재질로 density override 했을 때 선량 균등도 및 target coverage를 높이는 동시에 주변 정상조직에 대한 선량을 줄일 수 있었다. 따라서 fiducial marker을 최대한 피해서 치료계획을 세우는 것이 바람직하지만 beam path 상에 fiducial marker가 있는 경우 주변 재질의 density override 시행함으로써 보다 정밀한 양성자 치료 효과를 기대할 수 있을 것으로 사료된다. Purpose: The application of density override is very important to minimize dose calculation errors by fiducial markers of metal material in proton treatment plan. However, density override with actual material of the fiducial marker could make problem such as inaccurate target contouring and compensator fabrication. Therefore, we perform density override with surrounding material instead of actual material and we intend to evaluate the usefulness of density override with surrounding material of the fiducial marker by analyzing the dose distribution according to the position, material of the fiducial marker and number of beams. Materials and Method: We supposed that the fiducial marker of gold, steel, titanium is located in 1.5, 2.5, 4.0, 6.0 cm from the proton beam's end of range using water phantom. Treatment plans were created by applying density override with the surrounding material and actual material of the fiducial marker. Also, a liver cancer patient who received proton therapy was selected. We located the fiducial marker of gold, steel, titanium in 0, 1.5, 3.5 cm from the proton beam's end of range and the treatment plans were created by same method with water phantom. Homogeneity Index(HI), Conformity Index(CI) and maximum dose of Organ At Risk(OAR) in Planning Target Volume(PTV) as the evaluation index were compared according to the material, position of the fiducial marker and number of beam. Results: The HI value was more decreased when density override with surrounding material of the fiducial marker was performed comparing with density override with actual material. Especially the HI value was increased when the fiducial marker was located farther from the proton beam's end of the range for a single beam and the fiducial marker's position was closer to isocenter for two or more beams. The CI value was close to 1 and OAR maximum dose was greatly reduced when density override with surrounding material of the fiducial marker was performed comparing with density override with actual material. Conclusion: Density override with surrounding material can be expected to achieve more precise proton therapy than density override with actual material of the fiducial marker and could increase the dose uniformity and target coverage and reduce the dose to surrounding normal tissues for the small fiducial markers used in clinical practice. Most of all, it is desirable to plan the treatment by avoiding the fiducial marker of metal material as much as possible. However, if the fiducial marker have on the beam path, density override of the surrounding material can be expected to achieve more precise proton therapy.

Proton Linear Energy Transfer measurement using Emulsion Cloud Chamber

Shin, Jae-ik,Park, Seyjoon,Kim, Haksoo,Kim, Meyoung,Jeong, Chiyoung,Cho, Sungkoo,Lim, Young Kyung,Shin, Dongho,Lee, Se Byeong,Morishima, Kunihiro,Naganawa, Naotaka,Sato, Osamu,Kwak, Jungwon,Kim, Sung Elsevier 2015 Nuclear instruments & methods in physics research. Vol.349 No.-

<P><B>Abstract</B></P> <P>This study proposes to determine the correlation between the Volume Pulse Height (VPH) measured by nuclear emulsion and Linear Energy Transfer (LET) calculated by Monte Carlo simulation based on Geant4. The nuclear emulsion was irradiated at the National Cancer Center (NCC) with a therapeutic proton beam and was installed at 5.2m distance from the beam nozzle structure with various thicknesses of water-equivalent material (PMMA) blocks to position with specific positions along the Bragg curve. After the beam exposure and development of the emulsion films, the films were scanned by S-UTS developed in Nagoya University. The proton tracks in the scanned films were reconstructed using the ‘NETSCAN’ method. Through this procedure, the VPH can be derived from each reconstructed proton track at each position along the Bragg curve. The VPH value indicates the magnitude of energy loss in proton track. By comparison with the simulation results obtained using Geant4, we found the correlation between the LET calculated by Monte Carlo simulation and the VPH measured by the nuclear emulsion.</P>

Development of an analysis software for comparison between proton treatment planning system and Monte Carlo simulation

Dae-Hyun Kim,Jungwook Shin,Seyjoon Park,Seung Hoon Yoo,Se Byeong Lee,Tae-Suk Suh 대한방사선방어학회 2011 대한방사선방어학회 학술발표회 논문요약집 Vol.2011 No.11

Sparse-view proton computed tomography using modulated proton beams : Sparse-view proton CT

Lee, Jiseoc,Kim, Changhwan,Min, Byungjun,Kwak, Jungwon,Park, Seyjoon,Lee, Se Byeong,Park, Sungyong,Cho, Seungryong Published for the American Association of Physicis 2015 Medical physics Vol.42 No.2

<P>Proton imaging that uses a modulated proton beam and an intensity detector allows a relatively fast image acquisition compared to the imaging approach based on a trajectory tracking detector. In addition, it requires a relatively simple implementation in a conventional proton therapy equipment. The model of geometric straight ray assumed in conventional computed tomography (CT) image reconstruction is however challenged by multiple-Coulomb scattering and energy straggling in the proton imaging. Radiation dose to the patient is another important issue that has to be taken care of for practical applications. In this work, the authors have investigated iterative image reconstructions after a deconvolution of the sparsely view-sampled data to address these issues in proton CT.</P>

Initial Experience of Patient-Specific QA for Wobbling and Line-Scanning Proton Therapy at Samsung Medical Center

Jo, Kwanghyun,Ahn, Sung Hwan,Chung, Kwangzoo,Cho, Sungkoo,Shin, Eun Hyuk,Park, Seyjoon,Hong, Chae-Seon,Kim, Dae-Hyun,Lee, Boram,Lee, Woojin,Choi, Doo Ho,Lim, Do Hoon,Pyo, Hong Ryull,Han, Youngyih Korean Society of Medical Physics 2019 의학물리 Vol.30 No.1

Purpose: To report the initial experience of patient-specific quality assurance (pQA) for the wobbling and line-scanning proton therapy at Samsung Medical Center. Materials and Methods: The pQA results of 89 wobbling treatments with 227 fields and 44 line-scanning treatments with 118 fields were analyzed from December 2015 to June 2016. For the wobbling method, proton range and spread-out Bragg peak (SOBP) width were verified. For the line-scanning method, output and two-dimensional dose distribution at multiple depths were verified by gamma analysis with 3%/3 mm criterion. Results: The average range difference was -0.44 mm with a standard deviation (SD) of 1.64 mm and 0.1 mm with an SD of 0.53 mm for the small and middle wobbling radii, respectively. For the line-scanning method, the output difference was within ${\pm}3%$. The gamma passing rates were over 95% with 3%/3 mm criterion for all depths. Conclusions: For the wobbling method, proton range and SOBP width were within the tolerance levels. For the line-scanning method, the output and two-dimensional dose distribution showed excellent agreement with the treatment plans.

Initial clinical outcomes of proton beam radiotherapy for hepatocellular carcinoma

Yu, Jeong Il,Yoo, Gyu Sang,Cho, Sungkoo,Jung, Sang Hoon,Han, Youngyih,Park, Seyjoon,Lee, Boram,Kang, Wonseok,Sinn, Dong Hyun,Paik, Yong-Han,Gwak, Geum-Youn,Choi, Moon Seok,Lee, Joon Hyeok,Koh, Kwang C The Korean Society for Radiation Oncology 2018 Radiation Oncology Journal Vol.36 No.1

Purpose: This study aimed to evaluate the initial outcomes of proton beam therapy (PBT) for hepatocellular carcinoma (HCC) in terms of tumor response and safety. Materials and Methods: HCC patients who were not indicated for standard curative local modalities and who were treated with PBT at Samsung Medical Center from January 2016 to February 2017 were enrolled. Toxicity was scored using the Common Terminology Criteria for Adverse Events (CTCAE) version 4.0. Tumor response was evaluated using modified Response Evaluation Criteria in Solid Tumors (mRECIST). Results: A total of 101 HCC patients treated with PBT were included. Patients were treated with an equivalent dose of $62-92GyE_{10}$. Liver function status was not significantly affected after PBT. Greater than 80% of patients had Child-Pugh class A and albumin-bilirubin (ALBI) grade 1 up to 3-months after PBT. Of 78 patients followed for three months after PBT, infield complete and partial responses were achieved in 54 (69.2%) and 14 (17.9%) patients, respectively. Conclusion: PBT treatment of HCC patients showed a favorable infield complete response rate of 69.2% with acceptable acute toxicity. An additional follow-up study of these patients will be conducted.

Compensation method for respiratory motion in proton treatment planning for mobile liver cancer

Jeong, Hojin,Lee, Se Byeong,Yoo, Seung Hoon,Lim, Young Kyung,Kim, Tae Hyun,Park, Seyjoon,Chai, Gyu Young,Kang, Ki Mun,Shin, Dongho John Wiley and Sons Inc. 2013 Journal of applied clinical medical physics Vol.14 No.2

<P>We evaluated the dosimetric effect of a respiration motion, and sought an effective planning strategy to compensate the motion using four‐dimensional computed tomography (4D CT) dataset of seven selected liver patients. For each patient, we constructed four different proton plans based on: (1) average (AVG) CT, (2) maximum‐intensity projection (MIP) CT, (3) AVG CT with density override of tumor volume (OVR), and (4) AVG CT with field‐specific proton margin which was determined by the range difference between AVG and MIP plans (mAVG). The overall effectiveness of each planning strategy was evaluated by calculating the cumulative dose distribution over an entire breathing cycle. We observed clear differences between AV G and MIP CT‐based plans, with significant underdosages at expiratory and inspiratory phases, respectively. Only the mAVG planning strategy was fully successful as the field‐specific proton margin applied in the planning strategy complemented both the limitations of AVG and MIP CT‐based strategies. These results demonstrated that respiration motion induced significant changes in dose distribution of 3D proton plans for mobile liver cancer and the changes can be effectively compensated by applying field‐specific proton margin to each proton field.</P><P>PACS numbers: 87.55.D; 87.53.Bn; 87.53.Jw; 87.55.dk</P>

Initial clinical outcomes of proton beam radiotherapy for hepatocellular carcinoma

Jeong Il Yu,Gyu Sang Yoo,Sungkoo Cho,Sang Hoon Jung,Youngyih Han,Seyjoon Park,Boram Lee,Wonseok Kang,Dong Hyun Sinn,Yong-Han Paik,Geum-Youn Gwak,Moon Seok Choi,Joon Hyeok Lee,Kwang Cheol Koh,Seung Woo 대한방사선종양학회 2018 Radiation Oncology Journal Vol.36 No.1

Purpose: This study aimed to evaluate the initial outcomes of proton beam therapy (PBT) for hepatocellular carcinoma (HCC) in terms of tumor response and safety. Materials and Methods: HCC patients who were not indicated for standard curative local modalities and who were treated with PBT at Samsung Medical Center from January 2016 to February 2017 were enrolled. Toxicity was scored using the Common Terminology Criteria for Adverse Events (CTCAE) version 4.0. Tumor response was evaluated using modified Response Evaluation Criteria in Solid Tumors (mRECIST). Results: A total of 101 HCC patients treated with PBT were included. Patients were treated with an equivalent dose of 62–92 GyE 10 . Liver function status was not significantly affected after PBT. Greater than 80% of patients had Child-Pugh class A and albumin-bilirubin (ALBI) grade 1 up to 3-months after PBT. Of 78 patients followed for three months after PBT, infield complete and partial responses were achieved in 54 (69.2%) and 14 (17.9%) patients, respectively. Conclusion: PBT treatment of HCC patients showed a favorable infield complete response rate of 69.2% with acceptable acute toxicity. An additional follow-up study of these patients will be conducted.

Analysis of Treatment and Delay Times by Disease Site and Delivery Technique at Samsung Medical Center - Proton Therapy Center

Jo, Kwanghyun,Ahn, Sung Hwan,Chung, Kwangzoo,Cho, Sungkoo,Shin, Eunhyuk,Hong, Chae-Seon,Park, Seyjoon,Kim, Dae-Hyun,Lee, Boram,Lee, Woo-Jin,Seo, Se-Kwang,Jang, Jun-Young,Choi, Doo Ho,Lim, Do Hoon,Han, Korean Society of Medical Physics 2016 의학물리 Vol.27 No.4

We have treated various disease sites using wobbling and scanning proton therapy techniques since December 2015 at the Samsung Medical Center. In this study, we analyze the treatment time for each disease site in 65 wobbling and 50 scanning patient treatments. Treatment times are longest for liver and lung patients using the respiratory gating technique in the wobbling treatment and for cranio-spinal irradiation in pediatric patients with anesthesia in the scanning treatment. Moreover, we analyze the number of incidents causing treatment delays and the corresponding treatment delay time. The X-ray panel was the main reason for delays in the wobbling treatment; this decreased continually from January to June 2016, related closely to the proficiency of the human operators involved. The main reason for delays in the scanning treatment was interlocks during scanning pattern delivery; this was resolved by proton machine engineers. Through this work, we hope to provide other institutes with useful insight for initial operation of their proton therapy machines.