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Stroubinis T, Psarras M, Zygogianni A, Protopapa M, Kouloulias V, Platoni K. Craniospinal Irradiation: A Dosimetric Comparison Between O-Ring Linac and Conventional C-arm Linac. Adv Radiat Oncol 2022; 8:101139. [PMID: 36636383 PMCID: PMC9830104 DOI: 10.1016/j.adro.2022.101139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 10/16/2022] [Indexed: 12/12/2022] Open
Abstract
Purpose The aim of this study was to perform a dosimetric evaluation between craniospinal irradiation volumetric modulated arc therapy plans designed for an O-Ring and a conventional C-arm Linac. Methods and Materials Two adult patients were selected for this study. Two plans were designed one for a TrueBeam Edge and one for Halcyon O-ring Linac for each patient. The evaluation of the plans was conducted in terms of dose volume histogram analysis of the target volume and organs at risk (OARs) along with total plan monitor units and beam-on time. Paired sample t test was performed to compare Dmax and Dmean of OARs for each plan's comparison. The delivery of volumetric modulated arc therapy plans was evaluated using Octavius 4D phantom. Results All plans demonstrated dose distributions with sufficient planned target volume conformity and homogeneity. The Homogeneity Index and Conformity Index for all plans were found comparable. The paired sample t test did not demonstrate significant difference in terms of Dmax and Dmean of OARs between plans for both patients. All plans met the threshold of 90%, with Halcyon plans having higher gamma passing rates. Conclusions Craniospinal irradiation plans generated for Halcyon and Edge are equivalent in terms of plan quality and dose sparing at OARs. The small variations may have originated from the differences in beam profile or mean energy, the degree of the modulation for each plan and characteristics of multi leaf collimators for each treatment unit. Halcyon is able to deliver a distinctly faster treatment, but Edge provides an automatic rotational correction for patient positioning.
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Affiliation(s)
- Theodoros Stroubinis
- Department of Radiation Oncology and Stereotactic Radiosurgery, Mediterraneo Hospital, Athens, Greece,Corresponding author: Theodoros Stroubinis
| | - Michalis Psarras
- Department of Radiation Oncology and Stereotactic Radiosurgery, Mediterraneo Hospital, Athens, Greece
| | - Anna Zygogianni
- Radiation Oncology Unit, 1st Department of Radiology, Aretaieion University Hospital, National & Kapodistrian University of Athens, Medical School, Athens, Greece
| | - Maria Protopapa
- Department of Radiation Oncology and Stereotactic Radiosurgery, Mediterraneo Hospital, Athens, Greece
| | - Vassilis Kouloulias
- Radiation Oncology Unit, 2nd Department of Radiology, Attikon University Hospital, National & Kapodistrian University of Athens, Medical School, Athens, Greece
| | - Kalliopi Platoni
- Medical Physics Unit, 2nd Department of Radiology, Attikon University Hospital, National and Kapodistrian University of Athens, Medical School, Athens, Greece
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Ju SG, Ahn YC, Kim YB, Kim JM, Kwon DY, Park BS, Yang K. Dosimetric comparison between VMAT plans using the fast-rotating O-ring linac with dual-layer stacked MLC and helical tomotherapy for nasopharyngeal carcinoma. Radiat Oncol 2022; 17:155. [PMID: 36096874 PMCID: PMC9465858 DOI: 10.1186/s13014-022-02124-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 08/30/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND To compare the dosimetric profiles of volumetric modulated arc therapy (VMAT) plans using the fast-rotating O-ring linac (the Halcyon system) based on a dual-layer stacked multi-leaf collimator and helical tomotherapy (HT) for nasopharyngeal cancer (NPCa). METHODS For 30 NPCa patients, three sets of RT plans were generated, under the same policy of contouring and dose constraints: HT plan; Halcyon VMAT plan with two arcs (HL2arc); and Halcyon VMAT plan with four arcs (HL4arc), respectively. The intended dose schedule was to deliver 67.2 Gy to the planning gross target volume (P-GTV) and 56.0 Gy to the planning clinical target volume (P-CTV) in 28 fractions using the simultaneously integrated boost concept. Target volumes and organ at risks dose metrics were evaluated for all plans. Normal tissue complication probabilities (NTCP) for esophagus, parotid glands, spinal cord, and brain stem were compared. RESULTS The HT plan achieved the best dose homogeneity index for both P_GTV and P_CTV, followed by the HL4arc and L2arc plans. No significant difference in the dose conformity index (CI) for P_GTV was observed between the HT plan (0.80) and either the HL2arc plan (0.79) or the HL4arc plan (0.83). The HL4arc plan showed the best CI for P_CTV (0.88), followed by the HL2arc plan (0.83) and the HT plan (0.80). The HL4arc plan (median, interquartile rage (Q1, Q3): 25.36 (22.22, 26.89) Gy) showed the lowest Dmean in the parotid glands, followed by the HT (25.88 (23.87, 27.87) Gy) and HL2arc plans (28.00 (23.24, 33.99) Gy). In the oral cavity (OC) dose comparison, the HT (22.03 (19.79, 24.85) Gy) plan showed the lowest Dmean compared to the HL2arc (23.96 (20.84, 28.02) Gy) and HL4arc (24.14 (20.17, 27.53) Gy) plans. Intermediate and low dose regions (40-65% of the prescribed dose) were well fit to the target volume in HL4arc, compared to the HT and HL2arc plans. All plans met the dose constraints for the other OARs with sufficient dose margins. The between-group differences in the median NTCP values for the parotid glands and OC were < 3.47% and < 1.7% points, respectively. CONCLUSIONS The dosimetric profiles of Halcyon VMAT plans were comparable to that of HT, and HL4arc showed better dosimetric profiles than HL2arc for NPCa.
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Affiliation(s)
- Sang Gyu Ju
- Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Irwon-Ro 81, Gangnam-Gu, Seoul, 06351, Republic of Korea
| | - Yong Chan Ahn
- Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Irwon-Ro 81, Gangnam-Gu, Seoul, 06351, Republic of Korea.
| | - Yeong-Bi Kim
- Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Irwon-Ro 81, Gangnam-Gu, Seoul, 06351, Republic of Korea
| | - Jin Man Kim
- Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Irwon-Ro 81, Gangnam-Gu, Seoul, 06351, Republic of Korea
| | - Dong Yeol Kwon
- Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Irwon-Ro 81, Gangnam-Gu, Seoul, 06351, Republic of Korea
| | - Byoung Suk Park
- Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Irwon-Ro 81, Gangnam-Gu, Seoul, 06351, Republic of Korea
| | - Kyungmi Yang
- Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Irwon-Ro 81, Gangnam-Gu, Seoul, 06351, Republic of Korea
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Evaluation of an automated template-based treatment planning system for radiotherapy of anal, rectal and prostate cancer. Tech Innov Patient Support Radiat Oncol 2022; 22:30-36. [PMID: 35464888 PMCID: PMC9020095 DOI: 10.1016/j.tipsro.2022.04.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 03/11/2022] [Accepted: 04/05/2022] [Indexed: 11/21/2022] Open
Abstract
Automated treatment planning system compared to manual planning. Equivalent plan quality between VMAT manually generated- and IMRT automatically generated plans. Evaluation of anal, prostate and rectum treatment plans. Generation of highly consistent IMRT automated plan within 2 to 3.5 min.
Background and purpose The Ethos system has enabled online adaptive radiotherapy (oART) by implementing an automated treatment planning system (aTPS) for both intensity-modulated radiotherapy (IMRT) and volumetric modulated arc radiotherapy (VMAT) plan creation. The purpose of this study is to evaluate the quality of aTPS plans in the pelvic region. Material and Methods Sixty patients with anal (n = 20), rectal (n = 20) or prostate (n = 20) cancer were retrospectively re-planned with the aTPS. Three IMRT (7-, 9- and 12-field) and two VMAT (2 and 3 arc) automatically generated plans (APs) were created per patient. The duration of the automated plan generation was registered. The best IMRT-AP and VMAT-AP for each patient were selected based on target coverage and dose to organs at risk (OARs). The AP quality was analyzed and compared to corresponding clinically accepted and manually generated VMAT plans (MPs) using several clinically relevant dose metrics. Calculation-based pre-treatment plan quality assurance (QA) was performed for all plans. Results The median total duration to generate the five APs with the aTPS was 55 min, 39 min and 35 min for anal, prostate and rectal plans, respectively. The target coverage and the OAR sparing were equivalent for IMRT-APs and VMAT-MPs, while VMAT-Aps. demonstrated lower target dose homogeneity and higher dose to some OARs. Both conformity and homogeneity index were equivalent (rectal) or better (anal and prostate) for IMRT-APs compared to VMAT-MPs. All plans passed the patient-specific QA tolerance limit. Conclusions The aTPS generates plans comparable to MPs within a short time-frame which is highly relevant for oART treatments.
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Key Words
- AP, automatically generated plan
- Automated treatment planning
- CN, conformity number
- CT, computed tomography
- CTV, clinical target volume
- DVH, dose volume histogram
- FFF, flattening filter free
- GTV, gross tumor volume
- HI, homogeneity index
- IMRT, intensity modulated radiotherapy
- Intelligent optimization engine
- KPB, knowledge-based planning
- Linac, Linear accelerators
- MCO, multi-criteria optimization
- MLC, multileaf collimator
- MP, manually-generated plan
- MR, magnetic resonance
- MU, Monitor Unit
- OAR, Organ at risk
- Online adaptive radiotherapy
- PTV, planning target volume
- Pelvic cancer
- Plan quality
- QA, Quality assurance
- SD, standard deviation
- Template-based Ethos TPS
- VMAT, volumetric arc radiotherapy
- aTPS, automated treatment planning system
- oART, online adaptive radiotherapy
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Pokhrel D, Webster A, Mallory R, Visak J, Bernard ME, McGarry RC, Kudrimoti M. Feasibility of using ring‐mounted Halcyon Linac for single‐isocenter/two‐lesion lung stereotactic body radiation therapy. J Appl Clin Med Phys 2022; 23:e13555. [PMID: 35128795 PMCID: PMC9121043 DOI: 10.1002/acm2.13555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 01/14/2022] [Accepted: 01/26/2022] [Indexed: 11/07/2022] Open
Affiliation(s)
- Damodar Pokhrel
- Medical Physics Graduate ProgramDepartment of Radiation MedicineUniversity of KentuckyLexingtonKentuckyUSA
| | - Aaron Webster
- Medical Physics Graduate ProgramDepartment of Radiation MedicineUniversity of KentuckyLexingtonKentuckyUSA
| | - Richard Mallory
- Medical Physics Graduate ProgramDepartment of Radiation MedicineUniversity of KentuckyLexingtonKentuckyUSA
| | - Justin Visak
- Medical Physics Graduate ProgramDepartment of Radiation MedicineUniversity of KentuckyLexingtonKentuckyUSA
| | - Mark E. Bernard
- Medical Physics Graduate ProgramDepartment of Radiation MedicineUniversity of KentuckyLexingtonKentuckyUSA
| | - Ronald C. McGarry
- Medical Physics Graduate ProgramDepartment of Radiation MedicineUniversity of KentuckyLexingtonKentuckyUSA
| | - Mahesh Kudrimoti
- Medical Physics Graduate ProgramDepartment of Radiation MedicineUniversity of KentuckyLexingtonKentuckyUSA
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Duan X, Chen L, Zhou Y. Evaluation of target autocrop function in nasopharyngeal carcinoma SIB IMRT plan. Phys Eng Sci Med 2021; 45:97-105. [PMID: 34846672 DOI: 10.1007/s13246-021-01082-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 11/15/2021] [Indexed: 10/19/2022]
Abstract
A new target autocrop function was introduced in the Varian Eclipse™ treatment planning software (version 15.5 above) (Lohynská in Klin Onkol 33(4):288-294, 2020). The study aimed to evaluate this new target autocrop impact on nasopharyngeal carcinoma (NPC) plan quality and delivery efficiency. Randomly 66 approved NPC simultaneous integrated boost (SIB) intensity-modulated radiation therapy (IMRT) treatment plans were retrospectively studied. The manual cropping-based plans served as reference and were designed using sliding-window IMRT. Reference plans were re-optimized with identical plan parameters following the institutional clinical protocol, except for the redundant optimization objective of the manual cropping targets deleted. Additionally, each target within 5 mm of another had one minimum objective at 100% volume and one maximum objective at 0% volume for the autocrop plans. Plan quality was assessed based on selected parameters, including TCP (tumor control probability), NTCP (normal tissue complication probability), conformality index (CI), homogeneity index (HI), and dose-volume characteristics. Additionally, the delivery efficiency, the total plan treatment time defined as a sum of monitor units (MUs) for each treated field, and delivery accuracy, γ passing rate of treatment plan quality assurance (QA) also were compared. Both the manual cropping plans and the autocrop plans could be approved by an experienced oncologist. Overall, the autocrop plans could provide approximately a 13% reduction in linac MU while maintaining comparable plan quality, radiobiological ranking, and accuracy to the manual cropping plans. The new target autocrop tip facilitated the SIB IMRT plans for nasopharyngeal cancer patients. The autocrop could guarantee the quality and delivery accuracy of the radiotherapy plan and improved the planning efficiency, treatment efficiency, and reduced machine wear and tear. It was a promising tool for optimal plan selection for NPC SIB IMRT.
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Affiliation(s)
- Xiaojuan Duan
- Institute of Cancer Research, Xinqiao Hospital, ARMY Medical University, Chongqing, 400037, China
| | - Lu Chen
- Institute of Cancer Research, Xinqiao Hospital, ARMY Medical University, Chongqing, 400037, China
| | - Yibing Zhou
- Institute of Cancer Research, Xinqiao Hospital, ARMY Medical University, Chongqing, 400037, China.
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Dose Prediction Models Based on Geometric and Plan Optimization Parameter for Adjuvant Radiotherapy Planning Design in Cervical Cancer Radiotherapy. JOURNAL OF HEALTHCARE ENGINEERING 2021; 2021:7026098. [PMID: 34804459 PMCID: PMC8604605 DOI: 10.1155/2021/7026098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 10/16/2021] [Indexed: 11/18/2022]
Abstract
The prediction of an additional space for the dose sparing of organs at risk (OAR) in radiotherapy is still difficult. In this pursuit, the present study was envisaged to find out the factors affecting the bladder and rectum dosimetry of cervical cancer. Additionally, the relationship between the dose-volume histogram (DVH) parameters and the geometry and plan dose-volume optimization parameters of the bladder/rectum was established to develop the dose prediction models and guide the planning design for lower OARs dose coverage directly. Thirty volume modulated radiation therapy (VMAT) plans from cervical cancer patients were randomly chosen to build the dose prediction models. The target dose coverage was evaluated. Dose prediction models were established by univariate and multiple linear regression among the dosimetric parameters of the bladder/rectum, the geometry parameters (planning target volume (PTV), volume of bladder/rectum, overlap volume of bladder/rectum (OV), and overlapped volume as a percentage of bladder/rectum volume (OP)), and corresponding plan dose-volume optimization parameters of the nonoverlapping structures (the structure of bladder/rectum outside the PTV (NOS)). Finally, the accuracy of the prediction models was evaluated by tracking d = (predicted dose-actual dose)/actual in additional ten VMAT plans. V 30, V 35, and V 40 of the bladder and rectum were found to be multiple linearly correlated with the relevant OP and corresponding dose-volume optimization parameters of NOS (regression R 2 > 0.99, P < 0.001). The variations of these models were less than 0.5% for bladder and rectum. Percentage of bladder and rectum within the PTV and the dose-volume optimization parameters of NOS could be used to predict the dose quantitatively. The parameters of NOS as a limited condition could be used in the plan optimization instead of limiting the dose and volume of the entire OAR traditionally, which made the plan optimization more unified and convenient and strengthened the plan quality and consistency.
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7
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Ju E, Heo EJ, Park CG, Kim M, Kim KH, Shim JB, Park YJ, Lee NK, Kim CY, Lee S. Dosimetric comparison of VitalBeam ® and Halcyon TM 2.0 for hypofractionated VMAT with simultaneous integrated boost treatment of early-stage left-sided breast cancer. J Appl Clin Med Phys 2021; 22:232-238. [PMID: 34554605 PMCID: PMC8504599 DOI: 10.1002/acm2.13428] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 08/21/2021] [Accepted: 09/07/2021] [Indexed: 11/16/2022] Open
Abstract
Purpose This study compared the quality of treatment plans for early‐stage, left‐sided breast cancer, as planned for and delivered by the HalcyonTM and VitalBeam®. Materials and methods Fifteen patients diagnosed with early‐stage left‐sided breast cancer, who had received VMAT with hypofractionated SIB, were recruited. All cases were planned using HalcyonTM comprising a dual‐layer MLC (DL‐MLC) and VitalBeam® with a Millennium 120 MLC (VB‐MLC). For the PTVs, the quality of coverage (QC), conformity index (CI), and homogeneity index (HI) were calculated for each plan. The dosimetric differences between the two treatment plans were statistically compared using the Wilcoxon signed‐rank test (p < 0.05). To evaluate delivery efficiency, the average delivery time for each patient's treatment plan was recorded and compared. Results For the PTVs, the two plans (DL‐MLC and VB‐MLC) were comparable in terms of the QC, CI, and HI. However, V30Gy and Dmean for the heart in the DL‐MLC plan were significantly reduced by 0.49% and 14.6%, respectively, compared with those in the VB‐MLC plan (p < 0.05). The Dmean value for the ipsilateral lung in the DL‐MLC plan significantly decreased by 5.5%, compared with that in the VB‐MLC plan (p < 0.05). In addition, the delivery times for the DL‐MLC and VB‐MLC plans were 79 ± 10 and 101 ± 11 s, respectively. Conclusions DL‐MLC plans were found to improve OAR sparing. In particular, when treating left‐sided breast cancer via DL‐MLC plans, the risk of heart toxicity is expected to be reduced.
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Affiliation(s)
- Eunbin Ju
- Department of Radiation Oncology, College of Medicine, Korea University, Seoul, Korea.,Department of Bio-Medical Science, Graduate School of Korea University, Sejong, Korea
| | - Eun Jeong Heo
- Department of Radiation Oncology, College of Medicine, Korea University, Seoul, Korea.,Department of Bio-Medical Science, Graduate School of Korea University, Sejong, Korea
| | - Chun Gun Park
- Department of Mathematics, Kyonggi University, Gyeonggi, Korea
| | - Minseok Kim
- Department of Biostatistics and Computing, Yonsei University Graduate school, Seoul, Korea
| | - Kwang Hyeon Kim
- Department of Neurosurgery, Ilsan Paik Hospital, College of Medicine, Inje University, Goyang, Korea
| | - Jang Bo Shim
- Department of Radiation Oncology, Guro Hospital, Korea University Medical Center, Seoul, Korea
| | - Young Je Park
- Department of Radiation Oncology, College of Medicine, Korea University, Seoul, Korea
| | - Nam Kwon Lee
- Department of Radiation Oncology, College of Medicine, Korea University, Seoul, Korea
| | - Chul Yong Kim
- Department of Radiation Oncology, College of Medicine, Korea University, Seoul, Korea
| | - Suk Lee
- Department of Radiation Oncology, College of Medicine, Korea University, Seoul, Korea
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Hirashima H, Nakamura M, Mukumoto N, Ashida R, Fujii K, Nakamura K, Nakajima A, Sakanaka K, Yoshimura M, Mizowaki T. Reducing variability among treatment machines using knowledge-based planning for head and neck, pancreatic, and rectal cancer. J Appl Clin Med Phys 2021; 22:245-254. [PMID: 34151503 PMCID: PMC8292706 DOI: 10.1002/acm2.13316] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Revised: 05/14/2021] [Accepted: 05/17/2021] [Indexed: 11/18/2022] Open
Abstract
Purpose This study aimed to assess dosimetric indices of RapidPlan model‐based plans for different energies (6, 8, 10, and 15 MV; 6‐ and 10‐MV flattening filter‐free), multileaf collimator (MLC) types (Millennium 120, High Definition 120, dual‐layer MLC), and disease sites (head and neck, pancreatic, and rectal cancer) and compare these parameters with those of clinical plans. Methods RapidPlan models in the Eclipse version 15.6 were used with the data of 28, 42, and 20 patients with head and neck, pancreatic, and rectal cancer, respectively. RapidPlan models of head and neck, pancreatic, and rectal cancer were created for TrueBeam STx (High Definition 120) with 6 MV, TrueBeam STx with 10‐MV flattening filter‐free, and Clinac iX (Millennium 120) with 15 MV, respectively. The models were used to create volumetric‐modulated arc therapy plans for a 10‐patient test dataset using all energy and MLC types at all disease sites. The Holm test was used to compare multiple dosimetric indices in different treatment machines and energy types. Results The dosimetric indices for planning target volume and organs at risk in RapidPlan model‐based plans were comparable to those in the clinical plan. Furthermore, no dose difference was observed among the RapidPlan models. The variability among RapidPlan models was consistent regardless of the treatment machines, MLC types, and energy. Conclusions Dosimetric indices of RapidPlan model‐based plans appear to be comparable to the ones based on clinical plans regardless of energies, MLC types, and disease sites. The results suggest that the RapidPlan model can generate treatment plans independent of the type of treatment machine.
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Affiliation(s)
- Hideaki Hirashima
- Department of Radiation Oncology and Image-applied Therapy, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Mitsuhiro Nakamura
- Department of Radiation Oncology and Image-applied Therapy, Graduate School of Medicine, Kyoto University, Kyoto, Japan.,Division of Medical Physics, Department of Information Technology and Medical Engineering, Faculty of Human Health Science, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Nobutaka Mukumoto
- Department of Radiation Oncology and Image-applied Therapy, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Ryo Ashida
- Department of Radiation Oncology and Image-applied Therapy, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Kota Fujii
- Department of Radiation Oncology and Image-applied Therapy, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Kiyonao Nakamura
- Department of Radiation Oncology and Image-applied Therapy, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Aya Nakajima
- Department of Radiation Oncology and Image-applied Therapy, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Katsuyuki Sakanaka
- Department of Radiation Oncology and Image-applied Therapy, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Michio Yoshimura
- Department of Radiation Oncology and Image-applied Therapy, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Takashi Mizowaki
- Department of Radiation Oncology and Image-applied Therapy, Graduate School of Medicine, Kyoto University, Kyoto, Japan
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Chamberlain M, Krayenbuehl J, van Timmeren JE, Wilke L, Andratschke N, Garcia Schüler H, Tanadini-Lang S, Guckenberger M, Balermpas P. Head and neck radiotherapy on the MR linac: a multicenter planning challenge amongst MRIdian platform users. Strahlenther Onkol 2021; 197:1093-1103. [PMID: 33891126 PMCID: PMC8604891 DOI: 10.1007/s00066-021-01771-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 03/22/2021] [Indexed: 11/30/2022]
Abstract
Purpose Purpose of this study is to evaluate plan quality on the MRIdian (Viewray Inc., Oakwood Village, OH, USA) system for head and neck cancer (HNC) through comparison of planning approaches of several centers. Methods A total of 14 planners using the MRIdian planning system participated in this treatment challenge, centrally organized by ViewRay, for one contoured case of oropharyngeal carcinoma with standard constraints for organs at risk (OAR). Homogeneity, conformity, sparing of OARs, and other parameters were evaluated according to The International Commission on Radiation Units and Measurements (ICRU) recommendations anonymously, and then compared between centers. Differences amongst centers were assessed by means of Wilcoxon test. Each plan had to fulfil hard constraints based on dose–volume histogram (DVH) parameters and delivery time. A plan quality metric (PQM) was evaluated. The PQM was defined as the sum of 16 submetrics characterizing different DVH goals. Results For most dose parameters the median score of all centers was higher than the threshold that results in an ideal score. Six participants achieved the maximum number of points for the OAR dose parameters, and none had an unacceptable performance on any of the metrics. Each planner was able to achieve all the requirements except for one which exceeded delivery time. The number of segments correlated to improved PQM and inversely correlated to brainstem D0.1cc and to Planning Target Volume1 (PTV) D0.1cc. Total planning experience inversely correlated to spinal canal dose. Conclusion Magnetic Resonance Image (MRI) linac-based planning for HNC is already feasible with good quality. Generally, an increased number of segments and increasing planning experience are able to provide better results regarding planning quality without significantly prolonging overall treatment time. Supplementary Information The online version of this article (10.1007/s00066-021-01771-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Madalyne Chamberlain
- Department of Radiation Oncology, University Hospital Zurich, Zurich, Switzerland.
| | - Jerome Krayenbuehl
- Department of Radiation Oncology, University Hospital Zurich, Zurich, Switzerland
| | | | - Lotte Wilke
- Department of Radiation Oncology, University Hospital Zurich, Zurich, Switzerland
| | - Nicolaus Andratschke
- Department of Radiation Oncology, University Hospital Zurich, Zurich, Switzerland
| | | | | | | | - Panagiotis Balermpas
- Department of Radiation Oncology, University Hospital Zurich, Zurich, Switzerland
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10
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Barsky AR, Lin H, Mendes A, Dreyfuss A, Wright C, Anstadt EJ, Berman AT, Levin WP, Cengel KA, Anderson N, Dong L, Metz JM, Li T, Feigenberg S. Initial Clinical Experience Treating Patients With Lung Cancer on a 6MV-Flattening-Filter-Free O-Ring Linear Accelerator. Cureus 2020; 12:e10325. [PMID: 33052286 PMCID: PMC7546605 DOI: 10.7759/cureus.10325] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Introduction Modern technologies, like intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT), have improved the therapeutic ratio of thoracic radiotherapy (TRT) for lung cancer (LC). Halcyon™ (Varian Medical Systems, Palo Alto, CA, USA), a novel 6MV-flattening-filter-free O-ring linear accelerator (6X-FFF ORL), was designed to deliver IMRT and VMAT with greater speed than a C-arm linac. Herein, we report our initial clinical experience treating patients with LC on this linac. Methods All patients who received TRT for LC on the 6X-FFF ORL at our institution were retrospectively identified. Patients' clinicopathologic data, radiotherapy details, early disease-control and toxicity outcomes, dosimetric data, couch corrections, and treatment times are reported. Results Between 10/2018-12/2019, 30 consecutive patients (median age 66 years, range 54-94 years) received definitive or post-operative TRT for LC (median 66 Gy/33 fractions; range 5-70 Gy/2-37 fractions) following four-dimensional computed tomography (CT) simulation (97%) using daily kilovoltage KV cone-beam CT (CBCT) (100%) on a 6X-FFF ORL for non-small cell LC (84%) or small cell LC (16%), with 53% receiving VMAT, 43% receiving static-field IMRT, and 77% receiving concurrent systemic therapy. All plans were approved through institutional peer review. The average three-dimensional vector couch correction based on CBCT guidance was 0.90 ± 0.50 cm. The average beam-on and beam on plus CBCT times were 1.7 ± 1.1 min, and 5.0 ± 3.2 min, respectively. Grade 3 dyspnea and fatigue occurred in 3% and 3% of patients, respectively. There were no grade ≥4 toxicities. Conclusion In this first clinical report of TRT for LC on a 6X-FFF ORL, daily CBCT-guided treatment was fast and safe with respect to dosimetry and clinical outcomes. Thus, use of this linac for TRT may increase LC patient throughput without a detriment in radiotherapy quality.
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Affiliation(s)
- Andrew R Barsky
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Philadelphia, USA
| | - Hui Lin
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Philadelphia, USA
| | - Amberly Mendes
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Philadelphia, USA
| | - Alexandra Dreyfuss
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, USA
| | - Christopher Wright
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Philadelphia, USA
| | - Emily J Anstadt
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Philadelphia, USA
| | - Abigail T Berman
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Philadelphia, USA
| | - William P Levin
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Philadelphia, USA
| | - Keith A Cengel
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Philadelphia, USA
| | - Nathan Anderson
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Philadelphia, USA
| | - Lei Dong
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Philadelphia, USA
| | - James M Metz
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Philadelphia, USA
| | - Taoran Li
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Philadelphia, USA
| | - Steven Feigenberg
- Department of Radiation Oncology, Hospital of the University of Pennsylvania, Philadelphia, USA
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11
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Barsky AR, Kim MM, Dreyfuss A, Dong L, Metz JM, Anamalayil S, Li T, Taunk NK. Initial Clinical Experience Treating Patients With Gynecologic Cancers on a 6MV Flattening Filter Free O-Ring Linear Accelerator. Adv Radiat Oncol 2020; 5:920-928. [PMID: 33083654 PMCID: PMC7557142 DOI: 10.1016/j.adro.2020.01.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 01/26/2020] [Accepted: 01/26/2020] [Indexed: 11/29/2022] Open
Abstract
PURPOSE Radiation therapy (RT) is commonly used in the treatment of gynecologic cancers. Intensity-modulated RT (IMRT) has been shown to reduce gastrointestinal toxicity compared with 2-dimensional and 3-dimensional RT modalities. We report the initial clinical experience using IMRT for gynecologic cancers with a novel 6MV flattening filter free O-ring linear accelerator (6X-FFF ORL). METHODS AND MATERIALS We retrospectively identified consecutive women with uterine or cervical cancer who received pelvic RT on Halcyon (Varian Medical Systems, Palo Alto, CA), a novel 6X-FFF ORL. We report their clinicopathologic data, RT details, early disease-control outcomes, acute toxicities, dose-volume histogram data, couch corrections, and treatment times. RESULTS Seventeen women received RT on a 6X-FFF ORL for uterine cancer (76%) or cervical cancer (24%) between January 2017 and September 2019. RT was delivered postoperatively (82%) or to intact disease (18%), to a median dose of 50.4 Gy (range, 19.8-55.0 Gy) in 25 fractions (range, 11-28), with 12% receiving extended-field RT and 65% receiving chemotherapy. Target and organ-at-risk constraints were met in all plans. The 3-dimensional vector couch correction average was 0.90 ± 0.37 cm. The mean beam-on time was 2.9 ± 0.4 min and mean treatment time, from imaging start to beam-off, was 3.6 ± 0.4 min. Grade 2 fatigue, anorexia, diarrhea, bloating, and nausea occurred in 41%, 12%, 12%, 6%, and 6% of patients, respectively. There were no grade ≥3 toxicities. CONCLUSIONS In the initial clinical report of pelvic RT for gynecologic cancers using a 6X-FFF ORL, the linac showed versatility in treatment; comparability to flattening-filtered IMRT for early disease-control, toxicity, and dosimetry; and treatment speed that compared favorably to IMRT on a C-arm gantry. Accordingly, a 6X-FFF ORL may increase throughput or reduce day length in departments with high gynecologic cancer volumes, without compromising clinical outcomes.
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Affiliation(s)
- Andrew R Barsky
- Department of Radiation Oncology, Perelman School of Medicine of the University of Pennsylvania, Perelman Center for Advanced Medicine, Philadelphia, Pennsylvania
| | - Michele M Kim
- Department of Radiation Oncology, Perelman School of Medicine of the University of Pennsylvania, Perelman Center for Advanced Medicine, Philadelphia, Pennsylvania
| | - Alexandra Dreyfuss
- Department of Radiation Oncology, Perelman School of Medicine of the University of Pennsylvania, Perelman Center for Advanced Medicine, Philadelphia, Pennsylvania
| | - Lei Dong
- Department of Radiation Oncology, Perelman School of Medicine of the University of Pennsylvania, Perelman Center for Advanced Medicine, Philadelphia, Pennsylvania
| | - James M Metz
- Department of Radiation Oncology, Perelman School of Medicine of the University of Pennsylvania, Perelman Center for Advanced Medicine, Philadelphia, Pennsylvania
| | - Shibu Anamalayil
- Department of Radiation Oncology, Perelman School of Medicine of the University of Pennsylvania, Perelman Center for Advanced Medicine, Philadelphia, Pennsylvania
| | - Taoran Li
- Department of Radiation Oncology, Perelman School of Medicine of the University of Pennsylvania, Perelman Center for Advanced Medicine, Philadelphia, Pennsylvania
| | - Neil K Taunk
- Department of Radiation Oncology, Perelman School of Medicine of the University of Pennsylvania, Perelman Center for Advanced Medicine, Philadelphia, Pennsylvania
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12
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Tamura M, Matsumoto K, Otsuka M, Monzen H. Plan complexity quantification of dual-layer multi-leaf collimator for volumetric modulated arc therapy with Halcyon linac. Phys Eng Sci Med 2020; 43:947-957. [DOI: 10.1007/s13246-020-00891-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 06/23/2020] [Indexed: 12/31/2022]
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13
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Cusumano D, Dhont J, Boldrini L, Chiloiro G, Romano A, Votta C, Longo S, Placidi L, Azario L, De Spirito M, Verellen D, Valentini V. Reliability of ITV approach to varying treatment fraction time: a retrospective analysis based on 2D cine MR images. Radiat Oncol 2020; 15:152. [PMID: 32532334 PMCID: PMC7291491 DOI: 10.1186/s13014-020-01530-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 04/03/2020] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Internal Target Volume (ITV) is one of the most common strategies to passively manage tumour motion in Radiotherapy (RT). The reliability of this approach is based on the assumption that the tumour motion estimated during pre-treatment 4D Computed Tomography (CT) acquisition is representative of the motion during the whole RT treatment. With the introduction of Magnetic Resonance-guided RT (MRgRT), it has become possible to monitor tumour motion during the treatment and verify this assumption. Aim of this study was to investigate the reliability of the ITV approach with respect to the treatment fraction time (TFT) in abdominal and thoracic lesions. METHODS A total of 12 thoracic and 15 abdominal lesions was analysed. Before treatment, a 10-phase 4DCT was acquired and ITV margins were estimated considering the envelope of the lesion contoured on the different 4DCT phases. All patients underwent MRgRT treatment in free-breathing, monitoring the tumour position on a sagittal plane with 4 frames per second (sec). ITV margins were projected on the tumour trajectory and the percentage of treatment time in which the tumour was inside the ITV (%TT) was measured to varying of TFT. The ITV approach was considered moderately reliable when %TT ≥ 90% and strongly reliable when %TT ≥ 95%. Additional ITV margins required to achieve %TT ≥ 95% were also calculated. RESULTS In the analysed cohort of patients, ITV strategy can be considered strongly reliable only for lung lesions with TFT ≤ 7 min (min). The ITV strategy can be considered only moderately reliable for abdominal lesions, and additional margins are required to obtain %TT ≥ 95%. Considering a TFT ≤ 4 min, additional margins of 2 mm in cranio-caudal (CC) and 1 mm in antero-posterior (AP) are suggested for pancreatic lesions, 3 mm in CC and 2 mm in AP for renal and liver ones. CONCLUSIONS On the basis of the analysed cases, the ITV approach appears to be reliable in the thorax, while it results more challenging in the abdomen, due to the higher uncertainty in ITV definition and to the observed larger intra and inter-fraction motion variability. The addition of extra margins based on the TFT may represent a valid tool to compensate such limitations.
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Affiliation(s)
- Davide Cusumano
- Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Largo Agostino Gemelli,8, 00168 Rome, Italia
| | - Jennifer Dhont
- Department of Electronics and Informatics (ETRO), Vrije Universiteit Brussel (VUB), Pleinlaan 9, B-1050 Brussels, Imec, Leuven, Belgium
- Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Luca Boldrini
- Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Largo Agostino Gemelli,8, 00168 Rome, Italia
| | - Giuditta Chiloiro
- Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Largo Agostino Gemelli,8, 00168 Rome, Italia
| | - Angela Romano
- Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Largo Agostino Gemelli,8, 00168 Rome, Italia
| | - Claudio Votta
- Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Largo Agostino Gemelli,8, 00168 Rome, Italia
| | - Silvia Longo
- Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Largo Agostino Gemelli,8, 00168 Rome, Italia
| | - Lorenzo Placidi
- Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Largo Agostino Gemelli,8, 00168 Rome, Italia
| | - Luigi Azario
- Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Largo Agostino Gemelli,8, 00168 Rome, Italia
| | - Marco De Spirito
- Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Largo Agostino Gemelli,8, 00168 Rome, Italia
| | - Dirk Verellen
- Department of Radiotherapy, Iridium Kankernetwerk, University of Antwerp (Faculty of Medicine and Health Sciences), Antwerp, Belgium
| | - Vincenzo Valentini
- Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Largo Agostino Gemelli,8, 00168 Rome, Italia
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14
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Giaddui T, Geng H, Chen Q, Linnemann N, Radden M, Lee NY, Xia P, Xiao Y. Offline Quality Assurance for Intensity Modulated Radiation Therapy Treatment Plans for NRG-HN001 Head and Neck Clinical Trial Using Knowledge-Based Planning. Adv Radiat Oncol 2020; 5:1342-1349. [PMID: 33305097 PMCID: PMC7718499 DOI: 10.1016/j.adro.2020.05.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 04/04/2020] [Accepted: 05/02/2020] [Indexed: 11/24/2022] Open
Abstract
Purpose This study aimed to investigate whether a disease site–specific, multi-institutional knowledge based-planning (KBP) model can improve the quality of intensity modulated radiation therapy treatment planning for patients enrolled in the head and neck NRG-HN001clinical trial and to establish a threshold of improvements of treatment plans submitted to the clinical trial. Methods and Materials Fifty treatment plans for patients enrolled in the NRG-HN001 clinical trial were used to build a KBP model; the model was then used to reoptimize 50 other plans. We compared the dosimetric parameters of the submitted and KBP reoptimized plans. We compared differences between KBP and submitted plans for single- and multi-institutional treatment plans. Results Mean values for the dose received by 95% of the planning target volume (PTV_6996) and for the maximum dose (D0.03cc) of PTV_6996 were 0.5 Gy and 2.1 Gy higher in KBP plans than in the submitted plans, respectively. Mean values for D0.03cc to the brain stem, spinal cord, optic nerve_R, optic nerve_L, and chiasm were 2.5 Gy, 1.9 Gy, 6.4 Gy, 6.6 Gy, and 5.7 Gy lower in the KBP plans than in the submitted plans. Mean values for Dmean to parotid_R and parotid_L glands were 2.2 Gy and 3.8 Gy lower in KBP plans, respectively. In 33 out of 50 KBP plans, we observed improvements in sparing of at least 7 organs at risk (OARs) (brain stem, spinal cord, optic nerves (R & L), chiasm, and parotid glands [R & L]). A threshold of improvement of OARs sparing of 5% of the prescription dose was established for providing the quality assurance results back to the treating institution. Conclusions A disease site–specific, multi-institutional, clinical trial-based KBP model improved sparing of OARs in a large number of reoptimized plans submitted to the NRG-HN001 clinical trial, and the model is being used as an offline quality assurance tool.
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Affiliation(s)
- Tawfik Giaddui
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania.,Department of Radiation Oncology, Temple University Hospital, Philadelphia, Pennsylvania
| | - Huaizhi Geng
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Quan Chen
- Department of Radiation Oncology, Geisinger Commonwealth School of Medicine, Scranton, Pennsylvania
| | - Nancy Linnemann
- Department of Radiation Oncology, NRG Oncology/Imaging and Radiation Oncology Core (IROC), Philadelphia, Pennsylvania
| | - Marsha Radden
- Department of Radiation Oncology, NRG Oncology/Imaging and Radiation Oncology Core (IROC), Philadelphia, Pennsylvania
| | - Nancy Y Lee
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Ping Xia
- Department of Radiation Oncology, Cleveland Clinic Foundation, Cleveland, Ohio
| | - Ying Xiao
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania
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15
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Park H, Choi HJ, Hee Min C, Kim JI. Monte Carlo simulation of a 2D dynamic multileaf collimator to improve the plan quality in radiotherapy plan: a proof-of-concept study. Phys Med Biol 2019; 64:245009. [PMID: 31726432 DOI: 10.1088/1361-6560/ab57c4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The leaf width of a multileaf collimator (MLC) determines the dose conformity to the target volume. The objective of this study was to investigate the feasibility of a two-dimensional dynamic MLC (2DDMLC) to improve the treatment plan quality with a fixed leaf width. The treatment head of the Clinac™ linear accelerator with the Millennium 120™ MLC was modelled with the Geant4 (for GEometry ANd Tracking) tollkit using the Monte Carlo (MC) method. The 2DDMLC produces a beam aperture by moving the MLC bank vertically to the leaf movement. Thus, the effect of the 2DDMLC motion on beam divergence and beam fluence resolution was evaluated by comparing the dose distributions between the conventional MLC motion and the 2DDMLC. Finally, the 2DDMLC was employed for dynamic conformal arc therapy for 13 brain cancer patients. The dose-volumetric parameters, including the dose delivered to 98% of the target volume (D 98%), percent volume given 20% of the prescribed dose (V 20%), and conformity index (CI) were compared with those of the conventional MLC. For the 6 MV beam of the MC model, the depth dose and lateral dose distribution differed by less than 2% between the simulation and measurement. The 2DDMLC did not significantly influence beam divergence and sharpened the beam. In clinical use, the dose delivered to the target was almost identical between the 2DDMLC and conventional MLC (D 98% = 29.74 Gy versus 29.71 Gy, p = 0.18). The CI was improved with the use of the 2DDMLC (CI = 1.49 versus 1.47, p = 0.14). Moreover, irradiation of normal tissue was reduced with the 2DDMLC compared with conventional MLC (V 20% = 17.22% versus 17.45%, p < 0.001). The 2DDMLC improved the dose conformity to the target volume and reduced the irradiation of the normal tissue compared with the conventional MLC.
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Affiliation(s)
- Hyojun Park
- Department of Radiation Convergence Engineering, Yonsei University, Wonju, Republic of Korea
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16
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Gay SS, Netherton TJ, Cardenas CE, Ger RB, Balter PA, Dong L, Mihailidis D, Court LE. Dosimetric impact and detectability of multi-leaf collimator positioning errors on Varian Halcyon. J Appl Clin Med Phys 2019; 20:47-55. [PMID: 31294923 PMCID: PMC6698762 DOI: 10.1002/acm2.12677] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 05/06/2019] [Accepted: 06/21/2019] [Indexed: 11/11/2022] Open
Abstract
The purpose of this study is to investigate the dosimetric impact of multi‐leaf collimator (MLC) positioning errors on a Varian Halcyon for both random and systematic errors, and to evaluate the effectiveness of portal dosimetry quality assurance in catching clinically significant changes caused by these errors. Both random and systematic errors were purposely added to 11 physician‐approved head and neck volumetric modulated arc therapy (VMAT) treatment plans, yielding a total of 99 unique plans. Plans were then delivered on a preclinical Varian Halcyon linear accelerator and the fluence was captured by an opposed portal dosimeter. When comparing dose–volume histogram (DVH) values of plans with introduced MLC errors to known good plans, clinically significant changes to target structures quickly emerged for plans with systematic errors, while random errors caused less change. For both error types, the magnitude of clinically significant changes increased as error size increased. Portal dosimetry was able to detect all systematic errors, while random errors of ±5 mm or less were unlikely to be detected. Best detection of clinically significant errors, while minimizing false positives, was achieved by following the recommendations of AAPM TG‐218. Furthermore, high‐ to moderate correlation was found between dose DVH metrics for normal tissues surrounding the target and portal dosimetry pass rates. Therefore, it may be concluded that portal dosimetry on the Halcyon is robust enough to detect errors in MLC positioning before they introduce clinically significant changes to VMAT treatment plans.
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Affiliation(s)
- Skylar S Gay
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Tucker J Netherton
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.,The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Houston, TX, USA
| | - Carlos E Cardenas
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Rachel B Ger
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.,The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Houston, TX, USA
| | - Peter A Balter
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.,The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Houston, TX, USA
| | - Lei Dong
- Radiation Oncology, Hospital, University of Pennsylvania, Philadelphia, PA, USA
| | - Dimitris Mihailidis
- Radiation Oncology, Hospital, University of Pennsylvania, Philadelphia, PA, USA
| | - Laurence E Court
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.,The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Houston, TX, USA.,Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
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