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Thakur N, Bansal N, Sudan M, Sharma A. Optimising craniospinal irradiation for medulloblastoma: a dosimetric comparison of two VMAT planning methods. Ecancermedicalscience 2024; 18:1700. [PMID: 38774570 PMCID: PMC11108045 DOI: 10.3332/ecancer.2024.1700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Indexed: 05/24/2024] Open
Abstract
Background Craniospinal irradiation (CSI) poses a challenging planning process because of the complex target volume. Traditional 3D conformal CSI does not spare any critical organs, resulting in toxicity in patients. Here the dosimetric advantages of volumetric-modulated arc therapy (VMAT) using partial arc and avoidance sectors are compared with each other in planning in adult patients undergoing CSI to develop a clinically feasible technique that is both effective and efficient. Patient and methods Eight adult patients treated with CSI were retrospectively identified. In total 16 plans were made. We generated two plans for each patient: 1. VMAT plan using partial arc, namely VMAT_pa. 2. VMAT plan using avoidance sectors, namely VMAT_as. The dose prescribed was 36 Gy in 20 fractions. The dose-volume histogram for planning target volume (PTV) and organs at risk (OAR) (lens, eye, heart, thyroid, lungs, liver, gonads and kidneys) were analysed and compared. Dose parameters of mean dose, V95%, and V107% for the PTV were evaluated. Results The median length of PTV is 65.58 cm (45.8-79.5). The volume of PTV receiving 95% of the dose (V95%) in both the plans are 97.51% (VMAT_as) and 97.99% (VMAT_pa) (p = 0.121) while V107% are 0.733 and 0.742 for VMAT_as and VMAT_pa, respectively (p = 0.969). The doses of OARs such as lens, eye, liver and gonads were comparable. The mean heart dose was 10.4 and 9.0 Gy in VMAT_as and VMAT_pa plans, respectively (p = 0.005). Significant lower doses to the thyroid, kidneys and lungs were seen in VMAT plans using avoidance sectors. Conclusion This study provides a practically useful VMAT planning method for the treatment of CSI and illustrates the ability of VMAT using avoidance sectors to generate highly conformal and homogeneous treatment plans for CSI, while limiting the dose to the relevant OARs.
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Affiliation(s)
- Niketa Thakur
- Department of Radiation Oncology, All India Institute of Medical Sciences (AIIMS), Bilaspur 174037, India
| | - Nancy Bansal
- Department of Radiation Oncology, Sri Guru Ram Das Institute of Medical Sciences and Research, Amritsar 143501, India
| | - Meena Sudan
- Department of Radiation Oncology, Sri Guru Ram Das Institute of Medical Sciences and Research, Amritsar 143501, India
| | - Abhishek Sharma
- Department of Anesthesia and Critical Care, Sri Guru Ram Das Institute of Medical Sciences and Research, Amritsar, India
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Huang C, Nomura Y, Yang Y, Xing L. Fully automated segmentally boosted VMAT. Med Phys 2023; 50:3842-3851. [PMID: 36779662 PMCID: PMC10272012 DOI: 10.1002/mp.16295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 01/23/2023] [Accepted: 01/30/2023] [Indexed: 02/14/2023] Open
Abstract
PURPOSE Treatment planning for volumetric modulated arc therapy (VMAT) typically involves the use of multiple arcs to achieve sufficient intensity modulation. Alternatively, we can perform segment boosting to achieve similar intensity modulation while also reducing the number of control points used. Here, we propose the MetaPlanner Boosted VMAT (MPBV) approach, which generates boosted VMAT plans through a fully automated framework. METHODS The proposed MPBV approach is an open-source framework that consists of three main stages: meta-optimization of treatment plan hyperparameters, fast beam angle optimization on a coarse dose grid to select desirable segments for boosting, and final plan generation (i.e., constructing the boosted VMAT arc and performing optimization). RESULTS Performance for the MPBV approach is evaluated on 21 prostate cases and 6 head and neck cases using clinically relevant plan quality metrics (i.e., target coverage, dose conformity, dose homogeneity, and OAR sparing). As compared to two baseline methods with multiple arcs, MPBV maintains or improves dosimetric performance for the evaluated metrics while substantially reducing average estimated delivery times (from 2.6 to 2.1 min). CONCLUSION Our proposed MPBV approach provides an automated framework for producing high-quality VMAT plans that uses fewer control points and reduces delivery time as compared to traditional approaches with multiple arcs. MPBV applies automated treatment planning to segmentally boosted VMAT to address the beam utilization inefficiencies of traditional VMAT approaches that use multiple full arcs.
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Affiliation(s)
- Charles Huang
- Department of Bioengineering, Stanford University, Stanford, USA
| | - Yusuke Nomura
- Department of Radiation Oncology, Stanford University, Stanford, USA
| | - Yong Yang
- Department of Radiation Oncology, Stanford University, Stanford, USA
| | - Lei Xing
- Department of Radiation Oncology, Stanford University, Stanford, USA
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Ma M, Kidd E, Fahimian BP, Han B, Niedermayr TR, Hristov D, Xing L, Yang Y. Dose Prediction for Cervical Cancer Brachytherapy Using 3-D Deep Convolutional Neural Network. IEEE TRANSACTIONS ON RADIATION AND PLASMA MEDICAL SCIENCES 2022. [DOI: 10.1109/trpms.2021.3098507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Huang C, Yang Y, Xing L. Fully automated noncoplanar radiation therapy treatment planning. Med Phys 2021; 48:7439-7449. [PMID: 34519064 DOI: 10.1002/mp.15223] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 08/23/2021] [Accepted: 08/30/2021] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To perform fully automated noncoplanar (NC) treatment planning, we propose a method called NC-POPS to produce NC plans using the Pareto optimal projection search (POPS) algorithm. METHODS NC radiation therapy treatment planning has the potential to improve dosimetric quality as compared to traditional coplanar techniques. Likewise, automated treatment planning algorithms can reduce a planner's active treatment planning time and remove inter-planner variability. Our NC-POPS algorithm extends the original POPS algorithm to the NC setting with potential applications to both intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT). The proposed algorithm consists of two main parts: (1) NC beam angle optimization (BAO) and (2) fully automated inverse planning using the POPS algorithm. RESULTS We evaluate the performance of NC-POPS by comparing between various NC and coplanar configurations. To evaluate plan quality, we compute the homogeneity index (HI), conformity index (CI), and dose-volume histogram statistics for various organs-at-risk (OARs). As compared to the evaluated coplanar baseline methods, the proposed NC-POPS method achieves significantly better OAR sparing, comparable or better dose conformity, and similar dose homogeneity. CONCLUSIONS Our proposed NC-POPS algorithm provides a modular approach for fully automated treatment planning of NC IMRT cases with the potential to substantially improve treatment planning workflow and plan quality.
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Affiliation(s)
- Charles Huang
- Department of Bioengineering, Stanford University, Stanford, California, USA
| | - Yong Yang
- Department of Radiation Oncology, Stanford University, Stanford, California, USA
| | - Lei Xing
- Department of Radiation Oncology, Stanford University, Stanford, California, USA
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Shang H, Pu Y, Chen Z, Wang X, Yuan C, Jin X, Liu C. Impact of Multiple Beams on Plan Quality, Linear Energy Transfer Distribution, and Plan Robustness of Intensity Modulated Proton Therapy for Lung Cancer. ACS Sens 2021; 6:408-417. [PMID: 33125211 DOI: 10.1021/acssensors.0c01879] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The increase of proton beam number might provide higher degrees of freedom in the optimization of intensity-modulated proton therapy planning. In this study, we aimed to quantitatively explore the potential benefits of the increased beam number, including dose volume histogram (DVH), linear energy transfer volume histogram, and DVH bandwidth metrics. Twelve patients with lung cancer are retrospectively selected. Four plans were created based on internal target volume (ITV) robust optimization for each patient using the RayStation treatment planning system. Four plans were generated using different numbers (three, five, seven, and nine) of evenly separated coplanar beams. The three-beam plan was considered as the reference plan. Biologically equivalent doses were calculated using both constant relative biological effectiveness (RBE) and variable RBE models, respectively. To evaluate plan quality, DVH metrics in the target [ITV: D2%, CI, HI] and organs-at-risk [Lung: V5Gy[RBE], V20Gy[RBE], V30Gy[RBE]; Heart D2%; Spinal cord D2%] were calculated using both RBE models. To evaluate LET distributions, LET volume histogram metrics [ITV LETmean and LET2%; Lung LETmean and LET2%; Heart LET2%; Spinal cord LET2%] were quantified. To evaluate plan robustness, the metrics using DVH bandwidth [ITV: D2%, D99%; Lung: V5Gy[RBE], V20Gy[RBE], V30Gy[RBE]; Heart D2%; Spinal cord D2%] were also reported. For plan quality, the increase of proton beam number resulted in fewer target hot spots, improved target dose conformity, improved target dose homogeneity, lower median-dose lung volume, and fewer hot spots in spinal cord. As to LET distributions, target mean LET increased significantly as the beam number increased to seven or more. Lung LET hot spots were significantly reduced with the increase of proton beams. With respect to plan robustness, the robustness of target dose coverage, target hot spots, and low-dose lung volume were improved, while the robustness of heart hot spots became worse as the beam number increased to nine. The robustness of cord hot spots became worse using five and seven beams compared to that using three beams. As the proton beam number increased, plan quality and LET distributions were comparable or significantly improved. The robustness of target dose coverage, target dose hot spots, and low-dose lung volume were significantly improved.
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Affiliation(s)
- Haijiao Shang
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201800, P. R. China
- University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
- RaySearch China, Shanghai, 200120, P. R. China
| | - Yuehu Pu
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201800, P. R. China
- University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Zhiling Chen
- Shanghai Advanced Research Institute, Chinese Academy Sciences, Shanghai, 201210, P. R. China
| | - Xuetao Wang
- Department of Radiation Oncology, West China Hospital, Sichuan University, Chengdu, 610041, P. R. China
| | - Cuiyun Yuan
- Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital & Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, 518116, P. R. China
| | - Xiance Jin
- Department of Radiation and Medical Oncology, The 1st Affiliated Hospital of Wenzhou Medical University, Wenzhou, 32500, P. R. China
| | - Chenbin Liu
- Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital & Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, 518116, P. R. China
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MacFarlane M, Hoover DA, Wong E, Battista JJ, Chen JZ. Technical Note: A fast inverse direct aperture optimization algorithm for volumetric-modulated arc therapy. Med Phys 2020; 47:1558-1565. [PMID: 32027381 DOI: 10.1002/mp.14074] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 01/15/2020] [Accepted: 01/28/2020] [Indexed: 11/07/2022] Open
Abstract
PURPOSE In a recent article, our group proposed a fast direct aperture optimization (DAO) algorithm for fixed-gantry intensity-modulated radiation therapy (IMRT) called fast inverse direct aperture optimization (FIDAO). When tested on fixed-gantry IMRT plans, we observed up to a 200-fold increase in the optimization speed. Compared to IMRT, rotational volumetric-modulated arc therapy (VMAT) is a much larger optimization problem and has many more delivery constraints. The purpose of this work is to extend and evaluate FIDAO for inverse planning of VMAT plans. METHODS A prototype FIDAO algorithm for VMAT treatment planning was developed in MATLAB using the open-source treatment planning toolkit matRad (v2.2 dev_VMAT build). VMAT treatment plans using one 3600 arc were generated on the AAPM TG-119 phantom, as well as sample clinical liver and prostate cases. The plans were created by first performing fluence map optimization on 28° equispaced beams, followed by aperture sequencing and arc sequencing with a gantry angular sampling rate of 4°. After arc sequencing, a copy of the plan underwent DAO using the prototype FIDAO algorithm, while another copy of the plan underwent DAO using matRad's DAO method, which served as the conventional algorithm. RESULTS Both algorithms achieved similar plan quality, although the FIDAO plans had considerably fewer hot spots in the unspecified normal tissue. The optimization time (number of iterations) for FIDAO and the conventional DAO algorithm, respectively, were: 65 s (245) vs 602 s (275) in the TG-119 phantom case; 25 s (85) vs 803 s (159) in the liver case; and 99 s (174) vs 754 s (149) in the prostate case. CONCLUSIONS This study demonstrated promising speed enhancements in using FIDAO for the direct aperture optimization of VMAT plans.
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Affiliation(s)
- Michael MacFarlane
- London Regional Cancer Program, London Health Sciences Centre, London, ON, Canada, N6A 5W9.,Department of Medical Biophysics, Western University, London, ON, Canada, N6A 3K7.,Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Douglas A Hoover
- London Regional Cancer Program, London Health Sciences Centre, London, ON, Canada, N6A 5W9.,Department of Medical Biophysics, Western University, London, ON, Canada, N6A 3K7.,Department of Oncology, Western University, London, ON, Canada, N6A 3K7
| | - Eugene Wong
- London Regional Cancer Program, London Health Sciences Centre, London, ON, Canada, N6A 5W9.,Department of Medical Biophysics, Western University, London, ON, Canada, N6A 3K7.,Department of Oncology, Western University, London, ON, Canada, N6A 3K7.,Department of Physics & Astronomy, Western University, London, ON, Canada, N6A 3K7
| | - Jerry J Battista
- London Regional Cancer Program, London Health Sciences Centre, London, ON, Canada, N6A 5W9.,Department of Medical Biophysics, Western University, London, ON, Canada, N6A 3K7.,Department of Oncology, Western University, London, ON, Canada, N6A 3K7.,Department of Physics & Astronomy, Western University, London, ON, Canada, N6A 3K7
| | - Jeff Z Chen
- London Regional Cancer Program, London Health Sciences Centre, London, ON, Canada, N6A 5W9.,Department of Medical Biophysics, Western University, London, ON, Canada, N6A 3K7.,Department of Oncology, Western University, London, ON, Canada, N6A 3K7
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Rehman JU, Isa M, Ahmad N, Nasar G, Asghar HMNUHK, Gilani ZA, Chow JCL, Afzal M, Ibbott GS. Dosimetric, Radiobiological and Secondary Cancer Risk Evaluation in Head-and-Neck Three-dimensional Conformal Radiation Therapy, Intensity-Modulated Radiation Therapy, and Volumetric Modulated Arc Therapy: A Phantom Study. J Med Phys 2018; 43:129-135. [PMID: 29962691 PMCID: PMC6020619 DOI: 10.4103/jmp.jmp_106_17] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 03/13/2018] [Accepted: 03/15/2018] [Indexed: 12/02/2022] Open
Abstract
This analysis estimated secondary cancer risks after volumetric modulated arc therapy (VMAT) and compared those risks to the risks associated with other modalities of head-and-neck (H&N) radiotherapy. Images of H&N anthropomorphic phantom were acquired with a computed tomography scanner and exported via digital imaging and communications in medicine (DICOM) standards to a treatment planning system. Treatment plans were performed using a VMAT dual-arc technique, a nine-field intensity-modulated radiation therapy (IMRT) technique, and a four-field three-dimensional conformal therapy (3DCRT) technique. The prescription dose was 66.0 Gy for all three techniques, but to accommodate the range of dosimeter responses, we delivered a single dose of 6.60 Gy to the isocenter. The lifetime risk for secondary cancers was estimated according to National Council on Radiation Protection and Measurements (NCRP) Report 116. VMAT delivered the lowest maximum doses to esophagus (23 Gy), and normal brain (40 Gy). In comparison, maximum doses for 3DCRT were 74% and 40%, higher than those for VMAT for the esophagus, and normal brain, respectively. The normal tissue complication probability and equivalent uniform dose for the brain (2.1%, 0.9%, 0.8% and 3.8 Gy, 2.6 Gy, 2.3 Gy) and esophagus (4.2%, 0.7%, 0.4% and 3.7 Gy, 2.2 Gy, 1.8 Gy) were calculated for the 3DCRT, IMRT and VMAT respectively. Fractional esophagus OAR volumes receiving more than 20 Gy were 3.6% for VMAT, 23.6% for IMRT, and 100% for 3DCRT. The calculations for mean doses, NTCP, EUD and OAR volumes suggest that the risk of secondary cancer induction after VMAT is lower than after IMRT and 3DCRT.
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Affiliation(s)
- Jalil Ur Rehman
- Department of Physics, Balochistan University of Information Technology, Engineering and Management Sciences, Quetta, Pakistan
- Department of Physics, The Islamia University of Bahawalpur, Bahawalpur, Pakistan
- The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Muhammad Isa
- Department of Radiation Oncology, University of Toronto and Radiation Medicine Program, Princess Margaret Cancer Centre, Ontario, Toronto, Canada
- Department of Physics, Hafiz Hayat Campus, University of Gujrat, Gujrat, Pakistan
| | - Nisar Ahmad
- Department of Physics, Balochistan University of Information Technology, Engineering and Management Sciences, Quetta, Pakistan
| | - Gulfam Nasar
- Department of Chemistry, Balochistan University of Information Technology, Engineering and Management Sciences, Quetta, Pakistan
| | - H. M. Noor Ul Huda Khan Asghar
- Department of Physics, Balochistan University of Information Technology, Engineering and Management Sciences, Quetta, Pakistan
| | - Zaheer Abbas Gilani
- Department of Physics, Balochistan University of Information Technology, Engineering and Management Sciences, Quetta, Pakistan
| | - James C. L. Chow
- Department of Radiation Oncology, University of Toronto and Radiation Medicine Program, Princess Margaret Cancer Centre, Ontario, Toronto, Canada
| | - Muhammad Afzal
- Department of Physics, The Islamia University of Bahawalpur, Bahawalpur, Pakistan
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Fourie N, Ali OA, Rae WID. Development and verification of a time delivery model for prostate intensity modulated radiotherapy using a Siemens® Artiste™ 160 Multi-leaf Collimator Linac. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2017; 40:51-56. [DOI: 10.1007/s13246-016-0518-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Accepted: 12/24/2016] [Indexed: 11/30/2022]
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Lu JY, Huang BT, Xing L, Chang DT, Peng X, Xie LX, Lin ZX, Li M. Dosimetric analysis of isocentrically shielded volumetric modulated arc therapy for locally recurrent nasopharyngeal cancer. Sci Rep 2016; 6:25959. [PMID: 27173670 PMCID: PMC4865826 DOI: 10.1038/srep25959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 04/26/2016] [Indexed: 02/05/2023] Open
Abstract
This study aimed to investigate the dosimetric characteristics of an isocentrically shielded RapidArc (IS-RA) technique for treatment of locally recurrent nasopharyngeal cancer (lrNPC). In IS-RA, the isocenter was placed at the center of the pre-irradiated brainstem (BS)/spinal cord (SC) and the jaws were set to shield the BS/SC while ensuring the target coverage during the whole gantry rotation. For fifteen patients, the IS-RA plans were compared with the conventional RapidArc (C-RA) regarding target coverage, organ-at-risk (OAR) sparing and monitor units (MUs). The relationship between the dose reduction of BS/SC and some geometric parameters including the angle extended by the target with respect to the axis of BS/SC (Ang_BSSC), the minimum distance between the target and BS/SC (Dist_Min) and the target volume were evaluated. The IS-RA reduced the BS/SC doses by approximately 1-4 Gy on average over the C-RA, with more MUs. The IS-RA demonstrated similar target coverage and sparing of other OARs except for slightly improved sparing of optic structures. More dose reduction in the isocentric region was observed in the cases with larger Ang_BSSC or smaller Dist_Min. Our results indicated that the IS-RA significantly improves the sparing of BS/SC without compromising dosimetric requirements of other involved structures for lrNPC.
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Affiliation(s)
- Jia-Yang Lu
- Department of Radiation Oncology, Cancer Hospital of Shantou University Medical College, Shantou, Guangdong, China
| | - Bao-Tian Huang
- Department of Radiation Oncology, Cancer Hospital of Shantou University Medical College, Shantou, Guangdong, China
| | - Lei Xing
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California, USA
| | - Daniel T. Chang
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California, USA
| | - Xun Peng
- Department of Radiation Oncology, Cancer Hospital of Shantou University Medical College, Shantou, Guangdong, China
| | - Liang-Xi Xie
- Department of Radiation Oncology, Cancer Hospital of Shantou University Medical College, Shantou, Guangdong, China
| | - Zhi-Xiong Lin
- Department of Radiation Oncology, Cancer Hospital of Shantou University Medical College, Shantou, Guangdong, China
| | - Mei Li
- Department of Radiation Oncology, Cancer Hospital of Shantou University Medical College, Shantou, Guangdong, China
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An IMRT/VMAT Technique for Nonsmall Cell Lung Cancer. BIOMED RESEARCH INTERNATIONAL 2015; 2015:613060. [PMID: 26539515 PMCID: PMC4619809 DOI: 10.1155/2015/613060] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2015] [Revised: 07/13/2015] [Accepted: 07/21/2015] [Indexed: 01/22/2023]
Abstract
The study is to investigate a Hybrid IMRT/VMAT technique which combines intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) for the treatment of nonsmall cell lung cancer (NSCLC). Two partial arcs VMAT, 5-field IMRT, and hybrid plans were created for 15 patients with NSCLC. The hybrid plans were combination of 2 partial arcs VMAT and 5-field IMRT. The dose distribution of planning target volume (PTV) and organs at risk (OARs) for hybrid technique was compared with IMRT and VMAT. The monitor units (MUs) and treatment delivery time were also evaluated. Hybrid technique significantly improved the target conformity and homogeneity compared with IMRT and VMAT. The mean delivery time of IMRT, VMAT, and hybrid plans was 280 s, 114 s, and 327 s, respectively. The mean MUs needed for IMRT, VMAT, and hybrid plans were 933, 512, and 737, respectively. Hybrid technique reduced V5, V10, V30, and MLD of normal lung compared with VMAT and spared the OARs better with fewer MUs with the cost of a little higher V5, V10, and mean lung dose (MLD) of normal lung compared with IMRT. Hybrid IMRT/VMAT can be a viable radiotherapy technique with better plan quality.
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Zarepisheh M, Li R, Ye Y, Xing L. Simultaneous beam sampling and aperture shape optimization for SPORT. Med Phys 2015; 42:1012-22. [PMID: 25652514 DOI: 10.1118/1.4906253] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
PURPOSE Station parameter optimized radiation therapy (SPORT) was recently proposed to fully utilize the technical capability of emerging digital linear accelerators, in which the station parameters of a delivery system, such as aperture shape and weight, couch position/angle, gantry/collimator angle, can be optimized simultaneously. SPORT promises to deliver remarkable radiation dose distributions in an efficient manner, yet there exists no optimization algorithm for its implementation. The purpose of this work is to develop an algorithm to simultaneously optimize the beam sampling and aperture shapes. METHODS The authors build a mathematical model with the fundamental station point parameters as the decision variables. To solve the resulting large-scale optimization problem, the authors devise an effective algorithm by integrating three advanced optimization techniques: column generation, subgradient method, and pattern search. Column generation adds the most beneficial stations sequentially until the plan quality improvement saturates and provides a good starting point for the subsequent optimization. It also adds the new stations during the algorithm if beneficial. For each update resulted from column generation, the subgradient method improves the selected stations locally by reshaping the apertures and updating the beam angles toward a descent subgradient direction. The algorithm continues to improve the selected stations locally and globally by a pattern search algorithm to explore the part of search space not reachable by the subgradient method. By combining these three techniques together, all plausible combinations of station parameters are searched efficiently to yield the optimal solution. RESULTS A SPORT optimization framework with seamlessly integration of three complementary algorithms, column generation, subgradient method, and pattern search, was established. The proposed technique was applied to two previously treated clinical cases: a head and neck and a prostate case. It significantly improved the target conformality and at the same time critical structure sparing compared with conventional intensity modulated radiation therapy (IMRT). In the head and neck case, for example, the average PTV coverage D99% for two PTVs, cord and brainstem max doses, and right parotid gland mean dose were improved, respectively, by about 7%, 37%, 12%, and 16%. CONCLUSIONS The proposed method automatically determines the number of the stations required to generate a satisfactory plan and optimizes simultaneously the involved station parameters, leading to improved quality of the resultant treatment plans as compared with the conventional IMRT plans.
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Affiliation(s)
- Masoud Zarepisheh
- Department of Radiation Oncology, Stanford University, Stanford, California 94305
| | - Ruijiang Li
- Department of Radiation Oncology, Stanford University, Stanford, California 94305
| | - Yinyu Ye
- Department of Management Science and Engineering, Stanford University, Stanford, California 94305
| | - Lei Xing
- Department of Radiation Oncology, Stanford University, Stanford, California 94305
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Hoover DA, MacFarlane M, Wong E, Battista JJ, Chen JZ. Feasibility of a unified approach to intensity-modulated radiation therapy and volume-modulated arc therapy optimization and delivery. Med Phys 2015; 42:726-34. [PMID: 25652486 DOI: 10.1118/1.4905373] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
PURPOSE To study the feasibility of unified intensity-modulated arc therapy (UIMAT) which combines intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) optimization and delivery to produce superior radiation treatment plans, both in terms of dose distribution and efficiency of beam delivery when compared with either VMAT or IMRT alone. METHODS An inverse planning algorithm for UIMAT was prototyped within the pinnacle treatment planning system (Philips Healthcare). The IMRT and VMAT deliveries are unified within the same arc, with IMRT being delivered at specific gantry angles within the arc. Optimized gantry angles for the IMRT and VMAT phases are assigned automatically by the inverse optimization algorithm. Optimization of the IMRT and VMAT phases is done simultaneously using a direct aperture optimization algorithm. Five treatment plans each for prostate, head and neck, and lung were generated using a unified optimization technique and compared with clinical IMRT or VMAT plans. Delivery verification was performed with an ArcCheck phantom (Sun Nuclear) on a Varian TrueBeam linear accelerator (Varian Medical Systems). RESULTS In this prototype implementation, the UIMAT plans offered the same target dose coverage while reducing mean doses to organs at risk by 8.4% for head-and-neck cases, 5.7% for lung cases, and 3.5% for prostate cases, compared with the VMAT or IMRT plans. In addition, UIMAT can be delivered with similar efficiency as VMAT. CONCLUSIONS In this proof-of-concept work, a novel radiation therapy optimization and delivery technique that interlaces VMAT or IMRT delivery within the same arc has been demonstrated. Initial results show that unified VMAT/IMRT has the potential to be superior to either standard IMRT or VMAT.
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Affiliation(s)
- Douglas A Hoover
- Department of Physics and Engineering, London Regional Cancer Program, London, Ontario N6A 4L6, Canada; Department of Oncology, Western University, London, Ontario N6A 3K7, Canada; and Department of Medical Biophysics, Western University, London, Ontario N6A 3K7, Canada
| | - Michael MacFarlane
- Department of Physics and Engineering, London Regional Cancer Program, London, Ontario N6A 4L6, Canada and Department of Medical Biophysics, Western University, London, Ontario N6A 3K7, Canada
| | - Eugene Wong
- Department of Oncology, Western University, London, Ontario N6A 3K7, Canada; Department of Medical Biophysics, Western University, London, Ontario N6A 3K7, Canada; and Department of Physics and Astronomy, Western University, London, Ontario N6A 3K7, Canada
| | - Jerry J Battista
- Department of Physics and Engineering, London Regional Cancer Program, London, Ontario N6A 4L6, Canada; Department of Oncology, Western University, London, Ontario N6A 3K7, Canada; Department of Medical Biophysics, Western University, London, Ontario N6A 3K7, Canada; and Department of Physics and Astronomy, Western University, London, Ontario N6A 3K7, Canada
| | - Jeff Z Chen
- Department of Physics and Engineering, London Regional Cancer Program, London, Ontario N6A 4L6, Canada; Department of Oncology, Western University, London, Ontario N6A 3K7, Canada; and Department of Medical Biophysics, Western University, London, Ontario N6A 3K7, Canada
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Zhu L, Niu T, Choi K, Xing L. Total-variation regularization based inverse planning for intensity modulated arc therapy. Technol Cancer Res Treat 2015; 11:149-62. [PMID: 22335409 DOI: 10.7785/tcrt.2012.500244] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Intensity modulated arc therapy (IMAT) delivers conformal dose distributions through continuous gantry rotation with constant or variable speed while modulating the field aperture shape and weight. The enlarged angular space and machine delivery constraints make inverse planning of IMAT more intractable as compared to its counterpart of fixed gantry IMRT. Currently, IMAT inverse planning is being done using two extreme methods: the first one computes in beamlet domain with a subsequent arc leaf sequencing, and the second proceeds in machine parameter domain with entire emphasis placed on a pre-determined delivery method without exploring potentially better alternative delivery schemes. Towards truly optimizing the IMAT treatment on a patient specific basis, in this work we propose a total-variation based inverse planning framework for IMAT, which takes advantage of the useful features of the above two existing approaches while avoiding their shortcomings. A quadratic optimization algorithm has been implemented to demonstrate the performance and advantage of the proposed approach. Applications of the technique to a prostate case and a head and neck case indicate that the algorithm is capable of generating IMAT plans with patient specific numbers of arcs efficiently. Superior dose distributions and delivery time are achieved with a maximum number of apertures of three for each field. As compared to conventional beamlet-based algorithms, our method regularizes the field modulation complexity during optimization, and permits us to obtain the best possible plan with a pre-set modulation complexity of fluences. As illustrated in both prostate and head-and-neck case studies, the proposed method produces more favorable dose distributions than the segment-based algorithms, by optimally accommodating the clinical need of intensity modulation levels for each individual field. On a more fundamental level, our formulation preserves the convexity of optimization and makes the search of the global optimal solution possible with a deterministic method.
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Affiliation(s)
- Lei Zhu
- George W. Woodruff School, Nuclear and Radiological Engineering and Medical Physics Programs, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.
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14
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Rehman JU, Tailor RC, Isa M, Afzal M, Chow J, Ibbott GS. Evaluations of secondary cancer risk in spine radiotherapy using 3DCRT, IMRT, and VMAT: A phantom study. Med Dosim 2014; 40:70-5. [PMID: 25434808 DOI: 10.1016/j.meddos.2014.10.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2014] [Revised: 10/18/2014] [Accepted: 10/21/2014] [Indexed: 11/16/2022]
Abstract
This study evaluated the secondary cancer risk from volumetric-modulated arc therapy (VMAT) for spine radiotherapy compared with intensity-modulated radiotherapy (IMRT) and 3-dimensional conformal radiotherapy (3DCRT). Computed tomography images of an Radiological Physics Center spine anthropomorphic phantom were exported to a treatment planning system (Pinnacle(3), version 9.4). Radiation treatment plans for spine were prepared using VMAT (dual-arc), 7-field IMRT (beam angles: 110°, 130°, 150°, 180°, 210°, 230°, and 250°), and 4-field 3DCRT technique. The mean and maximum doses, dose-volume histograms, and volumes receiving more than 2 and 4Gy to organs at risk (OARs) were calculated and compared. The lifetime risk for secondary cancers was estimated according to the National Cancer Registry Programme Report 116. VMAT delivered the lowest maximum dose to the esophagus (4.03Gy), bone (8.11Gy), heart (2.11Gy), spinal cord (6.45Gy), and whole lung (5.66Gy) as compared with other techniques (IMRT and 3DCRT). The volumes of OAR (esophagus) receiving more than 4Gy were 0% for VMAT, 27.06% for IMRT, and up to 32.35% for 3DCRT. The estimated risk for secondary cancer in the respective OAR is considerably lower in VMAT compared with other techniques. The results of maximum doses and volumes of OARs suggest that the risk of secondary cancer induction for the spine in VMAT is lower than IMRT and 3DCRT, whereas VMAT has the best target coverage compared with the other techniques.
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Affiliation(s)
- Jalil ur Rehman
- Department of Physics, The Islamia University of Bahawalpur, Bahawalpur, Pakistan; Department of Radiation Physics, UT MD Anderson Cancer Center, Houston, TX.
| | - Ramesh C Tailor
- Department of Radiation Physics, UT MD Anderson Cancer Center, Houston, TX
| | - Muhammad Isa
- Department of Physics, The Islamia University of Bahawalpur, Bahawalpur, Pakistan; Princess Margaret Cancer Center, University Health Network, Toronto, Ontario, Canada
| | - Muhammad Afzal
- Department of Physics, The Islamia University of Bahawalpur, Bahawalpur, Pakistan
| | - James Chow
- Princess Margaret Cancer Center, University Health Network, Toronto, Ontario, Canada
| | - Geoffrey S Ibbott
- Department of Radiation Physics, UT MD Anderson Cancer Center, Houston, TX
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15
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Li R, Xing L, Horst KC, Bush K. Nonisocentric treatment strategy for breast radiation therapy: a proof of concept study. Int J Radiat Oncol Biol Phys 2014; 88:920-6. [PMID: 24606852 PMCID: PMC4010385 DOI: 10.1016/j.ijrobp.2013.12.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Revised: 12/06/2013] [Accepted: 12/18/2013] [Indexed: 11/17/2022]
Abstract
PURPOSE To propose a nonisocentric treatment strategy as a special form of station parameter optimized radiation therapy, to improve sparing of critical structures while preserving target coverage in breast radiation therapy. METHODS AND MATERIALS To minimize the volume of exposed lung and heart in breast irradiation, we propose a novel nonisocentric treatment scheme by strategically placing nonconverging beams with multiple isocenters. As its name suggests, the central axes of these beams do not intersect at a single isocenter as in conventional breast treatment planning. Rather, the isocenter locations and beam directions are carefully selected, in that each beam is only responsible for a certain subvolume of the target, so as to minimize the volume of irradiated normal tissue. When put together, the beams will provide an adequate coverage of the target and expose only a minimal amount of normal tissue to radiation. We apply the nonisocentric planning technique to 2 previously treated clinical cases (breast and chest wall). RESULTS The proposed nonisocentric technique substantially improved sparing of the ipsilateral lung. Compared with conventional isocentric plans using 2 tangential beams, the mean lung dose was reduced by 38% and 50% using the proposed technique, and the volume of the ipsilateral lung receiving ≥ 20 Gy was reduced by a factor of approximately 2 and 3 for the breast and chest wall cases, respectively. The improvement in lung sparing is even greater compared with volumetric modulated arc therapy. CONCLUSIONS A nonisocentric implementation of station parameter optimized radiation therapy has been proposed for breast radiation therapy. The new treatment scheme overcomes the limitations of existing approaches and affords a useful tool for conformal breast radiation therapy, especially in cases with extreme chest wall curvature.
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Affiliation(s)
- Ruijiang Li
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California.
| | - Lei Xing
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Kathleen C Horst
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
| | - Karl Bush
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California
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16
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Kim H, Becker S, Lee R, Lee S, Shin S, Candès E, Xing L, Li R. Improving IMRT delivery efficiency with reweighted L1-minimization for inverse planning. Med Phys 2014; 40:071719. [PMID: 23822423 DOI: 10.1118/1.4811100] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE This study presents an improved technique to further simplify the fluence-map in intensity modulated radiation therapy (IMRT) inverse planning, thereby reducing plan complexity and improving delivery efficiency, while maintaining the plan quality. METHODS First-order total-variation (TV) minimization (min.) based on L1-norm has been proposed to reduce the complexity of fluence-map in IMRT by generating sparse fluence-map variations. However, with stronger dose sparing to the critical structures, the inevitable increase in the fluence-map complexity can lead to inefficient dose delivery. Theoretically, L0-min. is the ideal solution for the sparse signal recovery problem, yet practically intractable due to its nonconvexity of the objective function. As an alternative, the authors use the iteratively reweighted L1-min. technique to incorporate the benefits of the L0-norm into the tractability of L1-min. The weight multiplied to each element is inversely related to the magnitude of the corresponding element, which is iteratively updated by the reweighting process. The proposed penalizing process combined with TV min. further improves sparsity in the fluence-map variations, hence ultimately enhancing the delivery efficiency. To validate the proposed method, this work compares three treatment plans obtained from quadratic min. (generally used in clinic IMRT), conventional TV min., and our proposed reweighted TV min. techniques, implemented by a large-scale L1-solver (template for first-order conic solver), for five patient clinical data. Criteria such as conformation number (CN), modulation index (MI), and estimated treatment time are employed to assess the relationship between the plan quality and delivery efficiency. RESULTS The proposed method yields simpler fluence-maps than the quadratic and conventional TV based techniques. To attain a given CN and dose sparing to the critical organs for 5 clinical cases, the proposed method reduces the number of segments by 10-15 and 30-35, relative to TV min. and quadratic min. based plans, while MIs decreases by about 20%-30% and 40%-60% over the plans by two existing techniques, respectively. With such conditions, the total treatment time of the plans obtained from our proposed method can be reduced by 12-30 s and 30-80 s mainly due to greatly shorter multileaf collimator (MLC) traveling time in IMRT step-and-shoot delivery. CONCLUSIONS The reweighted L1-minimization technique provides a promising solution to simplify the fluence-map variations in IMRT inverse planning. It improves the delivery efficiency by reducing the entire segments and treatment time, while maintaining the plan quality in terms of target conformity and critical structure sparing.
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Affiliation(s)
- Hojin Kim
- Department of Radiation Oncology, Stanford University, Stanford, California 94305-5847, USA
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17
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Matuszak MM, Steers JM, Long T, McShan DL, Fraass BA, Romeijn HE, Ten Haken RK. FusionArc optimization: a hybrid volumetric modulated arc therapy (VMAT) and intensity modulated radiation therapy (IMRT) planning strategy. Med Phys 2014; 40:071713. [PMID: 23822417 DOI: 10.1118/1.4808153] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To introduce a hybrid volumetric modulated arc therapy/intensity modulated radiation therapy (VMAT/IMRT) optimization strategy called FusionArc that combines the delivery efficiency of single-arc VMAT with the potentially desirable intensity modulation possible with IMRT. METHODS A beamlet-based inverse planning system was enhanced to combine the advantages of VMAT and IMRT into one comprehensive technique. In the hybrid strategy, baseline single-arc VMAT plans are optimized and then the current cost function gradients with respect to the beamlets are used to define a metric for predicting which beam angles would benefit from further intensity modulation. Beams with the highest metric values (called the gradient factor) are converted from VMAT apertures to IMRT fluence, and the optimization proceeds with the mixed variable set until convergence or until additional beams are selected for conversion. One phantom and two clinical cases were used to validate the gradient factor and characterize the FusionArc strategy. Comparisons were made between standard IMRT, single-arc VMAT, and FusionArc plans with one to five IMRT∕hybrid beams. RESULTS The gradient factor was found to be highly predictive of the VMAT angles that would benefit plan quality the most from beam modulation. Over the three cases studied, a FusionArc plan with three converted beams achieved superior dosimetric quality with reductions in final cost ranging from 26.4% to 48.1% compared to single-arc VMAT. Additionally, the three beam FusionArc plans required 22.4%-43.7% fewer MU∕Gy than a seven beam IMRT plan. While the FusionArc plans with five converted beams offer larger reductions in final cost--32.9%-55.2% compared to single-arc VMAT--the decrease in MU∕Gy compared to IMRT was noticeably smaller at 12.2%-18.5%, when compared to IMRT. CONCLUSIONS A hybrid VMAT∕IMRT strategy was implemented to find a high quality compromise between gantry-angle and intensity-based degrees of freedom. This optimization method will allow patients to be simultaneously planned for dosimetric quality and delivery efficiency without switching between delivery techniques. Example phantom and clinical cases suggest that the conversion of only three VMAT segments to modulated beams may result in a good combination of quality and efficiency.
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Affiliation(s)
- Martha M Matuszak
- Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan 48109, USA.
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Du W, Cho SH, Zhang X, Hoffman KE, Kudchadker RJ. Quantification of beam complexity in intensity-modulated radiation therapy treatment plans. Med Phys 2014; 41:021716. [DOI: 10.1118/1.4861821] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Li R, Xing L. An adaptive planning strategy for station parameter optimized radiation therapy (SPORT): Segmentally boosted VMAT. Med Phys 2013; 40:050701. [PMID: 23635247 DOI: 10.1118/1.4802748] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Conventional volumetric modulated arc therapy (VMAT) discretizes the angular space into equally spaced control points during planning and then optimizes the apertures and weights of the control points. The aperture at an angle in between two control points is obtained through interpolation. This approach tacitly ignores the differential need for intensity modulation of different angles. As such, multiple arcs are often required, which may oversample some angle(s) and undersample others. The purpose of this work is to develop a segmentally boosted VMAT scheme to eliminate the need for multiple arcs in VMAT treatment with improved dose distribution and∕or delivery efficiency. METHODS The essence of the new treatment scheme is how to identify the need of individual angles for intensity modulation and to provide the necessary beam intensity modulation for those beam angles that need it. We introduce a "demand metric" at each control point to decide which station or control points need intensity modulation. To boost the modulation at selected stations, additional segments are added in the vicinity of the selected stations. The added segments are then optimized together with the original set of station or control points as a whole. The authors apply the segmentally boosted planning technique to four previously treated clinical cases: two head and neck (HN) cases, one prostate case, and one liver case. The proposed planning technique is compared with conventional one-arc and two-arc VMAT. RESULTS The proposed segmentally boosted VMAT technique achieves better critical structure sparing than one-arc VMAT with similar or better target coverage in all four clinical cases. The segmentally boosted VMAT also outperforms two-arc VMAT for the two complicated HN cases, yet with ∼30% reduction in the machine monitor units (MUs) relative to two-arc VMAT, which leads to less leakage∕scatter dose to the patient and can potentially translate into faster dose delivery. For the less challenging prostate and liver cases, similar critical structure sparing as the two-arc VMAT plans was obtained using the segmentally boosted VMAT. The benefit for the two simpler cases is the reduction of MUs and improvement of treatment delivery efficiency. CONCLUSIONS Segmentally boosted VMAT achieves better dose conformality and∕or reduced MUs through effective consideration of the need of individual beam angles for intensity modulation. Elimination of the need for multiple arcs in rotational arc therapy while improving the dose distribution should lead to improved workflow and treatment efficacy, thus may have significant implication to radiation oncology practice.
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Affiliation(s)
- Ruijiang Li
- Department of Radiation Oncology, Stanford University, Stanford, California 94305-5847, USA
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Xing L, Phillips MH, Orton CG. Point/counterpoint. DASSIM-RT is likely to become the method of choice over conventional IMRT and VMAT for delivery of highly conformal radiotherapy. Med Phys 2013; 40:020601. [PMID: 23387721 DOI: 10.1118/1.4773025] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Affiliation(s)
- Lei Xing
- Department of Radiation Oncology, Stanford University, Stanford, CA 94305-5847, USA.
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Mittauer K, Lu B, Yan G, Kahler D, Gopal A, Amdur R, Liu C. A study of IMRT planning parameters on planning efficiency, delivery efficiency, and plan quality. Med Phys 2013; 40:061704. [DOI: 10.1118/1.4803460] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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Kim H, Li R, Lee R, Goldstein T, Boyd S, Candes E, Xing L. Dose optimization with first-order total-variation minimization for dense angularly sampled and sparse intensity modulated radiation therapy (DASSIM-RT). Med Phys 2012; 39:4316-27. [PMID: 22830765 DOI: 10.1118/1.4729717] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
PURPOSE A new treatment scheme coined as dense angularly sampled and sparse intensity modulated radiation therapy (DASSIM-RT) has recently been proposed to bridge the gap between IMRT and VMAT. By increasing the angular sampling of radiation beams while eliminating dispensable segments of the incident fields, DASSIM-RT is capable of providing improved conformity in dose distributions while maintaining high delivery efficiency. The fact that DASSIM-RT utilizes a large number of incident beams represents a major computational challenge for the clinical applications of this powerful treatment scheme. The purpose of this work is to provide a practical solution to the DASSIM-RT inverse planning problem. METHODS The inverse planning problem is formulated as a fluence-map optimization problem with total-variation (TV) minimization. A newly released L1-solver, template for first-order conic solver (TFOCS), was adopted in this work. TFOCS achieves faster convergence with less memory usage as compared with conventional quadratic programming (QP) for the TV form through the effective use of conic forms, dual-variable updates, and optimal first-order approaches. As such, it is tailored to specifically address the computational challenges of large-scale optimization in DASSIM-RT inverse planning. Two clinical cases (a prostate and a head and neck case) are used to evaluate the effectiveness and efficiency of the proposed planning technique. DASSIM-RT plans with 15 and 30 beams are compared with conventional IMRT plans with 7 beams in terms of plan quality and delivery efficiency, which are quantified by conformation number (CN), the total number of segments and modulation index, respectively. For optimization efficiency, the QP-based approach was compared with the proposed algorithm for the DASSIM-RT plans with 15 beams for both cases. RESULTS Plan quality improves with an increasing number of incident beams, while the total number of segments is maintained to be about the same in both cases. For the prostate patient, the conformation number to the target was 0.7509, 0.7565, and 0.7611 with 80 segments for IMRT with 7 beams, and DASSIM-RT with 15 and 30 beams, respectively. For the head and neck (HN) patient with a complicated target shape, conformation numbers of the three treatment plans were 0.7554, 0.7758, and 0.7819 with 75 segments for all beam configurations. With respect to the dose sparing to the critical structures, the organs such as the femoral heads in the prostate case and the brainstem and spinal cord in the HN case were better protected with DASSIM-RT. For both cases, the delivery efficiency has been greatly improved as the beam angular sampling increases with the similar or better conformal dose distribution. Compared with conventional quadratic programming approaches, first-order TFOCS-based optimization achieves far faster convergence and smaller memory requirements in DASSIM-RT. CONCLUSIONS The new optimization algorithm TFOCS provides a practical and timely solution to the DASSIM-RT or other inverse planning problem requiring large memory space. The new treatment scheme is shown to outperform conventional IMRT in terms of dose conformity to both the targetand the critical structures, while maintaining high delivery efficiency.
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Affiliation(s)
- Hojin Kim
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
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Volumetric modulated arc therapy planning method for supine craniospinal irradiation. ACTA ACUST UNITED AC 2012. [DOI: 10.1007/s13566-012-0028-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Vaitheeswaran R. Comment on “Bridging the gap between IMRT and VMAT: Dense angularly sampled and sparse intensity modulated radiation therapy” [Med. Phys. 38, 4912-4919 (2011)]. Med Phys 2012; 39:2312-3. [DOI: 10.1118/1.3687905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Li R, Xing L. Response to “Comment on ‘Bridging the gap between IMRT and VMAT: Dense angularly sampled and sparse intensity modulated radiation therapy’” [Med. Phys. 38, 4912-4919 (2011)]. Med Phys 2012; 39:1676. [DOI: 10.1118/1.3687906] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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