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Niu Y, Rashid A, Lee JM, Carrasquilla M, Conroy DR, Collins BT, Satinsky A, Unger KR, Pang D. Comparative analysis of plan quality and delivery efficiency: ZAP-X vs. CyberKnife for brain metastases treatment. Front Oncol 2024; 14:1333642. [PMID: 38939330 PMCID: PMC11210190 DOI: 10.3389/fonc.2024.1333642] [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: 11/05/2023] [Accepted: 05/21/2024] [Indexed: 06/29/2024] Open
Abstract
Purpose/Objectives ZAP-X, a novel and dedicated radiosurgery (SRS) system, has recently emerged, while CyberKnife has solidified its position as a versatile solution for SRS and stereotactic body radiation therapy over the past two decades. This study aims to compare the dosimetric performance and delivery efficiency of ZAP-X and CyberKnife in treating brain metastases of varying target sizes, employing circular collimation. Methods and materials Twenty-three patients, encompassing a total of 47 brain metastases, were included in the creation of comparative plans of ZAP-X and CyberKnife for analysis. The comparative plans were generated to achieve identical prescription doses for the targets, while adhering to the same dose constraints for organs at risk (OAR). The prescription isodose percentage was optimized within the range of 97-100% for each plan to ensure effective target-volume coverage. To assess plan quality, indices such as conformity, homogeneity, and gradient (CI, HI, and GI) were computed, along with the reporting of total brain volumes receiving 12Gy and 10Gy. Estimated treatment time and monitor units (MUs) were compared between the two modalities in evaluating delivery efficiency. Results Overall, CyberKnife achieved better CI and HI, while ZAP-X exhibited better GI and a smaller irradiated volume for the normal brain. The superiority of CyberKnife's plan conformity was more pronounced for target size less than 1 cc and greater than 10 cc. Conversely, the advantage of ZAP-X's plan dose gradient was more notable for target sizes under 10 cc. The homogeneity of ZAP-X plans, employing multiple isocenters, displayed a strong correlation with the target's shape and the planner's experience in placing isocenters. Generally, the estimated treatment time was similar between the two modalities, and the delivery efficiency was significantly impacted by the chosen collimation sizes for both modalities. Conclusion This study demonstrates that, within the range of target sizes within the patient cohort, plans generated by ZAP-X and CyberKnife exhibit comparable plan quality and delivery efficiency. At present, with the current platform of the two modalities, CyberKnife outperforms ZAP-X in terms of conformity and homogeneity, while ZAP-X tends to produce plans with a more rapid dose falloff.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Dalong Pang
- Department of Radiation Medicine, Georgetown University Hospital, Washington, DC, United States
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2
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Ding GX, Homann KL. The effects of different photon beam energies in stereotactic radiosurgery with cones. Med Phys 2023; 50:5201-5211. [PMID: 37122235 DOI: 10.1002/mp.16435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 04/13/2023] [Accepted: 04/13/2023] [Indexed: 05/02/2023] Open
Abstract
BACKGROUND Stereotactic radiosurgery (SRS) relies on small fields to ablate lesions. Currently, linac based treatment is delivered via circular cones using a 6 MV beam. There is interest in both lower energy photon beams, which can offer steeper dose fall off as well as higher energy photon beams, which have higher dose rates, thus reducing radiation delivery times. Of interest in this study is the 2.5 MV beam developed for imaging applications and both the 6 and 10 MV flattening-filter-free (FFF) beams, which can achieve dose rates up to 2400 cGy/min. PURPOSE This study aims to assess the benefit and feasibility among different energy beams ranging from 2.5 to 10 MV beams by evaluating the dosimetric effects of each beam and comparing the dose to organs-at-risk (OARs) for two separate patient plans. One based on a typical real patient tremor utilizing a 4 mm cone and the other a typical brain metastasis delivered with a 10 mm cone. METHODS The Monte Carlo codes BEAMnrc/DOSXYZnrc were used to generate beams of 2.5 MV, 6 MV-FFF, 6 MV-SRS, 6 MV, 10 MV-FFF, and 10 MV from a Varian TrueBeam except 6 MV-SRS, which is taken from a Varian TX model linear accelerator. Each beam's energy spectrum, mean energy, %dd curve, and dose profile were obtained by analyzing the simulated beams. Calculated patient dose distributions were compared among six different energy beam configurations based on a realistic treatment plan for thalamotomy and a conventional brain metastasis plan. Dose to OARs were evaluated using dose-volume histograms for the same target dose coverage. RESULTS The mean energies of photons within the primary beam projected area were insensitive to cone sizes and the values of percentage depth-dose curves (%dd) at d = 5 cm and SSD = 95 cm for a 4 mm (10 mm) cone ranges from 62.6 (64.4) to 82.2 (85.7) for beam energy ranging from 2.5 to 10 MV beams, respectively. Doses to OARs were evaluated among these beams based on real treatment plans delivering 15 000 and 2200 cGy to the target with a 4 and 10 mm cone, respectively. The maximum doses to the brainstem, which is 10 mm away from the isocenter, was found to be 434 (300), 632 (352), 691 (362), 733 (375), 822 (403), and 975 (441) cGy for 2.5 MV, 6 MV-FFF, 6 MV-SRS, 6 MV, 10 MV-FFF, and 10 MV beams delivering 15 000 (2200) cGy target dose, respectively. CONCLUSION Using the 6 MV-SRS as reference, changes of the maximum dose (691 cGy) to the brain stem are -37%, -9%, +6%, +19%, and 41% for 2.5 MV, 6 MV-FFF, 6 MV, 10 MV-FFF, and 10 MV beams, respectively, based on the thalamotomy plan, where the "-" or "+" signs indicate the percentage decrease or increase. Changes of the maximum dose (362 cGy) to brain stem, based on the brain metastasis plan are much less for respective beam energies. The sum of 21 arcs beam-on time was 39 min on our 6 MV-SRS beam with 1000 cGy/min for thalamotomy. The beam-on time can be reduced to 16 min with 10 MV-FFF.
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Affiliation(s)
- George X Ding
- Department of Radiation Oncology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Kenneth L Homann
- Department of Radiation Oncology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
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Church C, MacDonald RL, Parsons D, Syme A. Evaluation of plan quality and treatment efficiency in cranial stereotactic radiosurgery treatment plans with a variable source-to-axis distance. Med Phys 2023; 50:3039-3054. [PMID: 36774531 DOI: 10.1002/mp.16288] [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: 04/26/2022] [Revised: 10/03/2022] [Accepted: 01/31/2023] [Indexed: 02/13/2023] Open
Abstract
INTRODUCTION Radiotherapy deliveries with dynamic couch motions that shorten the source-to-axis distance (SAD) on a C-arm linac have the potential to increase treatment efficiency through the increase of the effective dose rate. In this investigation, we convert clinically deliverable volumetric modulated arc therapy (VMAT) and dynamic conformal arc (DCA) plans for cranial radiosurgery into virtual isocenter plans through implementation of couch trajectories that maintain the target at a shortened but variable SAD throughout treatment. MATERIALS AND METHODS A randomly sampled population of patients treated with cranial radiosurgery from within the last three years were separated into groups with one, two, and three lesions. All plans had a single isocenter (regardless of number of targets), and a single prescription dose. Patient treatment plans were converted from their original delivery at a standard isocenter to a dynamic virtual isocenter in MATLAB. The virtual isocenter plan featured a variable isocenter position based upon the closest achievable source-to-target distance (referred to herein as a virtual source-to-axis distance [vSAD]) which avoided collision zones on a TrueBeam STx platform. Apertures were magnified according to the vSAD and monitor units at a given control point were scaled based on the inverse square law. Doses were calculated for the plans with a virtual isocenter in the Eclipse (v13.6.23) treatment planning system (TPS) and were compared with the clinical plans. Plan metrics (MU, Paddick conformity index, gradient index, and the volume receiving 12 Gy or more), normal brain dose-volume differences, as well as maximum doses received by organs at risk (OARs) were assessed. The values were compared between standard and virtual isocenter plans with Wilcoxon Sign Ranked tests to determine significance. A subset of the plans were mapped to the MAX-HD anthropomorphic phantom which contained an insert housing EBT3 GafChromic film and a PTW 31010 microion chamber for dose verification on a linac. RESULTS Delivering plans at a virtual isocenter resulted in an average reduction of 20.9% (p = 3×10-6 ) and 20.6% (p = 3.0×10-6 ) of MUs across all VMAT and all DCA plans, respectively. There was no significant change in OAR max doses received by plans delivered at a virtual isocenter. The low dose wash (1.0-2.0 Gy or 5-11% of the prescription dose) was increased (by approximately 20 cc) for plans with three lesions. This was equivalent to a 2.7%-3.8% volumetric increase in normal tissue receiving the respective dose level when comparing the plan with a virtual isocenter to a plan with a standard isocenter. Gamma pass rates with a 5%/1mm analysis criteria were 96.40% ± 2.90% and 95.07% ± 3.10% for deliveries at standard and virtual isocenter, respectively. Absolute point dose agreements were within -0.36% ± 3.45% and -0.55% ± 3.39% for deliveries at a standard and virtual isocenter, respectively. Potential time savings per arc were found to have linear relationship with the monitor units delivered per arc (savings of 0.009 s/MU with an r2 = 0.866 when fit to plans with a single lesion). CONCLUSIONS Converting clinical plans at standard isocenter to a virtual isocenter design did not show any losses to plan quality while simultaneously improving treatment efficiency through MU reductions.
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Affiliation(s)
- Cody Church
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada
| | - R Lee MacDonald
- Department of Radiation Oncology and Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada
| | - David Parsons
- Department of Radiation Oncology, University of Texas Southwestern Medical Centre, Dallas, Texas, USA
| | - Alasdair Syme
- Department of Radiation Oncology and Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada
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MacDonald L, Lincoln J, Church CM, Thomas C, Syme A. Mean Arc Distance (MAD): a quantity to compare trajectory 4 πsampling in single target cranial stereotactic radiotherapy. Biomed Phys Eng Express 2022; 8. [PMID: 35764061 DOI: 10.1088/2057-1976/ac7c92] [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: 04/28/2022] [Accepted: 06/28/2022] [Indexed: 11/12/2022]
Abstract
Purpose:C-arm linac-based radiotherapy has seen a recent interest in 4 methods of delivery using simultaneous rotations of couch and gantry to reduce doses to organs-at-risk (OARs) and increase dose compactness. While many methods use heuristics to generate trajectories that avoid OARs, combined with arbitrary trajectory restrictions to prevent oversampling, a quantity has not yet been developed to succinctly compare sampling of the 4 space for candidate trajectories as a surrogate for dosimetric compactness.Methods:Evenly spaced sampling points were distributed across a 4 sphere centred on isocentre. A metric, mean arc distance (MAD), was defined that quantifies the average arc distance between all fields in a radiotherapy trajectory and their nearest sampling point. The relationship between isodose volume and MAD was examined in 2,047 plans: 900 unique trajectories of fixed port DCA plans, 900 unique trajectories of contiguous field DCA plans, 192 VMAT plans (eight volumes in four locations, each with six trajectories) in matRad with 5 VMAT plans repeated for validation in a clinical planning system, and 10 clinical VMAT cases replanned with five trajectories in a clinical treatment planning system.Results:All isodose volumes greater than 10 % of the prescription dose decreased with decreasing MAD in all comparisons. In the range of 10 % to 100 % of the prescription dose, the rate of isodose volume decrease was exponential as a function of MAD in all comparisons. Reduction of absolute isodose volume is seen with increased 4 sampling, with larger target volumes exhibiting larger absolute reductions. Very low isodoses (0 % to 10 % of prescription) increased with decreasing MAD.Conclusions:MAD is a 4 sampling quantity useful in quantifying the decrease of isodose volume, relevant for sparing normal tissues. By quantifying this feature, candidate dynamic trajectories can be efficiently compared for 4 sampling. This quantity is explored here for single target cranial radiotherapy but may have applications to other radiotherapy treatment site.
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Affiliation(s)
- Lee MacDonald
- Medical Physics, Nova Scotia Health Authority, 5788 University Avenue, Halifax, Halifax, Nova Scotia, B3L 2C2, CANADA
| | - John Lincoln
- Medical Physics, Dalhousie University, Department of Medical Physics, QEII Health Sciences Centre, 5820 University Ave, Dickson Building, Halifax, Nova Scotia, B3H 4R2, CANADA
| | - Cody Mathew Church
- Physics and Atmospheric Science, Dalhousie University, 6310 Coburg Road, Halifax, Nova Scotia, B3H 4R2, CANADA
| | - Christopher Thomas
- Medical Physics, Nova Scotia Health Authority, 5788 University Avenue, Halifax, Halifax, Nova Scotia, B3L 2C2, CANADA
| | - Alasdair Syme
- Radiation Oncology, Dalhousie University, Department of Medical Physics, QEII Health Sciences Centre, 5820 University Ave, Dickson Building, Halifax, Nova Scotia, B3H 4R2, CANADA
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Mann TD, Thind KS, Ploquin NP. Fast stereotactic radiosurgery planning using patient-specific beam angle optimization and automation. Phys Imaging Radiat Oncol 2022; 21:90-95. [PMID: 35243038 PMCID: PMC8885579 DOI: 10.1016/j.phro.2022.02.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 02/11/2022] [Accepted: 02/13/2022] [Indexed: 11/29/2022] Open
Affiliation(s)
- Thomas D. Mann
- Department of Physics and Astronomy, University of Calgary, Calgary, AB, Canada
- Department of Medical Physics, Tom Baker Cancer Center, Calgary, AB, Canada
- Corresponding author at: Department of Physics and Astronomy, University of Calgary, Department of Medical Physics, Tom Baker Cancer Center, 1331 – 29 St NW, Calgary, AB T2N 4N2, Canada.
| | - Kundan S. Thind
- Department of Physics and Astronomy, University of Calgary, Calgary, AB, Canada
- Department of Radiation Oncology, University of Calgary, Calgary, AB, Canada
- Department of Medical Physics, Henry Ford Health Systems, Detroit, MI, USA
| | - Nicolas P. Ploquin
- Department of Physics and Astronomy, University of Calgary, Calgary, AB, Canada
- Department of Medical Physics, Tom Baker Cancer Center, Calgary, AB, Canada
- Department of Radiation Oncology, University of Calgary, Calgary, AB, Canada
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Ventura T, Rocha H, da Costa Ferreira B, Dias J, do Carmo Lopes M. Comparison of non-coplanar optimization of static beams and arc trajectories for intensity-modulated treatments of meningioma cases. Phys Eng Sci Med 2021; 44:1273-1283. [PMID: 34618329 PMCID: PMC8668856 DOI: 10.1007/s13246-021-01061-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 09/24/2021] [Indexed: 11/30/2022]
Abstract
Two methods for non-coplanar beam direction optimization, one for static beams and another for arc trajectories, were proposed for intracranial tumours. The results of the beam angle optimizations were compared with the beam directions used in the clinical plans. Ten meningioma cases already treated were selected for this retrospective planning study. Algorithms for non-coplanar beam angle optimization (BAO) and arc trajectory optimization (ATO) were used to generate the corresponding plans. A plan quality score, calculated by a graphical method for plan assessment and comparison, was used to guide the beam angle optimization process. For each patient, the clinical plans (CLIN), created with the static beam orientations used for treatment, and coplanar VMAT approximated plans (VMAT) were also generated. To make fair plan comparisons, all plan optimizations were performed in an automated multicriteria calculation engine and the dosimetric plan quality was assessed. BAO and ATO plans presented, on average, moderate global plan score improvements over VMAT and CLIN plans. Nevertheless, while BAO and CLIN plans assured a more efficient OARs sparing, the ATO and VMAT plans presented a higher coverage and conformity of the PTV. Globally, all plans presented high-quality dose distributions. No statistically significant quality differences were found, on average, between BAO, ATO and CLIN plans. However, automated plan solution optimizations (BAO or ATO) may improve plan generation efficiency and standardization. In some individual patients, plan quality improvements were achieved with ATO plans, demonstrating the possible benefits of this automated optimized delivery technique.
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Affiliation(s)
- Tiago Ventura
- Physics Department of University of Aveiro, Aveiro, Portugal.
- Medical Physics Department of the Portuguese Oncology Institute of Coimbra Francisco Gentil, EPE, Coimbra, Portugal.
- Institute for Systems Engineering and Computers at Coimbra, Coimbra, Portugal.
| | - Humberto Rocha
- Institute for Systems Engineering and Computers at Coimbra, Coimbra, Portugal
- Economy Faculty of University of Coimbra and Centre for Business and Economics Research, Coimbra, Portugal
| | - Brigida da Costa Ferreira
- Institute for Systems Engineering and Computers at Coimbra, Coimbra, Portugal
- Instituto de Biofísica e Engenharia Biomédica, Faculdade de Ciências da Universidade de Lisboa, Lisboa, Portugal
- I3N Physics Department of University of Aveiro, Aveiro, Portugal
| | - Joana Dias
- Institute for Systems Engineering and Computers at Coimbra, Coimbra, Portugal
- Economy Faculty of University of Coimbra and Centre for Business and Economics Research, Coimbra, Portugal
| | - Maria do Carmo Lopes
- Medical Physics Department of the Portuguese Oncology Institute of Coimbra Francisco Gentil, EPE, Coimbra, Portugal
- Institute for Systems Engineering and Computers at Coimbra, Coimbra, Portugal
- I3N Physics Department of University of Aveiro, Aveiro, Portugal
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7
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Kutuzov I, Van Beek T, McCurdy BMC. Verification of the delivered patient radiation dose for non-coplanar beam therapy. J Appl Clin Med Phys 2021; 22:110-120. [PMID: 34021713 PMCID: PMC8292689 DOI: 10.1002/acm2.13280] [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: 11/13/2020] [Revised: 03/09/2021] [Accepted: 04/22/2021] [Indexed: 11/09/2022] Open
Abstract
PURPOSE There is an increased interest in using non-coplanar beams for radiotherapy, including SBRT and SRS. This approach can significantly reduce doses to organs-at-risk, however, it requires stringent quality assurance, especially when a dynamic treatment couch is used. In this work, new functionality that allows using non-coplanar beam arrangements in addition to conventional coplanar beams was added and validated to the previously developed in vivo dose verification system. METHODS The existing program code was modified to manage the additional treatment couch parameters: angle and positions. Ten non-coplanar test plans that use a static couch were created in the treatment planning system. Also, two plans that use a dynamic treatment couch were created and delivered using Varian Developer mode, since the treatment planning system does not support a dynamic couch. All non-coplanar test trajectories were delivered on a simple geometric phantom, using an Edge linear accelerator (Varian Medical Systems) with the megavoltage imager deployed and acquiring megavoltage transmission images that were used to calculate the delivered 3D dose distributions in the phantom with the updated dose calculation algorithm. The reconstructed dose distributions were compared using the 3D chi-comparison test with 2%/2mm tolerances to the corresponding reference dose distributions obtained from the treatment planning system. RESULTS The chi-comparison test resulted in at least a 97.0% pass rate over the entire 3D volume for all tested trajectories. For static gantry, static couch non-coplanar fields, and non-coplanar arcs using dynamic couch the pass rates observed were at least 98%, while for the static couch, non-transverse coplanar arc fields, pass rates were at least 97%. CONCLUSIONS A model-based 3D dose calculation algorithm has been extended and validated for a variety of non-coplanar beam trajectories of different complexities. This system can potentially be applied for quality assurance of treatment delivery systems that use complex, non-coplanar beam arrangements.
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Affiliation(s)
- Ivan Kutuzov
- Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba, Canada.,Medical Physics Department, CancerCare Manitoba, Winnipeg, Manitoba, Canada
| | - Timothy Van Beek
- Medical Physics Department, CancerCare Manitoba, Winnipeg, Manitoba, Canada
| | - Boyd M C McCurdy
- Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba, Canada.,Medical Physics Department, CancerCare Manitoba, Winnipeg, Manitoba, Canada.,Department of Radiology, University of Manitoba, Winnipeg, Manitoba, Canada
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Mullins J, Renaud MA, Heng V, Ruo R, DeBlois F, Seuntjens J. Trajectory-based VMAT for cranial targets with delivery at shortened SAD. Med Phys 2020; 47:3103-3112. [PMID: 32198933 DOI: 10.1002/mp.14151] [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: 10/16/2019] [Revised: 03/04/2020] [Accepted: 03/07/2020] [Indexed: 01/17/2023] Open
Abstract
INTRODUCTION Trajectory-based volumetric modulated arc therapy (tr-VMAT) treatment plans enable the option for noncoplanar delivery yielding steeper dose gradients and increased sparing of critical structures compared to conventional treatment plans. The addition of translational couch motion to shorten the effective source-to-axis distance (SAD) may result in improved delivery precision and an increased effective dose rate. In this work, tr-VMAT treatment plans using a noncoplanar "baseball stitch" trajectory were implemented, applied to patients presented with cranial targets, and compared to the clinical treatment plans. METHODS A treatment planning workflow was implemented: (a) beamlet doses were calculated for control points defined along a baseball stitch trajectory using a collapsed-cone convolution-superposition algorithm; (b) VMAT treatment plans were optimized using the column generation approach; (c) a final dose distribution was calculated in Varian Eclipse using the analytical anisotropic algorithm by importing the optimized treatment plan parameters. Tr-VMAT plans were optimized for ten patients presented with cranial targets at both standard and shortened SAD, and compared to the clinical treatment plans through isodose distributions, dose-volume histograms, and dosimetric indices. The control point specifications of the optimized tr-VMAT plans were used to estimate the delivery time. RESULTS The optimized tr-VMAT plans with both shortened and standard SAD delivery yielded a comparable plan quality to the clinical treatment plans. A statistically significant benefit was observed for dose gradient index and monitor unit efficiency for shortened SAD tr-VMAT plans, while improved target volume conformity was observed for the clinical treatment plan (P ≤ 0.05). A clear dosimetric benefit was not demonstrated between tr-VMAT delivery at shortened SAD compared to standard SAD, but shortened SAD delivery yielded a fraction size-dependent reduction in the estimated delivery time. CONCLUSION The implementation of "baseball stitch" tr-VMAT treatment plans to patients presented with cranial targets demonstrated comparable plan quality to clinical treatment plans. The delivery at shortened SAD produced a fraction size-dependent decrease in estimated delivery time.
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Affiliation(s)
- Joel Mullins
- Department of Physics & Medical Physics Unit, McGill University, Montréal, QC, H4A 3J1, Canada
| | - Marc-André Renaud
- Department of Mathematics and Industrial Engineering, Polytechnique Montréal, Montréal, QC, H3T 1J4, Canada
| | - Veng Heng
- Department of Physics & Medical Physics Unit, McGill University, Montréal, QC, H4A 3J1, Canada
| | - Russell Ruo
- Medical Physics Unit, McGill University Health Centre, Montréal, QC, H4A 3J1, Canada
| | - François DeBlois
- Centre Hospitalier de l'Université de Montréal & Département de Physique, Université de Montréal, Montréal, QC, H2X 3E4, Canada.,McGill University, Montréal, QC, H4A 3J1, Canada
| | - Jan Seuntjens
- Medical Physics Unit, McGill University & Research Institute of the McGill University Health Centre, Montréal, QC, H4A 3J1, Canada
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Knisely JP, Apuzzo ML. Historical Aspects of Stereotactic Radiosurgery: Concepts, People, and Devices. World Neurosurg 2019; 130:593-607. [DOI: 10.1016/j.wneu.2019.04.030] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 03/23/2019] [Accepted: 03/28/2019] [Indexed: 11/30/2022]
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Smyth G, Evans PM, Bamber JC, Bedford JL. Recent developments in non-coplanar radiotherapy. Br J Radiol 2019; 92:20180908. [PMID: 30694086 PMCID: PMC6580906 DOI: 10.1259/bjr.20180908] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 01/15/2019] [Accepted: 01/17/2019] [Indexed: 11/05/2022] Open
Abstract
This paper gives an overview of recent developments in non-coplanar intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT). Modern linear accelerators are capable of automating motion around multiple axes, allowing efficient delivery of highly non-coplanar radiotherapy techniques. Novel techniques developed for C-arm and non-standard linac geometries, methods of optimization, and clinical applications are reviewed. The additional degrees of freedom are shown to increase the therapeutic ratio, either through dose escalation to the target or dose reduction to functionally important organs at risk, by multiple research groups. Although significant work is still needed to translate these new non-coplanar radiotherapy techniques into the clinic, clinical implementation should be prioritized. Recent developments in non-coplanar radiotherapy demonstrate that it continues to have a place in modern cancer treatment.
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Affiliation(s)
- Gregory Smyth
- Joint Department of Physics, The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London, UK
| | | | - Jeffrey C Bamber
- Joint Department of Physics, The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London, UK
| | - James L Bedford
- Joint Department of Physics, The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London, UK
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Brezovich IA, Wu X, Popple RA, Covington E, Cardan R, Shen S, Fiveash J, Bredel M, Guthrie B. Stereotactic radiosurgery with MLC-defined arcs: Verification of dosimetry, spatial accuracy, and end-to-end tests. J Appl Clin Med Phys 2019; 20:84-98. [PMID: 30977297 PMCID: PMC6522994 DOI: 10.1002/acm2.12583] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 01/25/2019] [Accepted: 03/05/2019] [Indexed: 12/14/2022] Open
Abstract
Purpose To measure dosimetric and spatial accuracy of stereotactic radiosurgery (SRS) delivered to targets as small as the trigeminal nerve (TN) using a standard external beam treatment planning system (TPS) and multileaf collimator‐(MLC) equipped linear accelerator without cones or other special attachments or modifications. Methods Dosimetric performance was assessed by comparing computed dose distributions to film measurements. Comparisons included the γ‐index, beam profiles, isodose lines, maximum dose, and spatial accuracy. Initially, single static 360° arcs of MLC‐shaped fields ranging from 1.6 × 5 to 30 × 30 mm2 were planned and delivered to an in‐house built block phantom having approximate dimensions of a human head. The phantom was equipped with markings that allowed accurate setup using planar kV images. Couch walkout during multiple‐arc treatments was investigated by tracking a ball pointer, initially positioned at cone beam computed tomography (CBCT) isocenter, as the couch was rotated. Tracks were mapped with no load and a 90 kg stack of plastic plates simulating patient treatment. The dosimetric effect of walkout was assessed computationally by comparing test plans that corrected for walkout to plans that neglected walkout. The plans involved nine 160° arcs of 2.4 × 5 mm2 fields applied at six different couch angles. For end‐to‐end tests that included CT simulation, target contouring, planning, and delivery, a cylindrical phantom mimicking a 3 mm lesion was constructed and irradiated with the nine‐arc regimen. The phantom, lacking markings as setup aids was positioned under CBCT guidance by registering its surface and internal structures with CTs from simulation. Radiochromic film passing through the target center was inserted parallel to the coronal and the sagittal plane for assessment of spatial and dosimetric accuracy. Results In the single‐arc block phantom tests computed maximum doses of all field sizes agreed with measurements within 2.4 ± 2.0%. Profile widths at 50% maximum agreed within 0.2 mm. The largest targeting error was 0.33 mm. The γ‐index (3%, 1 mm) averaged over 10 experiments was >1 in only 1% of pixels for field sizes up to 10 × 10 mm2 and rose to 4.4% as field size increased to 20 × 20 mm2. Table walkout was not affected by load. Walkout shifted the target up to 0.6 mm from CBCT isocenter but, according to computations shifted the dose cloud of the nine‐arc plan by only 0.16 mm. Film measurements verified the small dosimetric effect of walkout, allowing walkout to be neglected during planning and treatment. In the end‐to‐end tests average and maximum targeting errors were 0.30 ± 0.10 and 0.43 mm, respectively. Gamma analysis of coronal and sagittal dose distributions based on a 3%/0.3 mm agreement remained <1 at all pixels. To date, more than 50 functional SRS treatments using MLC‐shaped static field arcs have been delivered. Conclusion Stereotactic radiosurgery (SRS) can be planned and delivered on a standard linac without cones or other modifications with better than 0.5 mm spatial and 5% dosimetric accuracy.
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Affiliation(s)
- Ivan A Brezovich
- Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Xingen Wu
- Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Richard A Popple
- Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Elizabeth Covington
- Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Rex Cardan
- Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Sui Shen
- Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - John Fiveash
- Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Markus Bredel
- Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Barton Guthrie
- Department of Neurosurgery, University of Alabama at Birmingham, Birmingham, AL, USA
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Smyth G, Evans PM, Bamber JC, Mandeville HC, Rollo Moore A, Welsh LC, Saran FH, Bedford JL. Dosimetric accuracy of dynamic couch rotation during volumetric modulated arc therapy (DCR-VMAT) for primary brain tumours. Phys Med Biol 2019; 64:08NT01. [PMID: 30808011 PMCID: PMC6877349 DOI: 10.1088/1361-6560/ab0a8e] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Radiotherapy treatment plans using dynamic couch rotation during volumetric modulated arc therapy (DCR-VMAT) reduce the dose to organs at risk (OARs) compared to coplanar VMAT, while maintaining the dose to the planning target volume (PTV). This paper seeks to validate this finding with measurements. DCR-VMAT treatment plans were produced for five patients with primary brain tumours and delivered using a commercial linear accelerator (linac). Dosimetric accuracy was assessed using point dose and radiochromic film measurements. Linac-recorded mechanical errors were assessed by extracting deviations from log files for multi-leaf collimator (MLC), couch, and gantry positions every 20 ms. Dose distributions, reconstructed from every fifth log file sample, were calculated and used to determine deviations from the treatment plans. Median (range) treatment delivery times were 125 s (123-133 s) for DCR-VMAT, compared to 78 s (64-130 s) for coplanar VMAT. Absolute point doses were 0.8% (0.6%-1.7%) higher than prediction. For coronal and sagittal films, respectively, 99.2% (96.7%-100%) and 98.1% (92.9%-99.0%) of pixels above a 20% low dose threshold reported gamma <1 for 3% and 3 mm criteria. Log file analysis showed similar gantry rotation root-mean-square error (RMSE) for VMAT and DCR-VMAT. Couch rotation RMSE for DCR-VMAT was 0.091° (0.086-0.102°). For delivered dose reconstructions, 100% of pixels above a 5% low dose threshold reported gamma <1 for 2% and 2 mm criteria in all cases. DCR-VMAT, for the primary brain tumour cases studied, can be delivered accurately using a commercial linac.
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Affiliation(s)
- Gregory Smyth
- Joint Department of Physics at The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London, United Kingdom. Author to whom any correspondence should be addressed
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Mueller S, Manser P, Volken W, Frei D, Kueng R, Herrmann E, Elicin O, Aebersold DM, Stampanoni MFM, Fix MK. Part 2: Dynamic mixed beam radiotherapy (DYMBER): Photon dynamic trajectories combined with modulated electron beams. Med Phys 2018; 45:4213-4226. [PMID: 29992574 DOI: 10.1002/mp.13085] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 06/27/2018] [Accepted: 06/28/2018] [Indexed: 11/08/2022] Open
Abstract
PURPOSE The purpose of this study was to develop a treatment technique for dynamic mixed beam radiotherapy (DYMBER) utilizing increased degrees of freedom (DoF) of a conventional treatment unit including different particle types (photons and electrons), intensity and energy modulation and dynamic gantry, table, and collimator rotations. METHODS A treatment planning process has been developed to create DYMBER plans combining photon dynamic trajectories (DTs) and step and shoot electron apertures collimated with the photon multileaf collimator (pMLC). A gantry-table path is determined for the photon DTs with minimized overlap of the organs at risk (OARs) with the target. In addition, an associated dynamic collimator rotation is established with minimized area between the pMLC leaves and the target contour. pMLC sequences of photon DTs and electron pMLC apertures are then simultaneously optimized using direct aperture optimization (DAO). Subsequently, the final dose distribution of the electron pMLC apertures is calculated using the Swiss Monte Carlo Plan (SMCP). The pMLC sequences of the photon DTs are then re-optimized with a finer control point resolution and with the final electron dose distribution taken into account. Afterwards, the final photon dose distribution is calculated also using the SMCP and summed together with the one of the electrons. This process is applied for a brain and two head and neck cases. The resulting DYMBER dose distributions are compared to those of dynamic trajectory radiotherapy (DTRT) plans consisting only of photon DTs and clinically applied VMAT plans. Furthermore, the deliverability of the DYMBER plans is verified in terms of dosimetric accuracy, delivery time and collision avoidance. For this purpose, The DYMBER plans are delivered to Gafchromic EBT3 films placed in an anthropomorphic head phantom on a Varian TrueBeam linear accelerator. RESULTS For each case, the dose homogeneity in the target is similar or better for DYMBER compared to DTRT and VMAT. Averaged over all three cases, the mean dose to the parallel OARs is 16% and 28% lower, D2% to the serial OARs is 17% and 37% lower and V10% to normal tissue is 12% and 4% lower for the DYMBER plans compared to the DTRT and VMAT plans, respectively. The DYMBER plans are delivered without collision and with a 4-5 min longer delivery time than the VMAT plans. The absolute dose measurements are compared to calculation by gamma analysis using 2% (global)/2 mm criteria with passing rates of at least 99%. CONCLUSIONS A treatment technique for DYMBER has been successfully developed and verified for its deliverability. The dosimetric superiority of DYMBER over DTRT and VMAT indicates utilizing increased DoF to be the key to improve brain and head and neck radiation treatments in future.
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Affiliation(s)
- S Mueller
- Division of Medical Radiation Physics, Department of Radiation Oncology, Inselspital, Bern University Hospital, University of Bern, CH-3010, Bern, Switzerland
| | - P Manser
- Division of Medical Radiation Physics, Department of Radiation Oncology, Inselspital, Bern University Hospital, University of Bern, CH-3010, Bern, Switzerland
| | - W Volken
- Division of Medical Radiation Physics, Department of Radiation Oncology, Inselspital, Bern University Hospital, University of Bern, CH-3010, Bern, Switzerland
| | - D Frei
- Division of Medical Radiation Physics, Department of Radiation Oncology, Inselspital, Bern University Hospital, University of Bern, CH-3010, Bern, Switzerland
| | - R Kueng
- Division of Medical Radiation Physics, Department of Radiation Oncology, Inselspital, Bern University Hospital, University of Bern, CH-3010, Bern, Switzerland
| | - E Herrmann
- Division of Medical Radiation Physics, Department of Radiation Oncology, Inselspital, Bern University Hospital, University of Bern, CH-3010, Bern, Switzerland
| | - O Elicin
- Division of Medical Radiation Physics, Department of Radiation Oncology, Inselspital, Bern University Hospital, University of Bern, CH-3010, Bern, Switzerland
| | - D M Aebersold
- Division of Medical Radiation Physics, Department of Radiation Oncology, Inselspital, Bern University Hospital, University of Bern, CH-3010, Bern, Switzerland
| | - M F M Stampanoni
- Institute for Biomedical Engineering, ETH Zürich and PSI, CH-5232, Villigen, Switzerland
| | - M K Fix
- Division of Medical Radiation Physics, Department of Radiation Oncology, Inselspital, Bern University Hospital, University of Bern, CH-3010, Bern, Switzerland
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Fix MK, Frei D, Volken W, Terribilini D, Mueller S, Elicin O, Hemmatazad H, Aebersold DM, Manser P. Part 1: Optimization and evaluation of dynamic trajectory radiotherapy. Med Phys 2018; 45:4201-4212. [PMID: 29992587 DOI: 10.1002/mp.13086] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 06/27/2018] [Accepted: 06/28/2018] [Indexed: 12/20/2022] Open
Abstract
PURPOSE Although volumetric modulated arc therapy (VMAT) is a well-accepted treatment technique in radiotherapy using a coplanar delivery approach, VMAT might be further improved by including dynamic table and collimator rotations leading to dynamic trajectory radiotherapy (DTRT). In this work, an optimization procedure for DTRT was developed and the potential benefit of DTRT was investigated for different treatment sites. METHODS For this purpose, a dedicated optimization framework for DTRT was developed using the Eclipse Scripting Research Application Programming Interface (ESRAPI). The contours of the target and organs at risk (OARs) structures were exported by applying the ESRAPI and were used to determine the fractional volume-overlap of the OARs with the target from several potential beam directions. Thereby, an additional weighting was applied taking into account the relative position of the OAR with respect to the target and radiation beam, that is, penalizing directions where the OAR is proximal to the target. The resulting two-dimensional gantry-table map was used as input for an A* path finding algorithm returning an optimized gantry-table path. Thereby, the process is also taking into account CT scan length and collision restrictions. The A* algorithm was used again to determine the dynamic collimator angle path by optimizing the area between the MLC leaves and the target contour for each gantry-table path leading to gantry-collimator paths. The resulting gantry-table and gantry-collimator paths are combined and serve as input for the intensity modulation optimization using a research VMAT optimizer and the ESRAPI resulting in dynamic trajectories. This procedure was evaluated for five clinically motivated cases: two head and neck, one lung, one esophagus, and one prostate. Final dose calculations were performed using the Swiss Monte Carlo Plan (SMCP). Resulting dose distributions for the DTRT treatment plans and for the standard VMAT plans were compared based on dose distributions and dose volume histogram (DVH) parameters. For this comparison, the dose distribution for the VMAT plans were recalculated using the SMCP. In addition, the suitability of the delivery of a DTRT treatment plan was demonstrated by means of gafchromic film measurements on a TrueBeam linear accelerator. RESULTS DVHs for the target volumes showed similar or improved coverage and dose homogeneity for DTRT compared with VMAT using equal or less number of dynamic trajectories for DTRT than arcs for VMAT for all cases studied. Depending on the case, improvements in mean and maximum dose for the DTRT plans were achieved for almost all OARs compared with the VMAT plans. Improvements in DTRT treatment plans for mean and maximum dose compared to VMAT plans were up to 16% and 38% relative to the prescribed dose, respectively. The measured and calculated dose values resulted in a passing rate of more than 99.5% for the two-dimensional gamma analysis using 2% and 2 mm criteria and a threshold of 10%. CONCLUSIONS DTRT plans for different treatment sites were generated and compared with VMAT plans. The delivery is suitable and dose comparisons demonstrate a high potential of DTRT to reduce dose to OARs using less dynamic trajectories than arcs, while target coverage is preserved.
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Affiliation(s)
- Michael K Fix
- Division of Medical Radiation Physics, Department of Radiation Oncology, Inselspital, Bern University Hospital, University of Bern, CH-3010, Bern, Switzerland
| | - Daniel Frei
- Division of Medical Radiation Physics, Department of Radiation Oncology, Inselspital, Bern University Hospital, University of Bern, CH-3010, Bern, Switzerland
| | - Werner Volken
- Division of Medical Radiation Physics, Department of Radiation Oncology, Inselspital, Bern University Hospital, University of Bern, CH-3010, Bern, Switzerland
| | - Dario Terribilini
- Division of Medical Radiation Physics, Department of Radiation Oncology, Inselspital, Bern University Hospital, University of Bern, CH-3010, Bern, Switzerland
| | - Silvan Mueller
- Division of Medical Radiation Physics, Department of Radiation Oncology, Inselspital, Bern University Hospital, University of Bern, CH-3010, Bern, Switzerland
| | - Olgun Elicin
- Division of Medical Radiation Physics, Department of Radiation Oncology, Inselspital, Bern University Hospital, University of Bern, CH-3010, Bern, Switzerland
| | - Hossein Hemmatazad
- Division of Medical Radiation Physics, Department of Radiation Oncology, Inselspital, Bern University Hospital, University of Bern, CH-3010, Bern, Switzerland
| | - Daniel M Aebersold
- Division of Medical Radiation Physics, Department of Radiation Oncology, Inselspital, Bern University Hospital, University of Bern, CH-3010, Bern, Switzerland
| | - Peter Manser
- Division of Medical Radiation Physics, Department of Radiation Oncology, Inselspital, Bern University Hospital, University of Bern, CH-3010, Bern, Switzerland
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Ding GX, Walters B. Dosimetric effects of incorrect jaw settings in cranial radiosurgery. Biomed Phys Eng Express 2018. [DOI: 10.1088/2057-1976/aaa162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Zhao B, Wen N, Chetty IJ, Huang Y, Brown SL, Snyder KC, Siddiqui F, Movsas B, Siddiqui MS. A prediction model of radiation-induced necrosis for intracranial radiosurgery based on target volume. Med Phys 2017; 44:4360-4367. [PMID: 28543402 DOI: 10.1002/mp.12360] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 03/22/2017] [Accepted: 05/11/2017] [Indexed: 11/08/2022] Open
Abstract
PURPOSE This study aims to extend the observation that the 12 Gy-radiosurgical-volume (V12Gy) correlates with the incidence of radiation necrosis in patients with intracranial tumors treated with radiosurgery by using target volume to predict V12Gy. V12Gy based on the target volume was used to predict the radiation necrosis probability (P) directly. Also investigated was the reduction in radiation necrosis rates (ΔP) as a result of optimizing the prescription isodose lines for linac-based SRS. METHODS Twenty concentric spherical targets and 22 patients with brain tumors were retrospectively studied. For each case, a standard clinical plan and an optimized plan with prescription isodose lines based on gradient index were created. V12Gy were extracted from both plans to analyze the correlation between V12Gy and target volume. The necrosis probability P as a function of V12Gy was evaluated. To account for variation in prescription, the relation between V12Gy and prescription was also investigated. RESULTS A prediction model for radiation-induced necrosis was presented based on the retrospective study. The model directly relates the typical prescribed dose and the target volume to the radionecrosis probability; V12Gy increased linearly with the target volume (R2 > 0.99). The linear correlation was then integrated into a logistic model to predict P directly from the target volume. The change in V12Gy as a function of prescription was modeled using a single parameter, s (=-1.15). Relatively large ΔP was observed for target volumes between 7 and 28 cm3 with the maximum reduction (8-9%) occurring at approximately 18 cm3 . CONCLUSIONS Based on the model results, optimizing the prescription isodose line for target volumes between 7 and 28 cm3 results in a significant reduction in necrosis probability. V12Gy based on the target volume could provide clinicians a predictor of radiation necrosis at the contouring stage thus facilitating treatment decisions.
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Affiliation(s)
- Bo Zhao
- Department of Radiation Oncology, Henry Ford Health System, 2799 W Grand Blvd, Detroit, MI, 48202, USA
| | - Ning Wen
- Department of Radiation Oncology, Henry Ford Health System, 2799 W Grand Blvd, Detroit, MI, 48202, USA
| | - Indrin J Chetty
- Department of Radiation Oncology, Henry Ford Health System, 2799 W Grand Blvd, Detroit, MI, 48202, USA
| | - Yimei Huang
- Department of Radiation Oncology, Henry Ford Health System, 2799 W Grand Blvd, Detroit, MI, 48202, USA
| | - Stephen L Brown
- Department of Radiation Oncology, Henry Ford Health System, 2799 W Grand Blvd, Detroit, MI, 48202, USA
| | - Karen C Snyder
- Department of Radiation Oncology, Henry Ford Health System, 2799 W Grand Blvd, Detroit, MI, 48202, USA
| | - Farzan Siddiqui
- Department of Radiation Oncology, Henry Ford Health System, 2799 W Grand Blvd, Detroit, MI, 48202, USA
| | - Benjamin Movsas
- Department of Radiation Oncology, Henry Ford Health System, 2799 W Grand Blvd, Detroit, MI, 48202, USA
| | - M Salim Siddiqui
- Department of Radiation Oncology, Henry Ford Health System, 2799 W Grand Blvd, Detroit, MI, 48202, USA
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Locke CB, Bush KK. Trajectory optimization in radiotherapy using sectioning (TORUS). Med Phys 2017; 44:3375-3392. [PMID: 28397968 DOI: 10.1002/mp.12270] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 04/05/2017] [Accepted: 04/05/2017] [Indexed: 12/17/2022] Open
Abstract
PURPOSE A challenging problem in trajectory optimization for radiotherapy is properly handling the synchronization of the medical accelerators dynamic delivery. The initial coarse sampling of control points implemented in a Progressive Resolution Optimization type approach (VMAT) routinely results in MLC aperture forming contention issues as the sampling resolution increases. This work presents an approach to optimize continuous, beam-on radiation trajectories through exploration of the anatomical topology present in the patient and formation of a novel dual-metric graph optimization problem. METHODS This work presents a new perspective on trajectory optimization in radiotherapy using the concept of sectioning (TORUS). TORUS avoids degradation of 3D dose optimization quality by mapping the connectedness of target regions from the BEV perspective throughout the space of deliverable coordinates. This connectedness information is then incorporated into a graph optimization problem to define ideal trajectories. The unique usage of two distance functions in this graph optimization permits the TORUS algorithm to generate efficient dynamic trajectories for delivery while maximizing the angular flux through all PTV voxels. 3D dose optimization is performed for trajectories using a commercial TPS progressive resolution optimizer. RESULTS The TORUS algorithm is applied to three example treatments: chest wall, scalp, and the TG-119 C-shape phantom. When static collimator coplanar trajectories are generated for the chest wall and scalp cases, the TORUS trajectories are found to outperform both 7 field IMRT and 2 arc VMAT plans in delivery time, organ at risk sparing, conformality, and homogeneity. For the TG-119 phantom, when static couch and collimator non-coplanar trajectories are optimized, TORUS trajectories have superior sparing of the central core avoidance with shorter delivery times, with similar dose conformality and homogeneity. CONCLUSIONS The TORUS algorithm is able to automatically generate trajectories having improved plan quality and delivery time over standard IMRT and VMAT treatments. TORUS offers an exciting and promising avenue forward toward increasing dynamic capabilities in radiation delivery.
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Affiliation(s)
- Christopher Barry Locke
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA, 94305-5847, USA
| | - Karl Kenneth Bush
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA, 94305-5847, USA
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Wilson B, Otto K, Gete E. A simple and robust trajectory-based stereotactic radiosurgery treatment. Med Phys 2017; 44:240-248. [PMID: 28102944 DOI: 10.1002/mp.12036] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 09/20/2016] [Accepted: 11/21/2016] [Indexed: 11/11/2022] Open
Abstract
INTRODUCTION We present a Trajectory-based Volumetric Modulated Arc Therapy (TVMAT) technique for Stereotactic Radiosurgery (SRS) that takes advantage of a modern linacs ability to modulate dose rate and move the couch dynamically. In addition, we investigate the quality of the developed TVMAT method and the dosimetric accuracy of the technique. METHODS The main feature of the TVMAT technique is a standard beam trajectory formed by dynamic motion of the treatment couch and the linac gantry. The couch rotates slowly through 180 degrees while the gantry delivers radiation through continuous sweeps of the gantry. The number of partial arcs that constitute the trajectory can be varied between two and eight and as the number of partial arcs increases, the trajectory more finely samples 4π geometry. Along these trajectories, the multi-leaf collimator (MLC) and dose rate are optimized through an inverse planning framework. The TVMAT method was tested on ten cranial SRS patients who were previously treated with the Dynamic Conformal Arc (DCA) technique. The plans were compared with the DCA and a four- arc VMAT technique with regards to dose to the OAR, dose falloff, V12Gy, and V4Gy. Validation measurements were performed using ion-chamber and Gafchromic film. In addition, the trajectory-log files were analyzed and compared with the treatment plan beam data. RESULTS The TVMAT treatment plans were successfully delivered with a treatment time between 3-8 min which mostly depended on total cumulated dose. Ion chamber measurements had an average measured error of 1.1 ± 0.6% and a maximum value of 2.2% of the delivered dose. The 2%, 2 mm gamma pass rates for the film measurements were 96% or greater. In a preliminary comparison of ten patients who underwent SRS treatments with the DCA technique, the TVMAT and VMAT techniques were able to produce plans with comparable dose falloff and OAR doses, while achieving better dose conformality, V4Gy and V12Gy when compared to the original DCA plans. The improvement of the TVMAT plans were as follows (mean % improvement ± standard err): Conformity (10 ± 2%), V4 (20 ± 20%), V12 (27 ± 10%), volume weighted mean dose to organs at risk (13 ± 13%), homogeneity index (2 ± 2%) and falloff (4 ± 2%). CONCLUSION We have developed and validated a trajectory-based dose delivery method which has dose distribution improvements while having a treatment time of 3-8 min. In addition, it has the potential for a simpler planning experience while maintaining an accurate delivery on the Varian Truebeam Linac.
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Affiliation(s)
- Byron Wilson
- Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada.,Medical Physics, BC Cancer Agency, Vancouver, British Columbia, V5Z 4E6, Canada
| | - Karl Otto
- Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada
| | - Ermias Gete
- Medical Physics, BC Cancer Agency, Vancouver, British Columbia, V5Z 4E6, Canada
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Luo G, Neimat JS, Cmelak A, Kirschner AN, Attia A, Morales-Paliza M, Ding GX. Margin of error for a frameless image guided radiosurgery system: Direct confirmation based on posttreatment MRI scans. Pract Radiat Oncol 2016; 7:e223-e231. [PMID: 27720703 DOI: 10.1016/j.prro.2016.08.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 07/12/2016] [Accepted: 08/15/2016] [Indexed: 11/18/2022]
Abstract
PURPOSE To report on radiosurgery delivery positioning accuracy in the treatment of tremor patients with frameless image guided radiosurgery using the linear accelerator (LINAC) based ExacTrac system and to describe quality assurance (QA) procedures used. METHODS AND MATERIALS Between 2010 and 2015, 20 patients underwent radiosurgical thalamotomy targeting the ventral intermediate nucleus for the treatment of severe tremor. The median prescription dose was 140 Gy (range, 120-145 Gy) in a single fraction. The median maximum dose was 156 Gy (range, 136-162 Gy). All treatment planning was performed with the iPlan system using a 4-mm circular cone with multiple arcs. Before each treatment, QA procedures were performed, including the imaging system. As a result of the extremely high dose delivered in a single fraction, a well-defined circular mark developed on the posttreatment magnetic resonance imaging (MRI). Eight of these 20 patients were selected to evaluate treatment localization errors because their circular marks were available in posttreatment MRI. In this study, the localization error is defined as the distance between the center of the intended target and the center of the posttreatment mark. RESULTS The mean error of distance was found to be 1.1 mm (range, 0.4-1.5 mm). The mean errors for the left-right, anteroposterior, and superoinferior directions are 0.5 mm, 0.6 mm, and 0.7 mm, respectively. CONCLUSIONS The result reported in this study includes all tremor patients treated at our institution when their posttreatment MRI data were available for study. It represents a direct confirmation of target positioning accuracy in radiosurgery with a LINAC-based frameless system and its limitations. This level of accuracy is only achievable with an appropriate QA program in place for a LINAC-based frameless radiosurgery system.
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Affiliation(s)
- Guozhen Luo
- Department of Radiation Oncology, Vanderbilt University Medical Center, Nashville, Tennessee; Department of Physics and Astronomy, Vanderbilt University, College of Art and sciences, Nashville, Tennessee
| | - Joseph S Neimat
- Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Anthony Cmelak
- Department of Radiation Oncology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Austin N Kirschner
- Department of Radiation Oncology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Albert Attia
- Department of Radiation Oncology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Manuel Morales-Paliza
- Department of Radiation Oncology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - George X Ding
- Department of Radiation Oncology, Vanderbilt University Medical Center, Nashville, Tennessee; Department of Physics and Astronomy, Vanderbilt University, College of Art and sciences, Nashville, Tennessee.
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Martin F, Magnier F, Berger L, Miroir J, Chautard E, Verrelle P, Lapeyre M, Biau J. Fractionated stereotactic radiotherapy of benign skull-base tumors: a dosimetric comparison of volumetric modulated arc therapy with Rapidarc® versus non-coplanar dynamic arcs. Radiat Oncol 2016; 11:58. [PMID: 27090091 PMCID: PMC4835934 DOI: 10.1186/s13014-016-0632-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 04/09/2016] [Indexed: 12/25/2022] Open
Abstract
Background Benign tumors of the skull base are a challenge when delivering radiotherapy. An appropriate choice of radiation technique may significantly improve the patient’s outcomes. Our study aimed to compare the dosimetric results of fractionated stereotactic radiotherapy between non-coplanar dynamic arcs and coplanar volumetric modulated arctherapy (Rapidarc®). Methods Thirteen patients treated with Novalis TX® were analysed: six vestibular schwannomas, four pituitary adenomas and three meningioma. Two treatment plans were created for each case: dynamic arcs (4–5 non coplanar arcs) and Rapidarc® (2 coplanar arcs). All tumors were >3 cm and accessible to both techniques. Patients had a stereotactic facemask (Brainlab) and were daily repositioned by Exactrac®. GTV and CTV were contoured according to tumor type. A 1-mm margin was added to the CTV to obtain PTV. Radiation doses were 52.2–54 Gy, using 1.8 Gy per fraction. Treatment time was faster with Rapidarc®. Results The mean PTV V95 % was 98.8 for Rapidarc® and 95.9 % for DA (p = 0.09). Homogeneity index was better with Rapidarc®: 0.06 vs. 0.09 (p = 0.01). Higher conformity index values were obtained with Rapidarc®: 75.2 vs. 67.9 % (p = 0.04). The volume of healthy brain that received a high dose (V90 %) was 0.7 % using Rapidarc® vs. 1.4 % with dynamic arcs (p = 0.05). Rapidarc® and dynamic arcs gave, respectively, a mean D40 % of 10.5 vs. 18.1 Gy (p = 0.005) for the hippocampus and a Dmean of 25.4 vs. 35.3 Gy (p = 0.008) for the ipsilateral cochlea. Low-dose delivery with Rapidarc® and dynamic arcs were, respectively, 184 vs. 166 cm3 for V20 Gy (p = 0.14) and 1265 vs. 1056 cm3 for V5 Gy (p = 0.67). Conclusions Fractionated stereotactic radiotherapy using Rapidarc® for large benign tumors of the skull base provided target volume coverage that was at least equal to that of dynamics arcs, with better conformity and homogeneity and faster treatment time. Rapidarc® also offered better sparing of the ipsilateral cochlea and hippocampus. Low-dose delivery were similar between both techniques.
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Affiliation(s)
- Fanny Martin
- Department of Radiotherapy, Centre Jean Perrin, 63011, Clermont-Ferrand, France
| | - Florian Magnier
- Department of Medical Physics, Centre Jean Perrin, 63011, Clermont-Ferrand, France
| | - Lucie Berger
- Department of Medical Physics, Centre Jean Perrin, 63011, Clermont-Ferrand, France
| | - Jessica Miroir
- Department of Radiotherapy, Centre Jean Perrin, 63011, Clermont-Ferrand, France
| | - Emmanuel Chautard
- Clermont Auvergne University, EA7283 CREaT, 63011, Clermont-Ferrand, France
| | - Pierre Verrelle
- Department of Radiotherapy, Centre Jean Perrin, 63011, Clermont-Ferrand, France.,Clermont Auvergne University, EA7283 CREaT, 63011, Clermont-Ferrand, France
| | - Michel Lapeyre
- Department of Radiotherapy, Centre Jean Perrin, 63011, Clermont-Ferrand, France
| | - Julian Biau
- Department of Radiotherapy, Centre Jean Perrin, 63011, Clermont-Ferrand, France. .,Clermont Auvergne University, EA7283 CREaT, 63011, Clermont-Ferrand, France.
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Abstract
ABSTRACT:The term radiosurgery has been used to describe a variety of radiotherapy techniques which deliver high doses of radiation to small, stereotactically defined intracranial targets in such a way that the dose fall-off outside the targeted volume is very sharp. Proton, charged particle, gamma unit, and linear accelerator-based techniques appear to be equivalent from the standpoint of accuracy, dose distributions, and clinical results. However, capital and operating costs associated with the use of linear accelerators in general clinical use are much lower. Radiosurgery has an established role in the treatment of arteriovenous malformations and acoustic neurinomas. Interest in these techniques is increasing in neurosurgical and radiation oncological communities, as radiosurgery is rapidly assuming a place in the management of several other conditions, including craniopharyngiomas, meningiomas, and selected malignant lesions.
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Early and Late Complications Following Dynamic Stereotactic Radiosurgery and Fractionated Stereotactic Radiotherapy. Can J Neurol Sci 2015. [DOI: 10.1017/s0317167100048186] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
ABSTRACT:Between December 1986 and June 1990, 112 patients (116 lesions), underwent treatment with dynamic stereotactic radiosurgery at McGill University. Of the treated lesions, 59 were arteriovenous malformations and 53 were a variety of other neoplastic or non-neoplastic conditions. In 86 lesions, the treatment was delivered in a single fraction and the treatment of the remaining 30 lesions was fractionated. Complications attributed to treatment developed in seven of the 112 patients (6.3%). No relationship was found between complications and prescribed dose, fractionation, collimator diameter, type and anatomical region of the lesion that was treated, or previous irradiation. Although extensive clinical experience will be necessary to determine optimal total doses, the potential role of fractionated treatment, and the tolerance of critical structures to radiosurgery, the relatively low incidence of complications in our series allows us to conclude that radiosurgery is well tolerated by the vast majority of patients.
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Mirza-Aghazadeh J, Andrade-Souza YM, Zadeh G, Scora D, Tsao MN, Schwartz ML. Radiosurgical Retreatment for Brain Arteriovenous Malformation. Can J Neurol Sci 2014; 33:189-94. [PMID: 16736728 DOI: 10.1017/s0317167100004959] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
ABSTRACT:Objective:To analyze our experience with a second radiosurgical treatment for brain arteriovenous malformations (BAVMs) after an unsuccessful first radiosurgical treatment.Methods:Between 1993 and 2000, 242 patients were treated by the Toronto Sunnybrook Regional Cancer Center using a LINAC system. Fifteen of these patients required a second radiosurgical intervention due to the failure of the first procedure. Data was collected on baseline patient characteristics, BAVM features, radiosurgery treatment plan and outcomes. Brain arteriovenous malformation obliteration was determined by follow-up MRI and angiography and the obliteration prediction index (OPI) calculated according to a previously established formula.Results:The median interval between the first and second treatment was 46 months (range 39-109). The median follow-up after the second procedure was 39 months (range 26 to 72). The mean BAVM volume before the first treatment was 8.9cm3 (range 0.3-21) and before the second treatment was 3.6cm3 (range 0.2-11.6). The mean marginal dose during the first treatment was 18Gy (range 12-25) and during the second treatment was 16Gy (range 12-20). After the second treatment, nine patients had obliteration of their BAVM confirmed by angiography and one patient had obliteration confirmed by MRI, resulting in an obliteration rate of 66.6%, which is very comparable to that predicted by the OPI (65%). After the second treatment two patients had a radiation-induced complication (13.3%).Conclusion:Retreatment of BAVM using a second radiosurgery procedure is a safe and effective option that offers the same rate of success as the initial radiosurgery and an acceptable risk of radiation-induced complication.
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Affiliation(s)
- Javad Mirza-Aghazadeh
- Division of Neurosurgery, Sunnybrook and Women's College Health Science Centre, Department of Radiation Oncology, Toronto-Sunnybrook Regional Cancer Centre, University of Toronto, Ontario, Canada
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Rodrigues A, Yin FF, Wu Q. Dynamic electron arc radiotherapy (DEAR): a feasibility study. Phys Med Biol 2013; 59:327-45. [DOI: 10.1088/0031-9155/59/2/327] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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26
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Improvement of the penumbra for small radiosurgical fields using flattening filter free low megavoltage beams. Z Med Phys 2013; 23:291-9. [DOI: 10.1016/j.zemedi.2013.03.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Revised: 03/12/2013] [Accepted: 03/18/2013] [Indexed: 11/21/2022]
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Smyth G, Bamber JC, Evans PM, Bedford JL. Trajectory optimization for dynamic couch rotation during volumetric modulated arc radiotherapy. Phys Med Biol 2013; 58:8163-77. [PMID: 24200876 DOI: 10.1088/0031-9155/58/22/8163] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Non-coplanar radiation beams are often used in three-dimensional conformal and intensity modulated radiotherapy to reduce dose to organs at risk (OAR) by geometric avoidance. In volumetric modulated arc radiotherapy (VMAT) non-coplanar geometries are generally achieved by applying patient couch rotations to single or multiple full or partial arcs. This paper presents a trajectory optimization method for a non-coplanar technique, dynamic couch rotation during VMAT (DCR–VMAT), which combines ray tracing with a graph search algorithm. Four clinical test cases (partial breast, brain, prostate only, and prostate and pelvic nodes) were used to evaluate the potential OAR sparing for trajectory-optimized DCR–VMAT plans, compared with standard coplanar VMAT. In each case, ray tracing was performed and a cost map reflecting the number of OAR voxels intersected for each potential source position was generated. The least-cost path through the cost map, corresponding to an optimal DCR–VMAT trajectory, was determined using Dijkstra's algorithm. Results show that trajectory optimization can reduce dose to specified OARs for plans otherwise comparable to conventional coplanar VMAT techniques. For the partial breast case, the mean heart dose was reduced by 53%. In the brain case, the maximum lens doses were reduced by 61% (left) and 77% (right) and the globes by 37% (left) and 40% (right). Bowel mean dose was reduced by 15% in the prostate only case. For the prostate and pelvic nodes case, the bowel V50 Gy and V60 Gy were reduced by 9% and 45% respectively. Future work will involve further development of the algorithm and assessment of its performance over a larger number of cases in site-specific cohorts.
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Abstract
Dynamic radiosurgery was first developed in Montreal and was subsequently adopted at the Toronto-Bayview Regional Cancer Centre in 1988. At that time radiosurgery was in its infancy in Canada. The opportunity of offering highly conformal radiation treatments for intracranial targets presented numerous technical challenges notably in the area of quality assurance. This review chronicles the development of radiosurgery at the Toronto-Bayview Regional Cancer Centre and summarises the successes and failures of the program over the following two decades.
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Roa DE, Schiffner DC, Zhang J, Dietrich SN, Kuo JV, Wong J, Ramsinghani NS, Al-Ghazi MSAL. The use of RapidArc volumetric-modulated arc therapy to deliver stereotactic radiosurgery and stereotactic body radiotherapy to intracranial and extracranial targets. Med Dosim 2012; 37:257-64. [PMID: 22365418 DOI: 10.1016/j.meddos.2011.09.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Accepted: 09/29/2011] [Indexed: 11/15/2022]
Abstract
Twenty-three targets in 16 patients treated with stereotactic radiosurgery (SRS) or stereotactic body radiotherapy (SBRT) were analyzed in terms of dosimetric homogeneity, target conformity, organ-at-risk (OAR) sparing, monitor unit (MU) usage, and beam-on time per fraction using RapidArc volumetric-modulated arc therapy (VMAT) vs. multifield sliding-window intensity-modulated radiation therapy (IMRT). Patients underwent computed tomography simulation with site-specific immobilization. Magnetic resonance imaging fusion and optical tracking were incorporated as clinically indicated. Treatment planning was performed using Eclipse v8.6 to generate sliding-window IMRT and 1-arc and 2-arc RapidArc plans. Dosimetric parameters used for target analysis were RTOG conformity index (CI(RTOG)), homogeneity index (HI(RTOG)), inverse Paddick Conformity Index (PCI), D(mean) and D5-D95. OAR sparing was analyzed in terms of D(max) and D(mean). Treatment delivery was evaluated based on measured beam-on times delivered on a Varian Trilogy linear accelerator and recorded MU values. Dosimetric conformity, homogeneity, and OAR sparing were comparable between IMRT, 1-arc RapidArc and 2-arc RapidArc plans. Mean beam-on times ± SD for IMRT and 1-arc and 2-arc treatments were 10.5 ± 7.3, 2.6 ± 1.6, and 3.0 ± 1.1 minutes, respectively. Mean MUs were 3041, 1774, and 1676 for IMRT, 1-, and 2-arc plans, respectively. Although dosimetric conformity, homogeneity, and OAR sparing were similar between these techniques, SRS and SBRT fractions treated with RapidArc were delivered with substantially less beam-on time and fewer MUs than IMRT. The rapid delivery of SRS and SBRT with RapidArc improved workflow on the linac with these otherwise time-consuming treatments and limited the potential for intrafraction organ and patient motion, which can cause significant dosimetric errors. These clinically important advantages make image-guided RapidArc useful in the delivery of SRS and SBRT to intracranial and extracranial targets.
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Affiliation(s)
- Dante E Roa
- Department of Radiation Oncology, Chao Family Comprehensive Cancer Center, University of California, Irvine-Medical Center, Orange, CA, USA.
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Historical Development of Stereotactic Ablative Radiotherapy. STEREOTACTIC BODY RADIATION THERAPY 2012. [DOI: 10.1007/174_2012_540] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Rahman M, Murad GJA, Bova F, Friedman WA, Mocco J. Stereotactic radiosurgery and the linear accelerator: accelerating electrons in neurosurgery. Neurosurg Focus 2009; 27:E13. [PMID: 19722815 DOI: 10.3171/2009.7.focus09116] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The search for efficacious, minimally invasive neurosurgical treatment has led to the development of the operating microscope, endovascular treatment, and endoscopic surgery. One of the most minimally invasive and exciting discoveries is the use of targeted, high-dose radiation for neurosurgical disorders. Radiosurgery is truly minimally invasive, delivering therapeutic energy to an accurately defined target without an incision, and has been used to treat a wide variety of pathological conditions, including benign and malignant brain tumors, vascular lesions such as arteriovenous malformations, and pain syndromes such as trigeminal neuralgia. Over the last 50 years, a tremendous amount of knowledge has been garnered, both about target volume and radiation delivery. This review covers the intense study of these concepts and the development of linear accelerators to deliver stereotactic radiosurgery. The fascinating history of stereotactic neurosurgery is reviewed, and a detailed account is given of the development of linear accelerators and their subsequent modification for radiosurgery.
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Affiliation(s)
- Maryam Rahman
- Department of Neurosurgery, University of Florida, Gainesville, Florida 32610, USA.
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Davey P, Schwartz ML, Scora D, Gardner S, O'Brien PF. Fractionated (split dose) radiosurgery in patients with recurrent brain metastases: implications for survival. Br J Neurosurg 2009; 21:491-5. [PMID: 17852114 DOI: 10.1080/02688690701534722] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Radiosurgery is conventionally prescribed for brain metastases with a single dose of radiation. Fractionation has been advocated to improve tumour control. A multivariate analysis of prognostic factors including fractionation has been performed in two consecutive prospective radiosurgery protocols with and without fractionation in order to identify an association, if any, between fractionation and survival. A surgically applied stereotactic head frame was used. Radiosurgery planning was based on a contrast-enhanced CT. Sixty-nine patients underwent the two-fraction regimen and 35 patients had a single treatment. Multivariate analysis showed that the presence of extracranial malignancy, performance status, multiple brain metastases, patient gender and the time from the initial treatment to radiosurgery were independent determinants for survival. Fractionation was also an independent determinant with two-fraction patients surviving a median of 30 weeks versus single fraction patients who survived a median of 16 weeks. Fractionated radiosurgery was associated with improved survival and deserves further investigation.
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Affiliation(s)
- P Davey
- Division of Radiation Oncology, Toronto Sunnybrook Regional Cancer Centre, Toronto, ON, Canada.
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Does intensity-modulated stereotactic radiotherapy achieve superior target conformity than conventional stereotactic radiotherapy in different intracranial tumours? Clin Oncol (R Coll Radiol) 2009; 21:408-16. [PMID: 19268555 DOI: 10.1016/j.clon.2009.02.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2008] [Revised: 01/03/2009] [Accepted: 02/02/2009] [Indexed: 11/22/2022]
Abstract
AIMS To compare the dosimetric outcome of various conventional stereotactic radiotherapy (SRT) techniques with intensity-modulated stereotactic radiotherapy (IMSRT) in brain tumours of varying shape, size, location and proximity to organs at risk (OARs). MATERIALS AND METHODS Fused computed tomography and magnetic resonance imaging datasets of four patients with different brain tumours previously treated with non-coplanar static conformal fields (SCF) were re-planned on the BrainScan treatment planning system using non-coplanar conformal arcs (CA), dynamic conformal arcs (DCA) and IMSRT with coplanar (IMSRT_CP) or non-coplanar (IMSRT_NCP) beam arrangement. Beam shaping and intensity modulation were carried out using a BrainLab micromultileaf collimator. The primary objective for each plan was to encompass >or=99% of the planning target volume (PTV) by >95% of the prescribed dose while minimising the dose to OARs. RESULTS The mean PTV coverage in SCF, CA, DCA, IMSRT_NCP and IMSRT_CP was 99.2, 99.5, 99.4, 99.2 and 99.2%, respectively. The highest dose within the target was <107% of the prescribed dose in all plans. Conformity was found to vary depending on the shape and location of the target. The best mean conformity index, ranging from 0.74 (CA) to 0.84 (IMSRT_NCP) was observed in spherical tumours. Among the three conventional SRT techniques, DCA and SCF appeared comparable (mean conformity index 0.72 and 0.71, respectively) and more conformal than CA (mean conformity index 0.67). In all cases, IMSRT showed better target conformity than conventional SRT techniques with a mean conformity index of 0.83 for non-coplanar and 0.81 for coplanar beam arrangement. The maximum improvement in conformity index was observed for IMSRT_NCP in complex, concave and irregularly shaped targets. The volume of normal brain and other OARs irradiated to high (>or=80%) and low (>or=30%) dose varied depending on the tumour shape, size, and location, but was essentially comparable in all three conventional SRT techniques. IMSRT (both coplanar as well as non-coplanar) reduced the volume of normal brain being irradiated to moderate to high doses compared with conventional SRT techniques, more so for large and irregular targets. CONCLUSIONS DCA and SCF are preferred conventional SRT techniques in terms of target conformity and reduction of doses to OARs. The use of IMSRT_NCP further improves conformity and reduces doses to OARs in a range of brain tumours commonly considered for stereotactic irradiation.
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Zygmanski P, Högele W, Cormack R, Chin L, Löschel R. A volumetric-modulated arc therapy using sub-conformal dynamic arc with a monotonic dynamic multileaf collimator modulation. Phys Med Biol 2008; 53:6395-417. [DOI: 10.1088/0031-9155/53/22/009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Benedict SH, Bova FJ, Clark B, Goetsch SJ, Hinson WH, Leavitt DD, Schlesinger DJ, Yenice KM. The role of medical physicists in developing stereotactic radiosurgery. Med Phys 2008; 35:4262-77. [DOI: 10.1118/1.2969268] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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Keller BM, Peressotti C, Pignol JP. Optical imaging analysis of microscopic radiation dose gradients in Gafchromic EBT film using a digital microscope. Med Phys 2008; 35:3740-7. [DOI: 10.1118/1.2953565] [Citation(s) in RCA: 5] [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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Yorke ED, Keall P, Verhaegen F. Anniversary Paper: Role of medical physicists and the AAPM in improving geometric aspects of treatment accuracy and precision. Med Phys 2008; 35:828-39. [DOI: 10.1118/1.2836420] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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Keller BM, Beachey DJ, Pignol JP. Experimental measurement of radiological penumbra associated with intermediate energy x-rays (1MV) and small radiosurgery field sizes. Med Phys 2007; 34:3996-4002. [DOI: 10.1118/1.2775666] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Hoh DJ, Liu CY, Chen JCT, Pagnini PG, Yu C, Wang MY, Apuzzo MLJ. CHAINED LIGHTNING, PART II. Neurosurgery 2007; 61:433-46; discussion 446. [PMID: 17881954 DOI: 10.1227/01.neu.0000290888.54578.f5] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Abstract
THE FUNDAMENTAL PRINCIPLE in the radiosurgical treatment of neurological conditions is the delivery of energy to a lesion with minimal injury to surrounding structures. The development of radiosurgical techniques from Leksell's original design has focused on the refinement of various methodologies to achieve energy containment within a target. This article is the second in a series reviewing the evolution of radiosurgical instruments with respect to issues of energy beam generation and delivery for improved conformal therapy.
Continuing with concepts introduced in an earlier article, this article examines specific aspects of beam delivery and the emergence of stereotactic radiosurgery as a measure for focusing energy beams within a target volume. The application of stereotactic principles and devices to gamma ray and linear accelerator-based energy sources provides the methodology by which energy beams are generated and targeted precisely in a focal lesion. Advanced technological systems are reviewed, including fixed beams, dynamic radiosurgery, multileaf collimation, beam shaping, and robotics as various approaches for manipulating beam delivery. Radiosurgical instruments are also compared with regard to mechanics, geometry, and dosimetry. Finally, new radiosurgical designs currently on the horizon are introduced. In exploring the complex history of radiosurgery, it is evident that the discovery and rediscovery of ideas invariably leads to the development of innovative technology for the next generation.
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Affiliation(s)
- Daniel J Hoh
- Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, California 90033, USA.
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Andrade-Souza YM, Ramani M, Scora D, Tsao MN, terBrugge K, Schwartz ML. EMBOLIZATION BEFORE RADIOSURGERY REDUCES THE OBLITERATION RATE OF ARTERIOVENOUS MALFORMATIONS. Neurosurgery 2007; 60:443-51; discussion 451-2. [PMID: 17327788 DOI: 10.1227/01.neu.0000255347.25959.d0] [Citation(s) in RCA: 197] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Abstract
OBJECTIVE
To evaluate the arteriovenous malformation (AVM) obliteration rate and the clinical outcome after radiosurgery in patients with and without previous embolization.
METHODS
Of 244 patients who underwent linear accelerator radiosurgery for AVMs at the Sunnybrook Health Sciences Centre between 1989 and 2000, 61 patients had embolization before radiosurgery and complete follow-up for at least 3 years. For 47 of these 61 patients (Group A, embolization plus radiosurgery), we were able to find 47 matching patients without previous embolization (Group B, radiosurgery alone). This group of matching patients had the same AVM volume (after embolization in Group A), location, and marginal dose. The radiosurgery-based AVM score and the obliteration prediction index were calculated.
RESULTS
The median follow-up period was 44 months. Nidus obliteration was achieved in 22 patients in Group A (47%) and 33 patients in Group B (70%, P = 0.036). Permanent deficit related to hemorrhage or radiation occurred in three patients (6%) in Group A and three patients (6%) in Group B. During the first 3 years after radiosurgery, two patients (4%) in Group A experienced hemorrhage; in Group B, five patients (11%) experienced hemorrhage (P = 0.2). In Group B, two patients (4%) died and two patients (4%) had their AVM surgically removed. Both deaths were related to hemorrhage during the latency period. The excellent outcome (obliteration plus no deficit) in Group A was 47% compared with 64% in Group B (P = 0.146). There was no difference in the obliteration prediction index and the radiosurgery-based AVM score between Groups A and B. The predicted rates of obliteration and excellent outcome were 55 and 62.5%, respectively, according to the obliteration prediction index and the radiosurgery-based AVM score.
CONCLUSION
Embolization before radiosurgery significantly decreases the obliteration rate, even in AVMs with the same volume, location, and marginal dose. Although an excellent outcome rate was higher in the group without embolization, this was not statistically significant.
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Affiliation(s)
- Yuri M Andrade-Souza
- Division of Neurosurgery, University of Toronto, Sunnybrook Health Sciences Centre, Toronto Western Hospital, Toronto, Canada
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Roberge D, Ruo R, Souhami L. Killing two birds with one stone: a dosimetric study of dual target radiosurgery using a single isocenter. Technol Cancer Res Treat 2007; 5:613-7. [PMID: 17121438 DOI: 10.1177/153303460600500609] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The treatment of hematogenous brain metastases is a frequent indication for stereotactic radiosurgery (SRS). It is common for more than one metastasis to be treated during the same SRS session. We retrospectively identified four cases where our m3 micro multileaf collimator (mMLC) was used to create two distinct apertures and treat adjacent lesions using a single isocenter. For these four cases, single isocenter plans with static conformal beams were dosimetrically compared to plans utilizing two isocenters with static conformal beams or conformal arcs. The effects on dose homogeneity, dose conformity, and the minimum isodose separating the two targets are minor and variable. On the other hand, the use of a single isocenter technique consistently halves delivery time and decreases the integral dose to normal tissue. For small adjacent metastases, which can simultaneously be encompassed within the high-resolution portion of the m3/Novalis mMLC collimator, the use of a single rather than a dual isocenter technique is feasible and generally advantageous.
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Affiliation(s)
- David Roberge
- Department of Oncology, Division of Radiation Oncology, McGill University, Montreal, Quebec, H3G 1A4, Canada.
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Andrade-Souza YM, Ramani M, Scora D, Tsao MN, TerBrugge K, Schwartz ML. Radiosurgical treatment for rolandic arteriovenous malformations. J Neurosurg 2006; 105:689-97. [PMID: 17121129 DOI: 10.3171/jns.2006.105.5.689] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Object
The authors reviewed the radiosurgical outcomes in patients with arteriovenous malformations (AVMs) located in the rolandic area, including the primary motor and sensory gyri.
Methods
The study population consisted of 38 patients with rolandic-area AVMs who underwent linear accelerator radiosurgery at the University of Toronto between 1989 and 2000. Obliteration rate, risk of hemorrhage during the latency period, radiation-induced complications, seizure control, and functional status were evaluated. Patients were also divided into two subgroups according to AVM volume (< 3 cm3 and ≥ 3 cm3).
Patients were followed up for a median of 42.4 months (range 30–103 months), and the median age of the patients was 40 years (range 12–67 years). The median AVM volume was 8.1 cm3 (range 0.32–21, mean 8.32 cm3), and the median dose at the tumor margin was 15 Gy (range 15–22, mean 16.8 Gy). The risk of hemorrhage after radiosurgery was 5.3% for the 1st year, 2.6% for the 2nd, and 0% for the 3rd. Two patients (5.3%) sustained adverse effects related to radiation for more than 6 months. Complete nidus obliteration after a single radiosurgical treatment was achieved in 23 patients (60.5%). The obliteration rate for AVMs smaller than 3 cm3 was 83.3% (10 of 12) and that for AVMs larger than or equal to 3 cm3 was 50% (13 of 26). Among the patients who had seizures as the initial presentation, 51.8% were free of seizures after radiosurgery and the seizure pattern improved in 40.7% during the 3rd and last year of follow up. Overall, excellent results (obliteration and no new or worsening neurological deficit) can be achieved in approximately 60% of patients. This percentage varies according to the AVM size and can reach 83% in patients with AVMs smaller than 3 cm3.
Conclusions
Radiosurgery is a safe and effective treatment for people with rolandic AVMs. The low rate of morbidity associated with radiosurgery, compared with other treatments, indicates that this method may be the first choice for patients with AVMs located in this area.
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Affiliation(s)
- Yuri M Andrade-Souza
- Division of Neurosurgery, Sunnybrook and Women's College Health Sciences Centre, Toronto, Ontario, Canada.
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Verhey LJ, Chen CC, Chapman P, Loeffler J, Curry WT. Single-Fraction Stereotactic Radiosurgery for Intracranial Targets. Neurosurg Clin N Am 2006; 17:79-97, v. [PMID: 16793501 DOI: 10.1016/j.nec.2006.04.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Stereotactic radiosurgery (SRS) is a technique for treating intracranial lesions with a high dose of ionizing radiation, usually in a single session, using a stereotactic apparatus for accurate localization and patient immobilization. This article describes several modalities of SRS and some of its applications, particularly for intracranial lesions.
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Affiliation(s)
- Lynn J Verhey
- Department of Radiation Oncology, University of California, San Francisco, 513 Parnassus Avenue, San Francisco, CA 94143, USA.
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Roberge D, Souhami L, Olivier A, Leblanc R, Podgorsak E. Hypofractionated stereotactic radiotherapy for low grade glioma at McGill University: long-term follow-up. Technol Cancer Res Treat 2006; 5:1-8. [PMID: 16417396 DOI: 10.1177/153303460600500101] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Small, well-defined, unresectable low-grade gliomas are attractive targets for stereotactic irradiation. Fractionated stereotactic irradiation of these targets has the theoretical benefit of increased normal tissue sparing beyond that provided by the physical characteristics of stereotactic radiosurgery. From July 1987 to November 1992, 21 patients were treated for low-grade glioma at our institution using a hypofractionated regimen of stereotactic radiotherapy. All patients had well-circumscribed, < 40 mm tumors. No patient had had prior radiotherapy. All lesions were histologically proven WHO grade I or II glial tumors. Lesions involved sensitive brain structures and were deemed unresectable. A typical dose of 42 Gy was delivered in 6 fractions over a two-week period using rigid immobilization and a linac-based dynamic stereotactic radiosurgical technique. Patients had a median age of 23 years (9-74) and were predominantly female (60%). Median tumor diameter was 20 mm. With a median follow-up for living patients of 13.3 years, the actuarial 5, 10, and 15-year overall survival rates are 76%, 71%, and 63%, respectively. Treatment was acutely well tolerated although three patients experienced late post-therapy complications. Our results and those of 241 patients treated in nine other institutional series are reviewed. Despite some examples of favorable short-term outcomes, all reported series are highly selected and thus likely biased. The data regarding the use of SRS is limited and, in our opinion, insufficient to claim a clear therapeutic advantage to SRS in the initial management of low-grade glioma. Our own results with hypofractionated stereotactic radiotherapy are similar to those expected with standard therapy.
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Affiliation(s)
- D Roberge
- Department of Oncology, Division of Radiation Oncology, McGill University Heath Center, Montreal General Hospital, 1650 Cedar Av., Room D5.400, Montreal, QC H3G 1A4, Canada.
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Andrade-Souza YM, Zadeh G, Ramani M, Scora D, Tsao MN, Schwartz ML. Testing the radiosurgery-based arteriovenous malformation score and the modified Spetzler—Martin grading system to predict radiosurgical outcome. J Neurosurg 2005; 103:642-8. [PMID: 16266046 DOI: 10.3171/jns.2005.103.4.0642] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Object. The aim of this study was to validate the radiosurgery-based arteriovenous malformation (AVM) score and the modified Spetzler—Martin grading system to predict radiosurgical outcome.
Methods. One hundred thirty-six patients with brain AVMs were randomly selected. These patients had undergone a linear accelerator radiosurgical procedure at a single center between 1989 and 2000. Patients were divided into four groups according to an AVM score, which was calculated from the lesion volume, lesion location, and patient age (Group 1, AVM score < 1; Group 2, AVM score 1–1.49; Group 3, AVM score 1.5–2; and Group 4, AVM score > 2). Patients with a Spetzler—Martin Grade III AVM were divided into Grades IIIA (lesion > 3 cm) and IIIB (lesion < 3 cm). Sixty-two female (45.6%) and 74 male (54.4%) patients with a median age of 37.5 years (mean 37.5 years, range 5–77 years) were followed up for a median of 40 months. The median tumor margin dose was 15 Gy (mean 17.23 Gy, range 15–25 Gy). The proportions of excellent outcomes according to the AVM score were as follows: 91.7% for Group 1, 74.1% for Group 2, 60% for Group 3, and 33.3% for Group 4 (chi-square test, degrees of freedom (df) = 3, p < 0.001). Based on the modified Spetzler—Martin system, Grade I lesions had 88.9% excellent results; Grade II, 69.6%; Grade IIIB, 61.5%; and Grades IIIA and IV, 44.8% (chi-square test, df = 3, p = 0.047).
Conclusions. The radiosurgery-based AVM score can be used accurately to predict excellent results following a single radiosurgical treatment for AVM. The modified Spetzler—Martin system can also predict radiosurgical results for AVMs, thus making it possible to use this system while deciding between surgery and radiosurgery.
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Affiliation(s)
- Yuri M Andrade-Souza
- Division of Neurosurgery and Department of Radiation Oncology, Sunnybrook and Women's College Health Sciences Center, University of Toronto, Ontario, Canada
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Andrade-Souza YM, Zadeh G, Scora D, Tsao MN, Schwartz ML. Radiosurgery for Basal Ganglia, Internal Capsule, and Thalamus Arteriovenous Malformation: Clinical Outcome. Neurosurgery 2005; 56:56-63; discussion 63-4. [PMID: 15617586 DOI: 10.1227/01.neu.0000145797.35968.ed] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2004] [Accepted: 09/10/2004] [Indexed: 11/19/2022] Open
Abstract
Abstract
OBJECTIVE:
Radiosurgery is accepted as the first option for treating deep arteriovenous malformations (AVMs), although the clinical outcome in this subgroup of brain AVMs is not well studied. The objective of this study is to review our experience with radiosurgical treatment for these AVMs.
METHODS:
Between October 1989 and December 2000, 45 patients with deep AVMs (including basal ganglia, internal capsule, and thalamus) underwent stereotactic radiosurgery. Three patients were lost to follow-up and therefore were excluded from this study. Patient characteristics and outcomes were collected and analyzed. The obliteration prediction index and the radiosurgery-based AVM score were calculated and tested.
RESULTS:
Forty-two patients were followed up for a median of 39 months (range, 25–90 mo; mean, 45.8 mo). The median maximum AVM diameter during the radiosurgery was 1.8 cm (range, 0.9–4.0 cm; mean, 2.07 cm), and the median AVM volume was 2.8 cm3 (range, 0.2–18.3 cm3; mean, 4.74 cm3). The mean marginal dose was 16.2 Gy (median, 15 Gy), and the median maximum dose was 22.4 Gy (range, 16.6–30 Gy). The AVM cure rate after the first radiosurgical treatment, using angiography- and magnetic resonance imaging-confirmed obliteration, was 61.9%. The predicted obliteration using the obliteration prediction index was 60%. Eight patients developed radiation-induced complications (19%). The deficit was transient in three patients (7.1%) and permanent in five patients (11.9%). The risk of postradiosurgical hemorrhage in this cohort was 9.5% for the first year, 4.7% for the second year, and 0% thereafter. Excellent outcome (obliteration plus no new deficit) was achieved in 70% of the patients in the group with radiosurgery-based AVM score less than 1.5 compared with 40.9% in the group with radiosurgery-based AVM score greater than 1.5% (P = 0.059).
CONCLUSION:
Radiosurgery for deep AVMs has a satisfactory obliteration rate and acceptable morbidity, considering the risk of hemorrhage without treatment and the risk of morbidity associated with other treatment modalities.
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Affiliation(s)
- Yuri M Andrade-Souza
- Division of Neurosurgery, Sunnybrook and Women's College, Health Science Centre,University of Toronto, Toronto, Ontario, Canada
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Yu C, Jozsef G, Apuzzo MLJ, Petrovich Z. Dosimetric Comparison of CyberKnife with Other Radiosurgical Modalities for an Ellipsoidal Target. Neurosurgery 2003; 53:1155-62; discussion 1162-3. [PMID: 14580283 DOI: 10.1227/01.neu.0000088805.01793.5a] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2002] [Accepted: 06/23/2003] [Indexed: 11/19/2022] Open
Abstract
Abstract
OBJECTIVE
To compare treatment plans obtained with the CyberKnife (CK) (Accuray, Inc., Sunnyvale, CA) with those of other commonly used radiosurgical modalities, such as the gamma knife (GK), linear accelerator multiple arcs, conformally shaped static fields, and intensity-modulated radiotherapy (IMRT).
METHODS
An ellipsoidal simulated target was chosen centrally located in a three-dimensional model of a patient's head acquired with magnetic resonance or computed tomographic imaging. It was 25 mm in diameter and 35 mm long. The aims of treatment plans were 100% target volume coverage with an appropriate isodose line, minimum radiation dose to normal tissue, and clinically acceptable delivery. These plans were evaluated by use of a dose-volume histogram and other commonly used radiosurgical parameters such as target coverage, homogeneity index, and conformity index.
RESULTS
All selected treatment modalities were equivalent in providing full target coverage. For dose homogeneity, all modalities except for multiple isocenter plans for GK (homogeneity index, 2.0) were similar (homogeneity index, ≅1.25). Dose conformity was essentially equivalent for all treatment plans except for IMRT, which had a slightly higher value (conformity index, ≅1.27). There was a substantial variation in the radiation dose to normal tissue between the studied modalities, particularly at the lower dose levels.
CONCLUSION
CK plans seemed to be more flexible for a given target size and shape. For a target of limited volume and essentially of any shape, one could obtain similarly good conformal dosimetry with CK and GK. For a regular-shaped but other than spherical target, homogeneous dose distribution could be obtained with all selected modalities except for multiple isocenters, linear accelerator multiple arcs, or GK. Both IMRT and conformally shaped static fields offered good alternative treatment modalities to CK, GK, or linear accelerator multiple arc radiosurgery, with slightly inferior dosimetry in conformity (IMRT).
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Affiliation(s)
- Cheng Yu
- Department of Radiation Oncology, Keck School of Medicine, University of Southern California, Los Angeles, California 90033-0804, USA.
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Pellet W, Regis J, Roche PH, Delsanti C. Relative indications for radiosurgery and microsurgery for acoustic schwannoma. Adv Tech Stand Neurosurg 2003; 28:227-82; discussion 282-4. [PMID: 12627811 DOI: 10.1007/978-3-7091-0641-9_4] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
The physical and biological principles underlying the use of radiosurgery for the treatment of vestibular schwannomas of up to 2.5 cm in diameter are reviewed together with the historical controversies that have surrounded its introduction. The results in terms of mortality, quality of life, preservation of facial movement and hearing, incidence of shunt-dependent hydrocephalus, cancer neogenesis and brain stem damage are compared in the Marseilles series of 600 microsurgical procedures and 830 Gamma knife procedures and with the peer-reviewed literature. The key principles of a steep profile to radiation exposure at the tumour margin, careful topographical planning of the radiation against the tumour shape to minimise the radiation dose to the cranial nerves and brain stem, early tumour swelling, tumour texture and national history of the tumour are analysed. Protocols for the management of unilateral schwannoma, Type II neurofibromatosis (both the Wishart and the Gardner types) and residual/recurrent tumours are presented. In summary, the growth of nearly 97% of vestibular schwannomas (up to 2.5 cm) is arrested by the Gamma knife, the facial nerve is preserved in almost all cases and hearing may be preserved at its pre-operative level in nearly 70% of cases without the complications of microsurgery.
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Affiliation(s)
- W Pellet
- Department of Otoneurosurgery, Hôpital Sainte Marguerite, Marseille, France
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