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Abdelgawad MH, Eldib AA, Elsayed TM, Ma CC. Investigation of the linear accelerator low dose rate mode for pulsed low-dose-rate radiotherapy delivery. Biomed Phys Eng Express 2024; 10:065012. [PMID: 39191263 DOI: 10.1088/2057-1976/ad73dd] [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: 03/22/2024] [Accepted: 08/27/2024] [Indexed: 08/29/2024]
Abstract
Purpose. Pulsed volumetric modulated arc therapy (VMAT) was proposed as an advanced treatment that combines the biological benefits of pulsed low dose rate (PLDR) and the dosimetric benefits of the intensity-modulated beams. In our conventional pulsed VMAT technique, a daily fractional dose of 200 cGy is delivered in 10 arcs with 3 min intervals between the arcs. In this study, we are testing the feasibility of pulsed VMAT that omits the need to split into ten arcs and excludes any beam-off gaps.Methods. The study was conducted using computed tomographic images of 24 patients previously treated at our institution with the conventional PLDR technique. Our newly installed Elekta machine has a low dose rate option on the order of 25 MU min-1. PLDR requires an effective dose rate of 6.7 cGy min-1with attention being paid to the maximum dose received within any point within the target not to exceed 13 cGy min-1. The quality of treatment plans was judged based on dose-volume histograms, isodose distribution, dose conformality to the target, and target dose homogeneity. The dose delivery accuracy was assessed by measurements using theMatriXXEvolution2D array system.Results. All cases were normalized to cover 95% of the target volume with 100% of the prescription dose. The average conformity index was 1.03 ± 0.08 while the average homogeneity index was 1.05 ± 0.02. The maximum reported dose rate at any point within the target was 10.44 cGy min-1. The mean dose rate for all pulsed VMAT plans was 6.88 ± 0.1 cGy min-1. All cases passed our gamma analysis with an average passing rate of 99.00% ± 0.48%.Conclusion. The study showed the applicability of planning pulsed VMAT using Eclipse and its successful delivery on our Elekta linac. Pulsed VMAT using the machine's low dose rate mode is more efficient than our previous pulsed VMAT delivery.
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Affiliation(s)
- Mahmoud H Abdelgawad
- Physics Department, Faculty of Science, Al-Azhar University, Nasr City, Cairo, Egypt
- Fox Chase Cancer Center, Temple University Health System, 333, Cottman Avenue Philadelphia, PA, 19111, United States of America
| | - Ahmed A Eldib
- Fox Chase Cancer Center, Temple University Health System, 333, Cottman Avenue Philadelphia, PA, 19111, United States of America
| | - Tamer M Elsayed
- Physics Department, Faculty of Science, Al-Azhar University, Nasr City, Cairo, Egypt
| | - Cm Charlie Ma
- Fox Chase Cancer Center, Temple University Health System, 333, Cottman Avenue Philadelphia, PA, 19111, United States of America
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Dai T, Sloop AM, Rahman MR, Sunnerberg JP, Clark MA, Young R, Adamczyk S, Voigts-Rhetz PV, Patane C, Turk M, Jarvis L, Pogue BW, Gladstone DJ, Bruza P, Zhang R. First Monte Carlo beam model for ultra-high dose rate radiotherapy with a compact electron LINAC. Med Phys 2024; 51:5109-5118. [PMID: 38493501 PMCID: PMC11316970 DOI: 10.1002/mp.17031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 03/04/2024] [Accepted: 03/04/2024] [Indexed: 03/19/2024] Open
Abstract
BACKGROUND FLASH radiotherapy based on ultra-high dose rate (UHDR) is actively being studied by the radiotherapy community. Dedicated UHDR electron devices are currently a mainstay for FLASH studies. PURPOSE To present the first Monte Carlo (MC) electron beam model for the UHDR capable Mobetron (FLASH-IQ) as a dose calculation and treatment planning platform for preclinical research and FLASH-radiotherapy (RT) clinical trials. METHODS The initial beamline geometry of the Mobetron was provided by the manufacturer, with the first-principal implementation realized in the Geant4-based GAMOS MC toolkit. The geometry and electron source characteristics, such as energy spectrum and beamline parameters, were tuned to match the central-axis percentage depth dose (PDD) and lateral profiles for the pristine beam measured during machine commissioning. The thickness of the small foil in secondary scatter affected the beam model dominantly and was fine tuned to achieve the best agreement with commissioning data. Validation of the MC beam modeling was performed by comparing the calculated PDDs and profiles with EBT-XD radiochromic film measurements for various combinations of applicators and inserts. RESULTS The nominal 9 MeV electron FLASH beams were best represented by a Gaussian energy spectrum with mean energy of 9.9 MeV and variance (σ) of 0.2 MeV. Good agreement between the MC beam model and commissioning data were demonstrated with maximal discrepancy < 3% for PDDs and profiles. Hundred percent gamma pass rate was achieved for all PDDs and profiles with the criteria of 2 mm/3%. With the criteria of 2 mm/2%, maximum, minimum and mean gamma pass rates were (100.0%, 93.8%, 98.7%) for PDDs and (100.0%, 96.7%, 99.4%) for profiles, respectively. CONCLUSIONS A validated MC beam model for the UHDR capable Mobetron is presented for the first time. The MC model can be utilized for direct dose calculation or to generate beam modeling input required for treatment planning systems for FLASH-RT planning. The beam model presented in this work should facilitate translational and clinical FLASH-RT for trials conducted on the Mobetron FLASH-IQ platform.
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Affiliation(s)
- Tianyuan Dai
- Thayer School of Engineering, Dartmouth College, Hanover NH 03755, USA
- Department of Radiation Oncology Physics and Technology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan Shandong 250000, China
| | - Austin M. Sloop
- Thayer School of Engineering, Dartmouth College, Hanover NH 03755, USA
| | | | | | - Megan A. Clark
- Thayer School of Engineering, Dartmouth College, Hanover NH 03755, USA
| | - Ralph Young
- IntraOp Medical Corporation, Sunnyvale CA 94085, USA
| | | | | | - Chris Patane
- IntraOp Medical Corporation, Sunnyvale CA 94085, USA
| | - Michael Turk
- IntraOp Medical Corporation, Sunnyvale CA 94085, USA
| | - Lesley Jarvis
- Department of Medicine, Geisel School of Medicine, Dartmouth College Hanover NH 03755 USA
- Dartmouth Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, NH 03756 USA
| | - Brian W. Pogue
- Thayer School of Engineering, Dartmouth College, Hanover NH 03755, USA
- Dartmouth Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, NH 03756 USA
- Department of Medical Physics, Wisconsin Institutes for Medical Research, University of Wisconsin, Madison WI 53705 USA
| | - David J. Gladstone
- Thayer School of Engineering, Dartmouth College, Hanover NH 03755, USA
- Department of Medicine, Geisel School of Medicine, Dartmouth College Hanover NH 03755 USA
- Dartmouth Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, NH 03756 USA
| | - Petr Bruza
- Thayer School of Engineering, Dartmouth College, Hanover NH 03755, USA
| | - Rongxiao Zhang
- Thayer School of Engineering, Dartmouth College, Hanover NH 03755, USA
- Department of Medicine, Geisel School of Medicine, Dartmouth College Hanover NH 03755 USA
- Department of Radiation Medicine, New York Medical College, Valhalla, NY 10595 USA
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Deng J, Liu S, Huang Y, Li X, Wu X. Evaluating AAPM-TG-218 recommendations: Gamma index tolerance and action limits in IMRT and VMAT quality assurance using SunCHECK. J Appl Clin Med Phys 2024; 25:e14277. [PMID: 38243604 PMCID: PMC11163510 DOI: 10.1002/acm2.14277] [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: 09/20/2023] [Revised: 10/23/2023] [Accepted: 12/17/2023] [Indexed: 01/21/2024] Open
Abstract
PURPOSE This study aimed to improve the safety and accuracy of radiotherapy by establishing tolerance (TL) and action (AL) limits for the gamma index in patient-specific quality assurance (PSQA) for intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) using SunCHECK software, as per AAPM TG-218 report recommendations. METHODS The study included 125 patients divided into six groups by treatment regions (H&N, thoracic and pelvic) and techniques (VMAT, IMRT). SunCHECK was used to calculate the gamma passing rate (%GP) and dose error (%DE) for each patient, for the planning target volume and organs at risk (OARs). The TL and AL were then determined for each group according to TG-218 recommendations. We conducted a comprehensive analysis to compare %DE among different groups and examined the relationship between %GP and %DE. RESULTS The TL and AL of all groups were more stringent than the common standard as defined by the TG218 report. The TL and AL values of the groups differed significantly, and the values for the thoracic groups were lower for both VMAT and IMRT. The %DE of the parameters D95%, D90%, and Dmean in the planning target volume, and Dmean and Dmax in OARs were significantly different. The dose deviation of VMAT was larger than IMRT, especially in the thoracic group. A %GP and %DE correlation analysis showed a strong correlation for the planning target volume, but a weak correlation for the OARs. Additionally, a significant correlation existed between %GP of SunCHECK and Delta4. CONCLUSION The study established TL and AL values tailored to various anatomical regions and treatment techniques at our institution. Establishing PSQA workflows for VMAT and IMRT offers valuable clinical insights and guidance. We also suggest developing a standard combining clinically relevant metrics with %GP to evaluate PSQA results comprehensively.
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Affiliation(s)
- Jia Deng
- Department of Radiation OncologyShaanxi Provincial Tumor HospitalXianShaanxiChina
- School of Nuclear Science and TechnologyXi'an Jiaotong UniversityXi'anShaanxiChina
| | - ShengYan Liu
- Department of Radiation OncologyYulin Xingyuan HospitalXi'anChina
| | - Yun Huang
- Department of OncologySecond Affiliated Hospital of Guizhou University of Traditional Chinese MedicineGuiyang CityGuizhou ProvinceChina
| | - Xiuquan Li
- Department of OncologyThe First Affiliated Hospital of Chongqing Medical UniversityChongqingChina
| | - Xiangyang Wu
- Department of Radiation OncologyShaanxi Provincial Tumor HospitalXianShaanxiChina
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Diamantopoulos S, Platoni K, Karaiskos P, Kouloulias V, Efstathopoulos E. Isodose surface differences: A novel tool for the comparison of dose distributions. J Appl Clin Med Phys 2023; 24:e14085. [PMID: 37794700 PMCID: PMC10647989 DOI: 10.1002/acm2.14085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 05/03/2023] [Accepted: 06/05/2023] [Indexed: 10/06/2023] Open
Abstract
BACKGROUND Comparing dose distributions is a routine task in radiotherapy, mainly in patient-specific quality assurance (PSQA). Currently, the evaluation of the dose distributions is being performed mainly with statistical methods, which could underestimate the clinical importance of the spotted differences, as per the literature. PURPOSE This paper aims to provide proof-of-concept for a novel dose distribution comparison method based on the difference of the isodose surfaces. The new method connects acceptance tolerance to QA limitations (equipment capabilities) and integrates a clinical approach into the analysis procedure. METHODS The distance of dose points from the isocenter can be used as a function to define the shape of an isodose surface expressed as a histogram. Isodose surface differences (ISD) are defined as the normalized differences of reference and evaluated surface histograms plotted against their corresponding isodose. Acceptance tolerances originate from actual QA tolerances and are presented clinically intuitively. The ISD method was compared to the gamma index using intentionally erroneous VMAT and IMRT plans. RESULTS Results revealed that the ISD method is sensitive to all errors induced in the plans. Discrepancies are presented per isodose, enabling the evaluation of the plan in two regions representing PTV and Normal Tissue. ISD manages to flag errors that would remain undetected under the gamma analysis. CONCLUSION The ISD method is a meaningful, QA-related, registration-free, and clinically oriented technique of dose distribution evaluation. This method can be used either as a standalone or an auxiliary tool to the well-established evaluation procedures, overcoming significant limitations reported in the literature.
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Affiliation(s)
- Stefanos Diamantopoulos
- 2nd Department of RadiologyUniversity General Hospital “Attikon”1 Rimini StreetNational and Kapodistrian University of AthensChaidariGreece
- Joint Department of PhysicsThe Royal Marsden NHS Foundation TrustLondonUK
| | - Kalliopi Platoni
- 2nd Department of RadiologyUniversity General Hospital “Attikon”1 Rimini StreetNational and Kapodistrian University of AthensChaidariGreece
| | - Pantelis Karaiskos
- Medical Physics LaboratoryMedical SchoolNational and Kapodistrian University of AthensAthensGreece
| | - Vassilis Kouloulias
- 2nd Department of RadiologyUniversity General Hospital “Attikon”1 Rimini StreetNational and Kapodistrian University of AthensChaidariGreece
| | - Efstathios Efstathopoulos
- 2nd Department of RadiologyUniversity General Hospital “Attikon”1 Rimini StreetNational and Kapodistrian University of AthensChaidariGreece
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Zuber SH, Hadi MFRA, Samson DO, Jayamani J, Rabaiee NA, Aziz MZA, Hashikin NAA, Ying CK, Yusof MFM, Hashim R. Dosimetric Analysis of Rhizophora-based Phantom Material in Radiation Therapy Applications Using Monte Carlo GATE Simulation. J Med Phys 2023; 48:358-364. [PMID: 38223797 PMCID: PMC10783191 DOI: 10.4103/jmp.jmp_75_23] [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: 06/14/2023] [Revised: 09/05/2023] [Accepted: 09/23/2023] [Indexed: 01/16/2024] Open
Abstract
Purpose This study aims to determine the percentage depth dose (PDD) of a phantom material made from soy-lignin bonded Rhizophora spp. particleboard coated with a gloss finish by using Monte Carlo Geant4 Application for Tomographic Emission (GATE) simulation. Materials and Methods The particleboard was fabricated using a hot pressing technique at target density of 1.0 g·cm-3 and the elemental fraction was recorded for the simulation. The PDD was simulated in the GATE simulation using the linear accelerator Elekta Synergy model for the water phantom and Rhizophora phantom, and the results were compared with the experimental PDD performed by several studies. Beam flatness and beam symmetry were also measured in this study. Results The simulated PDD for Rhizophora and water was in agreement with the experimental PDD of water with overall discrepancies of 0% to 8.7% at depth ranging from 1.0 to 15.0 cm. In the GATE simulation, all the points passed the clinical 3%/3 mm criterion in comparison with water, with the final percentage of 2.34% for Rhizophora phantom and 2.49% for the water phantom simulated in GATE. Both the symmetries are all within the range of an acceptable value of 2.0% according to the recommendation, with the beam symmetry of the water phantom and Rhizophora phantom at 0.58% and 0.28%, respectively. Conclusions The findings of this study provide the necessary foundation to confidently use the phantom for radiotherapy purposes, especially in treatment planning.
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Affiliation(s)
- Siti Hajar Zuber
- Diagnostic Imaging and Radiotherapy, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, 50300, Kuala Lumpur, Malaysia
| | | | | | | | - Nor Ain Rabaiee
- Department of Radiology, Kulliyyah of Medicine, International Islamic University Malaysia, 25200, Malaysia
| | - Mohd Zahri Abdul Aziz
- Oncology and Radiotherapy Unit, Advanced Medical and Dental Institute, Universiti Sains Malaysia, 13200, Malaysia
| | | | - Chee Keat Ying
- Oncology and Radiotherapy Unit, Advanced Medical and Dental Institute, Universiti Sains Malaysia, 13200, Malaysia
| | | | - Rokiah Hashim
- School of Industrial Technology, Universiti Sains Malaysia, 11800, Penang, Malaysia
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Panetta JV, Veltchev I, Price RA, Ma CMC. 2D IMRT QA passing rate dependency on coronal plane. Phys Med 2023; 110:102594. [PMID: 37116388 DOI: 10.1016/j.ejmp.2023.102594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Revised: 04/10/2023] [Accepted: 04/17/2023] [Indexed: 04/30/2023] Open
Abstract
Intensity modulated radiation therapy (IMRT) delivery involves a complex series of beam angles and multileaf collimator (MLC) arrangements, requiring quality assurance to be performed to validate delivery before treatment. The purpose of this work is to investigate the effect of dose gradient on quality assurance (QA) passing rate. Many (n = 40) IMRT plans were delivered and measured using a 2D planar array of ion chambers; additionally, eleven plans were measured at several coronal planes. For each measurement, dose gradient was assessed using a number of metrics and passing rate assessed at both 3%/3 mm and 3%/2 mm criteria. The passing rates of the various IMRT plans were shown to be generally correlated to gradient, with an average distance correlation of 0.54 ± 0.04 for the lateral dose gradient. The passing rate for an individual plan was shown to vary with coronal slice, though the correlation to dose gradient was not predictable. Even though the passing rate was strongly related to dose gradient for many of the plans, the signs of the correlations were not always negative, as hypothesized. The coronal plane at which QA is performed affects passing rate, though dose gradient may not easily be used to predict slices at which passing rate is higher.
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Affiliation(s)
- Joseph V Panetta
- Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA 19111, USA.
| | - Iavor Veltchev
- Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Robert A Price
- Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - C-M Charlie Ma
- Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
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U’wais FA, Radzi Y, Noor Rizan N, Zin HM. Validation of a digital method for patient-specific verification of VMAT treatment using a 2D ionisation detector array. Radiat Phys Chem Oxf Engl 1993 2023. [DOI: 10.1016/j.radphyschem.2022.110536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Das S, Kharade V, Pandey VP, KV A, Pasricha RK, Gupta M. Gamma Index Analysis as a Patient-Specific Quality Assurance Tool for High-Precision Radiotherapy: A Clinical Perspective of Single Institute Experience. Cureus 2022; 14:e30885. [PMID: 36337776 PMCID: PMC9626372 DOI: 10.7759/cureus.30885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/30/2022] [Indexed: 11/07/2022] Open
Abstract
Purpose Patient-specific quality assurance (QA) by gamma (γ) analysis is an important component of high-precision radiotherapy. It is important to standardize institute-specific protocol. In this study, we describe our institutional experience of patient-specific QA for high-precision radiotherapy from a clinical perspective. Methods The planning data of 56 patients treated with intensity-modulated radiotherapy (IMRT)/volumetric modulated arc therapy (VMAT) were included. γ index analysis was done using Octavius 4D IMRT QA phantom (PTW, Freiburg, Germany) using 3 mm/3% criteria. Local, global, and volumetric gammas were calculated and compared. The relationship of γ index in the transverse, coronal, and sagittal direction and anatomical region of treatment was explored. Results Global three-dimensional (3D) γ indices in the coronal, sagittal, and transverse axes were 96.73 ± 2.35, 95.66 ± 3.01, and 93.36 ± 4.87 (p < 0.05). The average local two-dimensional (2D) γ index was 78.23 ± 5.44 and the global γ index was 92.41 ± 2.41 (p < 0.005). The average local 3D γ index was 84.99 ± 4.24 and the global 3D γ index was 95.25 ± 1.72 (p < 0.005, paired t-test). The average local volumetric γ index was 84.29 ± 4.73 and the global volumetric γ index was 95.96 ± 2.08 (p < 0.005). 3D global gamma index was significantly different in different anatomical regions (p < 0.05). Conclusion Our study shows that γ index analysis is a useful parameter for routine clinical IMRT QA. The choice of type of γ index depends on the context of use and degree of stringency in measurement. Average 2D and 3D global γ were different in anatomical regions. The average 3D γ index was significantly different in axes. No difference was observed with techniques of IMRT/VMAT. Localization of failed points in CT anatomy can be advantageous for clinical decision-making.
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Krim DE, Bakari D, Zerfaoui M, Rrhioua A. Implementation of a new virtual source model in Gate 9.0 package to simulate Elekta Synergy MLCi2 6 MV accelerator. Biomed Phys Eng Express 2021; 7. [PMID: 34193645 DOI: 10.1088/2057-1976/ac1057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 06/30/2021] [Indexed: 11/11/2022]
Abstract
Monte Carlo simulation is appreciated as an extraordinary technique to investigate particle physic processes in Radiation Therapy. This task offers a new Virtual Source Model (VSM) based on an innovative reconstruction method to extract energy and angular distribution from the Python phase space output data. Extensive comparisons of dose distributions are performed to evaluate VSM simulation precision. Four squared field configurations extending from 3 × 3 to 20 × 20 cm2are chosen for dose calculation to test field size and symmetry influences. To evaluate simulation accuracy, the beam quality parameters (such asD10(%),dmax(cm),d80(cm), andTPR(20/10)) also validation tests (gamma index formalism for 2%/2 mm criteria, Distance To Agreement DTA, and the estimator standard error (ϵ,ϵmax)) are determined. Good agreement is achieved in terms of beam quality parameters and validation tests for each evaluated beam size, within a computation time of 58 hours and 17 hours on 20 nodes (presents 160 CPUs) of the full simulation and the VSM, respectively. This advanced VSM generated for the Elekta Synergy MLCi2 platform displays an uncomplicated approach. It is a great example of reconstructing different x-ray beams of various linac accelerators to facilitate its integration in cancer treatment.
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Affiliation(s)
- Deae-Eddine Krim
- Laboratory of Physics of Matter and Radiation Faculty of Sciences, Mohammed first University Oujda, Morocco
| | - Dikra Bakari
- National School of Applied Sciences, Mohammed first University, Oujda, Morocco
| | - Mustapha Zerfaoui
- Laboratory of Physics of Matter and Radiation Faculty of Sciences, Mohammed first University Oujda, Morocco
| | - Abdeslem Rrhioua
- Laboratory of Physics of Matter and Radiation Faculty of Sciences, Mohammed first University Oujda, Morocco
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Puvanasunthararajah S, Fontanarosa D, Wille M, Camps SM. The application of metal artifact reduction methods on computed tomography scans for radiotherapy applications: A literature review. J Appl Clin Med Phys 2021; 22:198-223. [PMID: 33938608 PMCID: PMC8200502 DOI: 10.1002/acm2.13255] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 03/21/2021] [Accepted: 03/30/2021] [Indexed: 12/22/2022] Open
Abstract
Metal artifact reduction (MAR) methods are used to reduce artifacts from metals or metal components in computed tomography (CT). In radiotherapy (RT), CT is the most used imaging modality for planning, whose quality is often affected by metal artifacts. The aim of this study is to systematically review the impact of MAR methods on CT Hounsfield Unit values, contouring of regions of interest, and dose calculation for RT applications. This systematic review is performed in accordance with the PRISMA guidelines; the PubMed and Web of Science databases were searched using the main keywords "metal artifact reduction", "computed tomography" and "radiotherapy". A total of 382 publications were identified, of which 40 (including one review article) met the inclusion criteria and were included in this review. The selected publications (except for the review article) were grouped into two main categories: commercial MAR methods and research-based MAR methods. Conclusion: The application of MAR methods on CT scans can improve treatment planning quality in RT. However, none of the investigated or proposed MAR methods was completely satisfactory for RT applications because of limitations such as the introduction of other errors (e.g., other artifacts) or image quality degradation (e.g., blurring), and further research is still necessary to overcome these challenges.
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Affiliation(s)
- Sathyathas Puvanasunthararajah
- School of Clinical SciencesQueensland University of TechnologyBrisbaneQLDAustralia
- Centre for Biomedical TechnologiesQueensland University of TechnologyBrisbaneQLDAustralia
| | - Davide Fontanarosa
- School of Clinical SciencesQueensland University of TechnologyBrisbaneQLDAustralia
- Centre for Biomedical TechnologiesQueensland University of TechnologyBrisbaneQLDAustralia
| | - Marie‐Luise Wille
- Centre for Biomedical TechnologiesQueensland University of TechnologyBrisbaneQLDAustralia
- School of MechanicalMedical & Process EngineeringFaculty of EngineeringQueensland University of TechnologyBrisbaneQLDAustralia
- ARC ITTC for Multiscale 3D Imaging, Modelling, and ManufacturingQueensland University of TechnologyBrisbaneQLDAustralia
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Zhong Y, Lu W, Chen M, Xiong Z, Cheng X, Hu K, Shao Y. Novel On-line PET Imaging for Intra-Beam Range Verification and Delivery Optimization: A Simulation Feasibility Study. IEEE TRANSACTIONS ON RADIATION AND PLASMA MEDICAL SCIENCES 2021; 4:212-217. [PMID: 33778233 DOI: 10.1109/trpms.2019.2950231] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
On-line PET image-based method uses an initial particle beam to measure the particle beam range (BR) within the same fraction so that any measured range-shift with respect to the predicted BR can be compensated before the rest therapeutic beam deliveries. However, the method requires to use a low-dose initial beam to minimize the risk of beam overshooting, which leads to low image count and inaccurate BR measurement. In this in-silico study, we evaluated the feasibility of a new on-line PET imaging method that measures BR at the mid-plane of a target volume with part of the high-dose therapy beams to verify BR and guide adaptive treatment re-planning. Simulations included various processes of proton beam radiations to a tumor inside a human brain phantom, positron and PET image generation at the mid-plane with initial beams, activity range measurement, and range-shift compensated beam delivery. The results demonstrated that the new method, under the simulated conditions, can achieve ~1.1 mm mid-plane BR measurement accuracy and closely match the delivered range-shift compensated dose distribution with the planned one. Overall, it is promising that this new method may significantly improve particle therapy accuracy.
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Affiliation(s)
- Yuncheng Zhong
- Division of Medical Physics and Engineering Department of Radiation Oncology University of Texas Southwestern Medical Center Dallas, Texas 75390 USA
| | - Weiguo Lu
- Division of Medical Physics and Engineering Department of Radiation Oncology University of Texas Southwestern Medical Center Dallas, Texas 75390 USA
| | - Mingli Chen
- Division of Medical Physics and Engineering Department of Radiation Oncology University of Texas Southwestern Medical Center Dallas, Texas 75390 USA
| | - Zhenyu Xiong
- Division of Medical Physics and Engineering Department of Radiation Oncology University of Texas Southwestern Medical Center Dallas, Texas 75390 USA
| | - Xinyi Cheng
- Division of Medical Physics and Engineering Department of Radiation Oncology University of Texas Southwestern Medical Center Dallas, Texas 75390 USA
| | - Kun Hu
- Division of Medical Physics and Engineering Department of Radiation Oncology University of Texas Southwestern Medical Center Dallas, Texas 75390 USA
| | - Yiping Shao
- Division of Medical Physics and Engineering Department of Radiation Oncology University of Texas Southwestern Medical Center Dallas, Texas 75390 USA
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Thaper D, Kamal R, Singh G, Oinam AS, Yadav HP, Kumar V. Derivative-based gamma index: a novel methodology for stringent patient-specific quality assurance in the stereotactic treatment planning of liver cancer. Biomed Phys Eng Express 2020; 6. [PMID: 35125347 DOI: 10.1088/2057-1976/ababf3] [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: 04/11/2020] [Accepted: 08/03/2020] [Indexed: 11/12/2022]
Abstract
Objective:The development of a stringent derivative-based gamma (DBG) index for patient-specific QA in stereotactic radiotherapy treatment planning (SRTP) to account for the spatial change in dose.Methods:Twenty-five patients of liver SBRT were selected retrospectively for this study. Deliberately, two different kinds of treatment planning approaches were used for each patient. Firstly, the treatment plans were generated using a conventional treatment planning (CTP) approach in which the target was covered with a homogeneous dose along with the nominal dose fall-off around the treatment field. Subsequently, the other treatment plans were generated using an SRTP approach with the intent of heterogeneous dose within the target region along with a steeper dose gradient outside the treatment field as much as possible. For both kinds of treatment plans, two dimensional (2D) conventional gamma (CG) and DBG analysis were performed using the 2D ion chamber array and radiochromic film.Results:Difference in the DBG index was statistically significant whereas, for CG analysis, the difference in CG index was insignificant for both types of treatment plans (CTP and SRTP). A significant positive correlation was observed between the difference in the DBG index and the difference in HI for high gamma criteria.Conclusion:The DBG evaluation is found to be more rigorous, and sensitive to the only SRTP. The proposed method could be opted-in the routine clinical practice in addition to CG.Advances in knowledge:DBG is more sensitive to detect the spatial change of dose, especially in high dose gradient regions.
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Affiliation(s)
- Deepak Thaper
- Centre for Medical Physics, Panjab University, Chandigarh, India.,Department of Radiation Oncology, Institute of Liver and Biliary Sciences, New Delhi, India
| | - Rose Kamal
- Centre for Medical Physics, Panjab University, Chandigarh, India.,Department of Radiation Oncology, Institute of Liver and Biliary Sciences, New Delhi, India
| | - Gaganpreet Singh
- Centre for Medical Physics, Panjab University, Chandigarh, India.,Department of Radiotherapy, PGIMER, Regional Cancer Centre, Chandigarh, India
| | - Arun S Oinam
- Department of Radiotherapy, PGIMER, Regional Cancer Centre, Chandigarh, India
| | - Hanuman P Yadav
- Department of Radiation Oncology, Institute of Liver and Biliary Sciences, New Delhi, India
| | - Vivek Kumar
- Centre for Medical Physics, Panjab University, Chandigarh, India
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Baran M, Kabat D, Tulik M, Rzecki K, Sośnicki T, Tabor Z. Statistical approach to the selection of the tolerances for distance to agreement improves the quality control of the dose delivery in radiotherapy. ACTA ACUST UNITED AC 2020; 65:145004. [DOI: 10.1088/1361-6560/ab86d5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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14
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Yu L, Kairn T, Trapp JV, Crowe SB. Characteristics of inverse gamma histograms. Phys Eng Sci Med 2020; 43:659-664. [PMID: 32462506 DOI: 10.1007/s13246-020-00873-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 04/20/2020] [Indexed: 11/26/2022]
Abstract
This work explores the characteristics of the inverse gamma histogram and its potential use as part of the patient specific quality assurance (PSQA) program for volumetric modulated arc therapy (VMAT). ArcCheck measured dose files and TPS predicted dose files were imported and analysed using the in-house inverse gamma code developed in the Python package. Inverse gamma with fixed distance-to-agreement of 2 mm were calculated for 23 VMAT arcs. Dose difference histograms were plotted for six arbitrarily selected arcs with the 95th and 90th percentile values calculated. Dose difference histograms enabled visualisation of the dose difference distribution information. The 95th and 90th percentile values are equivalent to the dose difference criteria where the gamma pass rate is 95% and 90% respectively. These values can be used as a guide to assess plan acceptability, especially for plans that failed the initial gamma evaluation. The inverse gamma histograms are demonstrated to be a useful tool for plan evaluation in addition to the traditional gamma evaluation method. It contains dose difference or distance-to-agreement distribution information, which could be clinically useful for plan evaluation.
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Affiliation(s)
- Liting Yu
- Royal Brisbane & Women's Hospital, Herston, 4029, Australia.
- Queensland University of Technology, Brisbane, 4000, Australia.
| | - Tanya Kairn
- Royal Brisbane & Women's Hospital, Herston, 4029, Australia
- Queensland University of Technology, Brisbane, 4000, Australia
| | - Jamie V Trapp
- Queensland University of Technology, Brisbane, 4000, Australia
| | - Scott B Crowe
- Royal Brisbane & Women's Hospital, Herston, 4029, Australia
- Queensland University of Technology, Brisbane, 4000, Australia
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15
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Yu L, Kairn T, Trapp J, Crowe SB. Technical note: A modified gamma evaluation method for dose distribution comparisons. J Appl Clin Med Phys 2019; 20:193-200. [PMID: 31282112 PMCID: PMC6612697 DOI: 10.1002/acm2.12606] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 01/25/2019] [Accepted: 02/20/2019] [Indexed: 11/09/2022] Open
Abstract
Purpose In this work we have developed a novel method of dose distribution comparison, the inverse gamma (IG) evaluation, by modifying the commonly used gamma evaluation method. Methods The IG evaluation calculates the gamma criteria (dose difference criterion, ΔD, or distance‐to‐agreement criterion, Δd) that are needed to achieve a predefined pass rate or gamma agreement index (GAI). In‐house code for evaluating IG with a fixed ΔD of 3% was developed using Python (v3.5.2) and investigated using treatment plans and measurement data from 25 retrospective patient specific quality assurance tests (53 individual arcs). Results It was found that when the desired GAI was set to 95%, approximately three quarters of the arcs tested were able to achieve Δd within 1 mm (mean Δd: 0.7 ± 0.5 mm). The mean Δd required in order for all points to pass the gamma evaluation (i.e., GAI = 100%) was 4.5 ± 3.1 mm. The possibility of evaluating IG by fixing the Δd or ΔD/Δd, instead of fixing the ΔD at 3%, was also investigated. Conclusion The IG method and its indices have the potential to be implemented clinically to quantify the minimum dose and distance criteria based on a specified GAI. This method provides additional information to augment standard gamma evaluation results during patient specific quality assurance testing of individual treatment plans. The IG method also has the potential to be used in retrospective audits to determine an appropriate set of local gamma criteria and action levels based on a cohort of patient specific quality assurance plans.
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Affiliation(s)
- Liting Yu
- Royal Brisbane & Women's Hospital, Herston, QLD, Australia.,Queensland University of Technology, Brisbane, QLD, Australia
| | - Tanya Kairn
- Royal Brisbane & Women's Hospital, Herston, QLD, Australia.,Queensland University of Technology, Brisbane, QLD, Australia
| | - Jamie Trapp
- Queensland University of Technology, Brisbane, QLD, Australia
| | - Scott B Crowe
- Royal Brisbane & Women's Hospital, Herston, QLD, Australia.,Queensland University of Technology, Brisbane, QLD, Australia
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Diamantopoulos S, Platoni K, Patatoukas G, Karaiskos P, Kouloulias V, Efstathopoulos E. Treatment plan verification: A review on the comparison of dose distributions. Phys Med 2019; 67:107-115. [PMID: 31706146 DOI: 10.1016/j.ejmp.2019.10.029] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 10/10/2019] [Accepted: 10/15/2019] [Indexed: 10/25/2022] Open
Abstract
PURPOSE The aim of this review article is to provide a useful reference for dose comparison techniques within the frame of treatment plan verification. Each technique is presented with a general description given along with advantages and disadvantage and the rationale for its development. METHODS The review was conducted in PubMed from 1993 to 2019 including articles referring to the methodology of dose comparison for treatment plan verification. RESULTS The search identified thirty-one dose comparison methods that were categorized according to the number of physical parameters that take into account for dose comparison. CONCLUSIONS Among the available methods for the comparison of two dose distributions, the γ-analysis (gamma analysis) has been widely adopted as the gold standard in verification procedures. However, due to various intrinsic limitations of gamma index, the development of a better metric taking into account both statistical and in clinical parameters is required.
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Affiliation(s)
- Stefanos Diamantopoulos
- 2nd Department of Radiology, University General Hospital "Attikon", National and Kapodistrian, University of Athens, Greece.
| | - Kalliopi Platoni
- 2nd Department of Radiology, University General Hospital "Attikon", National and Kapodistrian, University of Athens, Greece
| | - Georgios Patatoukas
- 2nd Department of Radiology, University General Hospital "Attikon", National and Kapodistrian, University of Athens, Greece
| | - Pantelis Karaiskos
- Medical Physics Laboratory, Medical School, National and Kapodistrian University of Athens, Greece
| | - Vassilis Kouloulias
- 2nd Department of Radiology, University General Hospital "Attikon", National and Kapodistrian, University of Athens, Greece
| | - Efstathios Efstathopoulos
- 2nd Department of Radiology, University General Hospital "Attikon", National and Kapodistrian, University of Athens, Greece
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Zhong Y, Vinogradskiy Y, Chen L, Myziuk N, Castillo R, Castillo E, Guerrero T, Jiang S, Wang J. Technical Note: Deriving ventilation imaging from 4DCT by deep convolutional neural network. Med Phys 2019; 46:2323-2329. [PMID: 30714159 DOI: 10.1002/mp.13421] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 12/20/2018] [Accepted: 01/22/2019] [Indexed: 01/10/2023] Open
Abstract
PURPOSE Ventilation images can be derived from four-dimensional computed tomography (4DCT) by analyzing the change in HU values and deformable vector fields between different respiration phases of computed tomography (CT). As deformable image registration (DIR) is involved, accuracy of 4DCT-derived ventilation image is sensitive to the choice of DIR algorithms. To overcome the uncertainty associated with DIR, we develop a method based on deep convolutional neural network (CNN) to derive ventilation images directly from the 4DCT without explicit image registration. METHODS A total of 82 sets of 4DCT and ventilation images from patients with lung cancer were used in this study. In the proposed CNN architecture, the CT two-channel input data consist of CT at the end of exhale and the end of inhale phases. The first convolutional layer has 32 different kernels of size 5 × 5 × 5, followed by another eight convolutional layers each of which is equipped with an activation layer (ReLU). The loss function is the mean-squared-error (MSE) to measure the intensity difference between the predicted and reference ventilation images. RESULTS The predicted images were comparable to the label images of the test data. The similarity index, correlation coefficient, and Gamma index passing rate averaged over the tenfold cross validation were 0.880 ± 0.035, 0.874 ± 0.024, and 0.806 ± 0.014, respectively. CONCLUSIONS The results demonstrate that deep CNN can generate ventilation imaging from 4DCT without explicit deformable image registration, reducing the associated uncertainty.
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Affiliation(s)
- Yuncheng Zhong
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | | | - Liyuan Chen
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Nick Myziuk
- Department of Radiation Oncology, Beaumont Health System, Royal Oak, MI, USA
| | - Richard Castillo
- Department of Radiation Oncology, Emory University, Atlanta, GA, USA
| | - Edward Castillo
- Department of Radiation Oncology, Beaumont Health System, Royal Oak, MI, USA
| | - Thomas Guerrero
- Department of Radiation Oncology, Beaumont Health System, Royal Oak, MI, USA
| | - Steve Jiang
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Jing Wang
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, USA
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Fang R, Mazur T, Mutic S, Khan R. The impact of mass density variations on an electron Monte Carlo algorithm for radiotherapy dose calculations. PHYSICS & IMAGING IN RADIATION ONCOLOGY 2018; 8:1-7. [PMID: 33458409 PMCID: PMC7807677 DOI: 10.1016/j.phro.2018.10.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 10/19/2018] [Accepted: 10/23/2018] [Indexed: 01/21/2023]
Abstract
Background and Purpose A key step in electron Monte Carlo dose calculation requires converting Computed Tomography (CT) numbers from a tomographic acquisition to a mass density. This study investigates the dosimetric consequences of perturbations applied to a calibration table between CT number and mass density. Materials and Methods A literature search was performed to define lower and upper bounds for physically reasonable perturbations to a reference CT number to mass density calibration table. Electron beam dose was calculated for ten patients using these variations and the results were compared to clinical plans originally derived with a reference calibration table. Dose differences both globally and in the Planning Target Volume (PTV) were assessed using dose- and volume-based metrics and 3- dimensional gamma analysis for each patient. Results Small but statistically significant differences were observed between perturbations and reference data for certain metrics including volume of the 50% prescription isodose. Upper and lower variations in CT number to mass density calibration yielded mean values of V50% that were 4.4% larger and 2.1% smaller than reference values respectively. Gamma analysis using 3%/3mm criteria indicated >99% passing rate for the PTV for all patients. Global gamma analysis for some patients showed larger discrepancies possibly due to large electron path lengths through inhomogeneities. Conclusions In most patients, physically reasonable perturbations in CT number to mass density curves will not induce clinically significant impact on calculated target dose distributions. Strong dependence of electron transport on voxel material may produce dose speckle throughout the volume. Care should be taken in evaluating critical structures at depths beyond the target volume in highly heterogeneous regions.
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Affiliation(s)
- Raymond Fang
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, USA
| | - Thomas Mazur
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, USA
| | - Sasa Mutic
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, USA
| | - Rao Khan
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, USA
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Kim DS, Kim S, Kang SH, Kim TH, Park SH, Kim KH, Cho MS, Shin DS, Noh YY, Chung JB, Suh TS. To propose adding index of achievement (IOA) to IMRT QA process. Radiat Oncol 2018; 13:112. [PMID: 29903025 PMCID: PMC6003087 DOI: 10.1186/s13014-018-1055-5] [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: 12/22/2017] [Accepted: 05/28/2018] [Indexed: 11/28/2022] Open
Abstract
Background In intensity modulated radiation therapy (IMRT) quality assurance (QA), evaluation of QA result using a pass/non-pass strategy under an acceptance criterion often suffers from lack of information on how good the plan is in absolute manner. In this study, we suggested adding an index system, previously developed for dose painting technique, to current IMRT QA process for better understanding of QA result. Methods The index system consists of three indices, index of achievement (IOA), index of hotness (IOH) and index of coldness (IOC). As indicated by its name, IOA does measure the level of agreement. IOH and IOC, on the other hand, measure the magnitude of overdose and underdose, respectively. A systematic analysis was performed with three 1-dimensional hypothetical dose distributions to investigate the characteristics of the index system. The feasibility of the system was also assessed with clinical volumetric modulated arc therapy (VMAT) QA cases from 8 head & neck and 5 prostate patients. In both simulation studies, certain amount of errors was intentionally induced to each dose distribution. Furthermore, we applied the proposed system to compare calculated with actual measured data for a total of 60 patients (30 head & neck and 30 prostate cases). QA analysis was made using both the index system and gamma method, and results were compared. Results While the gamma evaluation showed limited sensitivity in evaluating QA result depending on the level of tolerance criteria used, the proposed indices tended to better distinguish plans in terms of the amount of errors. Hotness and coldness of prescribed dose in the plan could be evaluated quantitatively by the indices. Conclusions The proposed index system provides information with which IMRT QA result would be better evaluated, especially when gamma pass rates are identical or similar among multiple plans. In addition, the independency of the index system on acceptance criteria would help making clear communications among readers of published articles and researchers in multi-institutional studies.
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Affiliation(s)
- Dong-Su Kim
- Department of Biomedical Engineering and Research Institute of Biomedical Engineering, College of Medicine, The Catholic University of Korea, 222. Banpo-daero, Seocho-gu, Seoul, 06591, South Korea
| | - Siyong Kim
- Department of Radiation Oncology, Virginia Commonwealth University, 401 College Street, Richmond, VA, 23298-0058, USA.
| | - Seong-Hee Kang
- Department of Biomedical Engineering and Research Institute of Biomedical Engineering, College of Medicine, The Catholic University of Korea, 222. Banpo-daero, Seocho-gu, Seoul, 06591, South Korea.,Department of Radiation Oncology, Seoul National University Bundang Hospital, Gumi-ro 173 beon-gil, Bundang-gu, Seongnam-si, Gyeonggi-do, 13620, South Korea
| | - Tae-Ho Kim
- Department of Biomedical Engineering and Research Institute of Biomedical Engineering, College of Medicine, The Catholic University of Korea, 222. Banpo-daero, Seocho-gu, Seoul, 06591, South Korea
| | - So-Hyun Park
- Department of Radiation Oncology, Jeju National University Hospital, 15, Aran 13-gil, Jeju-si, Jeju-do, 63241, South Korea
| | - Kyeong-Hyeon Kim
- Department of Biomedical Engineering and Research Institute of Biomedical Engineering, College of Medicine, The Catholic University of Korea, 222. Banpo-daero, Seocho-gu, Seoul, 06591, South Korea
| | - Min-Seok Cho
- Department of Radiation Oncology, Asan Medical Center, 88, Olympic-ro 43-gil, Songpa-gu, Seoul, 05505, South Korea
| | - Dong-Seok Shin
- Department of Biomedical Engineering and Research Institute of Biomedical Engineering, College of Medicine, The Catholic University of Korea, 222. Banpo-daero, Seocho-gu, Seoul, 06591, South Korea
| | - Yu-Yun Noh
- Department of Radiation Oncology, Eulji University Hospital, 95, Dunsanseo-ro, Seo-gu, Daejeon, 35233, South Korea
| | - Jin-Beom Chung
- Department of Radiation Oncology, Seoul National University Bundang Hospital, Gumi-ro 173 beon-gil, Bundang-gu, Seongnam-si, Gyeonggi-do, 13620, South Korea
| | - Tae Suk Suh
- Department of Biomedical Engineering and Research Institute of Biomedical Engineering, College of Medicine, The Catholic University of Korea, 222. Banpo-daero, Seocho-gu, Seoul, 06591, South Korea.
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Zavan R, McGeachy P, Madamesila J, Villarreal‐Barajas J, Khan R. Verification of Acuros XB dose algorithm using 3D printed low-density phantoms for clinical photon beams. J Appl Clin Med Phys 2018; 19:32-43. [PMID: 29575596 PMCID: PMC5978687 DOI: 10.1002/acm2.12299] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 10/21/2017] [Accepted: 12/06/2017] [Indexed: 11/09/2022] Open
Abstract
The transport-based dose calculation algorithm Acuros XB (AXB) has been shown to accurately account for heterogeneities primarily through comparisons with Monte Carlo simulations. This study aims to provide additional experimental verification of AXB for clinically relevant flattened and unflattened beam energies in low density phantoms of the same material. Polystyrene slabs were created using a bench-top 3D printer. Six slabs were printed at varying densities from 0.23 to 0.68 g/cm3 , corresponding to different density humanoid tissues. The slabs were used to form different single and multilayer geometries. Dose was calculated with Eclipse™ AXB 11.0.31 for 6MV, 15MV flattened and 6FFF (flattening filter free) energies for field sizes of 2 × 2 and 5 × 5 cm2 . EBT3 film was inserted into the phantoms, which were irradiated. Absolute dose profiles and 2D Gamma analyses were performed for 96 dose planes. For all single slab configurations and energies, absolute dose differences between the AXB calculation and film measurements remained <3% for both fields in the high-dose region, however, larger disagreement was seen within the penumbra. For the multilayered phantom, percentage depth dose with AXB was within 5% of discrete film measurements. The Gamma index at 2%/2 mm averaged 98% in all combinations of fields, phantoms and photon energies. The transport-based dose algorithm AXB is in good agreement with the experimental measurements for small field sizes using 6MV, 6FFF and 15MV beams adjacent to various low-density heterogeneous media. This work provides preliminary experimental grounds to support the use of AXB for heterogeneous dose calculation purposes.
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Affiliation(s)
- Rodolfo Zavan
- Department of Medical PhysicsTom Baker Cancer CenterCalgaryABCanada
| | - Philip McGeachy
- Department of Medical PhysicsTom Baker Cancer CenterCalgaryABCanada
| | | | | | - Rao Khan
- Department of Radiation OncologyWashington University School of MedicineSt. LouisMOUSA
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Atiq M, Atiq A, Iqbal K, Shamsi QA, Andleeb F, Buzdar SA. Interpretation of Gamma Index for Quality Assurance of Simultaneously Integrated Boost (SIB) IMRT Plans for Head and Neck Carcinoma. POLISH JOURNAL OF MEDICAL PHYSICS AND ENGINEERING 2017. [DOI: 10.1515/pjmpe-2017-0016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
Objective: The Gamma Index is prerequisite to estimate point-by-point difference between measured and calculated dose distribution in terms of both Distance to Agreement (DTA) and Dose Difference (DD). This study aims to inquire what percentage of pixels passing a certain criteria assure a good quality plan and suggest gamma index as efficient mechanism for dose verification of Simultaneous Integrated Boost Intensity Modulated Radiotherapy plans.
Method: In this study, dose was calculated for 14 head and neck patients and IMRT Quality Assurance was performed with portal dosimetry using the Eclipse treatment planning system. Eclipse software has a Gamma analysis function to compare measured and calculated dose distribution. Plans of this study were deemed acceptable when passing rate was 95% using tolerance for Distance to agreement (DTA) as 3mm and Dose Difference (DD) as 5%.
Result and Conclusion: Thirteen cases pass tolerance criteria of 95% set by our institution. Confidence Limit for DD is 9.3% and for gamma criteria our local CL came out to be 2.0% (i.e., 98.0% passing). Lack of correlation was found between DD and γ passing rate with R2 of 0.0509. Our findings underline the importance of gamma analysis method to predict the quality of dose calculation. Passing rate of 95% is achieved in 93% of cases which is adequate level of accuracy for analyzed plans thus assuring the robustness of SIB IMRT treatment technique. This study can be extended to investigate gamma criteria of 5%/3mm for different tumor localities and to explore confidence limit on target volumes of small extent and simple geometry.
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Affiliation(s)
- Maria Atiq
- Department of Physics , The Islamia University of Bahawalpur
| | - Atia Atiq
- Department of Physics , The Islamia University of Bahawalpur
| | - Khalid Iqbal
- Shaukat Khanum Memorial cancer hospital & research center Lahore Pakistan
| | | | - Farah Andleeb
- Department of Physics , The Islamia University of Bahawalpur
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22
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Challenges in calculation of the gamma index in radiotherapy – Towards good practice. Phys Med 2017; 36:1-11. [DOI: 10.1016/j.ejmp.2017.03.001] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 02/07/2017] [Accepted: 03/05/2017] [Indexed: 11/19/2022] Open
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Persoon L, Podesta M, Nijsten S, Troost E, Verhaegen F. Time-Resolved Versus Integrated Transit Planar Dosimetry for Volumetric Modulated Arc Therapy. Technol Cancer Res Treat 2016; 15:NP79-NP87. [PMID: 26655145 DOI: 10.1177/1533034615617668] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Revised: 09/16/2015] [Accepted: 10/23/2015] [Indexed: 11/16/2022] Open
Abstract
Purpose: It is desirable that dosimetric deviations during radiation treatments are detected. Integrated transit planar dosimetry is commonly used to evaluate external beam treatments such as volumetric-modulated arc therapy. This work focuses on patient geometry changes which result in differences between the planned and the delivered radiation dose. Integrated transit planar dosimetry will average out some deviations. Novel time-resolved transit planar dosimetry compares the delivered dose of volumetric-modulated arc therapy to the planned dose at various time points. Four patient cases are shown where time-resolved transit planar dosimetry detects patient geometry changes during treatment. Methods: A control point to control point comparison between the planned dose and the treatment dose of volumetric-modulated arc therapy beams is calculated using the planning computed tomography and the kV cone-beam computed tomography of the day and evaluated with a time-resolved γ function. Results were computed for 4 patients treated with volumetric-modulated arc therapy, each showing an anatomical change: pleural effusion, rectal gas pockets, and tumor regression. Results: In all cases, the geometrical change was detected by time-resolved transit planar dosimetry, whereas integrated transit planar dosimetry showed minor or no indication of the dose discrepancy. Both tumor regression cases were detected earlier in the treatment with time-resolved planar dosimetry in comparison to integrated transit planar dosimetry. The pleural effusion and the gas pocket were detected exclusively with time-resolved transit planar dosimetry. Conclusions: Clinical cases were presented in this proof-of-principle study in which integrated transit planar dosimetry did not detect dosimetrically relevant deviations to the same extent time-resolved transit planar dosimetry was able to. Time-resolved transit planar dosimetry also provides results that can be presented as a function of arc delivery angle allowing easier interpretation compared to integrated transit planar dosimetry.
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Affiliation(s)
- L.C.G.G. Persoon
- Department of Radiation Oncology (MAASTRO), GROW—School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - M. Podesta
- Department of Radiation Oncology (MAASTRO), GROW—School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - S.M.J.J.G. Nijsten
- Department of Radiation Oncology (MAASTRO), GROW—School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - E.G.C. Troost
- Department of Radiation Oncology (MAASTRO), GROW—School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - F. Verhaegen
- Department of Radiation Oncology (MAASTRO), GROW—School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, the Netherlands
- Medical Physics Unit, Department of Oncology, McGill University, Montréal, Québec, Canada
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Abstract
Originally developed as a tool for patient-specific quality assurance in advanced treatment delivery methods to compare between measured and calculated dose distributions, the gamma index (γ) concept was later extended to compare between any two dose distributions. It takes into effect both the dose difference (DD) and distance-to-agreement (DTA) measurements in the comparison. Its strength lies in its capability to give a quantitative value for the analysis, unlike other methods. For every point on the reference curve, if there is at least one point in the evaluated curve that satisfies the pass criteria (e.g., δDD = 1%, δDTA = 1 mm), the point is included in the quantitative score as "pass." Gamma analysis does not account for the gradient of the evaluated curve - it looks at only the minimum gamma value, and if it is <1, then the point passes, no matter what the gradient of evaluated curve is. In this work, an attempt has been made to present a derivative-based method for the identification of dose gradient. A mathematically derived reference profile (RP) representing the penumbral region of 6 MV 10 cm × 10 cm field was generated from an error function. A general test profile (GTP) was created from this RP by introducing 1 mm distance error and 1% dose error at each point. This was considered as the first of the two evaluated curves. By its nature, this curve is a smooth curve and would satisfy the pass criteria for all points in it. The second evaluated profile was generated as a sawtooth test profile (STTP) which again would satisfy the pass criteria for every point on the RP. However, being a sawtooth curve, it is not a smooth one and would be obviously poor when compared with the smooth profile. Considering the smooth GTP as an acceptable profile when it passed the gamma pass criteria (1% DD and 1 mm DTA) against the RP, the first and second order derivatives of the DDs (δD', δD") between these two curves were derived and used as the boundary values for evaluating the STTP against the RP. Even though the STTP passed the simple gamma pass criteria, it was found failing at many locations when the derivatives were used as the boundary values. The proposed derivative-based method can identify a noisy curve and can prove to be a useful tool for improving the sensitivity of the gamma index.
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Affiliation(s)
- Biplab Sarkar
- Department of Radiation Oncology, Fortis Memorial Research Institute, Gurgaon, Haryana, India; Department of Physics, GLA University, Mathura, Uttar Pradesh, India
| | - Anirudh Pradhan
- Department of Mathematics, GLA University, Mathura, Uttar Pradesh, India
| | - T Ganesh
- Department of Radiation Oncology, Fortis Memorial Research Institute, Gurgaon, Haryana, India
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Lewis D, Chan MF. Correcting lateral response artifacts from flatbed scanners for radiochromic film dosimetry. Med Phys 2015; 42:416-29. [PMID: 25563282 DOI: 10.1118/1.4903758] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE A known factor affecting the accuracy of radiochromic film dosimetry is the lateral response artifact (LRA) induced by nonuniform response of a flatbed scanner in the direction perpendicular to the scan direction. This work reports a practical solution to eliminate such artifacts for all forms of dose QA. METHODS EBT3 films from a single production lot (02181401) cut into rectangular 4 × 5 cm(2) pieces, with the long dimension parallel to the long dimension of the original 20.3 × 25.4 cm(2) sheets, were exposed at a depth of 5 cm on a Varian Trilogy at the center of a 20 × 20 cm(2) open field at seven doses between 50 and 1600 cGy using 6 MV photons. These films together with an unexposed film from the same production lot were lined one next to the other on an Epson 10000 XL or 11000 XL scanner in portrait orientation with their long dimension parallel to the scan direction. Scanned images were then obtained with the line of films positioned at seven discrete lateral locations perpendicular to the scan direction. The process was repeated in landscape orientation and on three other Epson scanners. Data were also collected for three additional production lots of EBT3 film (11051302, 03031401, and 03171403). From measurements at the various lateral positions, the scanner response was determined as a function of the lateral position of the scanned film. For a given color channel X, the response at any lateral position L is related to the response at the center, C, of the scanner by Response(C, D, X) = A(L,X) + B(L,X) ⋅ Response(L, D, X), where D is dose and the coefficients A(L,X) and B(L,X) are determined from the film measurements at the center of the scanner and six other discrete lateral positions. The values at intermediate lateral positions were obtained by linear interpolation. The coefficients were determined for the red, green, and blue color channels, preserving the ability to apply triple-channel dosimetry once corrections were applied to compensate for the lateral position response artifact. To validate this method, corrections were applied to several films that were exposed to 15 × 15 cm(2) open fields and large IMRT and VMAT fields and scanned at the extreme edges of the scan window in addition to the central location. Calibration and response data were used to generate dose maps and perform gamma analysis using single- or triple-channel dosimetry with FilmQAPro 2014 software. RESULTS The authors' study found that calibration curves at the different lateral positions could be correlated by a simple two-point rescaling using the response for unexposed film as well as the response of film exposed at high doses between 800 and 1600 cGy. The coefficients A(L,X) and BL,X for each color channel X were found to be independent of dose at each lateral location L. This made it possible to apply the relationship Response(C, D, X) = A(L,X) + B(L,X) ⋅ Response(L, D, X), to the raw film responses, permitting correction of the response values at any lateral position to an equivalent response, as if that part of the film was located at the center of the scanner. This correction method was validated for several films exposed to open as well as large IMRT and VMAT fields. CONCLUSIONS The work reported elaborates on the process using the correction procedures to eliminate the lateral response artifact and demonstrates improvements in the accuracy of radiochromic film dosimetry for the radiation therapy quality assurance applications.
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Affiliation(s)
- David Lewis
- RCF Consulting, LLC, 54 Benedict Road, Monroe, Connecticut 06468
| | - Maria F Chan
- Memorial Sloan-Kettering Cancer Center, 136 Mountain View Boulevard, Basking Ridge, New Jersey 07920
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Blanck O, Masi L, Damme MC, Hildebrandt G, Dunst J, Siebert FA, Poppinga D, Poppe B. Film-based delivery quality assurance for robotic radiosurgery: Commissioning and validation. Phys Med 2015; 31:476-83. [DOI: 10.1016/j.ejmp.2015.05.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Revised: 04/07/2015] [Accepted: 05/01/2015] [Indexed: 11/25/2022] Open
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Seravalli E, van Haaren PMA, van der Toorn PP, Hurkmans CW. A comprehensive evaluation of treatment accuracy, including end-to-end tests and clinical data, applied to intracranial stereotactic radiotherapy. Radiother Oncol 2015; 116:131-8. [PMID: 26094075 DOI: 10.1016/j.radonc.2015.06.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Revised: 04/30/2015] [Accepted: 06/04/2015] [Indexed: 10/23/2022]
Abstract
BACKGROUND AND PURPOSE A methodology is presented to quantify the uncertainty associated with linear accelerator-based frameless intracranial stereotactic radiotherapy (SRT) combining end-to-end phantom tests and clinical data. METHODS AND MATERIALS The following steps of the SRT chain were analysed: planning computed tomography (CT) and magnetic resonance (MR) scans registration, target volume delineation, CT and cone beam CT (CBCT) registration and intrafraction-patient displacement. The overall accuracy was established with an end-to-end test. The measured uncertainties were combined, deriving the total systematic (ΣT) and random (σT) error components, to estimate the GTV-PTV margin. RESULTS The uncertainty in the MR-CT registration was on average 0.40mm (averaged over AP, CC and LR directions). Rotational variations were smaller than 0.5° in all directions. Interobser variation in GTV delineation was on average 0.29mm. The uncertainty in the CBCT-CT registration was on average 0.15mm. Again, rotational variations were smaller than 0.5° in all directions. The systematic and random intrafraction displacement errors were on average 0.55mm and 0.45mm, respectively. The systematic and random positional errors from the end-to-end test were on average 0.49mm and 0.53mm, respectively. Combining these uncertainties resulted in an average ΣT=0.9mm and σT=0.7mm and an average GTV-PTV margin of 2.8mm. CONCLUSION This comprehensive methodology including end-to-end tests enabled a GTV-PTV margin calculation considering all sources of uncertainties. This generic method can also be used for other treatment sites.
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Affiliation(s)
- E Seravalli
- Department of Radiation Oncology (MAASTRO), University Medical Centre Maastricht, The Netherlands.
| | - P M A van Haaren
- Department of Radiation Oncology, Catharina Hospital, Eindhoven, The Netherlands
| | - P P van der Toorn
- Department of Radiation Oncology, Catharina Hospital, Eindhoven, The Netherlands
| | - C W Hurkmans
- Department of Radiation Oncology, Catharina Hospital, Eindhoven, The Netherlands
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Stojadinovic S, Ouyang L, Gu X, Pompoš A, Bao Q, Solberg TD. Breaking bad IMRT QA practice. J Appl Clin Med Phys 2015; 16:5242. [PMID: 26103484 PMCID: PMC5690124 DOI: 10.1120/jacmp.v16i3.5242] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 12/22/2014] [Accepted: 12/17/2014] [Indexed: 11/23/2022] Open
Abstract
Agreement between planned and delivered dose distributions for patient-specific quality assurance in routine clinical practice is predominantly assessed utilizing the gamma index method. Several reports, however, fundamentally question current IMRT QA practice due to poor sensitivity and specificity of the standard gamma index implementation. An alternative is to employ dose volume histogram (DVH)-based metrics. An analysis based on the AAPM TG 53 and ESTRO booklet No.7 recommendations for QA of treatment planning systems reveals deficiencies in the current "state of the art" IMRT QA, no matter which metric is selected. The set of IMRT benchmark plans were planned, delivered, and analyzed by following guidance of the AAPM TG 119 report. The recommended point dose and planar dose measurements were obtained using a PinPoint ionization chamber, EDR2 radiographic film, and a 2D ionization chamber array. Gamma index criteria {3% (global), 3 mm} and {3% (local), 3 mm} were used to assess the agreement between calculated and delivered planar dose distributions. Next, the AAPM TG 53 and ESTRO booklet No.7 recommendations were followed by dividing dose distributions into four distinct regions: the high-dose (HD) or umbra region, the high-gradient (HG) or penumbra region, the medium-dose (MD) region, and the low-dose (LD) region. A different gamma passing criteria was defined for each region, i.e., a "divide and conquer" (D&C) gamma method was utilized. The D&C gamma analysis was subsequently tested on 50 datasets of previously treated patients. Measured point dose and planar dose distributions compared favorably with TG 119 benchmark data. For all complex tests, the percentage of points passing the conventional {3% (global), 3 mm} gamma criteria was 97.2% ± 3.2% and 95.7% ± 1.2% for film and 2D ionization chamber array, respectively. By dividing 2D ionization chamber array dose measurements into regions and applying 3mm isodose point distance and variable local point dose difference criteria of 7%, 15%, 25%, and 40% for HD, HG, MD, and LD regions, respectively, a 93.4% ± 2.3% gamma passing rate was obtained. Identical criteria applied using the D&C gamma technique on 50 clinical treatment plans resulted in a 97.9% ± 2.3% gamma passing score. Based on the TG 119 standard, meeting or exceeding the benchmark results would indicate an exemplary IMRT QA program. In contrast to TG 119 analysis, a different scrutiny on the same set of data, which follows the AAPM TG 53 and ESTRO booklet No.7 guidelines, reveals a much poorer agreement between calculated and measured dose distributions with large local point dose differences within different dose regions. This observation may challenge the conventional wisdom that an IMRT QA program is producing acceptable results.
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Gallo JJ, Kaufman I, Powell R, Pandya S, Somnay A, Bossenberger T, Ramirez E, Reynolds R, Solberg T, Burmeister J. Single-fraction spine SBRT end-to-end testing on TomoTherapy, Vero, TrueBeam, and CyberKnife treatment platforms using a novel anthropomorphic phantom. J Appl Clin Med Phys 2015; 16:5120. [PMID: 25679169 PMCID: PMC5689980 DOI: 10.1120/jacmp.v16i1.5120] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Revised: 09/30/2014] [Accepted: 10/13/2014] [Indexed: 12/31/2022] Open
Abstract
Spine SBRT involves the delivery of very high doses of radiation to targets adjacent to the spinal cord and is most commonly delivered in a single fraction. Highly conformal planning and accurate delivery of such plans is imperative for successful treatment without catastrophic adverse effects. End-to-end testing is an important practice for evaluating the entire treatment process from simulation through treatment delivery. We performed end-to-end testing for a set of representative spine targets planned and delivered using four different treatment planning systems (TPSs) and delivery systems to evaluate the various capabilities of each. An anthropomorphic E2E SBRT phantom was simulated and treated on each system to evaluate agreement between measured and calculated doses. The phantom accepts ion chambers in the thoracic region and radiochromic film in the lumbar region. Four representative targets were developed within each region (thoracic and lumbar) to represent different presentations of spinal metastases and planned according to RTOG 0631 constraints. Plans were created using the TomoTherapy TPS for delivery using the Hi·Art system, the iPlan TPS for delivery using the Vero system, the Eclipse TPS for delivery using the TrueBeam system in both flattened and flattening filter free (FFF), and the MultiPlan TPS for delivery using the CyberKnife system. Delivered doses were measured using a 0.007 cm3 ion chamber in the thoracic region and EBT3 GAFCHROMIC film in the lumbar region. Films were scanned and analyzed using an Epson Expression 10000XL flatbed scanner in conjunction with FilmQAPro2013. All treatment platforms met all dose constraints required by RTOG 0631. Ion chamber measurements in the thoracic targets delivered an overall average difference of 1.5%. Specifically, measurements agreed with the TPS to within 2.2%, 3.2%, 1.4%, 3.1%, and 3.0% for all three measureable cases on TomoTherapy, Vero, TrueBeam (FFF), TrueBeam (flattened), and CyberKnife, respectively. Film measurements for the lumbar targets resulted in average global gamma index passing rates of 100% at 3%/3 mm, 96.9% at 2%/2mm, and 61.8% at 1%/1 mm, with a 10% minimum threshold for all plans on all platforms. Local gamma analysis was also performed with similar results. While gamma passing rates were consistently accurate across all platforms through 2%/2 mm, treatment beam-on delivery times varied greatly between each platform with TrueBeam FFF being shortest, averaging 4.4 min, TrueBeam using flattened beam at 9.5 min, TomoTherapy at 30.5 min, Vero at 19 min, and CyberKnife at 46.0 min. In spite of the complexity of the representative targets and their proximity to the spinal cord, all treatment platforms were able to create plans meeting all RTOG 0631 dose constraints and produced exceptional agreement between calculated and measured doses. However, there were differences in the plan characteristics and significant differences in the beam-on delivery time between platforms. Thus, clinical judgment is required for each particular case to determine most appropriate treatment planning/delivery platform.
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Kim JI, Park SY, Kim HJ, Kim JH, Ye SJ, Park JM. The sensitivity of gamma-index method to the positioning errors of high-definition MLC in patient-specific VMAT QA for SBRT. Radiat Oncol 2014; 9:167. [PMID: 25070065 PMCID: PMC4118611 DOI: 10.1186/1748-717x-9-167] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Accepted: 07/21/2014] [Indexed: 12/31/2022] Open
Abstract
Background To investigate the sensitivity of various gamma criteria used in the gamma-index method for patient-specific volumetric modulated arc therapy (VMAT) quality assurance (QA) for stereotactic body radiation therapy (SBRT) using a flattening filter free (FFF) photon beam. Methods Three types of intentional misalignments were introduced to original high-definition multi-leaf collimator (HD-MLC) plans. The first type, referred to Class Out, involved the opening of each bank of leaves. The second type, Class In, involved the closing of each bank of leaves. The third type, Class Shift, involved the shifting of each bank of leaves towards the ground. Patient-specific QAs for the original and the modified plans were performed with MapCHECK2 and EBT2 films. The sensitivity of the gamma-index method using criteria of 1%/1 mm, 1.5%/1.5 mm, 1%/2 mm, 2%/1 mm and 2%/2 mm was investigated with absolute passing rates according to the magnitudes of MLCs misalignments. In addition, the changes in dose-volumetric indicators due to the magnitudes of MLC misalignments were investigated. The correlations between passing rates and the changes in dose-volumetric indicators were also investigated using Spearman’s rank correlation coefficient (γ). Results The criterion of 2%/1 mm was able to detect Class Out and Class In MLC misalignments of 0.5 mm and Class Shift misalignments of 1 mm. The widely adopted clinical criterion of 2%/2 mm was not able to detect 0.5 mm MLC errors of the Class Out or Class In types, and also unable to detect 3 mm Class Shift errors. No correlations were observed between dose-volumetric changes and gamma passing rates (γ < 0.8). Conclusions Gamma criterion of 2%/1 mm was found to be suitable as a tolerance level with passing rates of 90% and 80% for patient-specific VMAT QA for SBRT when using MapCHECK2 and EBT2 film, respectively.
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Affiliation(s)
| | | | | | | | | | - Jong Min Park
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea.
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Quality assurance of Rapid Arc treatments: Performances and pre-clinical verifications of a planar detector (MapCHECK2). Phys Med 2014; 30:184-90. [DOI: 10.1016/j.ejmp.2013.05.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Revised: 04/23/2013] [Accepted: 05/13/2013] [Indexed: 11/18/2022] Open
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Hussein M, Adams EJ, Jordan TJ, Clark CH, Nisbet A. A critical evaluation of the PTW 2D-ARRAY seven29 and OCTAVIUS II phantom for IMRT and VMAT verification. J Appl Clin Med Phys 2013; 14:4460. [PMID: 24257288 PMCID: PMC5714639 DOI: 10.1120/jacmp.v14i6.4460] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2013] [Revised: 06/18/2013] [Accepted: 06/17/2013] [Indexed: 12/25/2022] Open
Abstract
Quality assurance (QA) for intensity- and volumetric-modulated radiotherapy (IMRT and VMAT) has evolved substantially. In recent years, various commercial 2D and 3D ionization chamber or diode detector arrays have become available, allowing for absolute verification with near real time results, allowing for streamlined QA. However, detector arrays are limited by their resolution, giving rise to concerns about their sensitivity to errors. Understanding the limitations of these devices is therefore critical. In this study, the sensitivity and resolution of the PTW 2D-ARRAY seven29 and OCTAVIUS II phantom combination was comprehensively characterized for use in dynamic sliding window IMRT and RapidArc verification. Measurement comparisons were made between single acquisition and a multiple merged acquisition techniques to improve the effective resolution of the 2D-ARRAY, as well as comparisons against GAFCHROMIC EBT2 film and electronic portal imaging dosimetry (EPID). The sensitivity and resolution of the 2D-ARRAY was tested using two gantry angle 0° modulated test fields. Deliberate multileaf collimator (MLC) errors of 1, 2, and 5 mm and collimator rotation errors were inserted into IMRT and RapidArc plans for pelvis and head & neck sites, to test sensitivity to errors. The radiobiological impact of these errors was assessed to determine the gamma index passing criteria to be used with the 2D-ARRAY to detect clinically relevant errors. For gamma index distributions, it was found that the 2D-ARRAY in single acquisition mode was comparable to multiple acquisition modes, as well as film and EPID. It was found that the commonly used gamma index criteria of 3% dose difference or 3 mm distance to agreement may potentially mask clinically relevant errors. Gamma index criteria of 3%/2 mm with a passing threshold of 98%, or 2%/2 mm with a passing threshold of 95%, were found to be more sensitive. We suggest that the gamma index passing thresholds may be used for guidance, but also should be combined with a visual inspection of the gamma index distribution and calculation of the dose difference to assess whether there may be a clinical impact in failed regions.
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Affiliation(s)
- Mohammad Hussein
- Royal Surrey County Hospital NHS Foundation Trust, University of Surrey.
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A comparison of the gamma index analysis in various commercial IMRT/VMAT QA systems. Radiother Oncol 2013; 109:370-6. [PMID: 24100148 DOI: 10.1016/j.radonc.2013.08.048] [Citation(s) in RCA: 111] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Revised: 08/26/2013] [Accepted: 08/31/2013] [Indexed: 11/21/2022]
Abstract
PURPOSE To investigate the variability of the global gamma index (γ) analysis in various commercial IMRT/VMAT QA systems and to assess the impact of measurement with low resolution detector arrays on γ. MATERIALS Five commercial QA systems (PTW 2D-Array, Scandidos Delta4, SunNuclear ArcCHECK, Varian EPID, and Gafchromic EBT2 film) were investigated. The response of γ analysis to deliberately introduced errors in pelvis and head & neck IMRT and RapidArc™ plans was evaluated in each system. A theoretical γ was calculated in each commercial QA system software (PTW Verisoft, Delta4 software, SNC Patient, Varian Portal Dosimetry and IBA OmniPro, respectively), using treatment planning system resolution virtual measurements and compared to an independent calculation. Error-induced plans were measured on a linear accelerator and were evaluated against the error-free dose distribution calculated using Varian Eclipse™ in the relevant phantom CT scan. In all cases, global γ was used with a 20% threshold relative to a point selected in a high dose and low gradient region. The γ based on measurement was compared against the theoretical to evaluate the response of each system. RESULTS There was statistically good agreement between the predicted γ based on the virtual measurements from each software (concordance correlation coefficient, ρc>0.92) relative to the independent prediction in all cases. For the actual measured data, the agreement with the predicted γ reduces with tightening passing criteria and the variability between the different systems increases. This indicates that the detector array configuration and resolution have greater impact on the experimental calculation of γ due to under-sampling of the dose distribution, blurring effects, noise, or a combination. CONCLUSIONS It is important to understand the response and limitations of the gamma index analysis combined with the equipment in use. For the same pass-rate criteria, different devices and software combinations exhibit varying levels of agreement with the predicted γ analysis.
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Sarkar B, Manikandan A, Nandy M, Gossman MS, Sureka CS, Ray A, Sujatha N. A mathematical approach to beam matching. Br J Radiol 2013; 86:20130238. [PMID: 23995874 DOI: 10.1259/bjr.20130238] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVE This report provides the mathematical commissioning instructions for the evaluation of beam matching between two different linear accelerators. METHODS Test packages were first obtained including an open beam profile, a wedge beam profile and a depth-dose curve, each from a 10×10 cm(2) beam. From these plots, a spatial error (SE) and a percentage dose error were introduced to form new plots. These three test package curves and the associated error curves were then differentiated in space with respect to dose for a first and second derivative to determine the slope and curvature of each data set. The derivatives, also known as bandwidths, were analysed to determine the level of acceptability for the beam matching test described in this study. RESULTS The open and wedged beam profiles and depth-dose curve in the build-up region were determined to match within 1% dose error and 1-mm SE at 71.4% and 70.8% for of all points, respectively. For the depth-dose analysis specifically, beam matching was achieved for 96.8% of all points at 1%/1 mm beyond the depth of maximum dose. CONCLUSION To quantify the beam matching procedure in any clinic, the user needs to merely generate test packages from their reference linear accelerator. It then follows that if the bandwidths are smooth and continuous across the profile and depth, there is greater likelihood of beam matching. Differentiated spatial and percentage variation analysis is appropriate, ideal and accurate for this commissioning process. ADVANCES IN KNOWLEDGE We report a mathematically rigorous formulation for the qualitative evaluation of beam matching between linear accelerators.
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Affiliation(s)
- B Sarkar
- Department of Radiation Oncology, Medical Physics Division, Advance Medicare and Research Institute Cancer Centre, Kolkata, West Bengal, India
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Wu C, Hosier KE, Beck KE, Radevic MB, Lehmann J, Zhang HH, Kroner A, Dutton SC, Rosenthal SA, Bareng JK, Logsdon MD, Asche DR. On using 3D γ-analysis for IMRT and VMAT pretreatment plan QA. Med Phys 2012; 39:3051-9. [DOI: 10.1118/1.4711755] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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