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Dosimetric comparison of Acuros XB, AAA, and XVMC in stereotactic body radiotherapy for lung cancer

MEDICAL PHYSICS 2014年第8期41卷 189-197页

作者： Tsuruta, Yusuke Nakata, Manabu Nakamura, Mitsuhiro Matsuo, Yukinori Higashimura, Kyoji Monzen, Hajime Mizowaki, Takashi Hiraoka, Masahiro Kyoto Univ Hosp Div Clin Radiol Serv Kyoto 6068507 Japan Kyoto Univ Grad Sch Med Dept Radiat Oncol & Image Appl Therapy Kyoto 6068507 Japan

Purpose: To compare the dosimetric performance of Acuros XB (AXB), anisotropic analytical algorithm (AAA), and x-ray voxel Monte Carlo (XVMC) in heterogeneous phantoms and lung stereotactic body radiotherapy (SBRT) plans. Methods: Water- and lung-equivalent phantoms were combined to evaluate the percentage depth dose and dose profile. The radiation treatment machine Novalis (BrainLab AG, Feldlcirchen, Germany) with an x-ray beam energy of 6 MV was used to calculate the doses in the composite phantom at a source-to-surface distance of 100 cm with a gantry angle of 0 degrees. Subsequently, the clinical lung SBRT plans for the 26 consecutive patients were transferred from the iPlan (ver. 4.1;BrainLab AG) to the Eclipse treatment planning systems (ver. 11.0.3;Varian Medical Systems, Palo Alto, CA). The doses were then recalculated with AXB and AAA while maintaining the XVMC-calculated monitor units and beam arrangement. Then the dose-volumetric data obtained using the three different radiation dose calculation algorithms were compared. Results: The results from AXB and XVMC agreed with measurements within 3.0% for the lungequivalent phantom with a 6 x 6 cm(2) field size, whereas AAA values were higher than measurements in the heterogeneous zone and near the boundary, with the greatest difference being 4.1%. AXB and XVMC agreed well with measurements in terms of the profile shape at the boundary of the heterogeneous zone. For the lung SBRT plans, AXB yielded lower values than XVMC in terms of the maximum doses of ITV and PTV;however, the differences were within 3.0%. In addition to the dose-volumetric data, the dose distribution analysis showed that AXB yielded dose distribution calculations that were closer to those with XVMC than did AAA. Means +/- standard deviation of the computation time was 221.6 +/- 53.1 s (range, 124-358s), 66.1 +/- 16.0 s (range, 42-94 s), and 6.7 +/- 1.1 s (range, 5-9 s) for XVMC, AXB, and AAA, respectively. Conclusions: In the phantom evaluati

关键词： dose calculation algorithm small field stereotactic body radiation therapy lung cancer

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Neutron flux evaluation algorithm with a combination of Monte Carlo and removal-diffusion calculation methods for boron neutron capture therapy

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MEDICAL PHYSICS 2024年第5期51卷 3711-3724页

作者： Nojiri, Mai Takata, Takushi Hu, Naonori Sakurai, Yoshinori Suzuki, Minoru Tanaka, Hiroki Kyoto Univ Grad Sch Engn Dept Nucl Engn Kyoto Japan Kyoto Univ Inst Integrated Radiat & Nucl Sci Osaka Japan Osaka Med & Pharmaceut Univ Kansai BNCT Med Ctr Takatsuki Osaka Japan Kumatori Cho Takatsuki Osaka 5690801 Japan

BackgroundIn Japan, the clinical treatment of boron neutron capture therapy (BNCT) has been applied to unresectable, locally advanced, and recurrent head and neck carcinomas using an accelerator-based neutron source since June of 2020. Considering the increase in the number of patients receiving BNCT, efficiency of the treatment planning procedure is becoming increasingly important. Therefore, novel and rapid dose calculation algorithms must be developed. We developed a novel algorithm for calculating neutron flux, which comprises of a combination of a Monte Carlo (MC) method and a method based on the removal-diffusion (RD) theory (RD calculation method) for the purpose of dose calculation of *** present the details of our novel algorithm and the verification results of the calculation accuracy based on the MC calculation *** this study, the "MC-RD" calculation method was developed, wherein the RD calculation method was used to calculate the thermalization process of neutrons and the MC method was used to calculate the moderation process. The RD parameters were determined by MC calculations in advance. The MC-RD calculation accuracy was verified by comparing the results of the MC-RD and MC calculations with respect to the neutron flux distributions in each of the cubic and head phantoms filled with *** the MC-RD calculation results with those of MC calculations, it was found that the MC-RD calculation accurately reproduced the thermal neutron flux distribution inside the phantom, with the exception of the region near the surface of the *** MC-RD calculation method is useful for the evaluation of the neutron flux distribution for the purpose of BNCT dose calculation, except for the region near the surface.

关键词： boron neutron capture therapy dose calculation algorithm Monte Carlo method removal-diffusion treatment planning

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Characterizing 3D printing in the fabrication of variable density phantoms for quality assurance of radiotherapy

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PHYSICA MEDICA-EUROPEAN JOURNAL OF MEDICAL PHYSICS 2016年第1期32卷 242-247页

作者： Madamesila, Joseph McGeachy, Philip Barajas, J. Eduardo Villarreal Khan, Rao Univ Calgary Dept Phys Astron & Oncol Calgary AB T2N 4N2 Canada

Purpose: To present characterization, process flow, and applications of 3D fabricated low density phantoms for radiotherapy quality assurance (QA). Material and methods: A Rostock 3D printer using polystyrene was employed to print slabs of varying relative electron densities (0.18-0.75). A CT scan was used to calibrate infill-to-density and characterize uniformity of the print. Two printed low relative density rods (0.18, 0.52) were benchmarked against a commercial CT-electron-density phantom. Density scaling of Anisotropic Analytical algorithm (AAA) was tested with EBT3 film for a 0.57 slab. Gamma criterion of 3% and 3 mm was used for analysis. Results: 3D printed slabs demonstrated uniformity for densities 0.4-0.75. The printed 0.52 rod had close agreement with the commercial phantom. Dosimetric comparison for 0.57 density slab showed >95% agreement between calculation and measurements. Conclusion: 3D printing allows fabrication of variable density phantoms for QA needs of a small clinic. Crown Copyright (C) 2015 Published by Elsevier Ltd on behalf of Associazione Italiana di Fisica Medica. All rights reserved.

关键词： 3D printing Desktop phantom fabrication Experimental verification dose calculation algorithm

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Verification of Acuros XB dose algorithm using 3D printed low-density phantoms for clinical photon beams

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JOURNAL OF APPLIED CLINICAL MEDICAL PHYSICS 2018年第3期19卷 32-43页

作者： Zavan, Rodolfo McGeachy, Philip Madamesila, Joseph Villarreal-Barajas, Jose-Eduardo Khan, Rao Tom Baker Canc Clin Dept Med Phys Calgary AB Canada Washington Univ Sch Med Dept Radiat Oncol St Louis MO USA

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/cm(3), 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 x 2 and 5 x 5 cm(2). 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.

关键词： 3D Printing Acuros XB dose calculation algorithm experimental verification radiochromic film

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Dosimetric impact of orthopedic metal artifact reduction (O-MAR) on spine SBRT patients

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JOURNAL OF APPLIED CLINICAL MEDICAL PHYSICS 2015年第5期16卷 106-116页

作者： Shen, Zhilei Liu Xia, Ping Klahr, Paul Djemila, Toufik Cleveland Clin Dept Radiat Oncol Cleveland OH 44195 USA Philips Healthcare CT Business Unit Cleveland OH USA

The dosimetric impact of orthopedic metal artifact reduction (O-MAR) on spine SBRT patients has not been comprehensively studied, particularly with spinal prostheses in high-dose gradient regions. Using both phantom and patient datasets, we investigated dosimetric effects of O-MAR in combination of various metal locations and dose calculation algorithms. A physical phantom, with and without a titanium insert, was scanned. A clinical patient plan was applied to the artifact-free reference, non-O-MAR, and O-MAR phantom images with the titanium located either inside or outside of the tumor. Subsequently, five clinical patient plans were calculated with pencil beam and Monte Carlo (iPlan) on non-O-MAR and O-MAR patient images using an extended CT-density table. The dose differences for phantom plans and patient plans were analyzed using dose distributions, dose-volume histograms (DVHs), gamma index, and selected dosimetric endpoints. From both phantom plans and patient plans, O-MAR did not affect dose distributions and DVHs while minimizing metal artifacts. Among patient plans, we found that, when the same dose calculation method was used, the difference in the dosimetric endpoints between non-O-MAR and O-MAR datasets were small. In conclusion, for spine SBRT patients with spinal prostheses, O-MAR image reconstruction does not affect dose calculation accuracy while minimizing metal artifacts. Therefore, O-MAR images can be safely used for clinical spine SBRT treatment planning.

关键词： metal artifact reduction CT image reconstruction dose calculation algorithm spine SBRT Monte Carlo

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Clinical implications of different calculation algorithms in breast radiotherapy: A comparison between pencil beam and collapsed cone convolution

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PHYSICA MEDICA-EUROPEAN JOURNAL OF MEDICAL PHYSICS 2014年第4期30卷 473-481页

作者： Cilla, S. Digesu, C. Macchia, G. Deodato, F. Sallustio, G. Piermattei, A. Morganti, A. G. Univ Cattolica Sacro Cuore Fdn Ric & Cura Giovanni Paolo 2 Med Phys Unit I-86100 Campobasso Italy Univ Cattolica Sacro Cuore Fdn Ric & Cura Giovanni Paolo 2 Radiotherapy Unit I-86100 Campobasso Italy Univ Cattolica Sacro Cuore Fdn Ric & Cura Giovanni Paolo 2 Radiol Unit I-86100 Campobasso Italy Univ Cattolica Sacro Cuore Policlin Univ A Gemelli Inst Phys Rome Italy Univ Cattolica Sacro Cuore Policlin Univ A Gemelli Radiotherapy Unit Rome Italy

Background: This investigation focused on the clinical implications of the use of the Collapsed Cone Convolution algorithm (CCC) in breast radiotherapy and investigated the dosimetric differences as respect to Pencil Beam Convolution algorithm (PBC). Material and methods: 15 breast treatment plans produced using the PBC algorithm were re-calculated using the CCC algorithm with the same MUs. In a second step, plans were re-optimized using CCC algorithm with modification of wedges and beam weightings to achieve optimal coverage (CCCr plans). For each patient, dosimetric comparison was performed using the standard tangential technique (SWT) and a forward-planned IMRT technique (f-IMRT). Results: The CCC algorithm showed significant increased dose inhomogeneity. Mean and minimum PTV doses decreased by 1.4% and 2.8% (both techniques). Mean V95% decreased to 83.7% and 90.3%, respectively for the SWT and f-IMRT. V95% was correlated to the ratio of PTV and lung volumes into the treatment field. The re-optimized CCCr plans achieved similar target coverage, but high-dose volume was significantly larger (V107%: 7.6% vs 2.3% (SWT), 7.1% vs 2.1% (f-IMRT). There was a significantly increase in the ipsilateral lung volume receiving low doses (V5 Gy: 31.3% vs 26.2% in SWT, 27.0% vs 23.0% in f-IMRT). MUs needed for PTV coverage in CCCr plans were higher by 3%. Conclusions: The PBC algorithm overestimated PTV coverage in terms of all important dosimetric metrics. If previous clinical experience are based on the use of PBC model, especially needed is discussion between medical physicists and radiation oncologists to fully understand the dosimetric changes. (C) 2014 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

关键词： Collapsed cone Pencil beam dose calculation algorithm Breast cancer

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Quantification of dose differences between two versions of Acuros XB algorithm compared to Monte Carlo simulations - the effect on clinical patient treatment planning

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JOURNAL OF APPLIED CLINICAL MEDICAL PHYSICS 2015年第6期16卷 213-225页

作者： Ojala, Jarkko Kapanen, Mika Tampere Univ Hosp Dept Oncol Unit Radiotherapy Tampere Finland Tampere Univ Hosp Dept Med Phys Med Imaging Ctr Tampere Finland

commercialized implementation of linear Boltzmann transport equation solver, the Acuros XB algorithm (AXB), represents a class of most advanced type ` c' photon radiotherapy dose calculation algorithms. The purpose of the study was to quantify the effects of the modifications implemented in the more recent version 11 of the AXB (AXB11) compared to the first commercial implementation, version 10 of the AXB (AXB10), in various anatomical regions in clinical treatment planning. Both versions of the AXB were part of Varian's Eclipse clinical treatment planning system and treatment plans for 10 patients were created using intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc radiotherapy (VMAT). The plans were first created with the AXB10 and then recalculated with the AXB11 and full Monte Carlo (MC) simulations. Considering the full MC simulations as reference, a DVH analysis for gross tumor and planning target volumes (GTV and PTV) and organs at risk was performed, and also 3D gamma agreement index (GAI) values within a 15% isodose region and for the PTV were determined. Although differences up to 12% in DVH analysis were seen between the MC simulations and the AXB, based on the results of this study no general conclusion can be drawn that the modifications made in the AXB11 compared to the AXB10 would imply that the dose calculation accuracy of the AXB10 would be inferior to the AXB11 in the clinical patient treatment planning. The only clear improvement with the AXB11 over the AXB10 is the dose calculation accuracy in air cavities. In general, no large deviations are present in the DVH analysis results between the two versions of the algorithm, and the results of 3D gamma analysis do not favor one or the other. Thus it may be concluded that the results of the comprehensive studies assessing the accuracy of the AXB10 may be extended to the AXB11.

关键词： dose calculation algorithm Acuros XB AXB Monte Carlo dose calculation photon beam radiotherapy

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The influence of basic plan parameters on calculated small field output factors-A multicenter study

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PHYSICA MEDICA-EUROPEAN JOURNAL OF MEDICAL PHYSICS 2021年 88卷 98-103页

作者： Falco, Maria Daniela Fusella, Marco Clemente, Stefania Fiandra, Christian Gallio, Elena Garibaldi, Cristina Bagala, Paolo Borzi, Giuseppina Casale, Michelina Casati, Marta Consorti, Rita Delana, Anna Esposito, Marco Malatesta, Tiziana Menghi, Enrico Reggiori, Giacomo Russo, Serenella Stasi, Michele Mancosu, Pietro Univ G dAnnunzio SS Annunziata Hosp Dept Radiat Oncol Chieti Italy Veneto Inst Oncol IOV IRCCS Med Phys Dept Via Gattamelata 64 Padua Italy Azienda Osped Univ Federico II Unit Med Phys & Radioprotect Naples Italy Univ Turin Dept Oncol Radiat Oncol Turin Italy European Inst Oncol IRCCS Unit Radiat Res IEO Milan Italy Univ Campus Biomed Roma Via Alvaro del Portillo 200 Rome Italy REM Radioterapia Via Penninazzo 11 Viagrande CT Italy Azienda Osped Santa Maria Terni Struttura Semplice Fis Sanitaria Terni Italy Azienda Osped Univ Careggi Med Phys Unit Florence Italy S Filippo Neri Hosp Med Phys Unit ASL Roma 1 Rome Italy Osped S Chiara APSS Trento Serv Fis Sanitaria Trento Italy Azienda USL Toscana Ctr Med Phys Unit Via Antella 58 I-50012 Florence Italy Osped Fatebenefratelli S Giovanni Calibita Rome Fis Med Rome Italy Ist Romagnolo Studio Tumori Dino Amadori IRST Srl Med Phys Unit Ist Ricovero & Cura Carattere Sci Meldola FC Italy Humanitas Clin & Res Hosp Med Phys Unit Radiat Oncol Dept Rozzano Milan Italy AO Ordine Mauriziano Med Phys Dept Turin Italy

Purpose: The influence of basic plan parameters such as slice thickness, grid resolution, algorithm type and field size on calculated small field output factors (OFs) was evaluated in a multicentric study. Methods and materials: Three computational homogeneous water phantoms with slice thicknesses (ST) 1, 2 and 3 mm were shared among twenty-one centers to calculate OFs for 1x1, 2x2 and 3x3 cm2 field sizes (FSs) (normalized to 10x10 cm2 FS), with their own treatment planning system (TPS) and the energy clinically used for stereotactic body radiation therapy delivery. OFs were calculated for each combination of grid resolution (GR) (1, 2 and 3 mm) and ST and finally compared with the OFs measured for the TPS commissioning. A multivariate analysis was performed to test the effect of basic plan parameters on calculated OFs. Results: A total of 509 data points were collected. Calculated OFs are slightly higher than measured ones. The multivariate analysis showed that Center, GR, algorithm type, and FS are predictive variables of the difference between calculated and measured OFs (p < 0.001). As FS decreases, the spread in the difference between calculated and measured OFs became larger when increasing the GR. Monte Carlo and Analytical Anisotropic algorithms, presented a dependence on GR (p < 0.01), while Collapsed Cone Convolution and Acuros did not. The effect of the ST was found to be negligible. Conclusions: Modern TPSs slightly overestimate the calculated small field OFs compared with measured ones. Grid resolution, algorithm, center number and field size influence the calculation of small field OFs.

关键词： TPS commissioning Output factors Grid resolution Slice thickness dose calculation algorithm

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Comparison of Pencil-beam, Collapsed-cone and Monte-Carlo algorithms in Radiotherapy Treatment Planning for 6-MV photons

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JOURNAL OF THE KOREAN PHYSICAL SOCIETY 2015年第1期67卷 153-158页

作者： Kim, Sung Jin Kim, Sung Kyu Kim, Dong Ho Yeungnam Univ Dept Phys Gyongsan 712749 South Korea Eulji Univ Hosp Dept Radiat Oncol Daejeon 302799 South Korea Yeungnam Univ Dept Radiat Oncol Coll Med Taegu 705717 South Korea

Treatment planning system calculations in inhomogeneous regions may present significant inaccuracies due to loss of electronic equilibrium. In this study, three different dose calculation algorithms, pencil beam (PB), collapsed cone (CC), and Monte-Carlo (MC), provided by our planning system were compared to assess their impact on the three-dimensional planning of lung and breast cases. A total of five breast and five lung cases were calculated by using the PB, CC, and MC algorithms. Planning treatment volume (PTV) and organs at risk (OARs) delineations were performed according to our institution's protocols on the Oncentra MasterPlan image registration module, on 0.3 - 0.5 cm computed tomography (CT) slices taken under normal respiration conditions. Intensity-modulated radiation therapy (IMRT) plans were calculated for the three algorithm for each patient. The plans were conducted on the Oncentra MasterPlan (PB and CC) and CMS Monaco (MC) treatment planning systems for 6 MV. The plans were compared in terms of the dose distribution in target, the OAR volumes, and the monitor units (MUs). Furthermore, absolute dosimetry was measured using a three-dimensional diode array detector (ArcCHECK) to evaluate the dose differences in a homogeneous phantom. Comparing the dose distributions planned by using the PB, CC, and MC algorithms, the PB algorithm provided adequate coverage of the PTV. The MUs calculated using the PB algorithm were less than those calculated by using. The MC algorithm showed the highest accuracy in terms of the absolute dosimetry. Differences were found when comparing the calculation algorithms. The PB algorithm estimated higher doses for the target than the CC and the MC algorithms. The PB algorithm actually overestimated the dose compared with those calculated by using the CC and the MC algorithms. The MC algorithm showed better accuracy than the other algorithms.

关键词： dose calculation algorithm Collapsed cone algorithm Monte-Carlo algorithm

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Monte Carlo dose verification for a single-isocenter VMAT plan in multiple brain metastases

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Medical Dosimetry 2019年第4期44卷 e51-e58页

作者： Hoshida, Kento Araki, Fujio Ohno, Takeshi Tominaga, Hirofumi Komatsu, Kazuki Tamura, Kentaro Graduate School of Health Sciences Kumamoto University Kumamoto 862-0976 Japan Department of Health Sciences Faculty of Life Sciences Kumamoto University Kumamoto 862-0976 Japan Varian Medical Systems Tokyo 103-0026 Japan Ion Beam Therapy Center SAGA HIMAT Foundation Tosu 841-0033 Saga Japan

The purpose of this study was to verify the accuracy of dose calculation algorithms of a treatment planning system for a single-isocenter volumetric modulated arc therapy (VMAT) plan in multiple brain metastases, by comparing the dose distributions of treatment planning system with those of Monte Carlo (MC) simulations. We used a multitarget phantom containing 9 acrylic balls with a diameter of 15.9 mm inside a Lucy phantom measuring 17 × 17 × 17 cm³. Seven VMAT plans were created using the multitarget phantom: 1 multitarget plan (MTP) and 6 single target plans (STP). Three of the STP plans had a large jaw field setting, almost equivalent to that of the MTP, while the other plans had a jaw field setting fitted to each planning target volume. The isocenter for all VMAT plans was set to the center of the phantom. The VMAT dose distributions were calculated using the analytical anisotropic algorithm (AAA) and were also recalculated through Acuros XB (AXB) and MC simulations under the same irradiation conditions. The AAA and AXB methods tended to overestimate dosage compared with the MC method in the MTP and in STPs with large jaw field settings. The dose distribution in single-isocenter VMAT plans for multiple brain metastases was influenced by jaw field settings. Finally, we concluded that MC-VMAT dose calculations are useful for 3D dose verification of single-isocenter VMAT plans for multiple brain metastases. © 2019 American Association of Medical Dosimetrists

关键词： dose calculation algorithm Monte Carlo method Multiple brain metastases Three-dimensional gamma analysis Volumetric modulated arc therapy

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