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Evaluation of the analytical anisotropic algorithm in an extreme water-lung interface phantom using Monte Carlo dose calculations

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JOURNAL OF APPLIED CLINICAL MEDICAL PHYSICS 2007年第1期8卷 33-46页

作者： Gagne, Isabelle Marie Zavgorodni, Sergei Vancouver Isl Ctr Dept Med Phys British Columbia Canc Agcy Victoria BC Canada Univ Victoria Dept Phys & Astron Victoria BC V8W 2Y2 Canada

Our study compares the performance of the analytical anisotropic algorithm ( AAA), a new superposition-convolution algorithm recently implemented in the Eclipse (Varian Medical Systems, Palo Alto, CA) Integrated Treatment Planning System (TPS), to that of the pencil beam convolution (PBC) algorithm in an extreme (C-shaped, horizontal and vertical boundaries) water-lung interface phantom. Monte Carlo ( MC) calculated dose distributions for a variety of clinical beam configurations at nominal energies of 6-MV and 18-MV are used as benchmarks in the comparison. Dose profiles extracted at three depths ( 4, 10, and 16 cm), two-dimensional (2D) maps of the dose differences, and dose difference statistics are used to quantify the accuracy of both photon-dose calculation algorithms. Results show that the AAA is considerably more accurate than the PBC, with the standard deviation of the dose differences within a region encompassing the lung block reduced by a factor of 2 and more. Confidence limits with the AAA were 4% or less for all beam configurations investigated;with the PBC, confidence limits ranged from 3.5% to 11.2%. Finally, AAA calculations for the small 4 x 4 18-MV beam, which is poorly modeled by PBC (dose differences as high as 16.1%), provided the same accuracy as the PBC model of the 6-MV beams commonly acceptable in clinical situations.

关键词： lung inhomogeneity correction Monte Carlo calculations analytical anisotropic algorithm pencil beam convolution AAA PBC

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Dosimetric comparison of analytical anisotropic algorithm and the two dose reporting modes of Acuros XB dose calculation algorithm in volumetric modulated arc therapy of carcinoma lung and carcinoma prostate

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MEDICAL DOSIMETRY 2022年第3期47卷 280-287页

作者： Gopalakrishnan, Zhenia Bhasi, Saju Raghukumar, P. V. Menon, Sharika Sarin, B. Thayil, Anna George Nair, Raghuram K. Reg Canc Ctr Div Radiat Phys Thiruvananthapuram 695011 Kerala India SUT Royal Hosp Thiruvananthapuram 695011 Kerala India

Volumetric Modulated Arc Therapy (VMAT) is an important modality for radical radiotherapy of all major treatment sites. This study aims to compare analytical anisotropic algorithm (AAA) and the two dosereporting modes of Acuros XB (AXB) algorithm -the dose to medium option (D m ) and the dose to water option (D w ) in Volumetric Modulated Arc Therapy (VMAT) of carcinoma lung and carcinoma prostate. We also compared the measured dose with Treatment Planning System calculated dose for AAA and the two dose reporting options of Acuros XB using Electronic Portal Imaging Device (EPID) and ArcCHECK phantom. Treatment plans of twenty patients each who have already undergone radiotherapy for cancer of lung and cancer of prostate were selected for the study. Three sets of VMAT plans were generated in Eclipse Treatment Planning System (TPS), one with AAA and two plans with Acuros-D m and Acuros-D w options. The Dose Volume Histograms (DVHs) were compared and analyzed for Planning Target Volume (PTV) and critical structures for all the plans. Verification plans were created for each plan and measured doses were compared with TPS calculated doses using EPID and ArcCHECK phantom for all the three algorithms. For lung plans, the mean dose to PTV in the AXB-D w plans was higher by 1.7% and in the AXB-D m plans by 0.66% when compared to AAA plans. For prostate plans, the mean dose to PTV in the AXB-D w plans was higher by 3.0% and in the AXB-D m plans by 1.6% when compared to AAA plans. There was no difference in the Conformity Index (CI) between AAA and AXB-D m and between AAA and AXBD w plans for both sites. But the homogeneity worsened in AXB-D w and AXB-D m plans when compared to AAA plans for both sites. AXB-D w calculated higher dose values for PTV and all the critical structures with significant differences with one or two exceptions. Point dose measurements in ArcCHECK phantom showed that AXB-D m and AXB-D w options showed very small deviations with measured dose distributio

关键词： Volumetric modulated arc therapy analytical anisotropic algorithm Acuros XB Dose to media (D m ) Dose to water (D w )

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Variation of the prescription dose using the analytical anisotropic algorithm in lung stereotactic body radiation therapy

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PHYSICA MEDICA-EUROPEAN JOURNAL OF MEDICAL PHYSICS 2017年 38卷 98-104页

作者： Kawai, Daisuke Takahashi, Ryo Kamima, Tatsuya Baba, Hiromi Yamamoto, Toshijiro Kubo, Yoko Ishibashi, Satoru Higuchi, Yoshihiro Tani, Kensuke Mizuno, Norifumi Jinno, Shunta Tachibana, Hidenobu Kanagawa Canc Ctr Div Radiol Technol Kanagawa 2410815 Japan Japanese Fdn Canc Res Canc Inst Hosp Dept Radiat Oncol Tokyo 1358550 Japan Natl Canc Ctr Res Ctr Innovat Oncol Particle Therapy Div Chiba 2778577 Japan Otemae Hosp Dept Radiol Technol Osaka 5400008 Japan Sasebo City Gen Hosp Dept Radiol Nagasaki 8578511 Japan St Lukes Int Hosp Dept Radiat Oncol Tokyo 1048560 Japan Komazawa Univ Grad Div Hlth Sci Tokyo 1548525 Japan

Purpose: The aim of the present investigation was to evaluate the dosimetric variation regarding the analytical anisotropic algorithm (AAA) relative to other algorithms in lung stereotactic body radiation therapy (SBRT). We conducted a multi-institutional study involving six institutions using a secondary check program and compared the AAA to the Acuros XB (AXB) in two institutions. Methods: All lung SBRT plans (128 patients) were generated using the AAA, pencil beam convolution with the Batho (PBC-B) and adaptive convolve (AC). All institutions used the same secondary check program (simple MU analysis [SMU]) implemented by a Clarkson-based dose calculation algorithm. Measurement was performed in a heterogeneous phantom to compare doses using the three different algorithms and the SMU for the measurements. A retrospective analysis was performed to compute the confidence limit (CL;mean +/- 2SD) for the dose deviation between the AAA, PBC, AC and SMU. The variations between the AAA and AXB were evaluated in two institutions, then the CL was acquired. Results: In comparing the measurements, the AAA showed the largest systematic dose error (3%). In calculation comparisons, the CLs of the dose deviation were 8.7 +/- 9.9% (AAA), 4.2 +/- 3.9% (PBC-B) and 5.7 +/- 4.9% (AC). The CLs of the dose deviation between the AXB and the AAA were 1.8 +/- 1.5% and -0.1 +/- 4.4%, respectively, in the two institutions. Conclusions: The CL of the AAA showed much larger variation than the other algorithms. Relative to the AXB, larger systematic and random deviations still appeared. Thus, care should be taken in the use of AAA for lung SBRT. (C) 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

关键词： Lung SBRT analytical anisotropic algorithm Independent dose verification

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Evaluating small field dosimetry with the Acuros XB (AXB) and analytical anisotropic algorithm (AAA) dose calculation algorithms in the eclipse treatment planning system

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JOURNAL OF RADIOTHERAPY IN PRACTICE 2019年第4期18卷 353-364页

作者： Behinaein, Sepideh Osei, Ernest Darko, Johnson Charland, Paule Bassi, Dylan Grand River Reg Canc Ctr Dept Med Phys Kitchener ON Canada Univ Waterloo Dept Phys & Astron Waterloo ON Canada Univ Guelph Ontario Vet Coll Dept Clin Studies Guelph ON Canada Univ Waterloo Dept Syst Design Engn Waterloo ON Canada

Background: An increasing number of external beam treatment modalities including intensity modulated radiation therapy, volumetric modulated arc therapy (VMAT) and stereotactic radiosurgery uses very small fields for treatment planning and delivery. However, there are major challenges in small photon field dosimetry, due to the partial occlusion of the direct photon beam source's view from the measurement point, lack of lateral charged particle equilibrium, steep dose-rate gradient and volume averaging effect of the detector response and variation of the energy fluence in the lateral direction of the beam. Therefore, experimental measurements of dosimetric parameters such as percent depth doses (PDDs), beam profiles and relative output factors (ROFs) for small fields continue to be a challenge. Materials and Methods: In this study, we used a homogeneous water phantom and the heterogeneous anthropomorphic stereotactic end-to-end verification (STEEV) head phantom for all dose measurements and calculations. PDDs, lateral dose profiles and ROFs were calculated in the Eclipse Treatment Planning System version 13.6 using the Acuros XB (AXB) and the analytical anisotropic algorithms (AAAs) in a homogenous water phantom. Monte Carlo (MC) simulations and measurements using the Exradin WI Scintillator were also accomplished for four photon energies: 6 MV, 6FFF, 10 MV and 10FFF. Two VMAT treatment plans were generated for two different targets: one located in the brain and the other in the neck (close to the trachea) in the head phantom (CIRS, Norfolk, VA, USA). A Varian Truebeam linear accelerator (Varian, Palo Alto, CA, USA) was used for all treatment deliveries. Calculated results with AXB and AAA were compared with MC simulations and measurements. Results: The average difference of PDDs between WI Exradin Scintillator measurements and MC simulations, AAA and AXB algorithm calculations were 1.2, 2.4 and 3.2%, respectively, for all field sizes and energies. AXB and AAA showe

关键词： Acuros XB analytical anisotropic algorithm EGSnrc Monte Carlo simulation Exradin W1 Scintillator measurement small field dosimetry

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Volumetric-modulated arc therapy in craniospinal irradiation: a dosimetric analysis of acuros XB and analytical anisotropic algorithm comparing flattened and flattening filter-free beams with different energies

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JOURNAL OF RADIOTHERAPY IN PRACTICE 2021年第2期20卷 196-202页

作者： Tamilarasu, Suresh Saminathan, Madeswaran Rajiv Gandhi Canc Inst & Res Ctr Sect 5 Rohini New Delhi 110085 India VIT Univ Vellore Tamil Nadu India

Aim: To compare the dosimetric performance of flattening filter-free (FFF) beam and flattened beams (FBs) utilising volumetric-modulated arc therapy (VMAT) for craniospinal irradiation (CSI) planning. Materials and Methods: Five medulloblastoma patients were randomly selected retrospectively and 40 plans were generated. The dose prescription to the planning target volume (PTV) was 36 Gy in 20 fractions. VMAT plans were created using 6 MV and 10 MV FB and FFF beam. Final dose calculations were performed using Acuros XB (AXB) and analytical anisotropic algorithm (AAA). Dosimetric parameters such as D-98%, D-95%, D-50%, V-110%, conformity index (CI), homogeneity index (HI), low-grade dose index, high-grade dose index, dose to the organ at risks (OARs) and normal tissue mean dose were noted. The effect of low-dose volume on normal tissue was also analysed. Results: The 6 MV and 10 MV flattened and FFF beam plan generates similar target coverage, and a significant difference was observed in the HI and CI. FFF beam plan produces lower doses in some of the OARs as compared to FB. Significant differences were also noted in monitor unit (MU), body-PTV mean dose and low-dose spillage regions (1-10 Gy) outside the PTV. In our study, 6 MV and 10 MV FFF beam beams need 23-25% more MUs to achieve planning goals when compared to FBs. The increased MUs in FFF plan decreases the body-PTV mean dose (0.07-0.09 Gy in 6 MV FFF and 0.31 Gy in 10 MV FFF in both algorithms) when compared to FB plans. Conclusion: FFF beams generate a highly conformal and homogenous plan in CSI cases. FFF beam plan reduced the non-tumour dose and will aid in reducing the probability of second malignancies.

关键词： Acuros XB algorithm analytical anisotropic algorithm craniospinal irradiation flattened and flattening filter-free beam

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Does dose calculation algorithm affect the dosimetric accuracy of synthetic CT for MR-only radiotherapy planning in brain tumors?

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JOURNAL OF APPLIED CLINICAL MEDICAL PHYSICS 2025年第0期 e70030页

作者： Lui, Jeffrey C. F. Lee, Francis K. H. Law, C. C. Chow, James C. H. Queen Elizabeth Hosp Dept Clin Oncol 30 Gascoigne Rd Hong Kong Peoples R China

PurposeThis study compares the dosimetric accuracy of deep-learning-based MR synthetic CT (sCT) in brain radiotherapy between the analytical anisotropic algorithm (AAA) and AcurosXB (AXB). Additionally, it proposes a novel metric to predict the dosimetric accuracy of sCT for individual post-surgical brain cases. Materials and MethodsA retrospective analysis was conducted on 20 post-surgical brain tumor patients treated with Volumetric Modulated Arc Therapy (VMAT). sCT and planning CT images were obtained for each patient. Treatment plans were optimized on sCT and recalculated on planning CT using both AAA and AXB. Dosimetric parameters and 3D global gamma analysis between sCT and planning CT were recorded. The bone volume ratio, a novel metric, was calculated for each patient and tested its correlation with gamma passing rates. ResultsFor AAA, the mean differences in Dmean and Dmax of PTV between sCT and planning CT were 0.2% and -0.2%, respectively, with no significant difference in PTV (p > 0.05). For AXB, mean differences in Dmean and Dmax of PTV were 0.3% and 0.2%, respectively, with significant differences in Dmean (p = 0.016). Mean gamma passing rates for AXB were generally lower than AAA, with the most significant drop being 9.3% using 1%/1 mm analyzed in PTV. The bone volume ratio showed significant correlation with gamma passing rates. ConclusionsCompared to AAA, AXB reveals larger dosimetric differences between sCT and planning CT in brain photon radiotherapy. For future dosimetric evaluation of sCT, it is recommended to employ AXB or Monte Carlo algorithms to achieve a more accurate assessment of sCT performance. The bone volume ratio can be used as an indicator to predict the suitability of sCT on a case-by-case basis.

关键词： AcurosXB analytical anisotropic algorithm brain deep-learning MR-only synthetic CT

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Large volume unresectable locally advanced non-small cell lung cancer: acute toxicity and initial outcome results with rapid arc

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RADIATION ONCOLOGY 2010年第2010期5卷 94-94页

作者： Scorsetti, Marta Navarria, Pierina Mancosu, Pietro Alongi, Filippo Castiglioni, Simona Cavina, Raffaele Cozzi, Luca Fogliata, Antonella Pentimalli, Sara Tozzi, Angelo Santoro, Armando IRCCS Ist Clin Humanitas Dept Radiat Oncol Milan Rozzano Italy IRCCS Ist Clin Humanitas Dept Clin Oncol Milan Rozzano Italy Oncol Inst So Switzerland Med Phys Unit Bellinzona Switzerland

Background: To report acute toxicity, initial outcome results and planning therapeutic parameters in radiation treatment of advanced lung cancer (stage III) with volumetric modulated arcs using RapidArc (RA). Methods: Twenty-four consecutive patients were treated with RA. All showed locally advanced non-small cell lung cancer with stage IIIA-IIIB and with large volumes (GTV:299 +/- 175 cm(3), PTV:818 +/- 206 cm(3)). Dose prescription was 66Gy in 33 fractions to mean PTV. Delivery was performed with two partial arcs with a 6 MV photon beam. Results: From a dosimetric point of view, RA allowed us to respect most planning objectives on target volumes and organs at risk. In particular: for GTV D-1% = 105.6 +/- 1.7%, D-99% = 96.7 +/- 1.8%, D-5%-D-95% = 6.3 +/- 1.4%;contralateral lung mean dose resulted in 13.7 +/- 3.9Gy, for spinal cord D-1% = 39.5 +/- 4.0Gy, for heart V-45Gy = 9.0 +/- 7.0Gy, for esophagus D-1% = 67.4 +/- 2.2Gy. Delivery time was 133 +/- 7s. At three months partial remission > 50% was observed in 56% of patients. Acute toxicities at 3 months showed 91% with grade 1 and 9% with grade 2 esophageal toxicity;18% presented grade 1 and 9% with grade 2 pneumonia;no grade 3 acute toxicity was observed. The short follow-up does not allow assessment of local control and progression free survival. Conclusions: RA proved to be a safe and advantageous treatment modality for NSCLC with large volumes. Long term observation of patients is needed to assess outcome and late toxicity.

关键词： Advanced NSCLC Gross Tumor Volume Advanced Lung Cancer Contralateral Lung analytical anisotropic algorithm

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