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Dosimetric verification of a commercial collapsed cone algorithm in simulated clinical situations

RADIOTHERAPY AND ONCOLOGY 2004年第1期73卷 79-88页

作者： Nisbet, A Beange, I Vollmar, HS Irvine, C Morgan, A Thwaites, DI Raigmore Hosp Dept Med Phys & Bioengn Highland Acute Hosp NHS Trust Inverness IV2 3UJ Scotland Cookridge Hosp Dept Med Phys Leeds LS16 6QB W Yorkshire England Western Gen Hosp Edinburgh EH4 2XU Midlothian Scotland

Background and purpose: This work reports a detailed study carried out in two UK radiotherapy centres of the dosimetric accuracy of the collapsed cone algorithm of a commercial treatment planning system (Helax-TMS) in simulated clinical situations. Materials and methods: Initially the accuracy of the collapsed cone algorithm in homogeneous media is evaluated for an extensive set of simple and complex fields. Water, lung and bone substitute epoxy resin material were then used to assess the algorithm in inhomogeneous media and compare its accuracy with the pencil beam algorithm currently in clinical use. Finally a semi-anatomic phantom and an anthropomorphic phantom were employed to assess the dosimetric accuracy using simulated clinical set ups. Thermoluminescence dosimeter (TLD) measurements were made with the anthropomorphic phantom and ionisation chambers otherwise. Nominal 4, 6 and 15 MV photon beams were studied. Results: For most homogeneous cases agreement between measured and calculated dose is within +/-2% or +/-2 mm, In cases with heterogeneities and simulated clinical situations it is observed that the accuracy is also generally within +/-2% or +/-2 mm. Specific instances where the difference between measured and calculated values exceed this are highlighted. Conclusions: It can be concluded that in clinical treatment planning situations where lung is present the collapsed cone algorithm should be considered in preference to pencil beam algorithms normally used but that there may still be some discrepancy between calculations and measurement. (C) 2004 Elsevier Ireland Ltd. All rights reserved.

关键词： dosimetric verification collapsed cone algorithm treatment planning systems

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Clinical Comparison of Dose Calculation Using the Enhanced collapsed cone algorithm vs. a New Monte Carlo algorithm

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STRAHLENTHERAPIE UND ONKOLOGIE 2011年第7期187卷 433-441页

作者： Fotina, Irina Kragl, Gabriele Kroupa, Bernhard Trausmuth, Robert Georg, Dietmar Med Univ Vienna Dept Radiotherapy Div Med Radiat Phys AKH Wien A-1090 Vienna Austria

Comparison of the dosimetric accuracy of the enhanced collapsed cone (eCC) algorithm with the commercially available Monte Carlo (MC) dose calculation for complex treatment techniques. A total of 8 intensity-modulated radiotherapy (IMRT) and 2 stereotactic body radiotherapy (SBRT) lung cases were calculated with eCC and MC algorithms with the treatment planning systems (TPS) Oncentra MasterPlan 3.2 (Nucletron) and Monaco 2.01 (Elekta/CMS). Fluence optimization as well as sequencing of IMRT plans was primarily performed using Monaco. Dose prediction errors were calculated using MC as reference. The dose-volume histrogram (DVH) analysis was complemented with 2D and 3D gamma evaluation. Both algorithms were compared to measurements using the Delta4 system (Scandidos). Recalculated with eCC IMRT plans resulted in lower planned target volume (PTV) coverage, as well as in lower organs-at-risk (OAR) doses up to 8%. Small deviations between MC and eCC in PTV dose (1-2%) were detected for IMRT cases, while larger deviations were observed for SBRT (up to 5%). Conformity indices of both calculations were similar;however, the homogeneity of the eCC calculated plans was slightly better. Delta4 measurements confirmed high dosimetric accuracy of both TPS. Mean dose prediction errors < 3% for PTV suggest that both algorithms enable highly accurate dose calculations under clinical conditions. However, users should be aware of slightly underestimated OAR doses using the eCC algorithm.

关键词： Dose calculation Monte Carlo collapsed cone algorithm IMRT

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Influence of calculation algorithm on dose distribution in irradiation of non-small cell lung cancer (NSCLC) - collapsed cone versus pencil beam

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STRAHLENTHERAPIE UND ONKOLOGIE 2004年第12期180卷 783-788页

作者： Koelbl, O Krieger, K Haedinger, U Sauer, O Flentje, M Univ Wurzburg Dept Radiotherapy Wurzburg Germany

Purpose:The influence of two different calculation algorithms ("pencil beam" [PB] versus "collapsed cone" [CC]) on dose distribution, as well as the dose-volume histograms (DVHs) of the planning target volume (PTV) and the organs at risk was analyzed for irradiation of Lung cancer. Material and Methods: Between 10/2001 and 02/2002 three-dimensional treatment planning was done in ten patients with lung cancer (Helax, TMS(R), V.6.01). The PTV, the ipsilateral Lung (IL) and the contralateral lung (CL) were defined in each axial CT slice (slice thickness 1 cm). Dose distributions for three-dimensional multiple-field technique were calculated using a PB and a CC algorithm, respectively. Normalization was in accordance with ICRU 50. The DVHs were analyzed relating the minimum, maximum, median and mean dose to the volumes of interest (VOI). Results: Median PTV amounted to 774 cm(3). Minimum dose within the PTV was 67.4% for CC and 75.6% for PB algorithm (p = 0.04). Using the CC algorithm, only 76.5% of the PTV was included by the 95% isodose, whereas 90.1% was included when the PB algorithm (p = 0.01) was used. Median volume of IL amounted to 1953 cm(3). Mean dose to IL was 43.0% for CC and 44.0% for PB algorithm (p = 0.02). Median volume of IL within the 80% isodose was 19.6% for CC and 24.1% for PB algorithm (p < 0.01). Median volume of CL amounted to 1847 CM3. Mean dose to CL was 17.4% for CC and 18.1% for PB algorithm (p < 0.01). Volume of CL within the 80% isodose was 3.3% for CC and 4.1% for PB algorithm (p = 0.03). Conclusion: The CC and PB calculation algorithms result in different dose distributions in case of Lung tumors. Particularly the minimum dose to the PTV, which may be relevant for tumor control, is significantly Lower for CC. Since it is generally accepted that the CC algorithm describes secondary particle transport more exactly than PB models, the use of the Latter should be critically evaluated in the treatment planning of Lung cancer.

关键词： lung cancer radiotherapy calculation algorithms collapsed cone algorithm pencil beam 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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Comparative assessment and QA measurement array validation of Monte Carlo and collapsed cone dose algorithms for small fields and clinical treatment plans

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JOURNAL OF APPLIED CLINICAL MEDICAL PHYSICS 2024年第12期25卷 e14522页

作者： Spenkelink, Guus B. Huijskens, Sophie C. Zindler, Jaap D. de Goede, Marc van der Star, Wilhelmus J. van Egmond, Jaap Petoukhova, Anna L. Haaglanden Med Ctr Dept Med Phys Leidschendam Netherlands Haaglanden Med Ctr Dept Radiat Oncol Leidschendam Netherlands HollandPTC Dept Radiotherapy Delft Netherlands

Purpose: Many studies have demonstrated superior performance of Monte Carlo (MC) over type B algorithms in heterogeneous structures. However, even in homogeneous media, MC dose simulations should outperform type B algorithms in situations of electronic disequilibrium, such as small and highly modulated fields. Our study compares MC and collapsed cone (CC) dose algorithms in RayStation 12A. Under consideration are 6 MV and 6 MV flattening filter-free (FFF) photon beams, relevant for VMAT plans such as head-and-neck and stereo- tactic lung treatments with heterogeneities, as well as plans for multiple brain metastases in one isocenter, involving highly modulated small fields. We aim to investigate collimator angle dependence of small fields and performance differences between different combinations of ArcCHECK configuration and dose algorithm. Methods: Several verification tests were performed, ranging from simple rectangular fields to highly modulated clinical plans. To evaluate and compare the performance of the models, the agreements between calculation and measurement are compared between MC and CC. Measurements include water tank measurements for test fields, ArcCHECK measurements for test fields and VMAT plans, and film dosimetry for small fields. Results and conclusions: In very small or narrow fields, our measurements reveal a strong dependency of dose output to collimator angle for VersaHD with Agility MLC, reproduced by both dose algorithms. ArcCHECK results highlight a suboptimal agreement between measurements and MC calculations for simple rectangular fields when using inhomogeneous ArcCHECK images. Therefore, we advocate for the use of homogeneous phantom images, particularly for static fields, in ArcCHECK verification with MC. MC might offer performance benefits for more modulated treatment fields. In ArcCHECK results for clinical plans, MC performed comparable to CC for 6 MV. For 6 MV FFF and the preferred homogeneous phantom image, MC resulted in consi

关键词： ArcCHECK collapsed cone algorithm Monte Carlo algorithm small field dosimetry

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Influence of calculation model on dose distribution in stereotactic radiotherapy for pulmonary targets

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INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS 2005年第1期61卷 239-249页

作者： Haedinger, U Krieger, T Flentje, M Wulf, J Univ Wurzburg Dept Radiotherapy Wurzburg Germany

Purpose: To compare the pencil beam (PB) and collapsed cone (CC)-based three-dimensional dose calculation used for stereotactic irradiation of pulmonary targets. Methods and Materials: Three-dimensional conformal dose distributions (using 6-MV and 18-MV photon beams) were generated for 33 pulmonary targets using the PB algorithm implemented in the Helax-TMS treatment planning system and then recalculated with the CC algorithm of TMS using an identical beam setup and parameters. The differences were analyzed by evaluating the dose-volume histograms for the planning target volume (PTV) and clinical target volume (CTV) and evaluating the computed absolute monitor units (MUs). The influence of the photon energy was also studied. For three cases, the results were compared with Monte-Carlo calculations. Results: Use of the CC model typically showed increased dose inhomogeneity. Owing to a more accurate modeling of secondary charged particle disequilibrium at the tumor-lung interface, the beam penumbra is broadened. The median and mean target dose decreased by 13.9% and 11.2% for the PTV and 9.2% and 9.4% for the CTV, respectively, using the CC algorithm. Consequently, the average PTV dose coverage decreased by 7.1% (SD, 6.5%). On average, the MUs calculated to achieve the prescribed dose were 5.4% (SD, 5.8%) greater for the CC algorithm. The difference in MUs between the PB and CC increased with decreasing PTV size and high photon energy (18 MV;r = -0.68), reaching 26% at the maximum. Conclusion: The absorbed dose at the lung-tumor interface calculated by the PB algorithm was considerably greater than the dose calculated using the CC algorithm. In small targets (PTV less than or equal to100 cm(3)) and for 18-MV photons, the MUs calculated with PB may lead to an insufficient dose to the target volume. (C) 2005 Elsevier Inc.

关键词： stereotactic radiotherapy lung tumors three-dimensional conformal radiotherapy pencil beam model collapsed cone algorithm Monte-Carlo calculation target dose coverage

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The influence of lateral electronic disequilibrium on the radiation treatment planning for lung cancer irradiation

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BIO-MEDICAL MATERIALS AND ENGINEERING 2004年第1期14卷 123-126页

作者： Fu, WH Dai, JR Hu, YM Chinese Acad Med Sci PUMC Canc Inst Hosp Dept Radiat Oncol Beijing 100021 Peoples R China

Using higher energy photons can obtain better target dose uniformity and skin sparing for treating deep lesions, but the effect of lacking lateral scattering in the low-density lung may degrade the target coverage. To analyze the influence of lateral electronic disequilibrium on the radiation treatment planning for lung cancer, three dimension conformal treatment (3D-CRT) plans of using 6 MV and 18 MV X-ray respectively for a lung cancer case have been worked out by using pencil beam algorithm and collapsed cone algorithm provided by Helax-TMS treatment planning system for the same radiation field arrangement for both energies. Dose volume histogram (DVH) in target and organs at risk (OARs) are used for comparison of different plans. The study shows that using pencil beam algorithm, the target DVH are similar for 6 MV and 18 MV plan. However, using collapsed cone algorithm that can make account of lateral electron scattering, the target is underdosed. The change is even more pronounced for 18 MV plan. The doses for lung and spinal cord are similar for these two energies and two algorithms. Therefore, for lung cancer, dose calculation algorithm should have the ability of handling accurately the effect of the tissue density heterogeneity. It is better to use the lower-energy photons (6 MV) than to use the higher-energy photons (18 MV).

关键词： lateral electronic disequilibrium pencil beam algorithm collapsed cone algorithm

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Advanced kernel methods vs. Monte Carlo-based dose calculation for high energy photon beams

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RADIOTHERAPY AND ONCOLOGY 2009年第3期93卷 645-653页

作者： Fotina, Irina Winkler, Peter Kuenzler, Thomas Reiterer, Jochen Simmat, Isabell Georg, Dietmar Med Univ Vienna AKH Wien Dept Radiotherapy A-1090 Vienna Austria Kaiser Franz Josef Spital Dept Radiotherapy Vienna Austria

Purpose. The aim of this study was to compare the dose calculation accuracy of advanced kernel-based methods and Monte Carlo algorithms in commercially available treatment planning systems. Materials and methods: Following dose calculation algorithms and treatment planning (TPS) systems were compared: the collapsed cone (CC) convolution algorithm available in Oncentia Masterplan, the XVMC Monte Carlo algorithm implemented in;Plan and Monaco. and the analytical anisotropic algorithm (AAA) implemented in Eclipse. Measurements were performed with a calibrated ionization chamber and radiochromic EBT type films in a homogenous polystyrene phantom and in heterogeneous lung phantoms Single beam tests, conformal treatment plans and IMRT plans were validated Dosimetric evaluations included absolute close measurements. 1D gamma-evaluation of depth-close curves and profiles using 2 mm and 2% dose difference criteria for single beam tests, and gamma-evaluation of axial planes for composite treatment plans applying 3 mm and 3% dose difference criteria Results' Absolute dosimetry revealed no large differences between MC and advanced kernel dose calculations 1D-evaluation showed significant discrepancies between depth-dose curves in different phantom geometries For the CC algorithm gamma(mean) values were 0 90 +/- 0 74 vs 0 43 +/- 0 41 in heterogeneous vs. homogeneous conditions and for the AAA gamma(mean) values were 1.13 +/- 0.91 vs 041 +/- 0.28, respectively. In general, 1D results obtained with both MC TPS were similar in both phantoms and on average equal to 0.5 both for profiles and depth-dose curves The results obtained with the CC algorithm in Heterogeneous phantoms were slightly better in comparison to the AAA algorithm. The 2D gamma-evaluation results of IMRT plans and four-field plans showed smaller mean gamma-values for MC dose calculations compared to the advanced kernel algorithms (gamma(mean) for four-field plan and IMRT obtained with Monaco MC were 0 28 and 0.5. re

关键词： Monte Carlo collapsed cone algorithm AAA algorithm EBT film dosimetry

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