检索结果-内蒙古大学图书馆

A novel lateral disequilibrium inclusive, (LDI) pencil-beam based dose calculation algorithm: Evaluation in inhomogeneous phantoms and comparison with Monte Carlo calculations

引用

MEDICAL PHYSICS 2011年第3期38卷 1627-1634页

作者： Wertz, Hansjoerg Jahnke, Lennart Schneider, Frank Polednik, Martin Fleckenstein, Jens Lohr, Frank Wenz, Frederik Heidelberg Univ Mannheim Med Ctr Dept Radiat Oncol D-68167 Mannheim Germany

Purpose: Pencil-beam (PB) based dose calculation for treatment planning is limited by inaccuracies in regions of tissue inhomogeneities, particularly in situations with lateral electron disequilibrium as is present at tissue/lung interfaces. To overcome these limitations, a new "lateral disequilibrium inclusive" (LDI) PB based calculation algorithm was introduced. In this study, the authors evaluated the accuracy of the new model by film and ionization chamber measurements and Monte Carlo simulations. Methods: To validate the performance of the new LDI algorithm implemented in Corvus 09 (R), eight test plans were generated on inhomogeneous thorax and pelvis phantoms. In addition, three plans were calculated with a simple effective path length (EPL) algorithm on the inhomogeneous thorax phantom. To simulate homogeneous tissues, four test plans were evaluated in homogeneous phantoms (homogeneous dose calculation). Results: The mean pixel pass rates and standard deviations of the gamma 4%/4 mm test for the film measurements were (96 +/- 3)% for the plans calculated with LDI, (70 +/- 5)% for the plans calculated with EPL, and (99 +/- 1)% for the homogeneous plans. Ionization chamber measurements and Monte Carlo simulations confirmed the high accuracy of the new algorithm (dose deviations <= 4%;gamma 3%/3 mm >= 96%) Conclusions: LDI represents an accurate and fast dose calculation algorithm for treatment planning. (C) 2011 American Association of Physicists in Medicine. [DOI: 10.1118/1.3557952]

关键词： dose calculation algorithm lateral electronic disequilibrium heterogeneity correction pencil beam dose verification

来源：评论

学校读者我要写书评

暂无评论

Performance evaluation of a collapsed cone dose calculation algorithm for HDR Ir-192 of APBI treatments

引用

MEDICAL PHYSICS 2017年第10期44卷 5475-5485页

作者： Terribilini, Dario Vitzthum, Veronika Volken, Werner Frei, Daniel Loessl, Kristina van Veelen, Bob Manser, Peter Fix, Michael K. Bern Univ Hosp Dept Radiat Oncol Inselspital Div Med Radiat Phys Bern Switzerland Univ Bern Bern Switzerland Elekta Brachytherapy NL-3905 TH Veenendaal Netherlands

Purpose: Most dose calculations for HDR brachytherapy treatments are based on the AAPM-TG43 formalism. Because patient's anatomy, heterogeneities, and applicator shielding are not considered, the dose calculation based on this formalism is inaccurate in some cases. Alternatively, collapsed cone (CC) methods as well as Monte Carlo (MC) algorithms belong to the model-based dose calculation algorithms, which are expected to improve the accuracy of calculated dose distributions. In this work, the performance of a CC algorithm, ACE in Oncentra Brachy 4.5 (ACE 4.5), has been investigated by comparing the calculated dose distributions to the AAPM-TG43 and MC calculations for 10 HDR brachytherapy accelerated partial breast irradiation treatments (APBI). Comparisons were also performed with a corrected version of ACE 4.5 (ACE 4.5/corr). Methods: The brachytherapy source microSelectron mHDR-v2 (Elekta Brachytherapy) has been implemented in a MC environment and validated by comparing MC dose distributions simulated in a water phantom of 80 cm in diameter with dose distributions calculated with the AAPM-TG43 algorithm. dose distributions calculated with ACE 4.5, ACE 4.5/corr, AAPM-TG43 formalism, and MC for 10 APBI patients plans have then been computed and compared using HU scaled densities. In addition, individual dose components have been computed using ACE 4.5, ACE 4.5/corr, and MC, and compared individually. Results: Local differences between MC and AAPM-TG43 calculated dose distributions in a large water phantom are < 1%. When using HUs scaled densities for the breast cancer patients, both accuracy levels of ACE 4.5 overestimate the MC calculated dose distributions for all analyzed dosimetric parameters. In the planning target volume (PTV), ACE 4.5 (ACE 4.5/corr) overestimates on average V-100%,V-PTV by 3% 1% (1% +/- 1%) and D-50,D- (PTV) by 3% +/- 1% (1% +/- 1%) and in the organs at risk D-1cc,D- skin by 4% +/- 2% (1% +/- 1%), D-0.5cc,D- ribs by 4% +/- 2% (0% +/- 1%), an

关键词： APBI brachytherapy collapsed cone dose calculation algorithm Monte Carlo

来源：评论

学校读者我要写书评

暂无评论

Clinical implementation and evaluation of the Acuros dose calculation algorithm

引用

JOURNAL OF APPLIED CLINICAL MEDICAL PHYSICS 2017年第5期18卷 195-209页

作者： Yan, Chenyu Combine, Anthony G. Bednarz, Greg Lalonde, Ronald J. Hu, Bin Dickens, Kathy Wynn, Raymond Pavord, Daniel C. Huq, M. Saiful UPMC Dept Radiat Oncol Canc Ctr Pittsburgh PA 15213 USA Loyola Univ Loyola Univ Hlth Syst Stritch Sch Med Dept Radiat Oncol Chicago IL 60611 USA Hlth Quest Poughkeepsie NY USA

Purpose: The main aim of this study is to validate the Acuros XB dose calculation algorithm for a Varian Clinac iX linac in our clinics, and subsequently compare it with the wildely used AAA algorithm. Methods and materials: The source models for both Acuros XB and AAA were configured by importing the same measured beam data into Eclipse treatment planning system. Both algorithms were validated by comparing calculated dose with measured dose on a homogeneous water phantom for field sizes ranging from 6 cm 9 6 cm to 40 cm 9 40 cm. Central axis and off-axis points with different depths were chosen for the comparison. In addition, the accuracy of Acuros was evaluated for wedge fields with wedge angles from 15 to 60 degrees. Similarly, variable field sizes for an inhomogeneous phantom were chosen to validate the Acuros algorithm. In addition, doses calculated by Acuros and AAA at the center of lung equivalent tissue from three different VMAT plans were compared to the ion chamber measured doses in QUASAR phantom, and the calculated dose distributions by the two algorithms and their differences on patients were compared. Computation time on VMAT plans was also evaluated for Acuros and AAA. Differences between doseto- water (calculated by AAA and Acuros XB) and dose-to-medium (calculated by Acuros XB) on patient plans were compared and evaluated. Results: For open 6 MV photon beams on the homogeneous water phantom, both Acuros XB and AAA calculations were within 1% of measurements. For 23 MV photon beams, the calculated doses were within 1.5% of measured doses for Acuros XB and 2% for AAA. Testing on the inhomogeneous phantom demonstrated that AAA overestimated doses by up to 8.96% at a point close to lung/ solid water interface, while Acuros XB reduced that to 1.64%. The test on QUASAR phantom showed that Acuros achieved better agreement in lung equivalent tissue while AAA underestimated dose for all VMAT plans by up to 2.7%. Acuros XB computation time was about three ti

关键词： Acuros XB dose calculation algorithm

来源：评论

学校读者我要写书评

暂无评论

Use of a second-dose calculation algorithm to check dosimetric parameters for the dose distribution of a first-dose calculation algorithm for lung SBRT plans

引用

PHYSICA MEDICA-EUROPEAN JOURNAL OF MEDICAL PHYSICS 2017年 44卷 86-95页

作者： Tsuruta, Yusuke Nakamura, Mitsuhiro Miyabe, Yuki Nakata, Manabu Ishihara, Yoshitomo Mukumoto, Nobutaka Akimoto, Mami Ono, Tomohiro Yano, Shinsuke Higashimura, Kyoji Matsuo, Yukinori 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 verify lung stereotactic body radiotherapy (SBRT) plans using a secondary treatment planning system (TPS) as an independent method of verification and to define tolerance levels (TLs) in lung SBRT between the primary and secondary TPSs. Methods: A total of 147 lung SBRT plans calculated using X-ray voxel Monte Carlo (XVMC) were exported from iPlan to Eclipse in DICOM format. dose distributions were recalculated using the Acuros XB (AXB) and the anisotropic analytical algorithm (AAA), while maintaining monitor units (MUs) and the beam arrangement. dose to isocenter and dose-volumetric parameters, such as D-2, D-50, D-95 and D-98, were evaluated for each patient. The TLs of all parameters between XVMC and AXB (TLAXB) and between XVMC and AAA (TLAAA) were calculated as the mean +/- 1.96 standard deviations. Results: AXB values agreed with XVMC values within 3.5% for all dosimetric parameters in all patients. By contrast, AAA sometimes calculated a 10% higher dose in PTV D-95 and D-98 than XVMC. The TLAXB and TLAAA of the dose to isocenter were -0.3 +/- 1.4% and 0.6 +/- 2.9%, respectively. Those of D-95 were 1.3 +/- 1.8% and 1.7 +/- 3.6%, respectively. Conclusions: This study quantitatively demonstrated that the dosimetric performance of AXB is almost equal to that of XVMC, compared with that of AAA. Therefore, AXB is a more appropriate algorithm for an independent verification method for XVMC. (C) 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

关键词： Monitor unit verification dose calculation algorithm Independent secondary TPS Lung SBRT

来源：评论

学校读者我要写书评

暂无评论

A commercial treatment planning system with a hybrid dose calculation algorithm for synchrotron radiotherapy trials

引用

PHYSICS IN MEDICINE AND BIOLOGY 2021年第5期66卷 055016页

作者： Day, L. R. J. Donzelli, M. Pellicioli, P. Smyth, L. M. L. Barnes, M. Bartzsch, S. Crosbie, J. C. RMIT Univ Sch Sci Melbourne Vic Australia European Synchrotron Radiat Facil Biomed Beamline ID17 Grenoble France Inst Canc Res London England Grenoble Alps Univ Inserm STROBE UA7 Grenoble France Swansea Univ Med Sch Singleton Pk Swansea W Glam Wales Univ Melbourne Royal Womens Hosp Dept Obstet & Gynaecol Melbourne Vic Australia Peter MacCallum Canc Ctr Phys Sci Melbourne Vic Australia Australian Synchrotron Imaging & Med Beamline Melbourne Vic Australia Tech Univ Munich Munich Germany

Synchrotron Radiotherapy (SyncRT) is a preclinical radiation treatment which delivers synchrotron x-rays to cancer targets. SyncRT allows for novel treatments such as Microbeam Radiotherapy, which has been shown to have exceptional healthy tissue sparing capabilities while maintaining good tumour control. Veterinary trials in SyncRT are anticipated to take place in the near future at the Australian Synchrotron's Imaging and Medical Beamline (IMBL). However, before veterinary trials can commence, a computerised treatment planning system (TPS) is required, which can quickly and accurately calculate the synchrotron x-ray dose through patient CT images. Furthermore, SyncRT TPS's must be familiar and intuitive to radiotherapy planners in order to alleviate necessary training and reduce user error. We have paired an accurate and fast Monte Carlo (MC) based SyncRT dose calculation algorithm with Eclipse(TM), the most widely implemented commercial TPS in the clinic. Using Eclipse(TM), we have performed preliminary SyncRT trials on dog cadavers at the IMBL, and verified calculated doses against dosimetric measurement to within 5% for heterogeneous tissue-equivalent phantoms. We have also performed a validation of the TPS against a full MC simulation for constructed heterogeneous phantoms in Eclipse(TM), and showed good agreement for a range of water-like tissues to within 5%-8%. Our custom Eclipse(TM) TPS for SyncRT is ready to perform live veterinary trials at the IMBL.

关键词： treatment planning dosimetry synchrotron microbeam radiotherapy dose calculation algorithm

来源：评论

学校读者我要写书评

暂无评论

Dosimetric evaluation of Acuros XB Advanced dose calculation algorithm in heterogeneous media

引用

RADIATION ONCOLOGY 2011年第2011期6卷 82-82页

作者： Fogliata, Antonella Nicolini, Giorgia Clivio, Alessandro Vanetti, Eugenio Cozzi, Luca Oncol Inst So Switzerland Med Phys Unit Bellinzona Switzerland

Background: A study was realised to evaluate and determine relative figures of merit of a new algorithm for photon dose calculation when applied to inhomogeneous media. Methods: The new Acuros XB algorithm implemented in the Varian Eclipse treatment planning system was compared against a Monte Carlo method (VMC++), and the Analytical Anisotropic algorithm (AAA). The study was carried out in virtual phantoms characterized by simple geometrical structures. An insert of different material and density was included in a phantom built of skeletal-muscle and HU = 0 (setting "A"): Normal Lung (lung, 0.198 g/cm(3));Light Lung (lung, 0.035 g/cm(3));Bone (bone, 1.798 g/cm(3));another phantom (setting "B") was built of adipose material and including thin layers of bone (1.85 g/cm(3)), adipose (0.92 g/cm(3)), cartilage (1.4745 g/cm(3)), air (0.0012 g/cm(3)). Investigations were performed for 6 and 15 MV photon beams, and for a large (13 x 13 cm(2)) and a small (2.8 x 13 cm(2)) field. Results: Results are provided in terms of depth dose curves, transverse profiles and Gamma analysis (3 mm/3% and 2 mm/2% distance to agreement/dose difference criteria) in planes parallel to the beam central axis;Monte Carlo simulations were assumed as reference. Acuros XB gave an average gamma agreement, with a 3 mm/3% criteria, of 100%, 86% and 100% for Normal Lung, Light Lung and Bone settings, respectively, and dose to medium calculations. The same figures were 86%, 11% and 100% for AAA, where only dose rescaled to water calculations are possible. Conclusions: In conclusion, Acuros XB algorithm provides a valid and accurate alternative to Monte Carlo calculations for heterogeneity management.

关键词： dose calculation algorithm Acuros AAA VMC plus inhomogeneity

来源：评论

学校读者我要写书评

暂无评论

Development and evaluation of dose calculation algorithm with a combination of Monte Carlo and point-kernel methods for boron neutron capture therapy

引用

BIOMEDICAL PHYSICS & ENGINEERING EXPRESS 2023年第3期9卷 035025-035025页

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

We developed a 'hybrid algorithm' that combines the Monte Carlo (MC) and point-kernel methods for fast dose calculation in boron neutron capture therapy. The objectives of this study were to experimentally verify the hybrid algorithm and to verify the calculation accuracy and time of a 'complementary approach' adopting both the hybrid algorithm and the full-energy MC method. In the latter verification, the results were compared with those obtained using the full-energy MC method alone. In the hybrid algorithm, the moderation process of neutrons is simulated using only the MC method, and the thermalization process is modeled as a kernel. The thermal neutron fluxes calculated using only this algorithm were compared with those measured in a cubic phantom. In addition, a complementary approach was used for dose calculation in a geometry simulating the head region, and its computation time and accuracy were verified. The experimental verification indicated that the thermal neutron fluxes calculated using only the hybrid algorithm reproduced the measured values at depths exceeding a few centimeters, whereas they overestimated those at shallower depths. Compared with the calculation using only the full-energy MC method, the complementary approach reduced the computation time by approximately half, maintaining nearly same accuracy. When focusing on the calculation only using the hybrid algorithm only for the boron dose attributed to the reaction of thermal neutrons, the computation time was expected to reduce by 95% compared with the calculation using only the full-energy MC method. In conclusion, modeling the thermalization process as a kernel was effective for reducing the computation time.

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

来源：评论

学校读者我要写书评

暂无评论

dose calculation validation of a convolution algorithm in a solid water phantom

引用

PHYSICA MEDICA-EUROPEAN JOURNAL OF MEDICAL PHYSICS 2021年 89卷 193-199页

作者： Dubus, Francois Reynaert, Nick Univ Hosp Med Phys Dept Lille France Ctr Bordet Med Phys Dept Brussels Belgium

Purpose: The dose calculated using a convolution algorithm should be validated in a simple homogeneous water equivalent phantom before clinical use. The dose calculation accuracy within a solid water phantom was investigated. Methods: The specific Gamma knife design requires a dose rate calibration within a spherical solid water phantom. The TMR10 algorithm, which approximates the phantom material as liquid water, correctly computes the absolute dose in water. The convolution algorithm, which considers electron density miscalculates the dose in water as the phantom Hounsfield units were converted into higher electron density when the original CT calibration curve was used. To address this issue, the electron density of liquid water was affected by modifying the CT calibration curve. The absolute dose calculated using the convolution algorithm was compared with that computed by the TMR10. The measured depth dose profiles were also compared to those computed by the convolution and TMR10 algorithms. A patient treatment was recalculated in the solid-water phantom and the delivery quality assurance was checked. Results: The convolution algorithm and the TMR10 calculate an absolute dose within 1% when using the modified CT calibration curve. The dose depth profile calculated using the convolution algorithms was superimposed on the TMR10 and measured dose profiles when the modified CT calibration curve was applied. The Gamma index was better than 93%. Conclusions: dose calculation algorithms, which consider electron density, require a CT calibration curve adapted to the phantom material to correctly compute the dose in water.

关键词： CT calibration curve Electron density Solid water phantom dose calculation algorithm

来源：评论

学校读者我要写书评

暂无评论

Influence of dose calculation algorithms on the predicted dose distributions and NTCP values for NSCLC patients

引用

MEDICAL PHYSICS 2011年第5期38卷 2412-2418页

作者： Nielsen, Tine B. Wieslander, Elinore Fogliata, Antonella Nielsen, Morten Hansen, Olfred Brink, Carsten Univ So Denmark Lab Radiat Phys Odense Univ Hosp DK-5000 Odense Denmark Univ Lund Hosp S-22185 Lund Sweden Oncol Inst So Switzerland Med Phys Unit Bellinzona Switzerland Odense Univ Hosp Dept Oncol DK-5000 Odense Denmark

Purpose: To investigate differences in calculated doses and normal tissue complication probability (NTCP) values between different dose algorithms. Methods: Six dose algorithms from four different treatment planning systems were investigated: Eclipse AAA, Oncentra MasterPlan Collapsed Cone and Pencil Beam, Pinnacle Collapsed Cone and XiO Multigrid Superposition, and Fast Fourier Transform Convolution. Twenty NSCLC patients treated in the period 2001-2006 at the same accelerator were included and the accelerator used for treatments were modeled in the different systems. The treatment plans were recalculated with the same number of monitor units and beam arrangements across the dose algorithms. dose volume histograms of the GTV, PTV, combined lungs (excluding the GTV), and heart were exported and evaluated. NTCP values for heart and lungs were calculated using the relative seriality model and the LKB model, respectively. Furthermore, NTCP for the lungs were calculated from two different model parameter sets. calculations and evaluations were performed both including and excluding density corrections. Results: There are found statistical significant differences between the calculated dose to heart, lung, and targets across the algorithms. Mean lung dose and V-20 are not very sensitive to change between the investigated dose calculation algorithms. However, the different dose levels for the PTV averaged over the patient population are varying up to 11%. The predicted NTCP values for pneumonitis vary between 0.20 and 0.24 or 0.35 and 0.48 across the investigated dose algorithms depending on the chosen model parameter set. The influence of the use of density correction in the dose calculation on the predicted NTCP values depends on the specific dose calculation algorithm and the model parameter set. For fixed values of these, the changes in NTCP can be up to 45%. Conclusions: Calculated NTCP values for pneumonitis are more sensitive to the choice of algorithm than mean lu

关键词： dose calculation algorithm dose NTCP NSCLC density correction

来源：评论

学校读者我要写书评

暂无评论

Enhancements to commissioning techniques and quality assurance of brachytherapy treatment planning systems that use model-based dose calculation algorithms

引用

MEDICAL PHYSICS 2010年第6期37卷 2645-2658页

作者： Rivard, Mark J. Beaulieu, Luc Mourtada, Firas Tufts Univ Sch Med Dept Radiat Oncol Boston MA 02111 USA Univ Texas MD Anderson Canc Ctr Dept Expt Diagnost Imaging Houston TX 77030 USA Univ Texas MD Anderson Canc Ctr Dept Radiat Phys Houston TX 77030 USA Univ Laval CHU Quebec Dept Radiooncol Quebec City PQ G1R 2J6 Canada Univ Laval CHU Quebec Ctr Rech Cancerol Quebec City PQ G1R 2J6 Canada Univ Laval Dept Phys Genie Phys & Opt Quebec City PQ G1R 2J6 Canada

The current standard for brachytherapy dose calculations is based on the AAPM TG-43 formalism. Simplifications used in the TG-43 formalism have been challenged by many publications over the past decade. With the continuous increase in computing power, approaches based on fundamental physics processes or physics models such as the linear-Boltzmann transport equation are now applicable in a clinical setting. Thus, model-based dose calculation algorithms (MBDCAs) have been introduced to address TG-43 limitations for brachytherapy. The MBDCA approach results in a paradigm shift, which will require a concerted effort to integrate them properly into the radiation therapy community. MBDCA will improve treatment planning relative to the implementation of the traditional TG-43 formalism by accounting for individualized, patient-specific radiation scatter conditions, and the radiological effect of material heterogeneities differing from water. A snapshot of the current status of MBDCA and AAPM Task Group reports related to the subject of QA recommendations for brachytherapy treatment planning is presented. Some simplified Monte Carlo simulation results are also presented to delineate the effects MBDCA are called to account for and facilitate the discussion on suggestions for (i) new QA standards to augment current societal recommendations, (ii) consideration of dose specification such as dose to medium in medium, collisional kerma to medium in medium, or collisional kerma to water in medium, and (iii) infrastructure needed to uniformly introduce these new algorithms. Suggestions in this Vision 20/20 article may serve as a basis for developing future standards to be recommended by professional societies such as the AAPM, ESTRO, and ABS toward providing consistent clinical implementation throughout the brachytherapy community and rigorous quality management of MBDCA-based treatment planning systems. (C) 2010 American Association of Physicists in Medicine. [DOI: 10.1118/1.342913

关键词： brachytherapy dose calculation algorithm treatment planning system QA

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：