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

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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

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

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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

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

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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

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Clinical implementation and evaluation of the Acuros dose calculation algorithm

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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

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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

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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

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Dosimetric verification of four dose calculation algorithms for spine stereotactic body radiotherapy

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JOURNAL OF RADIATION RESEARCH 2024年第1期65卷 109-118页

作者： Hirashima, Hideaki Nakamura, Mitsuhiro Nakamura, Kiyonao Matsuo, Yukinori Mizowaki, Takashi Kyoto Univ Grad Sch Med Dept Radiat Oncol & Image Appl Therapy 54 Kawahara ChoSakyo Ku Kyoto 6068507 Japan Kyoto Univ Grad Sch Med Dept Adv Med Phys 53 Kawahara ChoSakyo Ku Kyoto 6068507 Japan

The applications of Type B [anisotropic analytical algorithm (AAA) and collapsed cone (CC)] and Type C [Acuros XB (AXB) and photon Monte Carlo (PMC)] dose calculation algorithms in spine stereotactic body radiotherapy (SBRT) were evaluated. Water- and bone-equivalent phantoms were combined to evaluate the percentage depth dose and dose profile. Subsequently, 48 consecutive patients with clinical spine SBRT plans were evaluated. All treatment plans were created using AXB in Eclipse. The prescription dose was 24 Gy in two fractions at a 10 MV FFF on TrueBeam. The doses were then recalculated with AAA, CC and PMC while maintaining the AXB-calculated monitor units and beam arrangement. The dose index values obtained using the four dose calculation algorithms were then compared. The AXB and PMC dose distributions agreed with the bone-equivalent phantom measurements (within +/- 2.0%);the AAA and CC values were higher than those in the bone-equivalent phantom region. For the spine SBRT plans, PMC, AAA and CC were overestimated compared with AXB in terms of the near minimum and maximum doses of the target and organ at risk, respectively;the mean dose difference was within 4.2%, which is equivalent with within 1 Gy. The phantom study showed that the results from AXB and PMC agreed with the measurements within +/- 2.0%. However, the mean dose difference ranged from 0.5 to 1 Gy in the spine SBRT planning study when the dose calculation algorithms changed. Users should incorporate a clinical introduction that includes an awareness of these differences.

关键词： dosimetric verification dose calculation algorithm spine SBRT

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

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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

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Quantitative evaluation of dosimetric uncertainties in electron therapy by measurement and calculation using the electron Monte Carlo dose algorithm in the Eclipse treatment planning system

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JOURNAL OF APPLIED CLINICAL MEDICAL PHYSICS 2022年第1期23卷 e13478页

作者： Ali, Imad Alsbou, Nesreen Ahmad, Salahuddin Univ Oklahoma Hlth Sci Ctr Dept Radiat Oncol Oklahoma City OK USA Univ Cent Oklahoma Dept Engn & Phys Edmond OK USA

In the electron beam radiation therapy, customized blocks are mostly used to shape treatment fields to generate conformal doses. The goal of this study is to investigate quantitatively dosimetric uncertainties associated with heterogeneities, detectors used in the measurement of the beam data commissioning, and modeling of the interactions of high energy electrons with tissue. These uncertainties were investigated both by measurements with different detectors and calculations using electron Monte Carlo algorithm (eMC) in the Eclipse treatment planning system. dose distributions for different field sizes were calculated using eMC and measured with a multiple-diode-array detector (MapCheck2) for cone sizes ranging from 6 to 25 cm. The dose distributions were calculated using the CT images of the MapCheck2 and water-equivalent phantoms. In the umbra region (<20% isodose line), the eMC underestimated dose by a factor of 3 for high energy electron beams due to lack of consideration of bremsstrahlung emitted laterally that was not accounted by eMC in the low dose region outside the field. In the penumbra (20%-80% isodose line), the eMC overestimated dose (40%) for high energy 20 MeV electrons compared to the measured dose with small diodes in the high gradient dose region. This was mainly due to lack of consideration of volume averaging of the ion chamber used in beam data commissioning which was input to the eMC dose calculation algorithm. Large uncertainties in the CT numbers (25%) resulted from the image artifacts in the CT images of the MapCheck2 phantom due to metal artifacts. The eMC algorithm used the electron and material densities extracted from the CT numbers which resulted large dosimetric uncertainties (10%) in the material densities and corresponding stopping power ratios. The dose calculations with eMC are associated with large uncertainties particularly in penumbra and umbra regions and around heterogeneities which affect the low dose level that cover nearb

关键词： bremsstrahlung commissioning data dose calculation algorithm dosimetric uncertainties heterogeneity correction image artifacts

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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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Dependence of volume dose indices on dose calculation algorithms for VMAT-SBRT plans for peripheral lung tumor

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MEDICAL DOSIMETRY 2019年第3期44卷 284-290页

作者： Matsuoka, Takanori Araki, Fujio Ohno, Takeshi Sakata, Junichi Tominaga, Hirofumi Kumamoto Univ Grad Sch Hlth Sci Kumamoto Japan Kumamoto Univ Fac Life Sci Dept Hlth Sci Kumamoto Japan Kumamoto Radiosurg Clin Kumamoto Japan Varian Med Syst Tokyo 1030026 Japan

The purpose of this study was to investigate the dependence of volume dose indices on dose calculation algorithms for volumetric modulated arc therapy (VMAT) for stereotactic body radiotherapy (SBRT) plans to treat peripheral lung tumors by comparing them with those of Monte Carlo (MC) calculations. VMAT-SBRT plans for peripheral lung tumors were created using the Eclipse treatment planning system (TPS) for 24 patients with nonsmall cell lung cancer. VMAT dose distributions for gross tumor volume (GTV), internal target volume (ITV), and planning target volume (PTV) were calculated using the analytical anisotropic algorithm (AAA), the Acuros XB (AXB) algorithm, and a MC algorithm. VMAT dose distributions of the 3 algorithms were compared using their volume dose indices from dose volume histograms (DVHs), a dose difference map, and 3-dimensional gamma analysis. The DVHs for GTV and ITV from AAA, AXB, and MC were in good agreement. The difference between the ITV and PTV volume dose indices from AAA and MC increased as D-98, D-95, D-80, D-50, and D-2. In particular, the difference between D-98 for PTV from AAA and MC was up to 48%. A >5% difference between D-95 for PTV from AAA and MC was 11 patients, but only 2 patients for ITV. The volume dose indices for AXB were near those of MC. AAA tended to overestimate the PTV volume dose indices compared to AXB and MC. Thus, we propose that the volume dose indices for the ITV be used because they are independent of dose calculation algorithms. (C) 2018 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

关键词： Monte Carlo (MC) dose calculation algorithm Volume prescription Peripheral lung tumor Stereotactic body radiotherapy

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