المؤلفون: Bangho Shin, Chansoo Choi, Rui Qiu, Suhyeon Kim, Hyeonil Kim, Sungho Moon, Gahee Son, Jaehyo Kim, Haegin Han, Yeon Soo Yeom, Chan Hyeong Kim

المصدر: Nuclear Engineering and Technology, Vol 56, Iss 6, Pp 2195-2207 (2024)

مصطلحات موضوعية: Photon fluence-to-skeletal dose response function, Mesh-type reference Korean phantom, Red bone marrow, Bone endosteum, Monte Carlo dose calculation, Nuclear engineering. Atomic power, TK9001-9401

الوصف: To enhance skeletal dosimetry in conjunction with the adult mesh-type reference Korean phantoms (MRKPs), Korean/Asian photon fluence-to-skeletal dose response functions (DRFs) were established utilizing an updated version of micro-CT-based detailed bone models from Tsinghua University. These bone models were incorporated into the MRKPs using the parallel geometry feature of Geant4. We calculated bone-site-specific electron absorbed fractions and used them to generate DRFs, following a similar methodology employed for ICRP-116 DRFs that have been used with the ICRP reference phantoms for skeletal dosimetry. To assess dosimetric implications of the Korean/Asian DRFs, we calculated RBM and BE doses for the MRKPs exposed to photon beams in the antero-posterior direction using the Korean/Asian and ICRP-116 DRFs. For energies ≥200 keV, the Korean/Asian DRFs-based skeletal doses exhibited excellent agreement with the ICRP-116 DRFs-based skeletal doses, attributed to the existence of charged particle equilibrium across the bone site. Conversely, significant differences of up to ∼2.3 times were observed at lower energies, due to differences in the skeletal tissue distributions of bone models used to derive the Korean/Asian and ICRP-116 DRFs. The DRFs established in this study are expected to yield more accurate skeletal doses for Korean and Asian populations compared to the ICRP-116 DRFs.

وصف الملف: electronic resource

العلاقة: http://www.sciencedirect.com/science/article/pii/S1738573324000305Test; https://doaj.org/toc/1738-5733Test

الوصول الحر: https://doaj.org/article/c9a54b6c397c42a1b5b2424f3f37bfa0Test

المؤلفون: Yewei Wang, Yaoying Liu, Yanlin Bai, Qichao Zhou, Shouping Xu, Xueying Pang

المصدر: Zeitschrift für Medizinische Physik, Vol 34, Iss 2, Pp 208-217 (2024)

مصطلحات موضوعية: deep learning, super resolution, dose calculation, generalization performance, adaptive radiotherapy, Medical physics. Medical radiology. Nuclear medicine, R895-920

الوصف: Purpose: During the radiation treatment planning process, one of the time-consuming procedures is the final high-resolution dose calculation, which obstacles the wide application of the emerging online adaptive radiotherapy techniques (OLART). There is an urgent desire for highly accurate and efficient dose calculation methods. This study aims to develop a dose super resolution-based deep learning model for fast and accurate dose prediction in clinical practice. Method: A Multi-stage Dose Super-Resolution Network (MDSR Net) architecture with sparse masks module and multi-stage progressive dose distribution restoration method were developed to predict high-resolution dose distribution using low-resolution data. A total of 340 VMAT plans from different disease sites were used, among which 240 randomly selected nasopharyngeal, lung, and cervix cases were used for model training, and the remaining 60 cases from the same sites for model benchmark testing, and additional 40 cases from the unseen site (breast and rectum) was used for model generalizability evaluation. The clinical calculated dose with a grid size of 2 mm was used as baseline dose distribution. The input included the dose distribution with 4 mm grid size and CT images. The model performance was compared with HD U-Net and cubic interpolation methods using Dose-volume histograms (DVH) metrics and global gamma analysis with 1%/1 mm and 10% low dose threshold. The correlation between the prediction error and the dose, dose gradient, and CT values was also evaluated. Results: The prediction errors of MDSR were 0.06–0.84% of Dmean indices, and the gamma passing rate was 83.1–91.0% on the benchmark testing dataset, and 0.02–1.03% and 71.3–90.3% for the generalization dataset respectively. The model performance was significantly higher than the HD U-Net and interpolation methods (p

وصف الملف: electronic resource

العلاقة: http://www.sciencedirect.com/science/article/pii/S0939388922001003Test; https://doaj.org/toc/0939-3889Test

الوصول الحر: https://doaj.org/article/cce211a6712d4f9f91fcba5fc5eb4268Test

المؤلفون: Niloofar Kargar, Ahad Zeinali, Mikaeil Molazadeh

المصدر: Journal of Biomedical Physics and Engineering, Vol 14, Iss 2, Pp 129-140 (2024)

مصطلحات موضوعية: breast neoplasms, radiotherapy, tumor control probability, normal tissue complications probability, dose calculation algorithm, models, biological, Medical physics. Medical radiology. Nuclear medicine, R895-920

الوصف: Background: Breast cancer requires evaluating treatment plans using dosimetric and biological parameters. Considering radiation dose distribution and tissue response, healthcare professionals can optimize treatment plans for better outcomes. Objective: This study aimed to evaluate the effects of the different Dose Calculation Algorithms (DCAs) and Biologically Model-Related Parameters (BMRPs) on the prediction of cardiopulmonary complications due to left breast radiotherapy. Material and Methods: In this practical study, the treatment plans of 21 female patients were simulated in the Monaco Treatment Planning System (TPS) with a prescribed dose of 50 Gy in 25 fractions. Dose distribution was extracted using the three DCAs [Pencil Beam (PB), Collapsed Cone (CC), and Monte Carlo (MC)]. Cardiopulmonary complications were predicted by Normal Tissue Complication Probability (NTCP) calculations using different dosimetric and biological parameters. The Lyman-Kutcher-Burman (LKB) and Relative-Seriality (RS) models were used to calculate NTCP. The endpoint for NTCP calculation was pneumonitis, pericarditis, and late cardiac mortality. The ANOVA test was used for statistical analysis. Results: In calculating Tumor Control Probability (TCP), a statistically significant difference was observed between the results of DCAs in the Poisson model. The PB algorithm estimated NTCP as less than others for all Pneumonia BMRPs. Conclusion: The impact of DCAs and BMRPs differs in the estimation of TCP and NTCP. DCAs have a stronger influence on TCP calculation, providing more effective results. On the other hand, BMRPs are more effective in estimating NTCP. Consequently, parameters for radiobiological indices should be cautiously used s to ensure the appropriate consideration of both DCAs and BMRPs.

وصف الملف: electronic resource

العلاقة: https://jbpe.sums.ac.ir/article_49859_5048e2f7aee5585b1e12bc64a960c29f.pdfTest; https://doaj.org/toc/2251-7200Test

الوصول الحر: https://doaj.org/article/b89a489a1c434bd3b403cac25baad0feTest

المؤلفون: Wolfgang Lechner, Dávid Kanalas, Sarah Haupt, Lukas Zimmermann, Dietmar Georg

المصدر: Radiation Oncology, Vol 18, Iss 1, Pp 1-8 (2023)

مصطلحات موضوعية: CBCT based dose calculation, Deformable registration, Adaptive radiotherapy, Accuracy, Medical physics. Medical radiology. Nuclear medicine, R895-920, Neoplasms. Tumors. Oncology. Including cancer and carcinogens, RC254-282

الوصف: Abstract Background To evaluate a novel CBCT conversion algorithm for dose calculation implemented in a research version of a treatment planning system (TPS). Methods The algorithm was implemented in a research version of RayStation (v. 11B-DTK, RaySearch, Stockholm, Sweden). CBCTs acquired for each ten head and neck (HN), gynecology (GYN) and lung cancer (LNG) patients were collected and converted using the new algorithm (CBCTc). A bulk density overriding technique implemented in the same version of the TPS was used for comparison (CBCTb). A deformed CT (dCT) was created by using deformable image registration of the planning CT (pCT) to the CBCT to reduce anatomical changes. All treatment plans were recalculated on the pCT, dCT, CBCTc and the CBCTb. The resulting dose distributions were analyzed using the MICE toolkit (NONPIMedical AB Sweden, Umeå) with local gamma analysis, with 1% dose difference and 1 mm distance to agreement criteria. A Wilcoxon paired rank sum test was applied to test the differences in gamma pass rates (GPRs). A p value smaller than 0.05 considered statistically significant. Results The GPRs for the CBCTb method were systematically lower compared to the CBCTc method. Using the 10% dose threshold and the dCT as reference the median GPRs were for the CBCTc method were 100% and 99.8% for the HN and GYN cases, respectively. Compared to that the GPRs of the CBCTb method were lower with values of 99.8% and 98.0%, for the HN and GYN cases, respectively. The GPRs of the LNG cases were 99.9% and 97.5% for the CBCTc and CBCTb method, respectively. These differences were statistically significant. The main differences between the dose calculated on the CBCTs and the pCTs were found in regions near air/tissue interfaces, which are also subject to anatomical variations. Conclusion The dose distribution calculated using the new CBCTc method showed excellent agreement with the dose calculated using dCT and pCT and was superior to the CBCTb method. The main reasons for deviations of the calculated dose distribution were caused by anatomical variations between the pCT and the corrected CBCT.

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/1748-717XTest

الوصول الحر: https://doaj.org/article/0b67e2bddda74334bae72684dd0dd932Test

المؤلفون: Rajagopal, Abhejit, Vasquez, Elena, Sudhyadhom, Atchar, Larson, Peder, Scholey, Jessica

المصدر: Medical Physics. 49(10)

مصطلحات موضوعية: dose calculation for radiotherapy, magnetic resonance imaging, quantitative imaging, Humans, Magnetic Resonance Imaging, Neural Networks, Computer, Radiotherapy Dosage, Radiotherapy Planning, Computer-Assisted, Retrospective Studies, Tomography, X-Ray Computed

الوصف: BACKGROUND: Megavoltage computed tomography (MVCT) has been implemented on many radiotherapy treatment machines for on-board anatomical visualization, localization, and adaptive dose calculation. Implementing an MR-only workflow by synthesizing MVCT from magnetic resonance imaging (MRI) would offer numerous advantages for treatment planning and online adaptation. PURPOSE: In this work, we sought to synthesize MVCT (sMVCT) datasets from MRI using deep learning to demonstrate the feasibility of MRI-MVCT only treatment planning. METHODS: MVCTs and T1-weighted MRIs for 120 patients treated for head-and-neck cancer were retrospectively acquired and co-registered. A deep neural network based on a fully-convolutional 3D U-Net architecture was implemented to map MRI intensity to MVCT HU. Input to the model were volumetric patches generated from paired MRI and MVCT datasets. The U-Net was initialized with random parameters and trained on a mean absolute error (MAE) objective function. Model accuracy was evaluated on 18 withheld test exams. sMVCTs were compared to respective MVCTs. Intensity-modulated volumetric radiotherapy (IMRT) plans were generated on MVCTs of four different disease sites and compared to plans calculated onto corresponding sMVCTs using the gamma metric and dose-volume-histograms (DVHs). RESULTS: MAE values between sMVCT and MVCT datasets were 93.3 ± 27.5, 78.2 ± 27.5, and 138.0 ± 43.4 HU for whole body, soft tissue, and bone volumes, respectively. Overall, there was good agreement between sMVCT and MVCT, with bone and air posing the greatest challenges. The retrospective dataset introduced additional deviations due to sinus filling or tumor growth/shrinkage between scans, differences in external contours due to variability in patient positioning, or when immobilization devices were absent from diagnostic MRIs. Dose distributions of IMRT plans evaluated for four test cases showed close agreement between sMVCT and MVCT images when evaluated using DVHs and gamma dose metrics, which averaged to 98.9 ± 1.0% and 96.8 ± 2.6% analyzed at 3%/3 mm and 2%/2 mm, respectively. CONCLUSIONS: MVCT datasets can be generated from T1-weighted MRI using a 3D deep convolutional neural network with dose calculation on a sample sMVCT in close agreement with the MVCT. These results demonstrate the feasibility of using MRI-derived sMVCT in an MR-only treatment planning workflow.

وصف الملف: application/pdf

الوصول الحر: https://escholarship.org/uc/item/7d53k3gzTest

المؤلفون: Sarvenaz Keshmiri, Gaëtan Lemaire, Sylvan Brocard, Camille Verry, Yacine Bencheikh, Samy Kefs, Laura Eling, Raphaël Serduc, Jean-François Adam

المصدر: Physics and Imaging in Radiation Oncology, Vol 30, Iss , Pp 100565- (2024)

مصطلحات موضوعية: Synchrotron microbeam radiation therapy, Treatment planning, Monte-Carlo dose calculation, Translational research, Prediction models, Medical physics. Medical radiology. Nuclear medicine, R895-920, Neoplasms. Tumors. Oncology. Including cancer and carcinogens, RC254-282

الوصف: Background and Purpose: Microbeam Radiation Therapy (MRT) aims to deliver higher doses to the target while minimizing radiation damage to healthy tissues using synchrotron x-ray microbeams. Translational MRT research has now started, driven by promising results from preclinical studies. This study aimed to propose a first dose-outcome model by analyzing micrometric dose distributions obtained with high-resolution 3D dose calculations, accounting for the inherent physical dose distribution complexity in MRT. The feasibility of integrating penMRT, our full Monte Carlo multiscale dose calculation algorithm based on PENELOPE into translational research on veterinary patients was also investigated. Material and Methods: Micrometric dose distributions were calculated in tumor-bearing rats and for a veterinary patient with penMRT, for conformal multi-directional MRT treatment plans. Absorbed dose maps were obtained with 0.005 × 0.005 × 1 mm3 voxel sizes. High-resolution dose-volume histograms were extracted and analyzed against radiobiology studies. Results: The complexity of the MRT dose distribution was properly rendered at a micrometer scale on 3D dose maps, with well separated dose regions observed on the differential dose-volume histograms. The median survival time of glioma-bearing rats varied linearly with the volume fraction of the planning target volume that received doses higher than 50 Gy (R2 = 0.98). The feasibility of using penMRT for treatment planning in large volumes has been shown on a veterinary patient. Conclusions: This study demonstrated the significant added value of penMRT for planning and prescribing MRT treatments. It also shed light on the correlation between the high-resolution 3D dose distributions and the treatment outcome.

وصف الملف: electronic resource

العلاقة: http://www.sciencedirect.com/science/article/pii/S2405631624000356Test; https://doaj.org/toc/2405-6316Test

الوصول الحر: https://doaj.org/article/7cb4191bf72b42429bf04ab16a411b56Test

المؤلفون: Dylan Callens, Karel Aerts, Patrick Berkovic, Liesbeth Vandewinckele, Maarten Lambrecht, Wouter Crijns

المصدر: Technical Innovations & Patient Support in Radiation Oncology, Vol 29, Iss , Pp 100236- (2024)

مصطلحات موضوعية: NSCLC, Dose calculation, Adaptive radiotherapy, Medical physics. Medical radiology. Nuclear medicine, R895-920, Neoplasms. Tumors. Oncology. Including cancer and carcinogens, RC254-282

الوصف: Introduction: Decisions for plan-adaptations may be impacted by a transitioning from one dose-calculation algorithm to another. This study examines the impact on dosimetric-triggered offline adaptation in LA-NSCLC in the context of a transition from superposition/convolution dose calculation algorithm (Type-B) to linear Boltzmann equation solver dose calculation algorithms (Type-C). Materials & Methods: Two dosimetric-triggered offline adaptive treatment workflows are compared in a retrospective planning study on 30 LA-NSCLC patients. One workflow uses a Type-B dose calculation algorithm and the other uses Type-C. Treatment plans were re-calculated on the anatomy of a mid-treatment synthetic-CT utilizing the same algorithm utilized for pre-treatment planning. Assessment for plan-adaptation was evaluated through a decision model based on target coverage and OAR constraint violation. The impact of algorithm during treatment planning was controlled for by recalculating the Type-B plan with Type-C. Results: In the Type-B approach, 13 patients required adaptation due to OAR-constraint violations, while 15 patients required adaptation in the Type-C approach. For 8 out of 30 cases, the decision to adapt was opposite in both approaches. None of the patients in our dataset encountered CTV-target underdosage that necessitated plan-adaptation. Upon recalculating the Type-B approach with the Type-C algorithm, it was shown that 10 of the original Type-B plans revealed clinically relevant dose reductions (≥3%) on the CTV in their original plans. This re-calculation identified 21 plans in total that required ART. Discussion: In our study, nearly one-third of the cases would have a different decision for plan-adaption when utilizing Type-C instead of Type-B. There was no substantial increase in the total number of plan-adaptations for LA-NSCLC. However, Type-C is more sensitive to altered anatomy during treatment compared to Type-B. Recalculating Type-B plans with the Type-C algorithm revealed an increase from 13 to 21 cases triggering ART.

وصف الملف: electronic resource

العلاقة: http://www.sciencedirect.com/science/article/pii/S2405632424000039Test; https://doaj.org/toc/2405-6324Test

الوصول الحر: https://doaj.org/article/c29acbd206c74211a18ef4f8f2a02d2dTest

المؤلفون: CUI Weijie, ZHANG Jinlong, LI Zaixin, CAO Bo

المصدر: Fushe yanjiu yu fushe gongyi xuebao, Vol 42, Iss 3, Pp 030601-030601 (2024)

مصطلحات موضوعية: fusion reactor, tritium, radioactive dust, accidental release, dose calculation, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798, Medical physics. Medical radiology. Nuclear medicine, R895-920

الوصف: The deuterium-tritium fusion reaction is the fastest commercially achievable artificially controlled fusion reaction. However, tritium, as a fuel and neutron radiation-activated material, poses radioactive safety challenges. To simulate the migration of tritium and radioactive dust in the environment under accident conditions, a dispersion simulation program called ACCTRI (ACCidental model for TRItium release) has been developed based on the modified Gaussian multi-puff model, considering dry and wet deposition and tritium re-emission effects. The concentration and dose results calculated using ACCTRI are very close to those calculated using UFOTRI and HotSpot, with a maximum difference of no more than one order of magnitude. A comparison with the experimental results reveals that the results of ACCTRI with tritium buoyancy correction are close to the experimental data. ACCTRI has good accuracy and can be used as a reference for environmental radioactivity safety in fusion reactor site selection and hypothetical accident analysis.

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/1000-3436Test

الوصول الحر: https://doaj.org/article/a6500e116c9f4165b527dcc12f5dd1a1Test

المؤلفون: Marta Bogowicz, Didier Lustermans, Vicki Trier Taasti, Colien Hazelaar, Frank Verhaegen, Gabriel Paiva Fonseca, Wouter van Elmpt

المصدر: Physics and Imaging in Radiation Oncology, Vol 29, Iss , Pp 100566- (2024)

مصطلحات موضوعية: Radiotherapy, Image quality, Cone-beam computed tomography, Dose calculation, CT number accuracy, Metal artifact reduction, Medical physics. Medical radiology. Nuclear medicine, R895-920, Neoplasms. Tumors. Oncology. Including cancer and carcinogens, RC254-282

الوصف: Background and purpose: Dose calculation on cone-beam computed tomography (CBCT) images has been less accurate than on computed tomography (CT) images due to lower image quality and discrepancies in CT numbers for CBCT. As increasing interest arises in offline and online re-planning, dose calculation accuracy was evaluated for a novel CBCT imager integrated into a ring gantry treatment machine. Materials and methods: The new CBCT system allowed fast image acquisition (5.9 s) by using new hardware, including a large-size flat panel detector, and incorporated image-processing algorithms with iterative reconstruction techniques, leading to accurate CT numbers allowing dose calculation. In this study, CBCT- and CT-based dose calculations were compared based on three anthropomorphic phantoms, after CBCT-to-mass-density calibration was performed. Six plans were created on the CT scans covering various target locations and complexities, followed by CBCT to CT registrations, copying of contours, and re-calculation of the plans on the CBCT scans. Dose-volume histogram metrics for target volumes and organs-at-risk (OARs) were evaluated, and global gamma analyses were performed. Results: Target coverage differences were consistently below 1.2 %, demonstrating the agreement between CT and re-calculated CBCT dose distributions. Differences in Dmean for OARs were below 0.5 Gy for all plans, except for three OARs, which were below 0.8 Gy ( 97 %. Conclusions: This study demonstrated comparable results between dose calculations performed on CBCT and CT acquisitions. The new CBCT system with enhanced image quality and CT number accuracy opens possibilities for off-line and on-line re-planning.

وصف الملف: electronic resource

العلاقة: http://www.sciencedirect.com/science/article/pii/S2405631624000368Test; https://doaj.org/toc/2405-6316Test

الوصول الحر: https://doaj.org/article/5ee9dcb982ba4e108acc49be4a6ae858Test

المؤلفون: Tal Sarah Beckmann, Caroline Flora Samer, Hannah Wozniak, Georges Louis Savoldelli, Mélanie Suppan

المصدر: Heliyon, Vol 10, Iss 1, Pp e23545- (2024)

مصطلحات موضوعية: Local anaesthetics, Toxicity, Drug safety, Dose calculation, Web-based survey, Science (General), Q1-390, Social sciences (General), H1-99

الوصف: Background: The use of local anaesthetics (LAs) is usually associated with few adverse effects, but local anaesthetic systemic toxicity (LAST) can result in serious harm and even death. However, practitioner awareness regarding this risk has been little studied. Methods: This was a closed, web-based study carried out at two Swiss university hospitals using a fully automated questionnaire. The main objective was to evaluate LAST awareness and LA use among various medical practitioners. The secondary objective was to determine whether these physicians felt that a tool designed to compute maximum safe LA doses should be developed. Results: The overall participation rate was 40.2 % and was higher among anaesthesiologists (154/249, 61.8 % vs 159/530, 30.0 %; P

وصف الملف: electronic resource

العلاقة: http://www.sciencedirect.com/science/article/pii/S2405844023107535Test; https://doaj.org/toc/2405-8440Test

الوصول الحر: https://doaj.org/article/905f2d659e81465887dafcfbff07674dTest