Journal of Medical Physics最新文献

{"title":"An Analysis of Quality Assurance for Intensity-modulated Radiation Therapy and Volumetric Modulated Arc Therapy Treatment Plans Using Two Dosimetric Methods: The arcCHECK System and EPIbeam Based Dosimetric Approach.","authors":"Ajay Katake, Lalit Kumar, Balbir Singh, Amit Sharma, Deepak Basandrai","doi":"10.4103/jmp.jmp_226_25","DOIUrl":"10.4103/jmp.jmp_226_25","url":null,"abstract":"<p><strong>Aim: </strong>The current study is to assess and compare the performance of an electronic portal imaging device (EPID)-based dosimetry system electronic portal imaging beam (EPIbeam) and a three-dimensional (3D) diode array system (ArcCHECK) using various gamma criteria (3%/3 mm, 2%/2 mm, 3%/2 mm and 1%/1 mm) in verifying intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) plans at different anatomical sites.</p><p><strong>Materials and methods: </strong>A total of 100 clinical IMRT and VMAT treatment plans covering head and neck (HN), thoracic and pelvic sites were considered for patient specific quality assurance (PSQA). All the plans were calculated with the Monaco TPS (v6.1.4.0) and were treated with an Elekta Infinity linear accelerator with 6 MV photon beams. EPID-based portal dosimetry (EPIbeam, DosiSoft) and ArcCHECK (Sun Nuclear Corporation) were utilized to carry out PSQA. All plans were analyzed using global gamma with 10% dose threshold and 95% pass-rate.</p><p><strong>Results: </strong>A 3%/3 mm, EPID showed almost perfect pass rates (99.48%-100%) in HN, Thoracic, and Pelvic regions, and ArcCHECK was also close behind (97%-100%). EPID and ArcCHECK performed with a high level of accuracy (97.82-100 and 88.5%-98.8%, respectively) under stricter 2%/2 mm criteria. Using 3%/2 mm gamma criteria, EPID demonstrates higher pass rates (98.6%-100%), and ArcCHECK had also increased (93.2%-99.8%). In the most stringent 1%/1 mm, the performance of EPID declined moderately (77.28%-98.73%), and ArcCHECK had the lowest pass rates (61.6%-91.4%). In general, EPID exhibited better and more reproducible dose delivery accuracy in all conditions. The differences between the quality assurance (QA) systems were statistically significant (<i>P</i> < 0.05) (except thorax cases).</p><p><strong>Conclusion: </strong>The PSQA systems EPID-based and ArcCHECK-based are valuable dosimetric verification of IMRT and VMAT. Their sensitivity and accuracy are emphasized by gamma analysis on several criteria. The EPID system offers Logistical advantage in clinical workflow, whereas ArcCHECK provides 3D dose verification. Both modalities are viable in clinical QA protocols.</p>","PeriodicalId":51719,"journal":{"name":"Journal of Medical Physics","volume":"51 2","pages":"366-375"},"PeriodicalIF":1.1,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13345026/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148413682","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Comprehensive Dosimetric Evaluation and Performance Validation of the Newly Introduced HyperSight™ Cone-beam Computed Tomography System in India - Is It Now Feasible to Eliminate the Intermediate Step in Adaptive Radiotherapy Planning?: A Phantom Study.","authors":"N V N Madhusudhana Sresty, T Anil Kumar, V R P Lakshmi, B Devender Reddy, G Srikanth, R Sudhakar, M Paramesh, Deleep Kumar Gudipudi, V Sudhakar Kumar, Tasneem Rushdi, S Rohith, Heena Kauser, Ashwini Gopal, A Naga Prasanthi, Madhuri Kavikondala, P Vaishnavi","doi":"10.4103/jmp.jmp_20_26","DOIUrl":"10.4103/jmp.jmp_20_26","url":null,"abstract":"<p><strong>Purpose: </strong>Cone-beam computed tomography (CBCT) is integral to modern adaptive radiotherapy (ART) but is often limited by a small field of view, longer acquisition times, and inferior image quality compared with planning CT. Consequently, ART plan optimization and calculations are typically performed using synthetic CT. HyperSight™ is a recent technological advancement that addresses these limitations through a large-area detector, faster gantry rotation, and improved image quality. This system has been recently introduced in India, and this first Indian study represents the comprehensive, quality assurance (QA)-focused evaluation. In the second phase, its suitability for direct dose optimization and calculation was assessed using standard phantoms.</p><p><strong>Materials and methods: </strong>The study was conducted on a Halcyon equipped with the HyperSight™ CBCT platform. Fan-beam scans were acquired using both big-bore and conventional CT systems. Standard QA tools, along with QUART and Catphan phantoms, were employed. X-ray tube performance tests, Image quality tests, Hounsfield units (HU) accuracy and constancy tests etc., were evaluated in accordance with national and international guidelines. VMAT plans were generated on different CBCT image sets of the phantoms.</p><p><strong>Results: </strong>Coefficient of variation in the X-ray output consistency was 0.0012. Slice thickness measured was within the tolerance. Hypersight CBCT proved its equality with CT in low contrast and high contrast resolution, uniformity and noise. HU accuracy and constancy closely matched the expected values in iterative CBCT (iCBCT) Accuros calculations. Target dosimetry between CT and iCBCT Accuros calculations were within 1% in Catphan and gamma analysis demonstrated excellent agreement.</p><p><strong>Conclusions: </strong>Overall, dosimetric accuracy and image quality confirm the superiority of this system for image-guided radiotherapy. Phantom results support ART workflows without intermediate steps; however, further clinical studies across treatment sites and improved scatter correction are required.</p>","PeriodicalId":51719,"journal":{"name":"Journal of Medical Physics","volume":"51 2","pages":"265-276"},"PeriodicalIF":1.1,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13345031/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148413660","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Determination of Mean Energy and Energy Resolution of Standardized Diagnostic X-ray Beams from the Spectra Measured Using a Portable Cadmium Zinc Telluride Spectrometer.","authors":"Rahul Kumar Chaudhary, Sudhir Kumar, S D Sharma","doi":"10.4103/jmp.jmp_272_25","DOIUrl":"10.4103/jmp.jmp_272_25","url":null,"abstract":"<p><strong>Objective: </strong>The objective of this work was to measure the spectra of standardized diagnostic X-ray beams (DXRBs) using a cadmium zinc telluride (CdZnTe) spectrometer. The mean energy as well as energy resolution were also estimated from the measured spectra.</p><p><strong>Materials and methods: </strong>The CdZnTe radiation detector of nominal volume 500 mm³ in combination with an in-house-developed tungsten pinhole collimator was used to measure the spectra of standardized DXRBs of nominal energies 40 kV to 100 kV. The detector was placed at a distance of 1000 mm from the focal spot of the X-ray tube, and the field size of 200 mm × 200 mm was opened. The ²⁴¹Am, ¹³³Ba, and ⁵⁷Co reference gamma ray sources were used for the calibration of the CdZnTe spectrometer. The measured spectra were corrected using the stripping procedure and the methodology was validated by comparing the corrected and reference spectra. The mean energy values and energy resolution were determined from the corrected spectra. The effective energies of beams were also determined from the first half-value layer measured experimentally.</p><p><strong>Results: </strong>The mean energies estimated from corrected X-ray spectra agreed within 5% for the beam qualities studied. The energy resolution deteriorated with the energy of DXRBs.</p><p><strong>Conclusions: </strong>In-house-developed pinhole collimator, and CdZnTe spectrometer were successfully used for the measurement of DXRBs spectra. The X-ray beams have been fully characterized for the calibration of diagnostic X-ray dosimeters and quality control instruments.</p>","PeriodicalId":51719,"journal":{"name":"Journal of Medical Physics","volume":"51 2","pages":"414-423"},"PeriodicalIF":1.1,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13345030/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148413774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Relationship between Water-equivalent Diameter, Computed Tomography Dose Indices, and Image Noise in Pediatric Head Computed Tomography Under Active and Inactive Tube Current Modulation.","authors":"Evi Setiawati, Choirul Anam, Bella Diani Safitri, Much Azam, Qidir Maulana Binu Soesanto, Agus Margiantono","doi":"10.4103/jmp.jmp_289_25","DOIUrl":"10.4103/jmp.jmp_289_25","url":null,"abstract":"<p><strong>Purpose: </strong>This study investigated the relationships among water-equivalent diameter (D_w), volume computed tomography dose index (CTDI_vol), size-specific dose estimate (SSDE), and image noise in pediatric head computed tomography (CT) under active and inactive tube current modulation (TCM).</p><p><strong>Subjects and methods: </strong>Fifty pediatric patients (0-14 years) undergoing noncontrast head CT were retrospectively analyzed. Scans were performed on a 128-slice CT scanner at 120 kVp. Twenty-five patients were examined using active TCM, and 25 with fixed tube current. CTDI_vol and SSDE were calculated using IndoseCT software following American Association of Physicists in Medicine TG-293 recommendations. Image noise was quantified using the global noise index. Relationships among D_w, CTDI_vol, SSDE, and noise were evaluated using linear regression.</p><p><strong>Results: </strong>Active TCM reduced CTDI_vol from 38.5 ± 7.1 mGy to 32.8 ± 6.4 mGy (15.4%, <i>P</i> = 0.021) and SSDE from 39.2 ± 6.1 mGy to 29.6 ± 5.3 mGy (24.5%, <i>P</i> < 0.001). Image noise decreased from 10.2 ± 2.3 HU to 8.6 ± 1.9 HU (<i>P</i> = 0.037).</p><p><strong>Conclusion: </strong>Active TCM improves dose-noise efficiency in pediatric head CT by reducing radiation dose while maintaining stable image quality. Integration of D_w-based SSDE with automated noise analysis provides a quantitative framework for pediatric CT dose auditing and may support the development of size-specific diagnostic reference levels.</p>","PeriodicalId":51719,"journal":{"name":"Journal of Medical Physics","volume":"51 2","pages":"424-429"},"PeriodicalIF":1.1,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13345115/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148413824","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimizing Chest Computed Tomography Imaging Protocols: A Narrative Review on Dose Reduction and Diagnostic Efficacy.","authors":"Suhas Tivaskar, Anurag Luharia, Gaurav V Mishra, Aditya Shrivastav, Sarthak Das","doi":"10.4103/jmp.jmp_7_26","DOIUrl":"10.4103/jmp.jmp_7_26","url":null,"abstract":"<p><strong>Background: </strong>The worldwide deployment of chest computed tomography (CT) has increased substantially across cancer-related, respiratory and cardiac applications, leading to increasing aggregate radiation burden and substantially intercenter variability in radiation dose management strategies.</p><p><strong>Purpose: </strong>The purpose of this study was to comprehensively review existing literature on radiation dose optimization approaches in chest CT, with particular emphasis on phantom-based protocol optimization, deep learning-based reconstruction methods, and evidence-based protocol modification.</p><p><strong>Methods: </strong>This review was conducted using a systematic narrative synthesis with elements of systematic procedure to enrich transparency and reproducibility. PubMed, Scopus, and ScienceDirect were searched for English-language studies published between January 2015 and January 2025 that interrogated radiation dose optimization strategies in adult chest CT imaging. Human and phantom studies reporting radiation metrics and image-quality outcomes were included. Evidence was qualitatively synthesized across technological, methodological, and clinical implementation domains.</p><p><strong>Results: </strong>Iterative and model-based reconstruction techniques uniformly achieved dose reductions of approximately 30%-60% while without compromising image quality. Deep learning-based reconstruction demonstrated more effective noise reduction and preservation of anatomical detail, supporting dose reductions of up to 70% in selected thoracic applications. Phantom-based verification enhanced protocol reproducibility and reduced interscanner variability. Ultra-low-dose chest CT (<0.4 mSv) was shown to be clinically dependable for lung nodule detection in selected clinical settings.</p><p><strong>Conclusions: </strong>Incorporation of phantom-based verification with a state-of-the-art reconstruction algorithm facilitates substantial radiation dose reduction in chest CT without compromising diagnostic quality. Task-specific protocol optimization and centre-specific validation remain for safe and reproducible clinical implementation.</p>","PeriodicalId":51719,"journal":{"name":"Journal of Medical Physics","volume":"51 2","pages":"227-236"},"PeriodicalIF":1.1,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13345023/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148413799","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigating Image Distortion and Its Impact on Material Quantification in Photon-counting Computed Tomography.","authors":"Rayhan Uddin, Marzieh Anjomrouz, Neryda Duncan, Anthony Butler, Philip Butler","doi":"10.4103/jmp.jmp_180_25","DOIUrl":"10.4103/jmp.jmp_180_25","url":null,"abstract":"<p><strong>Background: </strong>Photon-counting computed tomography (PCCT) enables simultaneous spatial and spectral imaging for improved material discrimination. However, inaccuracies in scanner geometric calibration can introduce reconstruction distortions that degrade both image quality and spectral fidelity, thereby affecting quantitative material analysis.</p><p><strong>Aims and objectives: </strong>This study investigated the impact of scanner-induced geometric distortions on material quantification in the Medipix All Resolution System scanner and examined the relationship between spatial image degradation and spectral signal integrity in photon-counting CT.</p><p><strong>Materials and methods: </strong>Multiple phantoms were scanned using a geometrically calibrated system. Geometric reconstruction parameters were then systematically perturbed to generate intentionally distorted reconstructions and create a spectral image library for visual assessment. Distortion patterns, including edge blurring, shading artifacts, and ring artifacts, were analyzed alongside changes in spectral signatures and material reconstruction performance. A comprehensive geometric calibration framework was subsequently developed to mitigate spatial distortions and improve spectral consistency.</p><p><strong>Results: </strong>Geometric perturbations produced significant spatial distortions accompanied by measurable degradation in spectral response. Distorted reconstructions showed reduced material discrimination accuracy and altered spectral signatures. The proposed calibration approach effectively reduced reconstruction artifacts and improved both spatial image quality and spectral reliability.</p><p><strong>Conclusion: </strong>Spatial and spectral degradations in photon-counting CT are intrinsically interconnected. Accurate geometric calibration is therefore essential for reliable material quantification and optimal spectral reconstruction performance in photon-counting CT systems.</p>","PeriodicalId":51719,"journal":{"name":"Journal of Medical Physics","volume":"51 2","pages":"403-413"},"PeriodicalIF":1.1,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13345116/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148413750","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparative Evaluation of Curve-fitting Techniques for Electronic Portal Imaging Device-based Multileaf Collimator Picket Fence Analysis.","authors":"Vijay Kumar Mogulagani, Mohan Raj Uthiran, C H Raja Babu, Madhuri Dumpala","doi":"10.4103/jmp.jmp_28_26","DOIUrl":"10.4103/jmp.jmp_28_26","url":null,"abstract":"<p><strong>Purpose: </strong>The primary objective of this study was to identify the most suitable curve-fitting method for picket fence analysis by comparing commonly used mathematical fitting approaches with film-based reference measurements.</p><p><strong>Materials and methods: </strong>A picket fence test was planned on an Elekta Synergy linear accelerator equipped with an MLCi2 multileaf collimator (40 leaf pairs) using 6-mm slit widths and five pickets with a nominal field geometry of 0.6 cm × 24 cm, covering 24 leaf pairs per picket. For analysis, only the central 20 opposing leaf pairs in each picket were evaluated, yielding a total of 100 analyzed peaks. The identical picket fence plan was delivered to both the electronic portal imaging device (EPID) and Gafchromic film. EPID images were exported as TIFF files and analyzed using PTW MEPHYSTO software to obtain peak coordinates, followed by manual determination of peak center position, maximum amplitude, and full width at half maximum (FWHM).</p><p><strong>Results: </strong>Mean FWHM values were 6.90 mm (Gaussian), 5.69 mm (Lorentzian), 6.29 mm (pseudo-Voigt), 6.92 mm (manual), and 6.56 mm (film). Gaussian fitting and manual measurements demonstrated systematic overestimation of FWHM relative to film, while Lorentzian fitting showed the largest deviation and highest root mean square error (RMSE).</p><p><strong>Conclusion: </strong>Based on percentage error, RMSE, and Bonferroni-corrected nonparametric statistical analysis, pseudo-Voigt curve fitting provides the most accurate and consistent estimation of slit width in EPID-based picket fence analysis.</p>","PeriodicalId":51719,"journal":{"name":"Journal of Medical Physics","volume":"51 2","pages":"348-358"},"PeriodicalIF":1.1,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13345049/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148413658","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Feasibility of Using Machine Performance Check-enhanced Couch Check as a Daily Surrogate for Multisphere Winston-Lutz Testing in Single-isocenter Multitarget Stereotactic Radiosurgery.","authors":"Tae Kyu Lee","doi":"10.4103/jmp.jmp_30_26","DOIUrl":"10.4103/jmp.jmp_30_26","url":null,"abstract":"<p><p>Single-isocenter multitarget (SIMT) stereotactic radiosurgery (SRS) requires submillimeter geometric accuracy. Although Winston-Lutz (WL) testing remains the stereotactic standard, it is time-intensive. This study evaluated whether Varian's machine performance check (MPC)-enhanced couch check can serve as a surrogate for WL by comparing geometric agreement across routine clinical use. WL tests were performed on 23 SRS/SRT treatment days using a multisphere VisionRT phantom. MPC-enhanced couch check data were extracted for the same dates, including maximum positioning error (MPC-max) and rotation-induced couch shift (MPC-shift). Agreement between WL and MPC was evaluated using Pearson correlation and Bland-Altman analysis. WL values ranged from 0.27 to 0.67 mm. MPC-max and MPC-shift ranged from 0.37 to 0.44 mm and 0.33 to 0.49 mm, respectively. Correlation between WL and both MPC metrics was high (<i>r</i> > 0.85). Bland-Altman analysis showed minimal bias for MPC-max (+0.033 mm) and MPC-shift (+0.037 mm). The 95% limits of agreement (LOA) were -0.176 to + 0.243 mm (MPC-max) and -0.160 to +0.235 mm (MPC-shift), all within SIMT SRS geometric tolerances. MPC-enhanced couch check demonstrated strong agreement with WL measurements, with sub-0.05-mm bias and LOA within ± 0.25 mm. These findings support the use of MPC as a practical surrogate for WL in daily or high-frequency isocenter and couch-rotation verification within SIMT SRS workflows.</p>","PeriodicalId":51719,"journal":{"name":"Journal of Medical Physics","volume":"51 2","pages":"440-445"},"PeriodicalIF":1.1,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13345033/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148413763","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Deep Learning Guided Optimization of Primary Electron Source Parameters in Geant4 for Clinical Linac Modeling.","authors":"Nour-Eddine Sennan, Abdelkader El Hamli, Abdelilah Moussa","doi":"10.4103/jmp.jmp_24_26","DOIUrl":"10.4103/jmp.jmp_24_26","url":null,"abstract":"<p><strong>Background: </strong>Monte Carlo (MC) simulation is widely used in medical physics for radiation transport modeling, beam commissioning, and dose calculation. However, the optimization of primary electron source parameters for clinical linear accelerators using MC simulations can require many repeated simulations, making the process time-consuming.</p><p><strong>Aims and objectives: </strong>This study aimed to develop a data-driven surrogate framework to guide the optimization of primary electron beam parameters in Geant4 for an Elekta Synergy linear accelerator operated in 10 MeV electron mode. The objective was to predict the gamma pass rate for the 2%/2 mm criterion and to identify the most influential beam parameters.</p><p><strong>Materials and methods: </strong>A Geant4-based Monte Carlo model was used to simulate the 10 MeV electron beam. Simulated dose distributions were compared with experimental measurements in water under reference conditions. A feedforward neural network was trained to predict the gamma pass rate from four primary source parameters: mean energy, energy spread, spatial spread, and angular spread. A Gradient Boosting Regressor was also used to evaluate the relative importance of these parameters.</p><p><strong>Results: </strong>The feedforward neural network showed high predictive performance, with an R² value of 0.9924 for the training dataset and 0.9857 for the testing dataset. The model enabled rapid screening of beam parameter configurations. The Gradient Boosting Regressor indicated that the mean energy was the dominant parameter influencing agreement between simulated and measured dose distributions.</p><p><strong>Conclusion: </strong>The proposed deep learning-guided framework can reduce trial-and-error in Monte Carlo-based electron beam model tuning while maintaining clinically relevant accuracy. This approach may support more efficient optimization of primary electron source parameters for clinical linac modeling.</p>","PeriodicalId":51719,"journal":{"name":"Journal of Medical Physics","volume":"51 2","pages":"333-340"},"PeriodicalIF":1.1,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13345122/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148413733","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Monte Carlo-based Design and Comparative Evaluation of Intraoperative Radiotherapy Disks.","authors":"Mahnaz Bagheri, Hussein Hameed Al Shareefi","doi":"10.4103/jmp.jmp_231_25","DOIUrl":"10.4103/jmp.jmp_231_25","url":null,"abstract":"<p><strong>Background: </strong>Intraoperative radiotherapy (IORT) is a technique in which a single high radiation dose (10-20 Gy) is delivered directly to the tumor site during surgery. As this procedure is performed in the operating room, effective protection of the surrounding healthy tissues is of paramount importance. This protection is commonly achieved using shielding disks placed immediately adjacent to the tumor bed, where the material composition of these disks plays a crucial role in determining their shielding effectiveness.</p><p><strong>Aims and objectives: </strong>The present study aimed to identify the optimal material combination and thickness for double-layer protective disks in order to maximize healthy tissue protection.</p><p><strong>Materials and methods: </strong>Initially, the LIAC accelerator head, along with its applicator and a water phantom, was modeled using the MCNPX Monte Carlo code. The accuracy of the simulation was validated by comparing the percentage depth dose (PDD) obtained from Monte Carlo simulations with experimental dosimetry data. Optimization was performed by evaluating the transmission factor (TF), backscatter factor (BSF), and absorbed dose. Several new disk configurations-comprising PMMA + lead, PTFE + bismuth, steel + titanium, steel + copper, aluminum + copper, and aluminum + titanium-each with thicknesses of 6 mm and 8 mm, were simulated and compared with a reference disk.</p><p><strong>Results and conclusion: </strong>Among all evaluated configurations, the PMMA + lead disk demonstrated the highest attenuation (65.8% at 8 mm thickness), along with the lowest BSF (7.1%) and TF (62.8%), making it the most effective option for protecting healthy tissues.</p>","PeriodicalId":51719,"journal":{"name":"Journal of Medical Physics","volume":"51 2","pages":"359-365"},"PeriodicalIF":1.1,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13344922/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148413758","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}