Physics in medicine and biology最新文献

{"title":"Linear magnetic nanoparticle structures as key feature in magnetic particle imaging.","authors":"M Schoenen, L Göpfert, B Bauer, C Emonts, T Gries, E M Buhl, S Schober, T Schmitz-Rode, I Slabu","doi":"10.1088/1361-6560/ae05e5","DOIUrl":"10.1088/1361-6560/ae05e5","url":null,"abstract":"<p><p><i>Objective</i>. Magnetic particle imaging (MPI) opens huge possibilities in image-guided therapy. Its effectiveness is strongly influenced by the quality of the magnetic nanoparticles (MNP) used as tracers. Besides MNP optimisation following different synthesis routes, MNP assembly into linear structures can significantly enhance their performance in MPI. The present study investigates the influence of linear MNP structures on MPI signal for different MNP types. With regard to theranostic applications the role of linear structures in hybrid stent imaging is explored.<i>Approach</i>. Three MNP types were used to create linear MNP structures. MNP respectively the MNP structures were immobilised in a hydrogel and positioned at various orientations relative to the coordinate system of the MPI. A multi-channel reconstruction approach was applied to assess the orientation-specific signal. The insights gained were used to reconstruct a fibre-based polymer stent with incorporated linear structures.<i>Main results</i>. Different linear structure orientations could be delineated and visualised in multi-colour images. Linear structures orientated parallel to the direction of a magnetic excitation field lead to the highest signal intensities and peak positions of MPI frequency spectra were located near multiples of the frequency of the excitation coil. Image reconstructions of the stent were very sensitive to the orientation of linear structures within the fibres.<i>Significance</i>. This study reveals that the assembly of MNP results in non-linear contributions to the MPI signal. Consequently, the MPI signal intensity is not as usual merely linearly correlated with MNP concentration increasing the complexity in image reconstruction. The findings demonstrate the necessity of accounting for MNP structure orientation in image reconstruction. They also reveal the high potential of MPI to detect different MNP types and structures. Linear structures cause either significant signal reduction or signal increase depending on the angular position of the linear structures relative to the direction of MPI magnetic fields.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145034116","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bridging the resolution gap in alpha therapy dosimetry: a space for quantitative MRI?","authors":"Joshua K Marchant, Bruce R Rosen","doi":"10.1088/1361-6560/ae02dd","DOIUrl":"10.1088/1361-6560/ae02dd","url":null,"abstract":"<p><p>While external beam radiotherapy relies heavily on pre-treatment imaging for advanced treatment planning and radiation dosimetry, tools for predicting local dose delivery in systemic radiopharmaceutical therapies have generally lagged behind. Furthermore, targeted alpha particle-emitting radiopharmaceuticals, with their uniquely short range and high-energy dose deposition, require specialized dosimetry methods at the micro- and mesoscale. Magnetic resonance imaging methods may represent the missing link between standard diagnostic tumor imaging and personalized radionuclide treatment planning for patients. For example, dynamic susceptibility contrast magnetic resonance imaging reveals markedly heterogeneous tumor perfusion patterns and vascular permeability from patient to patient, suggesting variable local drug delivery, but this information is only used in rudimentary ways or not at all in treatment planning. Similarly, emerging diffusion magnetic resonance imaging (MRI) methods may provide information relevant to microscale dosimetry, such as local cell size and density. In this review, we explore advancements in MRI and computational modeling strategies that could improve our fundamental understanding of radionuclide transport in solid tumors and enable pre-treatment, patient-specific predictions of dose delivery at a biologically relevant length scale.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144993070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Feasibility of prototype diamond detectors for pulsed UHDR PBS small-field proton dosimetry for proton FLASH experiments.","authors":"Jufri Setianegara, Aoxiang Wang, Nicolas Gerard, Jarrick Nys, Mark Szczepanski, Hao Gao, Yuting Lin","doi":"10.1088/1361-6560/ae023b","DOIUrl":"10.1088/1361-6560/ae023b","url":null,"abstract":"<p><p><i>Objective.</i>This study aims to investigate the responses of prototype diamond detectors under pulsed ultra-high dose rates (UHDRs) pencil-beam-scanning (PBS) protons from a compact proton synchrocyclotron (IBA Proteus®ONE) for small-field UHDR dosimetry.<i>Approach</i>. flashDiamond detectors (fDs) were cross-calibrated with their relative proton responses characterized at conventional dose rates (CONV). Then, absolute UHDR dosimetry was performed and small-field response assessed. These experiments were also conducted with Razor Diode and microdiamond detectors (mDs) for cross-reference. Cross-calibrations were performed against an ADCL-calibrated PPC05 plane-parallel ionization chamber with 59.23 cGy nC^-1calibration coefficients. fD's linearity, dose-rate, energy, and linear-energy-transfer (LET) responses were assessed under CONV protons. Pulsed UHDR PBS protons of 228 MeV were produced from a medical proton synchrocyclotron (IBA Proteus®ONE) for 1.5 × 1.5-3.0 × 3.0 cm²square fields. Nominal absolute UHDR dosimetry was performed at 3 × 3 cm²field sizes with relative responses at smaller fields benchmarked against it.<i>Main results</i>. fD had 28.6 ± 0.1 cGy nC^-1sensitivities under CONV protons and were linear in response with dose-rate independence within ±0.50%. fD were similar to mD in proton energy and LET responses. However, there is an over-response of approximately 5.49%, 6.51% and 13.7% at the 226, 150 and 70 MeV Bragg peaks respectively. Under pulsed proton UHDR irradiation (0.80% s.t.d, 32.6 ± 0.5 cGy dose-per-pulse), fD responded within ±1% as PPC05 with negligible saturation. fD agreed within ±1% with other comparable small-field detectors under small-field UHDR beams and within ±2% of RayStation treatment planning system calculations. There is negligible partial volume averaging with fDs.<i>Significance</i>. Novel fD detectors did not saturate under pulsed UHDR PBS proton irradiation. Their miniscule active crystals make them suitable for small-field dosimetry but render them relatively insensitive compared to mDs. When cross-calibrated, they are suitable for absolute small-field UHDR dosimetry or for relative exit dosimetry monitoring purposes during UHDR radiobiological experiments.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12451744/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144965084","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Visual language model-assisted spectral CT reconstruction by diffusion and low-rank priors from limited-angle measurements.","authors":"Yizhong Wang, Ningning Liang, Junru Ren, Xinrui Zhang, Ye Shen, Ailong Cai, Zhizhong Zheng, Lei Li, Bin Yan","doi":"10.1088/1361-6560/ae0974","DOIUrl":"https://doi.org/10.1088/1361-6560/ae0974","url":null,"abstract":"<p><strong>Objective: </strong>Spectral computed tomography (CT) is a critical tool in clinical practice, offering capabilities in multi-energy spectrum imaging and material identification. The limited-angle (LA) scanning strategy has attracted attention for its advantages in fast data acquisition and reduced radiation exposure, aligning with the as low as reasonably achievable principle. However, most deep learning-based methods require separate models for each LA setting, which limits their flexibility in adapting to new conditions. In this study, we developed a novel Visual-Language model-assisted Spectral CT Reconstruction (VLSR) method to address LA artifacts and enable multi-setting adaptation within a single model.</p><p><strong>Approach: </strong>The VLSR method integrates the image-text perception ability of visual-language models and the image generation potential of diffusion models. Prompt engineering is introduced to better represent LA artifact characteristics, further improving artifact accuracy. Additionally, a collaborative sampling framework combining data consistency, low-rank regularization, and image-domain diffusion models is developed to produce high-quality and consistent spectral CT reconstructions.</p><p><strong>Main results: </strong>The performance of VLSR is superior to other comparison methods. Under the scanning angles of 90° and 60° for simulated data, the VLSR method improves peak signal noise ratio by at least 0.41 dB and 1.13 dB compared with other methods.</p><p><strong>Significance: </strong>VLSR method can reconstruct high-quality spectral CT images under diverse LA configurations, allowing faster and more flexible scans with dose reductions.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145092219","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design and testing of an MRI-conditional six-degree-of-freedom phantom robot.","authors":"Alexander Dunn, Mitchell Lee, Siddharth Sadanand, Mohammad Khoobani, Tanvir Hassan, M Ali Tavallaei, Dafna Sussman","doi":"10.1088/1361-6560/ae0973","DOIUrl":"https://doi.org/10.1088/1361-6560/ae0973","url":null,"abstract":"<p><strong>Objective: </strong>&#xD;Motion phantoms can help accelerate and reduce the associated costs of research focused on motion-robust imaging. Currently available phantom robots for magnetic resonance imaging (MRI) lack sufficient degrees of freedom (DOF) to replicate complex physiological motions. This work presents the design and testing of a six-DOF MRI-conditional phantom robot to simulate such motions. &#xD;Approach:&#xD;The system was fabricated predominantly with 3D printed components as well as DC stepper motors. Testing validated the actuator's functionality and conditionality with a 3T MRI system. A Faraday cage to house the motors and electronics was constructed using a conductive coating on a 3D-printed shell. &#xD;Main Results:&#xD;The Faraday cage was found to reduce the noise power produced by the motors to the baseline level measured in the MRI without the robot being present within the MRI suite. A positional accuracy measured using a modified version of ISO 9283 was found to be 0.2mm and a rotational accuracy of [-0.1°, 0.3°, -0.2°] were measured for the x, y, and z directions, respectively. Path accuracy for sample motions was found to have a positional accuracy of 0.3 mm and rotational accuracy of [0.1°, 0.1°, 0.1°].&#xD;Significance:&#xD;The created six-DOF robot enhances the development and validation of motion-robust imaging in MRI. The presented design is covered by WO patent #2023/184043, 2023/09/28.&#xD.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145092223","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"PWLS-SOM: alternative PWLS reconstruction for limited-view CT by strategic optimization of a deep learning model.","authors":"Changyu Chen, Li Zhang, Yuxiang Xing, Zhiqiang Chen","doi":"10.1088/1361-6560/adffe0","DOIUrl":"10.1088/1361-6560/adffe0","url":null,"abstract":"<p><p><i>Objective.</i>While deep learning (DL) methods have exhibited promising results in mitigating streaking artifacts caused by limited-view computed tomography (CT), their generalization to practical applications remains challenging. To address this challenge, we aim to develop a novel approach that integrates DL priors with targeted-case data consistency for improved artifact suppression and robust reconstruction.<i>Approach.</i>We propose an alternative penalized weighted least squares reconstruction framework by strategic optimization of a DL model (PWLS-SOM). This framework combines data-driven DL priors with data consistency constraints in a three-stage process: (1) Group-level embedding: DL network parameters are optimized on a large-scale paired dataset to learn general artifact elimination. (2) Significance evaluation: A novel significance score quantifies the contribution of DL model parameters, guiding the subsequent strategic adaptation. (3) Individual-level consistency adaptation: PWLS-driven strategic optimization further adapts DL parameters for target-specific projection data.<i>Main results.</i>Experiments were conducted on sparse-view (90 views) circular trajectory CT data and a multi-segment linear trajectory CT scan with a mixed data missing problem. PWLS-SOM reconstruction demonstrated superior generalization across variations in patients, anatomical structures, and data distributions. It outperformed supervised DL methods in recovering contextual structures and adapting to practical CT scenarios. The method was validated with real experiments on a dead rat, showcasing its applicability to real-world CT scans.<i>Significance.</i>PWLS-SOM reconstruction advances the field of limited-view CT reconstruction by uniting DL priors with PWLS adaptation. This approach facilitates robust and personalized imaging. The introduction of the significance score provides an efficient metric to evaluate generalization and guide the strategic optimization of DL parameters, enhancing adaptability across diverse data and practical imaging conditions.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144965080","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An adjustable three-layer skull phantom with realistic ultrasound transmission properties.","authors":"Jie Chen, Zhenyu Yi, Tiantian Chen, Haoyang Tong, Linming Zhou, Zijian Hong, Chengwei Tan, Jiale Qin, Feiyan Cai, Yongjun Wu, Juan Li, Yuhui Huang","doi":"10.1088/1361-6560/ae0556","DOIUrl":"10.1088/1361-6560/ae0556","url":null,"abstract":"<p><p>Transcranial ultrasound research has garnered significant attention due to its non-invasive nature, absence of ionizing radiation, and portability, making it advantageous for both imaging and therapy. A critical aspect of advancing transcranial research lies in understanding the ultrasound transmission performance of the human skull. However, inherent variations in skull shape, physical parameters, and age-related changes pose challenges for comparative studies. To address these challenges, we designed a three-layer structured skull (TSS) phantom that closely mimics the structural and ultrasound transmission properties of real skulls. The TSS substrate is composed of epoxy resin/Al₂O₃powders, with purple perilla seeds incorporated into the middle layer to replicate the porous structure found in real skulls. Both simulation and experimental results demonstrate that TSS phantom achieves acoustic transmission properties closely approximating those of human skull bone within the 1.25-1.75 MHz frequency range. Experimentally, the TSS phantom containing 27 wt% purple perilla seeds shows a sound pressure transmission coefficient ranging from 5.0% to 6.6%, closely matching the skull's transmission characteristics (4.2%-9.8%). This performance represents a significant improvement over conventional phantom materials, outperforming epoxy resin plate phantoms (42.6%-48.4%) and polyetheretherketone phantoms (64.5%-75.2%). Notably, the transmission performance of TSS can be adjusted by varying the mass fraction of purple perilla seeds, making it adaptable to diverse research needs. The TSS phantom holds significant potential as a valuable tool in transcranial research, offering a reliable and accessible alternative for comprehensive investigations into ultrasound applications in brain therapy.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145030442","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Efficient motion-corrected image reconstruction for 3D cardiac MRI through stochastic optimisation.","authors":"Letizia Protopapa, Margaret Duff, Johannes Mayer, Jeanette Schulz-Menger, Kris Thielemans, Christoph Kolbitsch, Edoardo Pasca","doi":"10.1088/1361-6560/adf609","DOIUrl":"10.1088/1361-6560/adf609","url":null,"abstract":"<p><p><i>Objective.</i>Motion-corrected image reconstruction (MCIR) allows for fast and efficient cardiac magnetic resonance imaging (MRI) acquisition with predictable scan times. Since data obtained in all phases of respiratory and cardiac motion can be exploited, the duration of the scan is not affected by changes in heart rate or irregular breathing patterns. Achieving high-quality reconstructions from MCIR data typically requires iterative optimisation algorithms with regularisation, where reconstruction time increases with the number of motion states. This is particularly relevant in cardiac MRI, where both cardiac and respiratory motion corrections are necessary to minimise motion artefacts.<i>Approach.</i>In this work, we present a stochastic optimisation approach for efficient MCIR of 3D cardiac MRI images using the stochastic primal dual hybrid gradient (SPDHG) algorithm.<i>Main results.</i>In phantom experiments with simulated motion, we demonstrate the improved convergence rates of SPDHG with respect to deterministic algorithms, while maintaining image quality. Convergence is improved both in terms of reconstruction times and computational effort. We validate the method's effectiveness on an<i>in vivo</i>3D whole-heart cardiac MR scan. The<i>in vivo</i>method demonstrates that the motion compensation method we use allows for non-rigid deformations and irregular breathing patterns.<i>Significance.</i>This study demonstrates that stochastic algorithms can converge significantly faster than deterministic algorithms for MCIR, especially for a large number of motion states. With the proposed approach, increasing the number of motion states reduces the number of epochs required to reconstruct the image and therefore it is no longer necessary to balance the competing requirements of accurate motion correction and computational effort.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144753990","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"MagRing-MPI: design of electrically controlled FFL-MPI system based on a dynamic ring-shaped gradient array.","authors":"Ziwei Chen, Zhongwei Bian, Jian'an Ye, Jie He, Yu An, Jie Tian","doi":"10.1088/1361-6560/ae0861","DOIUrl":"https://doi.org/10.1088/1361-6560/ae0861","url":null,"abstract":"<p><strong>Objective: </strong>This study aims to propose and validate a novel electrically controlled field-free line (FFL) magnetic particle imaging (MPI) system to address several aspects of existing electronically rotated FFL-MPI designs, including limitations in gradient enhancement, structural complexity of the drive system, and coil coupling effects.&#xD; Methods: We employ a dynamic ring-shaped magnetic-field-converging gradient array (dRMGA), consisting of multiple pairs of electromagnets symmetrically arranged along the radial and axial directions. This configuration ensures that the magnetic field direction of the generated FFL remains consistently perpendicular to both the gradient direction and the imaging plane. Tomographic imaging uses only one set of drive coils arranged orthogonally to the gradient coils. Three-dimensional FFL scanning is realized by dynamically modulating the current phase of the radial coil pairs in conjunction with differential current control of the axial coil pairs. In addition, we conduct electromagnetic and image reconstruction simulations to evaluate the FFL generation characteristics and reconstruction performance under magnetic configurations with different numbers of pole pairs.&#xD; Results: Simulation results demonstrate that the proposed system can achieve efficient and stable FFL rotation and axial translation, supporting rapid 3D tomographic scanning. In addition, we systematically analyzed how different pole-pair configurations affect the quality of the generated FFL and the resulting image resolution. These findings offer concrete guidance on how pole-pair scaling influences gradient strength, field uniformity, and system complexity.&#xD; Significance: The proposed MagRing-MPI system enhances magnetic field gradients and imaging quality, simplifies the drive-coil configuration to reduce system complexity, and minimizes electromagnetic coupling and feedthrough effects. These improvements provide a promising foundation for the development of scalable and high-performance MPI systems.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145081449","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geometry-optimized electron beam scattering foils enabling dose uniformity and dose rate enhancement for FLASH radiotherapy studies.","authors":"Jianfeng Lv, Jinghui Wang, Qiheng Li, Gen Yang, Wei Gai, Kun Zhu, Xueqing Yan","doi":"10.1088/1361-6560/ae0239","DOIUrl":"10.1088/1361-6560/ae0239","url":null,"abstract":"<p><p><i>Objective.</i>The development of FLASH radiotherapy (FLASH-RT) is limited by the availability of ultra-high dose rate (UHDR) irradiation platform. This study aims to optimize electron scattering foils (SFs) for a compact 6 MeV linear accelerator (linac) operating at a short source-to-surface distance (SSD), enabling lateral uniform dose delivery with UHDR for FLASH-RT studies.<i>Approach.</i>Based on a custom-built linac, optimized aluminum SFs were designed using the Nelder-Mead simplex algorithm coupled with Geant4 Monte-Carlo simulations to achieve lateral dose uniformity in 10 mm of water/PMMA below the surface at a reduced SSD. Two geometric optimization strategies, namely stacked-layer structure and ring structure, were utilized for different field sizes. Dose distributions were quantified using radiochromic EBT-3 films, while the operation parameters-electron-gun anode voltage, pulse width, and pulse frequency-were modulated to explore dose rate dependencies.<i>Main results.</i>Utilizing an optimized stacked-layer SF and a 4 cm diameter resin collimator, uniform integrated lateral dose profiles in the first 10 mm of PMMA (flatness <5%) were measured for a 3.5 cm diameter field at 11 cm SSD. By modulating the operation parameters including anode voltage, pulse width and frequency, dose-per-pulse was continuously adjustable from 0.09 to 8.37 Gy, yielding instantaneous dose rates of 4.25 × 10⁴to2.09×106Gy s^-1and the mean dose rates spanning from10-2to103 Gys-1. Simulations further demonstrated that a flatness <5% was achievable for fields up to 10 cm diameter at the same SSD when using the ring structure SFs combined with large-diameter collimators.<i>Significance.</i>The system's capability to operate across conventional and UHDR regimes within a single framework supports comparisons of conventional radiotherapy and FLASH-RT effects with minimized systematic errors. This work offers insights into SF design methodology and facilitates incremental refinements of UHDR irradiation parameters, findings applicable to develop compact FLASH platforms based on other electron beam systems.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144965099","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}