Physics in medicine and biology最新文献

{"title":"Bragg-peak FLASH Biological Optimization Enables Enhanced Normal Tissue Sparing and Dose Escalation for Ocular Stereotactic Body Radiation Therapy.","authors":"Muhammad Hamza, Balaji Selvaraj, Xingyi Zhao, Chingyun Cheng, Tyler Kaulfers, Grant Lattery, Huifang Zhai, Charles Simone, Christopher Barker, Jenghwa Chang, Haibo Lin, Minglei Kang","doi":"10.1088/1361-6560/ae0ef7","DOIUrl":"https://doi.org/10.1088/1361-6560/ae0ef7","url":null,"abstract":"<p><strong>Objective: </strong>To evaluate proton Bragg peak FLASH for ocular treatments to enhance normal tissue sparing and enable dose escalation via FLASH biological optimization(FBO).&#xD;Approach: The FLASH-sparing factors for normal tissues were derived from the literature in modeling the phenomenological FLASH normal tissue sparing effect. Using the single-energy BP-FLASH technique(SEBP-FLASH), an in-house treatment planning system was implemented with the FLASH FBO module. Ten consecutive ocular patients who were treated using conventional dose rate intensity-modulated proton therapy(CONV-IMPT) to 50Gy in 5 fractions were replanned using the FLASH technique. The dose metrics for the OARs were compared using the two different techniques. The fraction dose was then intentionally escalated from 10 to 12Gy through FBO to assess whether the plans still met clinical constraints. &#xD;Main results: In the FLASH regimen without FBO(50Gy/5 fractions), all ipsilateral OAR dosimetric metrics met clinical objectives with safe margins. While the clinical CONV-IMPT approach demonstrated slightly better dosimetric performance than SEBP-FLASH plans, the incorporation of FBO improved all OAR dose metrics beyond those of CONV- IMPT, except for the mean dose to the cornea (no difference). When the target dose was increased from 50 to 60Gy using FBO, all OARs remained within clinical limits. The mean and maximum doses to the cornea increased from 11.7 to 15.4Gy and from 22.8 to 23.6Gy, respectively, when transitioning from 50Gy CONV- IMPT to 60Gy FBO. However, in the 60Gy FBO plans, the maximum doses were reduced for the eye (102.0% to 87.0%), optic nerves (98.7% to 74.0%), retina (100.5% to 81.8%), lacrimal gland (84.9% to 73.2%), and conjunctiva (91% to 72.3%).&#xD;Significance: SEBP-FLASH achieves plan quality comparable to CONV-IMPT using 50 Gy/5 fractions and enables dose escalation via FLASH FBO while meeting clinical standards, potentially improving tumor control with acceptable toxicity.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145213467","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":"Inter-slice Complementarity Enhanced Ring Artifact Removal using Central Region Reinforced Neural Network.","authors":"Yikun Zhang, Guannan Liu, Zhanghao Chen, Zujian Huang, Shengqi Kan, Xu Ji, Shouhua Luo, Shouping Zhu, Jian Yang, Yang Chen","doi":"10.1088/1361-6560/ae0deb","DOIUrl":"https://doi.org/10.1088/1361-6560/ae0deb","url":null,"abstract":"<p><p>In computed tomography (CT), non-uniform detector responses often lead to ring artifacts in reconstructed images. For conventional energy-integrating detectors (EIDs), such artifacts can be effectively addressed through dead-pixel correction and flat-dark field calibration. However, the response characteristics of photon-counting detectors (PCDs) are more complex, and standard calibration procedures can only partially mitigate ring artifacts. Consequently, developing high-performance ring artifact removal algorithms is essential for PCD-based CT systems. To this end, we propose the Inter-slice Complementarity Enhanced Ring Artifact Removal (ICE-RAR) algorithm. Since artifact removal in the central region is particularly challenging, ICE-RAR utilizes a dual-branch neural network that could simultaneously perform global artifact removal and enhance the central region restoration. Moreover, recognizing that the detector response is also non-uniform in the vertical direction, ICE-RAR suggests extracting and utilizing inter-slice complementarity to enhance its performance in artifact elimination and image restoration. Experiments on simulated data and two real datasets acquired from PCD-based CT systems demonstrate the effectiveness of ICE-RAR in reducing ring artifacts while preserving structural details. More importantly, since the system-specific characteristics are incorporated into the data simulation process, models trained on the simulated data can be directly applied to unseen real data from the target PCD-based CT system, demonstrating ICE-RAR's potential to address the ring artifact removal problem in practical CT systems. The implementation is publicly available at https://github.com/DarkBreakerZero/ICE-RAR.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145200685","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":"Optimizing the ferumoxytol dose for vascular suppression in brachial plexus magnetic resonance neurography.","authors":"Allison S Lowe, Darryl B Sneag, Shayna E Turbin, Mylinh Duong, Shu-Han Wang, Daniel M Alschuler, Ek T Tan","doi":"10.1088/1361-6560/ae0864","DOIUrl":"10.1088/1361-6560/ae0864","url":null,"abstract":"<p><p><i>Background.</i>Magnetic resonance neurography (MRN) enables visualization of peripheral nerves using T2-weighted, fat-suppressed sequences. However, vascular signal contamination in the brachial plexus remains a challenge. Ferumoxytol, an ultra-small paramagnetic iron oxide agent, can suppress vascular signal in MRN due to its high T2 relaxivity and longer half-life, but the optimal dose is unknown.<i>Objective.</i>To evaluate whether a subject-specific dose of Ferumoxytol, based on weight and estimated blood volume, improves vascular suppression in brachial plexus MRN, as compared to using a fixed-dose.<i>Approach.</i>Thirty-four healthy adult subjects (16 female, age = 25.0 ± 2.2 years, mean [range] weight = 66.90 [44.00, 97.52] kg) underwent slow Ferumoxytol infusion (<36 mg Fe min^-1) followed by unilateral brachial plexus MRN at 3.0T. Subjects were divided into three cohorts: variable dose (6%-26% of full 510 mg dose), fixed 25% dose (Cohort 2), and fixed 50% dose (Cohort 3). Signal intensities of nerve, artery, vein, and muscle were obtained via manual segmentation. Contrast ratios (CR) between vessel-muscle and nerve-muscle were compared between cohorts using two-sample<i>t</i>-tests. Regression analysis was performed between vessel-muscle CR and the Ferumoxytol dose calculated by mg, mg kg^-1, and mg l^-1. The doses required to achieve a target vessel-muscle CR of 0.2 were calculated.<i>Main results.</i>Cohort 3 had superior vascular suppression compared to Cohort 1 (i.e. lower vessel-muscle CR,<i>p</i>< 0.05). Higher correlations of vein-muscle CR with subject-specific dosing (<i>R</i>²= 0.396-0.409) were obtained than with absolute dose (<i>R</i>²= 0.341). Doses of 101.49 mg (17.81 mg-581.80 mg), 1.57 mg kg^-1(0.42 mg kg^-1-5.82 mg kg^-1), and 23.8 mg l^-1(5.88 mg l^-1-96.17 mg l^-1) were estimated to achieve the required diagnostic CRs of 0.2.<i>Significance.</i>Subject-specific Ferumoxytol dosing based on weight and estimated blood volume provided improved modeling and prediction of vascular suppression in brachial plexus MRN. This helps to optimize dose requirements, improve safety, while providing optimal vascular suppression needed for nerve visualization.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145080554","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":"TOPAS-based 4D Monte Carlo simulation of transit dose in esophageal HDR brachytherapy: A phantom study.","authors":"Farhad Moradi, Ali Taheri, Roya Boodaghi Malidarre, Hairul A Abdul-Rashid","doi":"10.1088/1361-6560/ae0dec","DOIUrl":"https://doi.org/10.1088/1361-6560/ae0dec","url":null,"abstract":"<p><strong>Objective: </strong>Intraluminal high-dose-rate (HDR) brachytherapy is a well-established treatment modality for esophageal cancer, where a radioactive source moves through a catheter to deliver dose at discrete dwell positions. However, during the source's transit phase non-negligible dose may be delivered to surrounding healthy tissues. This study utilizes the time-dependent (4D) Monte Carlo (MC) simulation approach to quantify the transit dose to organs at risk (OARs) during esophageal brachytherapy using the TOPAS tool.</p><p><strong>Approach: </strong>A simplified yet anatomically representative male anthropomorphic phantom was modeled in TOPAS, incorporating key anatomical structures including the esophagus, trachea, spinal cord, pharynx, and other OARs. The motion of an Ir-192 HDR source was dynamically simulated through a brachytherapy catheter, with source acceleration and deceleration explicitly modeled to reflect clinical delivery. Focusing on a 6 cm tumor in the upper esophagus, absorbed doses were calculated under varying conditions: constant versus variable source speeds and differing numbers of dwell points, to evaluate the dosimetric impact of source motion.</p><p><strong>Main results: </strong>Compared to static simulations that neglect source movement, the inclusion of realistic source motion led to a substantial increase in dose to the tumor itself, up to 31%. Transit dose to OARs along the catheter path and those adjacent to the esophagus, such as the pre-pharyngeal region and pharynx, reached up to 11.7% of the tumor dose under variable speed profiles. These results reveal significant underestimation in static dose calculations, highlighting the importance of accounting for source motion.</p><p><strong>Significance: </strong>This study underscores the dosimetric importance of accounting for source transit in HDR brachytherapy and demonstrates the value of TOPAS's time-feature for conducting 4D MC simulations of realistic source motion. The findings indicate that transit dose can contribute substantially to overall dose distributions and should be considered in treatment planning, particularly for tumors situated in anatomically complex or radiosensitive regions.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145200725","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":"Chebyshev-polynomial-based deformable registration of magnetic resonance images with a specific application in adaptive gantry-less proton therapy.","authors":"Hyeongseok Kim, Samantha Hickey, Gregory Buti, Ali Ajdari, Gregory C Sharp, Susu Yan, Thomas Bortfeld","doi":"10.1088/1361-6560/ae077e","DOIUrl":"10.1088/1361-6560/ae077e","url":null,"abstract":"<p><p><i>Objective.</i>Efficient image guidance and online adaptive treatment are essential for the success of gantry-less proton therapy (PT). Low-field magnetic resonance imaging (MRI) is a viable option for image guidance, but scan time can limit the quality of low-field MRI images. This study aims to investigate the impact of MRI image quality on deformable image registration (DIR) performance.<i>Approach.</i>We propose a Chebyshev-polynomial-based DIR method, which calculates a mapping between the voxels of a high-quality source image and a lower-quality target image. We prepared a longitudinal breast MRI dataset and synthesized lower-quality target images with four image resolutions and noise levels. For evaluation, we assumed the registration between a pair of high-quality images as the reference registration. We calculated the root-mean-square error (RMSE) between the warped image and the reference target image, as well as between the warped images aligned with high- and lower-quality target images. Deformable vector field (DVF) errors were calculated based on the reference DVF. We obtained binary masks for glandular tissue and calculated Dice coefficients after DIR. The method was further validated with a volunteer breast MRI study with intentional movements between two scan sets and a longitudinal pelvic MRI dataset that includes two contours. Comparison studies with commercial software and open-source software were performed.<i>Main results.</i>Although the quantitative metrics worsened with higher levels of undersampling or increased noise, the RMSE between the warped and target images was substantially reduced compared to the RMSE between the source and target images before registration, even when the target images were severely degraded. Dice coefficients were also considerably increased under various image degradation scenarios.<i>Significance.</i>We have developed a Chebyshev-polynomial-based DIR method and demonstrated its performance with high-quality source and lower-quality target images. This study could help optimize MRI for adaptive gantry-less PT.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145075900","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":"Hybrid-MedNet: a hybrid CNN-transformer network with multi-dimensional feature fusion for medical image segmentation.","authors":"Yumna Memon, Feng Zeng","doi":"10.1088/1361-6560/ae0976","DOIUrl":"10.1088/1361-6560/ae0976","url":null,"abstract":"<p><p>Twin-to-twin transfusion syndrome (TTTS) is a complex prenatal condition in which monochorionic twins experience an imbalance in blood flow due to abnormal vascular connections in the shared placenta. Fetoscopic laser photocoagulation is the first-line treatment for TTTS, aimed at coagulating these abnormal connections. However, the procedure is complicated by a limited field of view, occlusions, poor-quality endoscopic images, and distortions caused by artifacts. To optimize the visualization of placental vessels during surgical procedures, we propose Hybrid-MedNet, a novel hybrid CNN-transformer network that incorporates multi-dimensional deep feature learning techniques. The network introduces a BiPath tokenization module that enhances vessel boundary detection by capturing both channel dependencies and spatial features through parallel attention mechanisms. A context-aware transformer block addresses the weak inductive bias problem in traditional transformers while preserving spatial relationships crucial for accurate vessel identification in distorted fetoscopic images. Furthermore, we develop a multi-scale trifusion module that integrates multi-dimensional features to capture rich vascular representations from the encoder and facilitate precise vessel information transfer to the decoder for improved segmentation accuracy. Experimental results show that our approach achieves a Dice score of 95.40% on fetoscopic images, outperforming ten state-of-the-art segmentation methods. The consistent superior performance across four segmentation tasks and ten distinct datasets confirms the robustness and effectiveness of our method for diverse and complex medical imaging applications.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145092208","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":"Kidney stone classification by speckle x-ray imaging.","authors":"Werneri A Lindberg, Henning Richter, Fayez Alfayez, Killang Pratama, Olivier Bonny, Damien Terebenec, René M Rossi, Antonia Neels, Robert Zboray","doi":"10.1088/1361-6560/ae09ed","DOIUrl":"10.1088/1361-6560/ae09ed","url":null,"abstract":"<p><p><i>Objective.</i>Urinary stone-related diseases affect approximately 6% of the global population, with nearly half of the patients experiencing recurrence. The diagnosis and management of the disease depend on the stone type and composition. Yet, current clinical imaging modalities (ultrasound, computed tomography, and radiography) lack the sensitivity and specificity required for accurate classification. Speckle-based dark-field x-ray imaging offers a potential non-invasive method for classifying urinary stones with the required hardware simplicity and robustness for potential<i>in vivo</i>, clinical applicability. However, the influence of diffuser masks and state-of-the-art speckle x-ray image retrievals on classification remains underexplored.<i>Approach.</i>This<i>ex vivo</i>study systematically compared the efficacy of custom diffuser masks and state-of-the-art speckle x-ray retrieval algorithms, using both grid and custom speckle masks, for single-shot dark-field imaging in urinary stone classification at high x-ray energy (80 kVp).<i>Main Results.</i>Among the various types of urinary stones examined in this study, canine ammonium urate showed the most distinct visibility contrast difference, deviating by 32%from the average x-ray transmission value. Overall, the results indicate a potential to differentiate between three main groups of urinary stones based on their attenuation-to-scattering coefficients: ammonium urate, calcium-based stones, and a third group comprising cystine and struvite. Regarding the different diffuser masks, the periodic grid mask is found to be the most suitable candidate for application to urinary stones. The different dark-field visibility reduction retrieval algorithms yielded nearly identical classification trends for the urinary stone samples. We recommend nonetheless, the Fokker-Planck-based approach due to its strong physical basis and favorable image quality characteristics, especially if the noise level can be kept low.<i>Significance.</i>The findings in this study establish a technical foundation for advancing speckle-based dark-field x-ray imaging toward clinical translation for non-invasive urinary stone classification.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145125887","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":"Predicting lymphocyte dose and surviving fraction for VMAT and IMPT treatments with a dynamic lymphocyte flow model for locally advanced cervical cancer.","authors":"Sander Cyril Kuipers, Marianne van Tuyll van Serooskerken, Danny Lathouwers, Anouk Corbeau, Stephanie M de Boer, Remi A Nout, Mischa S Hoogeman, Jeremy Godart","doi":"10.1088/1361-6560/ae0d29","DOIUrl":"https://doi.org/10.1088/1361-6560/ae0d29","url":null,"abstract":"<p><strong>Objective: </strong>A dynamic model is developed to predict the impact of radiotherapy on circulating lymphocyte counts in women with locally advanced cervical cancer (LACC). This study aims to compare the effects of photon and proton therapy, as well as the influence of bone marrow sparing techniques, on relative lymphocyte preservation over time.&#xD;Approach. A dynamic lymphocyte flow model was developed to simulate the migration of lymphocytes based on seven compartments. Biological cell death and lymphocyte production were integrated across compartments. The lymphocyte flow model was applied to 19 LACC patients. Volumetric modulated arc therapy (VMAT) and intensity modulated proton therapy (IMPT) treatment plans were created for each patient without bone marrow sparing (BMS) and with BMS. The model calculated radiation dose to lymphocytes to estimate radiation-induced cell death over time. The output of the model was the relative lymphocyte count relative to baseline (RLC) over time and the RLC nadir in the blood and total body.&#xD;Main results. According to the model, IMPT resulted in lower doses to lymphocytes and higher RLC nadir than VMAT for all 19 patients. The total RLC nadir (mean ± SD) was 48.4% ± 4.0% for VMAT and 62.5% ± 5.1% for IMPT. In the blood compartment, the RLC nadir was 32.7% ± 3.5% for VMAT and 47.7% ± 5.9% for IMPT. The RLC nadir in the blood compartment improved with 3 Gy BMS from 32.7% ± 3.5% to 33.0% ± 3.5%, while it decreased for IMPT from 47.7% ± 5.9% to 46.6% ± 6.0%. Total RLC nadir decreased with BMS for VMAT from 48.4% ± 4.0% to 48.2% ± 3.9% and for IMPT from 62.5% ± 5.1% to 60.9% ± 5.3%.&#xD;Significance. By incorporating a dynamic flow model, we predicted the RLC over time. The model predicted a substantial sparing effect IMPT has on the lymphocytes compared to VMAT. This sparing was both present in the blood and the total body. Sparing the bone marrow showed only a minimal effect on the RLC.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145192403","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":"MODD: Multicenter one-shot medical landmark detection and denoising.","authors":"Jialin Shi, Xiangde Li, Ning Zhang, Zongjie Wang","doi":"10.1088/1361-6560/ae0d40","DOIUrl":"https://doi.org/10.1088/1361-6560/ae0d40","url":null,"abstract":"<p><strong>Objective: </strong>One-shot landmark detection on lateral cephalometric X-ray images has advantages for label-efficient training. As clinical datasets are typically small and do not generalize well to variations in equipment or imaging environments. When using datasets from multiple studies (multi-center data) for joint training, the imbalance in the number of images and the differences in image properties can lead to poor generalization performance. In this work, we aim to propose a method that leverages more data from multiple experiments to improve the accuracy of a single experiment.&#xD;Approach. To address these challenges, we propose a Multicenter One-shot landmark Detection and Denoising framework (MODD). It incorporates a self-supervised one-shot mapping based on multicenter template transformation and the pseudo-label denoising module. Label denoising is used to reduce the impact of inaccurate pseudo-labels on the algorithm, focusing on label quality rather than signal noise in X-ray images.&#xD;For denoising module, we propose the shuffled dynamic sample selection and contrastive correction of multicenter pseudo labels. These two components together enable more accurate one-shot landmarks detection on lateral cephalometric X-ray images in multicenter scenarios.&#xD;Main results. Experiments are conducted with the publicly available multicenter cephalometric X-ray datasets. MODD achieves a landmark detection accuracy of 79.27% within a 4.0 mm range and the mean radial error of 2.94 mm, demonstrating satisfactory performance compared to state-of-the-art methods. &#xD;Significance. This study expands the application of medical landmark detection to the multi-center one-shot filed and demonstrates the potential of the MODD architecture.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145192433","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":"Multifactorial Analysis of MRI Gradient Safety for Active Implantable Medical Devices: Coil Design, Implant Trajectories, and Scan Configurations.","authors":"Xu Boya, Changqing Jiang, Peishan Li, Wanxuan Sang, Luming Li","doi":"10.1088/1361-6560/ae0d28","DOIUrl":"https://doi.org/10.1088/1361-6560/ae0d28","url":null,"abstract":"<p><strong>Objective: </strong>Electromagnetic (EM) modelling is an effective method for evaluating the gradient safety of magnetic resonance imaging (MRI) for patients with active implantable medical devices (AIMDs). However, the combined effects of multiple factors-including gradient coil design constraints, implanted lead path, gradient strength, and scan configuration-on gradient-induced voltage (GIV) risk has not been systematically investigated. In particular, the magnetic field distribution outside the region of linearity (ROL) of gradient coils cannot be uniquely determined from their nominal gradient profile, and its impact on AIMD gradient safety assessment remains poorly understood.</p><p><strong>Approach: </strong>This study presents a multifactorial analysis of MRI gradient safety by integrating gradient coil modelling with anatomical lead path tracing using a reference human body shell. We examine how variations in coil design constraints affect magnetic field distributions and how these, in turn, influence GIV for three representative AIMDs' pathways: deep brain stimulators (DBS), cardiac pacemakers (PM), and sacral nerve stimulators (SNM). Multiple gradient strengths, coil excitation modes, and scanning positions are assessed.</p><p><strong>Results: </strong>Magnetic field distributions vary significantly between coil designs, particularly in the concomitant Bx and By components, with differences reaching up to 53%. These variations result in GIV difference that increases with gradient strength. The maximum GIV differences for DBS, SNM, and PM reach 1.08V, 0.52V, and 0.93V, respectively, under Y-axis excitation. The concomitant field plays a significant role in these differences. Simultaneous excitation of all axes does not always produce the highest GIV due to cancellation effects. Cross-AIMD analysis shows high-risk zones are concentrated in and around the ROL.</p><p><strong>Significance: </strong>This work fills a gap by systematically evaluating how coil design, implant characteristics, gradient strength, and scan configurations influence GIV risk, providing a foundation for more comprehensive, individualized MRI gradient safety assessments.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145192427","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}