Physics in medicine and biology最新文献

{"title":"An extended local effect model for Auger-emitting radionuclide therapy.","authors":"Tae Wan Kim, Chang-Min Lee, Taeyun Kim, Rodrigo Hernandez Millares, Sung-Joon Ye","doi":"10.1088/1361-6560/ae6968","DOIUrl":"https://doi.org/10.1088/1361-6560/ae6968","url":null,"abstract":"<p><strong>Objective: </strong>Auger-emitting radionuclide therapy (RNT) is strongly influenced by spatial and temporal dose distributions of radionuclides within a cell. The local effect model (LEM) was extended to predict the radiobiological effects resulting from both spatial and temporal subcellular dose distributions of Auger-emitting radionuclides.</p><p><strong>Approach: </strong>Radionuclides of 103Pd, 111In, and 125I were prominent candidates for Auger-therapy. Their dose point kernels, calculated using the Geant4-DNA toolkit, were used to determine the nanometer-scale dose distribution characteristics of the radionuclides. These kernels were integrated into the LEM to investigate the treatment scenarios for three cell lines of MDA-MB-468, SQ20B, and 231-H2N. Then, the extended LEM was completed by implementing a full Monte Carlo simulation for a kinetic extension of the Giant Loop Binary Lesion (GLOBLE) model. The simulation took into account not only heterogeneities of source locations but also varying dose and DNA repair rates for specific radionuclides and cell lines. It was validated against published in vitro experimental results available for 111In. We then used the model to quantify the impact of subcellular localization and cellular activity of radionuclides on biological effectiveness. In addition, it was applied to compute tumor control probability (TCP) for micrometastases.</p><p><strong>Main results: </strong>This model provides a mechanistic basis for evaluating biological effectiveness across various radionuclide species and cell lines by accounting for their intrinsic radiosensitivity. Validation against experimental data for 111In showed close agreement in survival fractions. Furthermore, the model quantified a RBE dependence on subcellular localization, reaching up to an RBE10 of 4.19 in the case of intranuclear 125I in 231-H2N. It could also capture dose-rate effects at high uptake activities. Correspondingly, the derived TCP curves revealed significant variations depending on the radionuclide species and the intranuclear uptake fraction.</p><p><strong>Significance: </strong>The extended LEM was established as a mechanistic platform that integrated nanometer-scale dose distributions with cell-specific DNA damage kinetics.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2026-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147841356","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":"IPEM Topical Report: a national survey of MRI use for external beam radiotherapy treatment planning in the UK: 2025 IPEM survey results.","authors":"R Speight, S Allwood-Spiers, Michael J Dubec, Ben George, C Hamill-Taylor, S Hedley, L McDaid, M Schmidt, J Wyatt, Trina Herbert","doi":"10.1088/1361-6560/ae62f2","DOIUrl":"10.1088/1361-6560/ae62f2","url":null,"abstract":"<p><p>Magnetic resonance imaging (MRI) offers superior soft tissue contrast compared to computed tomography (CT), making it highly valuable in external beam radiotherapy (EBRT) planning. However, there are a number of barriers that have limited widespread use of MRI for EBRT planning in the UK such as limited access to MRI scanners and lack of training and guidance. Following the 2018 Institute of Physics And Engineering In Medicine (IPEM) survey on MRI use in UK RT centres, data were collected from 68 centres across the UK in 2025 to reassess MRI access, utilisation, and adherence to 2021 IPEM guidance on MRI in EBRT planning. With a 79% (54/68) complete response rate, the survey revealed increased integration of MRI into EBRT planning workflows, particularly for brain, spine, and prostate cancers. However, access remains variable, with only five centres reporting MRI scanners dedicated for RT. Compliance with recommended imaging MRI sequences and quality assurance procedures has improved but remains variable, especially among centres relying on Picture archiving and communication systems-sourced images. Barriers such as capital investment, staffing, and training persist, although clinical engagement and future planning for MRI-only workflows and Artificial Intelligence-based tools are increasing. These findings underscore the need for continued investment, updated guidance, and multidisciplinary collaboration to support the safe and effective expansion of MRI in RT planning.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2026-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147778616","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":"Free flight angular acceptance (FFAA) variance reduction technique for SPECT Monte Carlo simulations.","authors":"David Sarrut, Ane Etxebeste, Maxime Jacquet, Jean Michel Létang","doi":"10.1088/1361-6560/ae622a","DOIUrl":"10.1088/1361-6560/ae622a","url":null,"abstract":"<p><p><i>Objective.</i>While several variance reduction techniques (VRTs) exist for SPECT Monte Carlo simulations, many require system-specific pre-calculations (e.g. angular response function) or patient-specific training (e.g. generative adversarial networks), limiting their flexibility for novel detector design and research. To address this, we introduce free flight angular acceptance (FFAA), a novel VRT that integrates methods into an on-the-fly, pre-calculation-free framework.<i>Approach.</i>The method utilizes a two-step approach to separately handle primary and scattered photons. Primary photons are emitted with a forced direction towards the detector and transported using a free flight (FF) biasing method, with their statistical weights adjusted to account for attenuation. For scatter, the technique employs splitting at each Compton and Rayleigh interaction site, where scattered photons are only tracked further if they satisfy an angular acceptance criterion before being transported with FF. By deactivating FF transport at the entrance to the SPECT head and reverting to a conventional analog Monte Carlo simulation for passage through the collimator and detector, the method accurately models complex physical interactions without relying on pre-calculated detector response functions.<i>Main results.</i>When compared with analog Monte Carlo simulations, FFAA achieves mean voxel speedup of about 200 in high-count regions and 100 in low-count regions. The method preserves high fidelity for critical effects, such as collimator scatter and septal penetration, ensuring that the speedup does not compromise the accuracy of complex physical interactions.<i>Significance.</i>This makes FFAA particularly suitable for the development and optimization of novel SPECT collimator designs. To facilitate adoption, FFAA is integrated into the open-source GATE 10 software and is accessible via simple Python functions.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2026-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147729595","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 harmonic shear wave elastography over three distinct frequency regimes.","authors":"Gilmer Flores Barrera, Stefano E Romero, Kevin J Parker","doi":"10.1088/1361-6560/ae6228","DOIUrl":"10.1088/1361-6560/ae6228","url":null,"abstract":"<p><p><i>Objective.</i>To investigate how excitation frequency and source configuration influence shear wave propagation in bounded soft tissues, and to establish practical guidelines for optimizing shear wave elastography across different operating regimes.<i>Approach.</i>We analyze shear wave propagation using theoretical modeling, numerical simulations, and experimental observations across a wide range of frequencies and source configurations. The study identifies distinct propagation regimes based on the relationship between wavelength, attenuation, and geometry, and evaluates their impact on shear wave behavior.<i>Main results</i>. We demonstrate that shear wave fields exhibit three distinct regimes-quasistatic, modal, and free-space-each associated with different propagation characteristics and limitations for inverse reconstruction. We further show that optimized source configurations can significantly enhance shear wave dominance while minimizing compressional components, leading to order-of-magnitude improvements in signal-to-noise ratio and spatial resolution at higher frequencies.<i>Significance</i>. These findings provide a unified framework for understanding frequency-dependent wave behavior in elastography and highlight that frequency selection is a critical determinant of both wave physics and reconstruction validity. The proposed guidelines offer practical insight for translating experimental optimization strategies into clinically relevant settings.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2026-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147729617","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":"Reduction of CT number location dependency using photon-counting detector CT and virtual monoenergetic imaging.","authors":"Maryam Sadeghian, Joseph R Swicklik, Cynthia H McCollough, Yanle Hu, Shuai Leng","doi":"10.1088/1361-6560/ae62f1","DOIUrl":"10.1088/1361-6560/ae62f1","url":null,"abstract":"<p><p><i>Objective.</i>Computed tomography (CT) number accuracy is critical in radiotherapy planning. This study aimed to investigate the potential of photon-counting-detector (PCD) CT to reduce location dependency of CT numbers compared to energy-integrated-detector (EID) CT across imaging modes, tissue types, and patient sizes.<i>Approach.</i>Four inserts of typical tissue types: cortical bone, liver, lung, and adipose were placed inside a body size (40 × 30 cm²) multi-energy CT phantom (Gammex). To simulate a larger patient, tissue-equivalent material (Superflab) was added to increase phantom lateral width to 50 cm. Both phantoms were scanned on a PCD-CT (NAEOTOM Alpha, Siemens), a dual-source EID-CT (Force, Siemens; EID-A), and a dual-layer EID-CT (7500 Spectral, Philips; EID-B). All scans were performed with 120 kV, except dual-energy mode of EID-A (100/Sn150 kV, Sn: Tin filter). Volume CT dose index (CTDI_vol) was matched across scanners. Each insert was scanned in seven locations: iso-center and six peripheral locations. In addition to single-energy images, 70 keV virtual-monoenergetic images (VMIs) were reconstructed. CT numbers were measured using circular regions of interest. Mean CT number, standard deviation (std), coefficient of variation (CV), max-to-min and central-to-peripheral differences were quantified. CT number variation across seven locations was assessed using the Friedman test and Bonferroni corrected pairwise Wilcoxon signed-rank tests.<i>Main results.</i>PCD-VMI demonstrated lower CT number locational variation compared to EID-CTs among most tissue inserts and phantom sizes. For cortical bone in the standard phantom, PCD-VMI achieved std of 3.31 HU, showing 70.3% reduction compared to single-energy PCD (11.15 HU) and lower than single-energy EID-A (9.75 HU), single-energy EID-B (10.93 HU), EID-A VMI (12.65 HU), and EID-B VMI (4.10 HU). PCD-VMI CV remained below 1% and 3% for small and large phantoms, respectively. Increasing phantom size increased CT number variations, with lowest differences for PCD-VMI. PCD-VMI showed significantly lower CT number locational variation than all other scans across most inserts and phantom sizes.<i>Significance.</i>PCD-VMI reduces CT number locational dependency compared to most imaging modes. The greatest improvements were observed for high-<i>Z</i>materials and larger patients. PCD-VMIs are promising for radiation therapy applications.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2026-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147778621","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":"Validation of an analytical approach for<i>in vivo</i>PET verification in carbon ion therapy: comparison with Monte Carlo simulations and PET monitoring measurements.","authors":"Tianxue Du, Julia Bauer, Thomas Tessonnier, Katia Parodi, Marco Pinto","doi":"10.1088/1361-6560/ae6226","DOIUrl":"10.1088/1361-6560/ae6226","url":null,"abstract":"<p><strong>Objective: </strong>As carbon ion therapy is highly sensitive to range uncertainties, it can benefit greatly from range verification. Positron emission tomography (PET) provides a valuable approach, in which predicted positron emitter distributions (PED) can be used to calculate the expected activity distribution, which is then compared with the irradiation-induced PET signal. In a previous work, we developed an analytical approach to predict 3D PED from dose distributions, providing a faster alternative to Monte Carlo (MC) simulations at a comparable accuracy, and with potential for integration into analytical treatment planning systems (TPS). The purpose of this work is to validate this analytical approach using real clinical cases where offline PET/Computed tomography (CT) monitoring was employed.</p><p><strong>Approach: </strong>Four carbon ion therapy patients treated at the Heidelberg Ion Beam Therapy Center were selected, and their treatment plans and CT images were used for MC simulations and analytical prediction ofβ+-activity distributions. The analytically predicted activity distributions, derived from the simulated dose distributions with our analytical approach, were then compared with both simulated results and measured offline PET data.Main results.The analytical and MC activity distributions demonstrated a good match in range with mean deviations less than 0.5 mm, and in amplitude with mean normalized root-mean-square error less than 2%. Range shifts between the measured PET signals and the analytical activity patterns were evaluated and found to be consistent with published results.</p><p><strong>Significance: </strong>The obtained results demonstrate the capability of our analytical approach to predict PET images for range verification in carbon ion therapy under real clinical scenarios, offering faster predictions than MC simulations while maintaining comparable accuracy. The solution proposed also offers the possibility of a straightforward integration into TPS by leveraging the commonly used pencil beam algorithms present in analytical carbon ion dose engines.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2026-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147729630","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":"Quality assurance phantoms for deep hyperthermia devices: design principles informed by computational modeling.","authors":"Mattia De Lazzari, Hana Dobsicek Trefna, Carolina Carrapiço-Seabra, Patrick Vincent Granton, Sergio Curto, Dario Rodrigues","doi":"10.1088/1361-6560/ae6748","DOIUrl":"https://doi.org/10.1088/1361-6560/ae6748","url":null,"abstract":"<p><strong>Objective: </strong>Accurate thermal dose delivery is essential for the clinical success of deep hyperthermia (DHT). As the European Society for Hyperthermic Oncology (ESHO) shifts toward temperature-based QA metrics, standardized tissue-mimicking phantoms for DHT become increasingly important. This study provides quantitative evidence to guide phantom design using computational modeling supported by experimental validation.&#xD;Approach: Numerical simulations were performed using a simplified model of a clinical DHT applicator operating at 75 and 100 MHz. Parametric studies assessed the influence of phantom geometry (diameter, length, wall thickness) and dielectric properties (relative permittivity and electrical conductivity) on specific absorption rate and temperature distributions. Agreement with patient models was evaluated by comparing phantom simulations with temperature profiles derived from anatomical models. A gel phantom was constructed to validate simulations experimentally. The effects of thermal mapping and positioning errors on thermal profiles were also analyzed.&#xD;Main results: Simulations demonstrated that dielectric properties, especially electrical conductivity, had the strongest effect on heating patterns and temperature gradients; lower conductivity produced steeper focal profiles and reduced peripheral hotspots. Comparisons with patient models revealed good agreement in the focal region. Experimental measurements matched simulated temperatures near the applicator focus, with an average deviation of 0.7 ± 0.5 °C in the most reproducible series. Larger deviations near boundaries were attributed to thermal mapping uncertainties, catheter bending, and phantom misalignment. Including these uncertainties in the model indicated the need for margins reflecting average positioning errors of ±2.5 cm along the probe axis and ±0.5 cm perpendicular to it.&#xD;Significance: This study provides a validated modeling framework and design recommendations that support temperature-based QA procedures for DHT. By clarifying how phantom parameters influence measurable temperature profiles and quantifying key sources of experimental uncertainty, this work strengthens the basis for standardized QA phantoms and enhances the reliability of performance assessment for clinical DHT systems.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2026-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147819543","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":"Mid-range arc therapy for efficient and RBE-robust proton treatment.","authors":"Qingying Wang, Mingli Chen, Yinheng Zhu, Xingyi Zhao, You Zhang, Xuejun Gu, Weiguo Lu","doi":"10.1088/1361-6560/ae674c","DOIUrl":"10.1088/1361-6560/ae674c","url":null,"abstract":"<p><strong>Objective: </strong>Proton arc therapy (PAT) has the potential to improve plan conformity while enhancing normal tissue sparing; however, its clinical translation faces practical barriers related to radiobiological uncertainties and delivery inefficiency. This study introduces a novel planning approach, Mid-Range Proton Arc Therapy (MRPAT), designed to enhance delivery efficiency and mitigate range-related uncertainties in PAT.</p><p><strong>Approach: </strong>MRPAT employs a single mid-range energy layer (MREL) per beam direction, positioning the Bragg peak near the target center (mid-range) plane to confine range uncertainty within the target while reducing dose-averaged linear energy transfer (LETd) and relative biological effectiveness (RBE) hotspots in adjacent organs at risk (OARs). The feasibility of MRPAT was investigated on an ellipse phantom and three clinical cases (prostate, spine, and head and neck). Physical dose distributions, LETd distributions, RBE-weighted dose distributions, and delivery efficiency were compared with full-range arc employing all possible energy layers (Full-Arc) and intensity-modulated proton therapy (IMPT) plans with two beams.</p><p><strong>Main results: </strong>Compared with IMPT, arc plans provided substantial improvements in entrance dose control and OAR sparing. The MRPAT plan achieved comparable target coverage and OAR sparing compared to the baseline Full-Arc plan, demonstrating the redundancy of utilizing all possible energy layers. MRPAT effectively confined LETd and RBE hotspots to the center of the target, reducing potential biological weighted dose spillage over the surroundings. In terms of delivery efficiency, MRPAT eliminates energy layer switching within the same control point by using less than 5% of the energy layers, requiring only about 20% of the total beam delivery time compared with the Full-Arc plan.</p><p><strong>Significance: </strong>MRPAT demonstrates a simple, efficient, and high‑LETd/RBE hotspot‑containment planning concept that is practical for clinical use and adaptable to future adaptive PAT workflows.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2026-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147819576","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":"Real-time CBCT reconstructions using Krylov solvers in repeated scanning procedures.","authors":"Fred Hastings, S M Ragib Shahriar Islam, Malena Sabate Landman, Sepideh Hatamikia, Carola-Bibiane Schönlieb, Ander Biguri","doi":"10.1088/1361-6560/ae676e","DOIUrl":"https://doi.org/10.1088/1361-6560/ae676e","url":null,"abstract":"<p><p>This work introduces a new efficient iterative solver for the reconstruction of real-time cone-beam computed tomography (CBCT), which is based on the Prior Image Constrained Compressed Sensing (PICCS) regularization and leverages the efficiency of Krylov subspace methods. In particular, we focus on the setting where a sequence of under-sampled CT scans are taken on the same object with only local changes (e.g. changes in a tumour size or the introduction of a surgical tool). This is very common, for example, in image-guided surgery, where the amount of measurements is limited to ensure the safety of the patient. In this case, we can also typically assume that a (good) initial reconstruction for the solution exists, coming from a previously over-sampled scan, so we can use this information to aid the subsequent reconstructions. The effectiveness of this method is demonstrated in both a synthetic scan and using real CT data, where it can be observed that the PICCS framework is very effective for the reduction of artifacts, and that the new method is faster than other common alternatives used in the same setting.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2026-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147819552","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":"Deformable 3D dosimetry of MRI-tracking radiotherapy.","authors":"Morgan J Wheatley, Jarrad Begg, Yves De Deene","doi":"10.1088/1361-6560/ae674a","DOIUrl":"https://doi.org/10.1088/1361-6560/ae674a","url":null,"abstract":"<p><p>During breathing, anatomical structures within the torso move which can result in inaccurate radiation dose delivery. With the introduction of MRI-linear accelerators (MRI-linacs), the ability to simultaneously acquire high-contrast soft tissue images during irradiation allows for compensation of intrafraction motion and deformation by gating or tracking the target volume. The implementation of MRI-guided tracking radiotherapy is not without risks as any lag or organ deformation may not be accounted for. Polymer gel dosimetry has the potential to measure the integral dose delivered to deforming and moving targets as the gels are flexible and provide a high-resolution 3D dose profile. &#xD;Spherical silicone casts filled with polymer gel and silica beads were compressed to measure the deformation of gel phantoms. The effect of compression on the dose response was studied by irradiating and scanning the spherical phantoms in various states of compression. End-to-end gel dosimetry experiments with MRI-guided tracking radiotherapy were conducted on a prototype MRI-linac (Australian MRI-Linac) using a moving, non-deformable, rectangular-shaped gel dosimeter phantom and an MRI-safe, pneumatically actuated, anthropomorphic, breathing phantom containing a liver-shaped gel dosimeter. Radiochromic film dosimeters within the phantoms were used as secondary validations of the dose profile. The tracking performance of the MRI-linac was assessed by comparing measured dose distributions in the phantoms in static and actuated experiments.&#xD;There was no significant impact of compression on the dose response in the irradiated spheres. The gel-measured dose profiles in the phantoms matched closely with the film dosimeters for tracked and non-tracked scenarios. The end-to-end gel dosimeter experiments illustrate the improvement in dose conformality with MRI-guided tracking. &#xD;Deformable 3D gel dosimeters in an anthropomorphic body phantom can be used for assessing 3D geometric accuracy of tracked treatments on MRI-linacs, but care should be taken to account for the oxygen inhibition at the edges of the dosimeter.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2026-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147819364","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}