Zeitschrift fur Medizinische Physik最新文献

{"title":"Improving quantitative susceptibility mapping for the identification of traumatic brain injury neurodegeneration at the individual level","authors":"Juan F Domínguez D ,&nbsp;Ashley Stewart ,&nbsp;Alex Burmester ,&nbsp;Hamed Akhlaghi ,&nbsp;Kieran O'Brien ,&nbsp;Steffen Bollmann ,&nbsp;Karen Caeyenberghs","doi":"10.1016/j.zemedi.2024.01.001","DOIUrl":"10.1016/j.zemedi.2024.01.001","url":null,"abstract":"<div><h3>Background</h3><div>Emerging evidence suggests that traumatic brain injury (TBI) is a major risk factor for developing neurodegenerative disease later in life. Quantitative susceptibility mapping (QSM) has been used by an increasing number of studies in investigations of pathophysiological changes in TBI. However, generating artefact-free quantitative susceptibility maps in brains with large focal lesions, as in the case of moderate-to-severe TBI (ms-TBI), is particularly challenging. To address this issue, we utilized a novel two-pass masking technique and reconstruction procedure (two-pass QSM) to generate quantitative susceptibility maps (QSMxT; Stewart et al., 2022, <em>Magn Reson Med</em>.) in combination with the recently developed virtual brain grafting (VBG) procedure for brain repair (Radwan et al., 2021, <em>NeuroImage</em>) to improve automated delineation of brain areas. We used QSMxT and VBG to generate personalised QSM profiles of individual patients with reference to a sample of healthy controls.</div></div><div><h3>Methods</h3><div>Chronic ms-TBI patients (<em>N</em> = 8) and healthy controls (<em>N</em> = 12) underwent (multi-echo) GRE, and anatomical MRI (MPRAGE) on a 3T Siemens PRISMA scanner. We reconstructed the magnetic susceptibility maps using two-pass QSM from QSMxT. We then extracted values of magnetic susceptibility in grey matter (GM) regions (following brain repair via VBG) across the whole brain and determined if they deviate from a reference healthy control group [Z-score &lt; −3.43 or &gt; 3.43, relative to the control mean], with the aim of obtaining personalised QSM profiles.</div></div><div><h3>Results</h3><div>Using two-pass QSM, we achieved susceptibility maps with a substantial increase in quality and reduction in artefacts irrespective of the presence of large focal lesions, compared to single-pass QSM. In addition, VBG minimised the loss of GM regions and exclusion of patients due to failures in the region delineation step. Our findings revealed deviations in magnetic susceptibility measures from the HC group that differed across individual TBI patients. These changes included both increases and decreases in magnetic susceptibility values in multiple GM regions across the brain.</div></div><div><h3>Conclusions</h3><div>We illustrate how to obtain magnetic susceptibility values at the individual level and to build personalised QSM profiles in ms-TBI patients. Our approach opens the door for QSM investigations in more severely injured patients. Such profiles are also critical to overcome the inherent heterogeneity of clinical populations, such as ms-TBI, and to characterize the underlying mechanisms of neurodegeneration at the individual level more precisely. Moreover, this new personalised QSM profiling could in the future assist clinicians in assessing recovery and formulating a neuroscience-guided integrative rehabilitation program tailored to individual TBI patients.</div></div>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"35 3","pages":"Pages 357-374"},"PeriodicalIF":4.2,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139713622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhanced direct joint attenuation and scatter correction of whole-body PET images via context-aware deep networks","authors":"Saeed Izadi ,&nbsp;Isaac Shiri ,&nbsp;Carlos F. Uribe ,&nbsp;Parham Geramifar ,&nbsp;Habib Zaidi ,&nbsp;Arman Rahmim ,&nbsp;Ghassan Hamarneh","doi":"10.1016/j.zemedi.2024.01.002","DOIUrl":"10.1016/j.zemedi.2024.01.002","url":null,"abstract":"<div><div>In positron emission tomography (PET), attenuation and scatter corrections are necessary steps toward accurate quantitative reconstruction of the radiopharmaceutical distribution. Inspired by recent advances in deep learning, many algorithms based on convolutional neural networks have been proposed for automatic attenuation and scatter correction, enabling applications to CT-less or MR-less PET scanners to improve performance in the presence of CT-related artifacts. A known characteristic of PET imaging is to have varying tracer uptakes for various patients and/or anatomical regions. However, existing deep learning-based algorithms utilize a fixed model across different subjects and/or anatomical regions during inference, which could result in spurious outputs. In this work, we present a novel deep learning-based framework for the direct reconstruction of attenuation and scatter-corrected PET from non-attenuation-corrected images in the absence of structural information in the inference. To deal with inter-subject and intra-subject uptake variations in PET imaging, we propose a novel model to perform subject- and region-specific filtering through modulating the convolution kernels in accordance to the contextual coherency within the neighboring slices. This way, the context-aware convolution can guide the composition of intermediate features in favor of regressing input-conditioned and/or region-specific tracer uptakes. We also utilized a large cohort of 910 whole-body studies for training and evaluation purposes, which is more than one order of magnitude larger than previous works. In our experimental studies, qualitative assessments showed that our proposed CT-free method is capable of producing corrected PET images that accurately resemble ground truth images corrected with the aid of CT scans. For quantitative assessments, we evaluated our proposed method over 112 held-out subjects and achieved an absolute relative error of <span><math><mrow><mn>14.30</mn><mo>±</mo><mn>3.88</mn></mrow></math></span>% and a relative error of <span><math><mrow><mo>-</mo><mn>2.11</mn><mo>%</mo><mo>±</mo><mn>2.73</mn></mrow></math></span>% in whole-body.</div></div>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"35 3","pages":"Pages 304-317"},"PeriodicalIF":4.2,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139661196","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessment of resolution and noise in magnetic resonance images reconstructed by data driven approaches","authors":"Jonas Kleineisel ,&nbsp;Katja Lauer ,&nbsp;Alfio Borzì ,&nbsp;Thorsten A. Bley ,&nbsp;Herbert Köstler ,&nbsp;Tobias Wech","doi":"10.1016/j.zemedi.2023.08.007","DOIUrl":"10.1016/j.zemedi.2023.08.007","url":null,"abstract":"<div><h3>Introduction</h3><div>Deep learning-based approaches are increasingly being used for the reconstruction of accelerated MRI scans. However, presented analyses are frequently lacking in-detail evaluation of basal measures like resolution or signal-to-noise ratio. To help closing this gap, spatially resolved maps of image resolution and noise enhancement (g-factor) are determined and assessed for typical model- and data-driven MR reconstruction methods in this paper.</div></div><div><h3>Methods</h3><div>MR data from a routine brain scan of a patient were undersampled in retrospect at R = 4 and reconstructed using two data-driven (variational network (VN), U-Net) and two model based reconstructions methods (GRAPPA, TV-constrained compressed sensing). Local resolution was estimated by the width of the main-lobe of a local point-spread function, which was determined for every single pixel by reconstructing images with an additional small perturbation. G-factor maps were determined using a multiple replica method.</div></div><div><h3>Results</h3><div>GRAPPA showed good spatial resolution, but increased g-factors (1.43–1.84, 75% quartile) over all other methods. The images delivered from compressed sensing suffered most from low local resolution, in particular in homogeneous areas of the image. VN and U-Net show similar resolution with mostly moderate local blurring, slightly better for U-Net. For all methods except GRAPPA the resolution as well as the g-factors depend on the anatomy and the direction of undersampling.</div></div><div><h3>Conclusion</h3><div>Objective image quality parameters, local resolution and g-factors have been determined. The examined data driven methods show less local blurring than compressed sensing. The noise enhancement for reconstructions using CS, VN and U-Net is elevated at anatomical contours but is drastically reduced with respect to GRAPPA. Overall, the applied framework provides the possibility for more detailed analysis of novel reconstruction approaches incorporating non-linear and non-stationary transformations.</div></div>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"35 3","pages":"Pages 343-356"},"PeriodicalIF":4.2,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10243559","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of RADIANCE Monte Carlo algorithm for treatment planning in electron based Intraoperative Radiotherapy (IOERT)","authors":"Charoula Iliaskou,&nbsp;Giulio Rossi,&nbsp;Ilias Sachpazidis,&nbsp;Vasilios Boronikolas,&nbsp;Mark Gainey,&nbsp;Dimos Baltas","doi":"10.1016/j.zemedi.2023.12.002","DOIUrl":"10.1016/j.zemedi.2023.12.002","url":null,"abstract":"<div><h3>Purpose</h3><div>To perform experimental as well as independent Monte Carlo (MC) evaluation of the MC algorithm implemented in RADIANCE version 4.0.8, a dedicated treatment planning system (TPS) for 3D electron dose calculations in intraoperative radiation therapy (IOERT).</div></div><div><h3>Methods and materials</h3><div>The MOBETRON 2000 (IntraOp Medical Corporation, Sunnyvale, CA) IOERT accelerator was employed. PDD and profiles for five cylindrical plastic applicators with 50–90 mm diameter and 0°, 30° beveling were measured in a water phantom, at nominal energies of 6, 9 and 12 MeV. Additional PDD measurements were performed for all the energies without applicator. MC modeling of the MOBETRON was performed with the user code BEAMnrc and egs_chamber of the MC simulation toolkit EGSnrc. The generated phase space files of the two 0°-bevel applicators (50 mm, 80 mm) and three energies in both RADIANCE and BEAMnrc, were used to determine PDD and profiles in various set-ups of virtual water phantoms with air and bone inhomogeneities. 3D dose distributions were also calculated in image data sets of an anthropomorphic tissue-equivalent pelvis phantom. Image acquisitions were realized with a CT scanner (Philips Big Bore CT, Netherlands). Gamma analysis was applied to quantify the deviations of the RADIANCE calculations to the measurements and EGSnrc calculations. Gamma criteria normalized to the global maximum were investigated between 2%, 2 mm and 3%, 3 mm.</div></div><div><h3>Results</h3><div>RADIANCE MC calculations satisfied the gamma criteria of 3%, 3 mm with a tolerance limit of 85% passing rate compared to in- water phantom measurements, except for the dose profiles of the 30° beveled applicators. Mismatches lay in surface doses, in umbra regions and in the beveled end of the 30° applicators. A very good agreement to the EGSnrc calculations in heterogeneous media was observed. Deviations were more pronounced for the larger applicator diameter and higher electron energy. In 3D dose comparisons in the anthropomorphic phantom, gamma passing rates were higher than 96 % for both simulated applicators.</div></div><div><h3>Conclusions</h3><div>RADIANCE MC algorithm agrees within 3%, 3 mm criteria with in-water phantom measurements and EGSnrc MC dose distributions in heterogeneous media for 0°-bevel applicators. The user should be aware of missing scattering components and the 30° beveled applicators should be used with attention.</div></div>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"35 3","pages":"Pages 282-291"},"PeriodicalIF":4.2,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139107067","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Implementation and validation of 2-D-array based tests in routine linac quality assurance","authors":"Jiří Valenta,&nbsp;Manfred Schmidt,&nbsp;Christoph Bert","doi":"10.1016/j.zemedi.2024.01.006","DOIUrl":"10.1016/j.zemedi.2024.01.006","url":null,"abstract":"<div><h3>Purpose</h3><div>In medical linac quality assurance (QA), to replace film dosimetry with low-resolution 2-D ionization chamber array measurements, to validate the procedures, and to perform a comprehensive sensitivity analysis.</div></div><div><h3>Methods</h3><div>A 2-D ionization chamber array with a spatial resolution of 7.62 mm was deployed to perform the following tests: Junction tests, MLC transmission test, beam profile constancy vs. gantry angle test, beam profile constancy vs. low dose delivery test, and beam energy constancy vs. low dose delivery test. Test validation and sensitivity analyses based on short- and long-term statistics of the test results were performed.</div></div><div><h3>Results</h3><div>All selected mechanical and dosimetry tests could be successfully performed with a 2-D array. Considering the tolerance limits recommended by the AAPM Task Group 142 report (2009), sensitivities of 99.0% or better and specificities ranging from 99.5% to 99.9% could be achieved in all tests when the proper metrics were chosen.</div></div><div><h3>Conclusions</h3><div>The results showed that a low-resolution 2-D ionization chamber array could replace film dosimetry without having to sacrifice high test sensitivity. Its implementation in the routine clinical linac QA program may involve considerable QA time savings.</div></div>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"35 3","pages":"Pages 270-281"},"PeriodicalIF":4.2,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139898425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of 2D ion chamber arrays for patient specific quality assurance using a static phantom at a 0.35 T MR-Linac","authors":"C. Katharina Renkamp ,&nbsp;Daniela Eulenstein ,&nbsp;Moritz Sebald ,&nbsp;Fabian Schlüter ,&nbsp;Carolin Buchele ,&nbsp;Carolin Rippke ,&nbsp;Jürgen P. Debus ,&nbsp;Sebastian Klüter","doi":"10.1016/j.zemedi.2023.12.003","DOIUrl":"10.1016/j.zemedi.2023.12.003","url":null,"abstract":"<div><h3>Introduction</h3><div>Patient specific quality assurance (QA) in MR-Linacs can be performed with MR-compatible ion chamber arrays. However, the presence of a static magnetic field can alter the angular response of such arrays substantially. This works investigates the suitability of two ion chamber arrays, an air-filled and a liquid-filled array, for patient specific QA at a 0.35 T MR-Linac using a static phantom.</div></div><div><h3>Methods</h3><div>In order to study the angular response, the two arrays were placed in a static, solid phantom and irradiated with 9.96 × 9.96 cm² fields every 10° beam angle at a 0.35 T MR-Linac. Measurements were compared to the TPS calculated dose in terms of gamma passing rate and relative dose to the central chamber. 20 patient specific quality assurance plans were measured using the liquid-filled array.</div></div><div><h3>Results</h3><div>The air-filled array showed asymmetric angular response changes of central chamber dose of up to 18% and down to local 3 mm / 3% gamma rates of 20%, while only minor differences within 3% (excluding parallel irradiation and beams through the couch edges) were found for the liquid-filled ion chamber array without rotating the phantom. Patient plan QA using the liquid-filled array yielded a median local 3 mm / 3% 3D gamma passing rate of 99.8% (range 96.9%–100%).</div></div><div><h3>Conclusion</h3><div>A liquid-filled ionization chamber array in combination with a static phantom can be used for efficient patient specific plan QA in a single measurement set-up in a 0.35 T MR-Linac, while the air-filled ion chamber array phantom shows large angular response changes and has its limitations regarding patient specific QA measurements.</div></div>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"35 3","pages":"Pages 375-384"},"PeriodicalIF":4.2,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139111420","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of the maximum ring difference on image quality and noise characteristics of a total-body PET/CT scanner","authors":"Fabian P. Schmidt ,&nbsp;Julia G. Mannheim ,&nbsp;Pia M. Linder ,&nbsp;P. Will ,&nbsp;Lena Sophie Kiefer ,&nbsp;Maurizio M. Conti ,&nbsp;Christian la Fougère ,&nbsp;Ivo F. Rausch","doi":"10.1016/j.zemedi.2023.09.001","DOIUrl":"10.1016/j.zemedi.2023.09.001","url":null,"abstract":"<div><div>The sensitivity of a PET system highly depends on the axial acceptance angle or maximum ring difference (MRD), which can be particularly high for total-body scanners due to their larger axial field of views (aFOVs). This study aims to evaluate the impact on image quality (IQ) and noise performance when MRD85 (18°), the current standard for clinical use, is increased to MRD322 (52°) for the Biograph Vision Quadra (Siemens Healthineers).</div></div><div><h3>Methods</h3><div>Studies with a cylindrical phantom covering the 106 cm aFOV and an IEC phantom filled with ¹⁸F, ⁶⁸Ga and ⁸⁹Zr were performed for acquisition times from 60 to 1800 s and activity concentrations from 0.4 to 3 kBq/ml to assess uniformity, contrast recovery coefficients (CRCs) and to characterize noise by coefficient of variation (CV). Spatial resolution was compared for both MRDs by sampling a quadrant of the FOV with a point source. Further IQ, CV, liver SUV_mean and SUV_max were compared for a cohort of 5 patients scanned with [¹⁸F]FDG (3 MBq/kg, 1 h p.i.) from 30 to 300 s.</div></div><div><h3>Results</h3><div>CV was improved by a factor of up to 1.49 and is highest for short acquisition times, peaks at the center field of view and mitigates parabolic in axial direction with no difference to MRD85 beyond the central 80 cm. No substantial differences between the two evaluated MRDs in regards to uniformity, SUV_mean or CRC for the different isotopes were observed. A degradation of the average spatial resolution of 0.9 ± 0.2 mm in the central 40 cm FOV was determined with MRD322. Depending on the acquisition time MRD322 resulted in a decrease of SUV_max between 23.8% (30 s) and 9.0% (300 s).</div></div><div><h3>Conclusion</h3><div>Patient and phantom studies revealed that scan time could be lowered by approximately a factor of two with MRD322 while maintaining similar noise performance. The moderate degradation in spatial resolution for MRD322 is worth to exploit the full potential of the Quadra by either shorten scan times or leverage noise performance in particular for low count scenarios such as ultra-late imaging or dynamic studies with high temporal resolution.</div></div>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"35 3","pages":"Pages 292-303"},"PeriodicalIF":4.2,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49695836","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Application of NEMA protocols to verify GATE models based on the Digital Biograph Vision and the Biograph Vision Quadra scanners","authors":"Miriam Magela Peña-Acosta,&nbsp;Sergio Gallardo,&nbsp;María Lorduy-Alós,&nbsp;Gumersindo Verdú","doi":"10.1016/j.zemedi.2024.01.005","DOIUrl":"10.1016/j.zemedi.2024.01.005","url":null,"abstract":"<div><h3>Purpose</h3><div>The Monte Carlo method is an effective tool to simulate and verify PET systems. Furthermore, it can help in the design and optimization of new medical imaging devices and algorithms. In this framework, the goal of this work is to verify the GATE toolkit performance when applied to simulate two Siemens Healthineers PET scanners: a standard axial field-of-view Biograph Vision scanner and the new long axial field-of-view Biograph Vision Quadra scanner.</div></div><div><h3>Methods</h3><div>The simulation toolkit GATE is based on GEANT4, comprising its main functionalities and a set of domain-specific features in the field of medical physics. To accomplish our purpose, the guidelines described in the NEMA NU 2-2018 protocol are reproduced. Then the simulated results are compared to experimental data available in the literature for both PET scanners. The assessment of the models includes different studies of sensitivity, count rate performances, spatial resolution and image quality. These tests are intended to evaluate the image quality of PET devices.</div></div><div><h3>Results</h3><div>In the spatial resolution test, relative errors lower than 8% are obtained between the experiments and GATE models. The sensitivity is 17.2 cps/kBq (Vision) and 175.9 cps/kBq (Quadra), representing relative differences with the experiment of 6% and 0.3%, respectively. Deviations from peak NECR are less than 9%. In the Image Quality test, the contrast recovery coefficient for hot spheres, with 8 iterations and 5 subsets, ranges between 57–83% for Vision and 54–86% for Quadra. These values represent a maximum deviation between the simulations and the experiments of 10% for the Quadra scanner. In the case of the Vision scanner, the highest difference is observed for the 10 mm sphere (∼38%) due to the higher contrast recovery of the experiment caused by the Gibbs artifact from the use of PSF reconstruction.</div></div><div><h3>Conclusions</h3><div>The results of the simulations have provided evidence of a good agreement between the experimental data and the results obtained with GATE. Thus, this work supports the capability of this MC toolkit to accurately simulate the models of the Vision and Quadra scanners. This study has laid the basis for further research in this field and has identified several areas that could be explored.</div></div>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"35 3","pages":"Pages 318-330"},"PeriodicalIF":4.2,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139716810","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Radiation-induced double-strand breaks by internal ex vivo irradiation of lymphocytes: Validation of a Monte Carlo simulation model using GATE and Geant4-DNA","authors":"Maikol Salas-Ramirez ,&nbsp;Lydia Maigne ,&nbsp;Giovanna Fois ,&nbsp;Harry Scherthan ,&nbsp;Michael Lassmann ,&nbsp;Uta Eberlein","doi":"10.1016/j.zemedi.2023.07.007","DOIUrl":"10.1016/j.zemedi.2023.07.007","url":null,"abstract":"&lt;div&gt;&lt;div&gt;This study describes a method to validate a radiation transport model that quantifies the number of DNA double-strand breaks (DSB) produced in the lymphocyte nucleus by internal &lt;em&gt;ex vivo&lt;/em&gt; irradiation of whole blood with the radionuclides &lt;sup&gt;90&lt;/sup&gt;Y, &lt;sup&gt;99m&lt;/sup&gt;Tc, &lt;sup&gt;123&lt;/sup&gt;I, &lt;sup&gt;131&lt;/sup&gt;I, &lt;sup&gt;177&lt;/sup&gt;Lu, &lt;sup&gt;223&lt;/sup&gt;Ra, and &lt;sup&gt;225&lt;/sup&gt;Ac in a test vial using the GATE/Geant4 code at the macroscopic level and the Geant4-DNA code at the microscopic level.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;&lt;h3&gt;Methods&lt;/h3&gt;&lt;div&gt;The simulation at the macroscopic level reproduces an 8 mL cylindrical water-equivalent medium contained in a vial that mimics the geometry for internal &lt;em&gt;ex vivo&lt;/em&gt; blood irradiation. The lymphocytes were simulated as spheres of 3.75 µm radius randomly distributed, with a concentration of 125 spheres/mL. A phase-space actor was attached to each sphere to register all the entering particles. The simulation at the microscopic level for each radionuclide was performed using the Geant4-DNA tool kit, which includes the &lt;em&gt;clustering&lt;/em&gt; example centered on a density-based spatial clustering of applications with noise (DBSCAN) algorithm. The irradiation source was constructed by generating a single phase space from the sum of all phase spaces. The lymphocyte nucleus was defined as a water sphere of a 3.1 µm radius. The absorbed dose coefficients for lymphocyte nuclei (d&lt;sub&gt;Lymph&lt;/sub&gt;) were calculated and compared with macroscopic whole blood absorbed dose coefficients (d&lt;sub&gt;Blood&lt;/sub&gt;). The DBSCAN algorithm was used to calculate the number of DSBs. Lastly, the number of DSB∙cell&lt;sup&gt;−1&lt;/sup&gt;∙mGy&lt;sup&gt;−1&lt;/sup&gt; (simulation) was compared with the number of radiation-induced foci per cell and absorbed dose (RIF∙cell&lt;sup&gt;−1&lt;/sup&gt;∙mGy&lt;sup&gt;−1&lt;/sup&gt;) provided by experimental data for gamma and beta emitting radionuclides. For alpha emitters, d&lt;sub&gt;Lymph&lt;/sub&gt; and the number of α-tracks∙100 cell&lt;sup&gt;−1&lt;/sup&gt;∙mGy&lt;sup&gt;−1&lt;/sup&gt; and DSBs∙µm&lt;sup&gt;−1&lt;/sup&gt; were calculated using experiment-based thresholds for the α-track lengths and DSBs/track values. The results were compared with the results of an &lt;em&gt;ex vivo&lt;/em&gt; study with &lt;sup&gt;223&lt;/sup&gt;Ra.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;&lt;h3&gt;Results&lt;/h3&gt;&lt;div&gt;The d&lt;sub&gt;Lymph&lt;/sub&gt; values differed from the d&lt;sub&gt;Blood&lt;/sub&gt; values by −1.0% (&lt;sup&gt;90&lt;/sup&gt;Y), −5.2% (&lt;sup&gt;99m&lt;/sup&gt;Tc), −22.3% (&lt;sup&gt;123&lt;/sup&gt;I), 0.35% (&lt;sup&gt;131&lt;/sup&gt;I), 2.4% (&lt;sup&gt;177&lt;/sup&gt;Lu), −5.6% (&lt;sup&gt;223&lt;/sup&gt;Ra) and −6.1% (&lt;sup&gt;225&lt;/sup&gt;Ac). The number of DSB∙cell&lt;sup&gt;−1&lt;/sup&gt;∙mGy&lt;sup&gt;−1&lt;/sup&gt; for each radionuclide was 0.014 DSB∙cell&lt;sup&gt;−1&lt;/sup&gt;∙mGy&lt;sup&gt;−1&lt;/sup&gt; (&lt;sup&gt;90&lt;/sup&gt;Y), 0.016 DSB∙cell&lt;sup&gt;−1&lt;/sup&gt;∙mGy&lt;sup&gt;−1&lt;/sup&gt; (&lt;sup&gt;99m&lt;/sup&gt;Tc), 0.013&lt;!--&gt; &lt;!--&gt;DSB∙cell&lt;sup&gt;−1&lt;/sup&gt;∙mGy&lt;sup&gt;−1&lt;/sup&gt; (&lt;sup&gt;123&lt;/sup&gt;I), 0.012 DSB∙cell&lt;sup&gt;−1&lt;/sup&gt;∙mGy&lt;sup&gt;−1&lt;/sup&gt; (&lt;sup&gt;131&lt;/sup&gt;I), and 0.012 DSB∙cell&lt;sup&gt;−1&lt;/sup&gt;∙mGy&lt;sup&gt;−1&lt;/sup&gt; (&lt;sup&gt;177&lt;/sup&gt;Lu). These values agree very well with experimental data. The number of α-tracks∙100 cells&lt;sup&gt;−1&lt;/sup&gt;","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"35 3","pages":"Pages 235-247"},"PeriodicalIF":4.2,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10088978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"MPE training in Germany – Perspectives of the next generation","authors":"Tim Felgenhauer,&nbsp;Laura Garajová,&nbsp;Jonas Meyer,&nbsp;Andre Karius","doi":"10.1016/j.zemedi.2025.07.001","DOIUrl":"10.1016/j.zemedi.2025.07.001","url":null,"abstract":"","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"35 3","pages":"Pages 232-234"},"PeriodicalIF":4.2,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144746728","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}