Physica Medica-European Journal of Medical Physics最新文献

{"title":"Verification of Geant4-DNA step-by-step-reaction-diffusion master equation model for long-term radiolysis simulation","authors":"Euntaek Yoon ,&nbsp;Ngoc Hoang Tran ,&nbsp;Sebastien Incerti ,&nbsp;Chang Heon Choi","doi":"10.1016/j.ejmp.2025.104983","DOIUrl":"10.1016/j.ejmp.2025.104983","url":null,"abstract":"<div><h3>Purpose</h3><div>This paper describes the verification of the step-by-step-reaction-diffusion Master Equation (SBS-RDME) model, implemented in Geant4-DNA, for long-term radiolysis simulations in the Fricke dosimeter.</div></div><div><h3>Methods</h3><div>Scaling for reaction rate constants due to the high acidity of the Fricke solution was applied. The secondary electrons generated by gamma irradiation from Co-60 were used as the radiation source for the simulations. Model parameters were optimized by observing changes in output and computation time in response to variations in the starting time <em>t</em> and initial voxel resolution ℎ of the compartment-based simulation. The yields of ferric ion G(Fe³⁺) and chemical species influencing its formation were calculated using the SBS-RDME model and using the IRT method for comparison. The time evolution of the yields of Fe³⁺, ^<img>OH, H^<img>, HO₂^<img>, H₂O₂, and H₂ were compared, and the reactions affecting the yield of each chemical species were analyzed.</div></div><div><h3>Results</h3><div>The model parameters were set to <em>t</em> = 5 ns and <em>h</em> = 12.5 nm. The yield trends over time for chemical species were consistent between the SBS-RDME model and the IRT method. At 50 s, the G(Fe³⁺) from the two calculations agreed within 3.2 %. Contribution analysis of the reactions affecting the generation/removal of each chemical species indicated that the main reason for this discrepancy between the two calculations might be the inability of the SBS method to consider specific reaction types during simulation.</div></div><div><h3>Conclusions</h3><div>The SBS-RDME model was verified for long-term simulations by comparing its results to those obtained from the IRT method.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"133 ","pages":"Article 104983"},"PeriodicalIF":3.3,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143887482","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 upfront patient selection strategy based on personalized data-driven computed tomography generation for deep inspiration breath-hold in breast radiotherapy","authors":"Yunxiang Wang ,&nbsp;Yihang Zhang ,&nbsp;Si-Ye Chen ,&nbsp;Tie Lv ,&nbsp;Yuxiang Liu ,&nbsp;Hui Fang ,&nbsp;Hao Jing ,&nbsp;Ning-Ning Lu ,&nbsp;Yi-Rui Zhai ,&nbsp;Yong-Wen Song ,&nbsp;Yue-Ping Liu ,&nbsp;Wen-Wen Zhang ,&nbsp;Shu-Nan Qi ,&nbsp;Yuan Tang ,&nbsp;Bo Chen ,&nbsp;Ye-Xiong Li ,&nbsp;Kuo Men ,&nbsp;Xinyuan Chen ,&nbsp;Wei Zhao ,&nbsp;Shu-Lian Wang","doi":"10.1016/j.ejmp.2025.104964","DOIUrl":"10.1016/j.ejmp.2025.104964","url":null,"abstract":"<div><h3>Background</h3><div>Currently there is no widely used upfront selection method to determine whether patients are suitable for deep inspiration breath-hold (DIBH) in left-sided breast radiotherapy.</div></div><div><h3>Purpose</h3><div>To establish an upfront patient selection strategy to improve the decision-making efficiency of DIBH and avoid extra computed tomography (CT) exposure to patients.</div></div><div><h3>Methods</h3><div>A total of 174 patients who underwent both free-breathing (FB) and DIBH scans were enrolled. A general principal component analysis model for DIBH-CT synthesis was trained and consists of principal component feature vectors extracted from paired FB-CT and DIBH-CT in training set. The coefficients of the vectors were optimized to minimize the difference between synthetic CT and breath-hold scout image of each patient in test set, leading to personalized DIBH-CT synthesis. An upfront patient selection strategy was established based on cardiac dose in synthetic DIBH-CT plan. The performance of DIBH-CT synthesis was analyzed in terms of geometric and dosimetric consistency between synthetic and scanned DIBH-CTs. The accuracy of the patient selection strategy was evaluated. Time assumption of the patient selection workflow was analyzed.</div></div><div><h3>Results</h3><div>Synthetic DIBH-CTs had average Dice similarity coefficients of 0.84 for the heart and 0.91 for the lungs compared with scanned DIBH-CTs. Synthetic DIBH-CT plans revealed an average mean heart dose reduction of 1.46 Gy, which was not significantly different from 1.51 Gy in scanned DIBH-CT plans (p = 0.878). The patient selection strategy yielded the correct benefit results with accuracy of 86.7 %. The average time assumption for patient selection was 11.9 ± 3.6 min.</div></div><div><h3>Conclusions</h3><div>The proposed patient selection strategy can accurately identify patients benefiting from DIBH and provides a more efficient workflow for DIBH.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"133 ","pages":"Article 104964"},"PeriodicalIF":3.3,"publicationDate":"2025-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143873225","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":"Revisiting artifact spread function evaluation in digital breast tomosynthesis systems","authors":"Jesus G. Ovejero ,&nbsp;Miguel Alarcia ,&nbsp;José Carlos Barba ,&nbsp;Belén Cabañero ,&nbsp;José Antonio Cuesta ,&nbsp;Ana García-Sanz ,&nbsp;José Miguel Megías ,&nbsp;Julia Garayoa ,&nbsp;Margarita Chevalier","doi":"10.1016/j.ejmp.2025.104982","DOIUrl":"10.1016/j.ejmp.2025.104982","url":null,"abstract":"<div><h3>Background</h3><div>Digital Breast Tomosynthesis (DBT) has proved to be a powerful tool in breast cancer detection. However, the presence of zipper artifacts poses challenges in accurate diagnosis and there is not global methodology to evaluate its effects.</div></div><div><h3>Purpose</h3><div>The purpose of this study is to determine the most suitable method to characterize zipper artifact using the Full Width at Half Maximum (FWHM) of the Artifact Spread Function (ASF) as figure of merit and the adequacy Al sphere phantom as zipper artifact generators.</div></div><div><h3>Methods</h3><div>The study compares the zipper artifact on General Electric Senographe Pristine (SP-GE) and Hologic Selenia Dimensions (SD-HO) by calculating ASF in three different ways: maximum value method, mean value method and a hybrid method proposed by the authors.</div><div>Besides, the ASF generated by 1 mm aluminum sphere phantom was compared to those generated by 1 mm lead and tungsten markers, 2.3 mm ceramic markers and Mammo 156^TM Phantom from Gammex.</div></div><div><h3>Results</h3><div>For the SP-GE system, the ASF calculated with the hybrid method resulted the most suitable approach in terms of reliability. In contrast, for the SD-HO system, the mean value method aligns better with system characteristics. The study underscores the importance of considering system-specific nuances in methodology selection for artifact evaluation. The data indicates that, for most of the methods, ceramic and lead (Pb) markers replicates better the artifacts observed in clinical practice.</div></div><div><h3>Conclusions</h3><div>The article emphasizes the need for standardized methodologies that can accommodate system-specific differences while ensuring accurate artifact assessment.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"133 ","pages":"Article 104982"},"PeriodicalIF":3.3,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143864468","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":"Diagnostic Reference Levels in nuclear medicine for Positron Emission Tomography examinations: First Italian multicenter data collection","authors":"Alessandra Zorz ,&nbsp;Sabrina Morzenti ,&nbsp;Claudia Bianchi ,&nbsp;Federica Campanaro ,&nbsp;Francesca De Monte ,&nbsp;Elena De Ponti ,&nbsp;Sara Berti ,&nbsp;Paola Anna Erba ,&nbsp;Luca Guerra ,&nbsp;Gian Luca Poli","doi":"10.1016/j.ejmp.2025.104984","DOIUrl":"10.1016/j.ejmp.2025.104984","url":null,"abstract":"<div><h3>Introduction</h3><div>Diagnostic Reference Levels (DRLs) are essential for optimizing patient protection in radiological imaging. PET/CT acquisitions are fundamental in modern nuclear medicine for diagnosis, staging and tumor response evaluation. The hybrid nature of PET/CT results in a total dose to the patient from both modalities. Therefore, it is appropriate to set and evaluate DRLs independently for each modality. While DRLs for some PET tracers are extensively described by various national and international guidelines, similarly established guidelines for the low-dose CT component are lacking.</div></div><div><h3>Methods</h3><div>In 2022, a multicenter collaboration was established among three Italian Hospitals to evaluate dosimetric indices for almost 13,000 PET/CT scans using various scanner technologies and tracers. The dosimetric data were classified based on the radiopharmaceuticals injected and further stratified according to scan length: Whole Body (WB), head vertex-to-feet and brain.</div></div><div><h3>Results</h3><div>The results for all tracers and imaging procedures evaluated are compliant with or lower than available DRLs. For some exam types, national DRLs are not currently defined and so typical values, calculated as the median of the data distribution in this study, are proposed. For the PET the typical values are proposed in terms of total and per kilogram administered activity, while for the CT they are proposed in terms of CTDI_vol and DLP.</div></div><div><h3>Conclusion</h3><div>In line with Directive 2013/29/Euratom, these collected data could be valuable for a future review of DRLs for both PET tracers and low-dose CT component in WB studies, and for defining new DRLs for low-dose CT component in vertex-to-feet and brain studies.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"133 ","pages":"Article 104984"},"PeriodicalIF":3.3,"publicationDate":"2025-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143859920","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":"Multicatheter-guided rigid registration for high-dose-rate interstitial brachytherapy for mobile tongue cancer","authors":"Akito S Koganezawa ,&nbsp;Takeo Nakashima ,&nbsp;Masaru Konishi ,&nbsp;Kiichi Shimabukuro ,&nbsp;Junichi Hirokawa ,&nbsp;Ikuno Nishibuchi ,&nbsp;Naoya Kakimoto ,&nbsp;Yuji Murakami","doi":"10.1016/j.ejmp.2025.104981","DOIUrl":"10.1016/j.ejmp.2025.104981","url":null,"abstract":"<div><h3>Purpose</h3><div>We aimed to develop a multicatheter-guided rigid registration (MCgRR) to assess the displacement of catheters and changes in distance between neighboring catheters of high-dose-rate (HDR) interstitial brachytherapy (ISBT) for mobile tongue cancer.</div></div><div><h3>Methods</h3><div>We analyzed two cases of mobile tongue cancer treated by the HDR ISBT with a two-step method, with the first plan on the initial computed tomography (CT) (P1) and the second plan created on the CT images acquired on the third day (P2). An in-house software of the MCgRR to fit P2 to P1 was developed using Python. Transverse shift (TS) to the mean catheter direction of each catheter and the change in the inter-catheter distance (<span><math><mrow><mi>Δ</mi><mi>I</mi><mi>C</mi><mi>D</mi></mrow></math></span>) for neighboring catheters were analyzed.</div></div><div><h3>Results</h3><div>The TS and <span><math><mrow><mi>Δ</mi><mi>I</mi><mi>C</mi><mi>D</mi></mrow></math></span> were successfully calculated as a function of <em>Z</em>, which is the longitudinal direction along the catheters. The maximum TS was 2.0 and 3.4 mm for Cases #1 and #2, respectively. Visualized TS was found useful for identifying the location of specific areas with large deformation. The <span><math><mrow><mi>Δ</mi><mi>I</mi><mi>C</mi><mi>D</mi></mrow></math></span> was also successfully calculated as a function of <em>Z</em> and ranged from −1.8 to 1.3 mm for Case #1 and from −1.8 to 2.5 mm for Case #2.</div></div><div><h3>Conclusion</h3><div>The MCgRR developed in this study demonstrated sufficient performance in visualization and identification of areas with large deformation of the CTV in HDR ISBT for mobile tongue cancer.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"133 ","pages":"Article 104981"},"PeriodicalIF":3.3,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143855519","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":"Suitability of a BeO-based OSLD system for end-to-end remote dosimetry tests in SRS/SRT applications","authors":"Alexandra Drakopoulou ,&nbsp;Polymnia Glampedaki ,&nbsp;Vasiliki Peppa ,&nbsp;Efi Koutsouveli ,&nbsp;Georgios Kollias ,&nbsp;Pantelis Karaiskos ,&nbsp;Eleftherios P. Pappas","doi":"10.1016/j.ejmp.2025.104975","DOIUrl":"10.1016/j.ejmp.2025.104975","url":null,"abstract":"<div><h3>Purpose</h3><div>The aim of this study is to evaluate the suitability of a commercially available Optically Stimulated Luminescence Dosimetry (OSLD) system for remote dosimetry end-to-end tests in Stereotactic Radiosurgery and Radiotherapy (SRS/SRT). This is achieved by performing a dose–response characterization focusing on the relevant irradiation and readout conditions, followed by dosimetry protocol development and implementation.</div></div><div><h3>Methods</h3><div>The myOSLchip^TM Beryllium Oxide- (BeO-) based OSLD system (RadPro, Germany) was employed throughout this study. Measurements were performed to assess element sensitivity, signal depletion, linearity (up to 16 Gy), potential beam quality (6MV and 10MV) and angular dependence, signal fading rate, and potential sensitivity changes with lifetime accumulated dose (up to 98 Gy). Correction factors and uncertainties were determined following the AAPM TG-191 recommendations. The dosimetry system and protocol were implemented in an end-to-end remote dosimetry test, considering a clinically realistic single-isocenter multiple brain metastases case. For this purpose, 17 dosimeters were placed in a head phantom involving bone-mimicking inhomogeneities.</div></div><div><h3>Results</h3><div>A fixed depletion correction factor may not be applicable to all OSLDs. In 6MV, a sublinear dose–response behavior (up to 5%) was observed for the dose range, reader and readout parameters investigated, while an edge-on irradiation resulted in a 2.8% under-response compared to en face. OSLD sensitivity was stable up to at least 98 Gy of accumulated dose. Overall spatial and dosimetric experimental uncertainties in the end-to-end test were estimated at 0.6 mm and 3%, respectively. The local gamma index passing rate was 100%.</div></div><div><h3>Conclusion</h3><div>The evaluated OSLD system is suitable for end-to-end tests in SRS/SRT. This study can serve as an implementation guide in such applications.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"133 ","pages":"Article 104975"},"PeriodicalIF":3.3,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143829877","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":"Utilizing Pix2Pix conditional generative adversarial networks to recover missing data in preclinical PET scanner sinogram gaps","authors":"Zahra Karimi ,&nbsp;Khadijeh Rezaee Ebrahim Saraee ,&nbsp;Mohammad Reza Ay ,&nbsp;Peyman Sheikhzadeh","doi":"10.1016/j.ejmp.2025.104971","DOIUrl":"10.1016/j.ejmp.2025.104971","url":null,"abstract":"<div><h3>Background</h3><div>The presence of a gap between adjacent detector blocks in Positron Emission Tomography (PET) scanners introduces a partial loss of projection data, which can degrade the image quality and quantitative accuracy of reconstructed PET images. This study suggests a novel approach for filling missing data from sinograms generated from preclinical PET scanners using a combination of an inpainting method and the Pix2Pix conditional generative adversarial network (cGAN).</div></div><div><h3>Materials and methods</h3><div>Twenty mice and Image Quality (IQ) phantom were scanned by a small animal Xtrim PET scanner, resulting in 7500 raw sinograms used for network training and test datasets. The absence of gap-free sinograms as the target for neural network training was a challenge. This issue was solved by artificially generating gap-free sinograms from the original sinogram. To assess the performance of the proposed approach, the sinograms were reconstructed using the ordered subset expectation maximization (OSEM) algorithm. The overall performance of the proposed network and the quality of the resulting images were quantitatively compared using various metrics, including the root mean squared error (RMSE), structural similarity index (SSIM), peak signal-to-noise ratio (PSNR), contrast-to-noise ratio (CNR), and signal-to-noise ratio (SNR).</div></div><div><h3>Results</h3><div>The Pix2Pix cGAN approach achieved an RMSE of 9.34 × 10⁻⁴ ± 5.7 × 10⁻⁵ and an SSIM of 99.984 × 10⁻² ± 1.8 × 10⁻⁵, considering the corresponding inpainted sinograms as the target.</div></div><div><h3>Conclusion</h3><div>The proposed approach can retrieve missing sinogram data by learning a map derived from the whole sinogram compared to the adjacent pixels, which leads to better quantitative accuracy and improved reconstructed images.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"133 ","pages":"Article 104971"},"PeriodicalIF":3.3,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143829884","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":"Commissioning of a reference beam model-based Monte Carlo dose calculation algorithm for cranial stereotactic radiosurgery","authors":"Yohan A. Walter ,&nbsp;Anne N. Hubbard ,&nbsp;Philip F. Durham ,&nbsp;William E. Burrell ,&nbsp;Chiachien J. Wang ,&nbsp;Hsinshun T. Wu","doi":"10.1016/j.ejmp.2025.104976","DOIUrl":"10.1016/j.ejmp.2025.104976","url":null,"abstract":"<div><h3>Purpose</h3><div>In treatment planning system (TPS) commissioning for stereotactic radiosurgery (SRS), the required measurements and precision necessary to generate an accurate beam model make the process taxing and time-consuming. Recently, Brainlab AG released reference beam models available for use with the Elements TPS. In this work, we detail our implementation of reference beam model-based Monte Carlo dose calculations for our Elements 4.0 TPS.</div></div><div><h3>Methods</h3><div>Depth dose, output factor, and beam profile measurements were used to select a reference beam model. 9 treatment plans encompassing the range of clinical use cases were created. Patient QA measurements were performed using a high-resolution detector array. Dose distributions were mapped to the QA array using the reference beam model with 1–2 mm grid resolution. Independent MU verifications were performed for each test plan. An end-to-end test was performed for final verification of system performance and data integrity.</div></div><div><h3>Results</h3><div>Acceptable agreement was demonstrated between measured data and the reference beam model. All QA gamma pass rates exceeded 95 %. Measured peak dose differences were over 5 % for targets with diameter &lt;7 mm when using a 1.0 mm Monte Carlo grid resolution. 1 of the 46 tested arcs had over a 5 % difference between MU verification and the TPS-calculated MU. End-to-end testing verified system performance.</div></div><div><h3>Conclusion</h3><div>Validation testing demonstrated good agreement between the reference beam dataset and machine performance for targets with diameters ≥7 mm. The use of a reference beam model may significantly reduce measurement burden while mitigating potential failure modes associated with TPS commissioning.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"133 ","pages":"Article 104976"},"PeriodicalIF":3.3,"publicationDate":"2025-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143825411","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":"Small-scale bone marrow dosimetry study for 225Ac","authors":"Stephen Tronchin ,&nbsp;Jake Forster ,&nbsp;Kevin Hickson ,&nbsp;Eva Bezak","doi":"10.1016/j.ejmp.2025.104966","DOIUrl":"10.1016/j.ejmp.2025.104966","url":null,"abstract":"<div><h3>Background</h3><div>Targeted alpha therapy (TAT) with ²²⁵Ac-labelled radiopharmaceuticals is a growing therapeutic option for the treatment of various cancers. Due to the short range of alpha particles in tissue, the absorbed dose can be non-uniform on a microscopic scale. Therefore, understanding bone marrow toxicity in TAT requires small-scale dosimetry.</div></div><div><h3>Method</h3><div>We developed a voxelised trabecular bone model, based off µCT slices, with a voxel size of (37 × 37 × 37) µm³. A small-scale dosimetry study was performed to assess the marrow toxicity from uptake of unlabelled ²²⁵Ac in the trabecular bone. The Particle and Heavy Ion Transport Code System (PHITS) was used to simulate the decays and score the absorbed dose to each voxel from the alpha and beta emissions of the ²²⁵Ac decay chain.</div></div><div><h3>Results</h3><div>For the alpha decays on the trabecular surface, 43 % of the marrow voxels were irradiated. The maximum voxel dose for the marrow was 1.1 Gy, and the mean non-zero voxel dose was 0.2 Gy (σ = 0.2 Gy). The beta-emissions from the trabecular surface irradiated all the marrow voxels, with a mean voxel dose of 3.9 mGy (σ = 1.7 mGy).</div></div><div><h3>Conclusion</h3><div>Our model demonstrated a non-uniform absorbed dose profile to the red marrow due to alpha emissions on the trabecular bone surface. The alpha emissions irradiated less than half of the marrow voxels,<!--> <!-->while the beta emissions irradiated all marrow voxels. This could potentially suggest a lower marrow toxicity from alpha-emitters compared to beta-emitters when skeletal metastases are present.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"133 ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143814807","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":"Leveraging deep learning for improving parameter extraction from perfusion MR images: A narrative review","authors":"Elisa Scalco ,&nbsp;Giovanna Rizzo ,&nbsp;Nicola Bertolino ,&nbsp;Alfonso Mastropietro","doi":"10.1016/j.ejmp.2025.104978","DOIUrl":"10.1016/j.ejmp.2025.104978","url":null,"abstract":"<div><h3>Background</h3><div>Perfusion magnetic resonance imaging (MRI) is a non-invasive technique essential for assessing tissue microcirculation and perfusion dynamics. Various perfusion MRI techniques like Dynamic Contrast-Enhanced (DCE), Dynamic Susceptibility Contrast (DSC), Arterial Spin Labeling (ASL), and Intravoxel Incoherent Motion (IVIM) provide critical insights into physiological and pathological processes. However, traditional methods for quantifying perfusion parameters are time-consuming, often prone to variability, and limited by noise and complex tissue dynamics.</div><div>Recent advancements in artificial intelligence (AI), particularly in deep learning (DL), offer potential solutions to these challenges. DL algorithms can process large datasets efficiently, providing faster, more accurate parameter extraction with reduced subjectivity.</div></div><div><h3>Aim</h3><div>This paper reviews the state-of-the-art DL-based techniques applied to perfusion MRI, considering DCE, DSC, ASL and IVIM acquisitions, focusing on their advantages, challenges, and potential clinical applications.</div></div><div><h3>Main findings</h3><div>DL-driven methods promise significant improvements over conventional approaches, addressing limitations like noise, manual intervention, and inter-observer variability. Deep learning techniques such as convolutional neural networks (CNNs), recurrent neural networks (RNNs), and generative adversarial networks (GANs) are particularly valuable in handling spatial and temporal data, enhancing image quality, and facilitating precise parameter extraction.</div></div><div><h3>Conclusions</h3><div>These innovations could revolutionize diagnostic accuracy and treatment planning, offering a new frontier in perfusion MRI by integrating DL with traditional imaging methods. As the demand for precise, efficient imaging grows, DL’s role in perfusion MRI could significantly improve clinical outcomes, making personalized treatment a more realistic goal.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"133 ","pages":"Article 104978"},"PeriodicalIF":3.3,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143816266","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}