Physica Medica-European Journal of Medical Physics最新文献

{"title":"Exposure control at the first dark-field chest radiography demonstrator system","authors":"M.E. Lochschmidt ,&nbsp;M. Frank ,&nbsp;K. Willer ,&nbsp;H. Bast ,&nbsp;L. Kaster ,&nbsp;T. Urban ,&nbsp;W. Noichl ,&nbsp;R. Schick ,&nbsp;F. De Marco ,&nbsp;T. Koehler ,&nbsp;I. Maack ,&nbsp;G.S. Zimmermann ,&nbsp;D. Pfeiffer ,&nbsp;B. Renger ,&nbsp;F. Pfeiffer","doi":"10.1016/j.ejmp.2025.105013","DOIUrl":"10.1016/j.ejmp.2025.105013","url":null,"abstract":"<div><h3>Purpose:</h3><div>A first demonstrator system for clinical dark-field chest radiography was recently constructed. Due to its scanning acquisition, conventional exposure regulation systems are not possible. This study presents the adaptation of exposure to each patient individually, using a conventional radiograph as a reference. Additionally, an alternative approach for individual exposure planning based on the patient’s body mass index (BMI) is proposed.</div></div><div><h3>Methods:</h3><div>Using exposure settings from a conventional radiography system with automatic exposure control (AEC), a patient-specific equivalent attenuator thickness was calculated with polyoxymethylene (POM) as a surrogate material. The tube current at the dark-field system was adapted to reach the target detector dose based on this thickness. This approach was verified with both phantom measurements and patient examinations. The correlation between patient body parameters (weight, BMI, upper bust girth, and under-bust girth) and desired tube current was also evaluated.</div></div><div><h3>Results:</h3><div>A calibration curve was found to transfer individual exposure settings from a conventional device to the dark-field system. Achieved detector doses for both phantom and patient examinations were within permitted ranges. A strong correlation was found between each body parameter and the desired tube current, with BMI showing the strongest correlation (<span><math><mrow><mi>r</mi><mo>=</mo><mn>0</mn><mo>.</mo><mn>87</mn><mo>,</mo><mspace></mspace><mi>p</mi><mo>&lt;</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>29</mn></mrow></msup></mrow></math></span>).</div></div><div><h3>Conclusions:</h3><div>An exposure planning approach was successfully implemented at the first clinical dark-field chest radiography system, delivering a detector dose within the required range for different patient sizes. A conventional radiograph with AEC is necessary for this implementation. The strong correlation between BMI and tube current offers an alternative approach for patient-specific exposure control.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"135 ","pages":"Article 105013"},"PeriodicalIF":3.3,"publicationDate":"2025-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144264054","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":"Geant4 simulation of the enhanced in-vivo 220Rn spread in DaRT","authors":"Laura Ballisat ,&nbsp;Chiara De Sio ,&nbsp;Susanna Guatelli ,&nbsp;Dousatsu Sakata ,&nbsp;Lujin Abu Sabah ,&nbsp;Jinyan Duan ,&nbsp;Yuyao Shi ,&nbsp;Jaap Velthuis ,&nbsp;Anatoly Rosenfeld","doi":"10.1016/j.ejmp.2025.105005","DOIUrl":"10.1016/j.ejmp.2025.105005","url":null,"abstract":"<div><h3>Introduction:</h3><div>Recent in-vivo experimental measurements of DaRT seeds have shown that the spread of ²²⁰Rn away from the DaRT seed is greater than expected. This has implications for accurate treatment planning.</div></div><div><h3>Methods:</h3><div>Geant4 and Geant4-DNA have been used to simulate the additional spread of ²²⁰Rn and study the impact on particle and RBE (relative biological effectiveness) weighted dose distribution from the whole DaRT decay chain. A percentage of ²²⁰Rn is assumed to migrate with a higher effective diffusion constant due to transport in the blood flow in the surrounding vasculature. The DNA damage was simulated for the fit to the measurement showing the greatest additional spread.</div></div><div><h3>Results:</h3><div>Good agreement was found between the simulation and experimental in-vivo results. The additional spread of ²²⁰Rn increases the number of <span><math><mi>α</mi></math></span>-particles from these decays distally from the DaRT seed. However, the distribution of <span><math><mi>α</mi></math></span>-particles emitted from later stages of the decay chain is not as significantly affected. There is an increase in DSB yield and the RBE weighted dose extends further from the DaRT seed with the additional spread. The distance of the 1 Gy RBE weighted isodose from the DaRT seed surface moves from 4.4 mm without the additional spread to 5.7 mm including it.</div></div><div><h3>Conclusion:</h3><div>The increase DSB induction distally from the DaRT seed has the potential to increase treatment efficacy. However, this additional spread cannot easily be predicted. Understanding this uncertainty is important for the dose calculations in treatment planning for tumours and normal tissues.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"135 ","pages":"Article 105005"},"PeriodicalIF":3.3,"publicationDate":"2025-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144241755","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":"U2-Attention-Net: a deep learning automatic delineation model for parotid glands in head and neck cancer organs at risk on radiotherapy localization computed tomography images","authors":"Xiaobo Wen ,&nbsp;Yanhong Wang ,&nbsp;Daijun Zhang ,&nbsp;Yutao Xiu ,&nbsp;Li Sun ,&nbsp;Biao Zhao ,&nbsp;Ting Liu ,&nbsp;Xinyi Zhang ,&nbsp;Jinfei Fan ,&nbsp;Junlin Xu ,&nbsp;Tianen An ,&nbsp;Weimin Li ,&nbsp;Yi Yang ,&nbsp;Dongming Xing","doi":"10.1016/j.ejmp.2025.105024","DOIUrl":"10.1016/j.ejmp.2025.105024","url":null,"abstract":"<div><h3>Objective</h3><div>This study aimed to develop a novel deep learning model, U₂-Attention-Net (U₂A-Net), for precise segmentation of parotid glands on radiotherapy localization CT images.</div></div><div><h3>Methods</h3><div>CT images from 79 patients with head and neck cancer were selected, on which the label maps were delineated by relevant practitioners to construct a dataset. The dataset was divided into the training set (n = 60), validation set (n = 6), and test set (n = 13), with the training set augmented. U₂A-Net, divided into U₂A-Net V₁ (sSE) and U₂A-Net V₂ (cSE) based on different attention mechanisms, was evaluated for parotid gland segmentation based on the DL loss function with U-Net, Attention U-Net, DeepLabV3+, and TransUNet as comparision models. Segmentation was also performed using GDL and GD-BCEL loss functions. Model performance was evaluated using DSC, JSC, PPV, SE, HD, RVD, and VOE metrics.</div></div><div><h3>Results</h3><div>The quantitative results revealed that U₂A-Net based on DL outperformed the comparative models. While U₂A-Net V₁ had the highest PPV, U₂A-Net V₂ demonstrated the best quantitative results in other metrics. Qualitative results showed that U₂A-Net’s segmentation closely matched expert delineations, reducing oversegmentation and undersegmentation, with U₂A-Net V₂ being more effective. In comparing loss functions, U₂A-Net V₁ using GD-BCEL and U₂A-Net V₂ using DL performed best.</div></div><div><h3>Conclusion</h3><div>The U₂A-Net model significantly improved parotid gland segmentation on radiotherapy localization CT images. The cSE attention mechanism showed advantages with DL, while sSE performed better with GD-BCEL.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"135 ","pages":"Article 105024"},"PeriodicalIF":3.3,"publicationDate":"2025-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144241754","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":"Quantitative assessment of dose accumulation uncertainty using a commercial deformable image registration algorithm in adaptive intensity-modulated proton therapy for prostate cancer","authors":"Yihang Xu ,&nbsp;John Chetley Ford ,&nbsp;Kyle R. Padgett ,&nbsp;Nesrin Dogan","doi":"10.1016/j.ejmp.2025.105011","DOIUrl":"10.1016/j.ejmp.2025.105011","url":null,"abstract":"<div><h3>Introduction</h3><div>This work aims to quantify the dose accumulation uncertainty for prostate adaptive intensity modulated proton therapy (IMPT).</div></div><div><h3>Methods</h3><div>Pelvic CT images from ten prostate patients with 6 repeat CT (rCT) scans were selected. The reference DVFs (DVF_ref) were generated by performing DIR between planning CT (pCT) and rCTs using a reference DIR algorithm. Pseudo-rCTs were created by deforming pCT to rCTs using the DVF_ref. An IMPT plan was created for each patient on pCT, which was recalculated on each pseudo-rCT. The fractional dose was warped back to pCT using DVF (DVF_test) generated by a commercial DIR algorithm which uses a ‘deformable multi pass (DMP)’ algorithm or ‘structure-guided deformable (SGD)’ if DMP failed. The DVF_test deformed dose was compared to the DVF_ref deformed dose. Registration error (RE) and inverse consistency error (ICE) were assessed for DVF_test.</div></div><div><h3>Results</h3><div>When using only DMP, the RE throughout the whole body was 1.17 ± 1.22 mm. Overall, the ICE for all voxels was 0.18 ± 0.5 mm. The dose deformation uncertainty was 0.02 % ± 2.53 % over the whole body, with the highest uncertainty observed in the bladder (0.83 % ± 6.66 %) and high dose gradient regions. When incorporating SGD, the dose deformation uncertainty inside the CTV was changed from 0.11 % ± 2.42 % to 0.15 % ± 1.4 %, and the uncertainty range of dose accumulation for CTV V100 was reduced from (−3.39 %, 5.49 %) to (−0.31 %, 3.43 %).</div></div><div><h3>Conclusions</h3><div>This study demonstrated that a commercial DIR algorithm is well-suited for prostate IMPT dose accumulation with acceptable geometric and dosimetric uncertainty. The incorporation of SGD has the potential to reduce the uncertainty.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"135 ","pages":"Article 105011"},"PeriodicalIF":3.3,"publicationDate":"2025-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144241841","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":"Iodine quantification performance with deep silicon-based Photon-Counting CT: A virtual imaging trial study","authors":"Raj Kumar Panta ,&nbsp;Zhye Yin ,&nbsp;Fredrik Grönberg ,&nbsp;Mridul Bhattarai ,&nbsp;Ehsan Abadi ,&nbsp;Paul Segars ,&nbsp;Ehsan Samei","doi":"10.1016/j.ejmp.2025.105003","DOIUrl":"10.1016/j.ejmp.2025.105003","url":null,"abstract":"<div><h3>Purpose</h3><div>This study investigates the imaging performance of a deep silicon-based photon-counting CT (Si-PCCT) in quantifying iodine contrast through a virtual imaging trial (VIT).</div></div><div><h3>Methods</h3><div>We developed a VIT framework using Si-PCCT simulator and benchmarked it against a prototype using an ACR phantom for assessing spatial resolution and noise characteristics, and a geometric phantom for iodine quantification. We imaged geometrical phantoms (20 – 40 cm) with iodine concentrations ranging from 1 to 19.7 mg/ml and XCAT human models with iodine contrast at BMI of 19 to 38 kg/m² across different radiation dose levels (13.9, 27.8, and 41.7 mGy of CTDI_vol). We performed material decomposition, reconstructed iodine CT images, and evaluated iodine quantification accuracy.</div></div><div><h3>Results</h3><div>The Si-PCCT simulator closely matched with the prototype, with differences within 3 % in MTF (f₅₀ and f₁₀) and 3.7 % (f_peak) in NNPS, and Root-Mean-Square Error of 0.12 mg/ml in iodine quantification. The mean absolute errors (MAE) between the estimated and ground-truth iodine concentration were 0.10, 0.25, and 1.80 mg/ml for 20, 30, and 40 cm phantoms, and 0.31, 0.37, and 0.70 mg/ml for XCAT human models with BMIs of 19, 28, and 38 kg/m², respectively. Similarly, the MAEs were 0.88, 0.45, and 0.31 mg/ml for the geometrical phantoms, and 0.66, 0.5, and 0.46 mg/ml for human models at CTDI_vol of 13.9, 27.8, and 41.7 mGy respectively. These results demonstrate accurate iodine quantification performance, influenced by object size and radiation dose.</div></div><div><h3>Conclusion</h3><div>This study shows the promising clinical utility of Si-PCCT for accurate iodine quantification under clinically relevant imaging conditions.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"135 ","pages":"Article 105003"},"PeriodicalIF":3.3,"publicationDate":"2025-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144222665","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":"Reconstruction of time-activity curves in molecular radiotherapy using a Bayesian unfolding","authors":"F. Nicolanti ,&nbsp;L. Arsini ,&nbsp;L. Campana ,&nbsp;F. Collamati ,&nbsp;R. Faccini ,&nbsp;R. Mirabelli ,&nbsp;S. Morganti ,&nbsp;E. Solfaroli Camillocci ,&nbsp;C.Mancini Terracciano","doi":"10.1016/j.ejmp.2025.104980","DOIUrl":"10.1016/j.ejmp.2025.104980","url":null,"abstract":"<div><h3>Purpose:</h3><div>Personalizing Molecular Radiotherapy (MRT) is crucial for enhancing treatment efficacy and minimizing toxicity. The WIDMApp (Wearable Individual Dose Monitoring Apparatus) project aims to estimate patient-specific biokinetics -<em>i.e</em>., time-activity curves (TACs), through several radiation detectors and a data processing system. This study presents an advanced Bayesian unfolding algorithm that avoids assumptions about the functional form of the TACs.</div></div><div><h3>Methods:</h3><div>The proposed unfolding employs a recursive approach over time to infer organs’ activity. To test the algorithm’s performance, we developed four virtual patient types undergoing prostate cancer treatment with <span><math><msup><mrow></mrow><mrow><mn>177</mn></mrow></msup></math></span>Lu, each characterized by different radiopharmaceutical biokinetics based on literature data. MC simulations using the ICRP110 male anthropomorphic phantom modeled radiation detection probabilities by six WIDMApp sensors placed near organs of interest. Using this simulation and literature TAC profiles, we generated Time-Count Curves (TCCs) detected by the sensors. Stability studies assessed the algorithm’s robustness in reconstructing TACs under various noise conditions and initial activity uncertainties.</div></div><div><h3>Results:</h3><div>The proposed unfolding algorithm inferred organ cumulative activities with errors ranging from 5% to 24%, even when the data were smeared with uniform noise up to 70% and sampling the initial priors from uniform distributions around the true values within 50%.</div></div><div><h3>Conclusions:</h3><div>We developed and tested a Bayesian unfolding algorithm that does not assume the TACs’ functional form of the organs, able to estimate the TACs from the TCCs. The results obtained are crucial for the ongoing development of WIDMApp and its translation into clinical practice.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"135 ","pages":"Article 104980"},"PeriodicalIF":3.3,"publicationDate":"2025-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144222663","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":"A Novel Live-Cell Microscopy Platform for Real-Time Visualization of 53BP1 Foci Dynamics and Accurate Dosimetry in Proton Therapy","authors":"Tim Heemskerk ,&nbsp;Marta Rovituso ,&nbsp;Ernst van der Wal ,&nbsp;Gert-Jan Kremers ,&nbsp;Johan A. Slotman ,&nbsp;Mischa Hoogeman ,&nbsp;Jeroen Essers","doi":"10.1016/j.ejmp.2025.105020","DOIUrl":"10.1016/j.ejmp.2025.105020","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Proton-induced cell death is primarily driven by the induction and repair of DNA double strand breaks. While DNA damage dynamics have been extensively studied, the early cellular responses to proton irradiation remain underexplored. To address this, we developed a novel live-cell microscopy platform that enables real-time visualization of cellular responses to DNA damage induced by proton therapy.</div></div><div><h3>Materials and methods</h3><div>We designed a modular set-up with the requirement that it can be assembled and disassembled within 30 minutes, allowing for efficient deployment in an R&amp;D proton beam line. An inverted fluorescence microscope was mounted at a 90-degree angle relative to the horizontal proton beam, enabling accurate irradiation at various depths along the spread-out Bragg peak with precise dosimetry and control over dose rates. As a proof-of-concept, we investigated the formation of 53BP1 foci following proton irradiation and determined the foci dynamics over time.</div></div><div><h3>Results</h3><div>With this setup, we observed endogenous 53BP1 foci pre-irradiation, with radiation-induced foci appearing as early as 4 minutes post-irradiation. The maximum number of 53BP1 foci was observed 12 minutes after irradiation, and the foci could be tracked up to 30 minutes post-irradiation.</div></div><div><h3>Conclusions</h3><div>Our platform enabled precise dosimetry and real-time monitoring of 53BP1-mClover-labeled FaDu cells during proton exposure. This robust setup holds significant potential for studying DNA damage repair dynamics at various positions along the Bragg peak and across different dose rates, including ultrahigh dose rates (FLASH).</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"135 ","pages":"Article 105020"},"PeriodicalIF":3.3,"publicationDate":"2025-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144222664","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":"Patient radiation dose during hospitalization for acute ischemic Stroke: Five years of experience of a single tertiary referral hospital","authors":"Sergio Zucca ,&nbsp;Federico Fusaro ,&nbsp;Alberto Fenu ,&nbsp;Antonio Ferrari ,&nbsp;Federica Schirru ,&nbsp;Marco Erta ,&nbsp;Simona Corraine ,&nbsp;Giuseppe Fenu ,&nbsp;Jessica Moller ,&nbsp;Giovanni Cossu ,&nbsp;Giovanni Maria Argiolas ,&nbsp;Paolo Siotto ,&nbsp;Simone Comelli","doi":"10.1016/j.ejmp.2025.105016","DOIUrl":"10.1016/j.ejmp.2025.105016","url":null,"abstract":"<div><h3>Purpose</h3><div>To assess local radiation dose levels and quantify the contribution of individual X-ray procedures to the cumulative effective dose during hospitalization for acute ischemic stroke (AIS).</div></div><div><h3>Methods</h3><div>A dosimetric survey was conducted in AIS patients undergoing fluoroscopically guided mechanical thrombectomy (MT). Radiation dose data were collected using a commercial Radiation Dose Monitoring System (RDMS) while clinical data were extracted from the Hospital Information System (HIS) and merged with dose records for comprehensive analysis. Local dose levels were determined for all X-ray procedures, including admission diagnostic CT scans, MT, and follow-up CT before discharge.</div></div><div><h3>Results</h3><div>A total of 670 MT procedures were analyzed. The median Kerma Area Product (KAP) was 115 Gy·cm² (IQR: 69–189). Median dose-length product (DLP) values for CT scans were: Brain CT at admission, 1091 mGy·cm (IQR: 782–1171); CT angiography, 1077 mGy·cm (IQR: 773–1187); CT perfusion, 2529 mGy·cm (IQR: 2055–2961); and Brain CT at discharge, 844 mGy·cm (IQR: 689–946). The estimated cumulative effective dose for the complete workflow was 22.4 mSv (IQR: 17.1–29.7), with interventional procedures contributing approximately 50 %. CT perfusion accounted for an additional 5 mSv.</div></div><div><h3>Conclusions</h3><div>This study quantified local radiation dose levels for MT and associated CT imaging in AIS patients treated in a high-volume interventional radiology suite. A cumulative effective dose of 22 mSv is associated with the entire patient workflow, with MT procedures accounting for approximately 50 %. Further research is needed to assess organ dose in complex care pathways, as an estimate of patient-specific radiation risk.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"135 ","pages":"Article 105016"},"PeriodicalIF":3.3,"publicationDate":"2025-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144211988","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":"Homogeneous Gamma Knife boost following Linac-RT: A feasibility study for nasopharyngeal carcinoma","authors":"Manon Spaniol ,&nbsp;Yasser Abo-Madyan ,&nbsp;Arne M. Ruder ,&nbsp;Beate Schweizer ,&nbsp;Jens Fleckenstein ,&nbsp;Frank A. Giordano ,&nbsp;Florian Stieler","doi":"10.1016/j.ejmp.2025.105022","DOIUrl":"10.1016/j.ejmp.2025.105022","url":null,"abstract":"<div><h3>Purpose</h3><div>Radiotherapy plays a critical role in the treatment of nasopharyngeal carcinoma (NPC). However, the number and close proximity of organs at risk (OAR) hampers dose escalation using classical techniques. The Leksell Gamma Knife® (LGK, Elekta AB) achieves a steep dose gradient, which might be beneficial to apply sequential/upfront boosts to these tumors. This study explores the feasibility of fractionated, homogeneous LGK Icon boost compared to a linear accelerator (LINAC) boost.</div></div><div><h3>Methods</h3><div>Eight NPC patients treated with LINAC-based therapy at our institution were retrospectively analyzed. Each patient received a base plan (60/2Gy) to the primary tumor and nodes, followed by a boost (10/2Gy) targeting the primary tumor. LGK boost plans were generated using a research prototype version of LGK Lightning® (Elekta AB) for enhanced homogeneity in order to reduce hot spots within critical regions. Gradient index (GI), Paddick conformity index (PCI), and institutional OAR constraints were evaluated.</div></div><div><h3>Results</h3><div>Over all patients, the LGK boost plans had improved GI compared to the LINAC boost plans (3.11vs.5.46) and decreased PCI (0.79vs.0.81). The sum of base and LGK boost plans showed overall lower OAR doses [0.5–1.3 Gy] compared to the sum of base and LINAC boost. With the LGK boost plans, hot spots inside the PTV were in mean 1.6 Gy higher compared to the LINAC boost.</div></div><div><h3>Conclusion</h3><div>This study demonstrated the feasibility and dosimetric benefits of using fractionated LGK boost following LINAC base treatment for NPC. The prototype version effectively reduced doses to OAR and controlled hot spots within the target.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"135 ","pages":"Article 105022"},"PeriodicalIF":3.3,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144203168","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":"Simulation of digital mammographic images using GAMOS: Proof of concept","authors":"F.R. Lozano ,&nbsp;V. Sanchez-Lara ,&nbsp;C. Huerga ,&nbsp;Luis C. Martinez-Gomez ,&nbsp;D. Garcia-Pinto","doi":"10.1016/j.ejmp.2025.104995","DOIUrl":"10.1016/j.ejmp.2025.104995","url":null,"abstract":"<div><h3>Purpose:</h3><div>To present a simulation pipeline for digital mammography based on the GAMOS framework, enabling realistic image formation and dose estimation using high-fidelity anatomical phantoms and flexible detector modeling.</div></div><div><h3>Methods:</h3><div>A complete <em>in silico</em> model was implemented using GAMOS and GEANT4, including a Siemens Mammomat Inspiration system geometry, VICTRE voxelized breast phantoms, and two detector models: a direct conversion detector (MCD) and a virtual detector (VD). The simulation incorporated an anti-scatter grid, dose scoring tools, and a GUI for parameter adjustment. Performance metrics were calculated according to IEC 62220-1-2:2007.</div></div><div><h3>Results:</h3><div>The simulation yielded realistic mammographic images and accurate dose estimates. The MTF, NNPS, and DQE were calculated for both detector models and compared against published values. Maximum DQE differences were approximately 20%, with comparisons performed at spatial frequencies of 0.5, 2.0 and 5.0 mm⁻¹. The MTF<span><math><msub><mrow></mrow><mrow><mn>50</mn><mtext>%</mtext></mrow></msub></math></span> was 4.25 mm⁻¹ (VD) and 4.35 mm⁻¹ (MCD). Anatomical noise analysis showed <span><math><mi>β</mi></math></span> values between 2.67 and 3.16, consistent with clinical data. Dose validation against AAPM TG-195 showed differences below 1.08%.</div></div><div><h3>Conclusion:</h3><div>The proposed simulation framework is capable of producing realistic mammographic images and accurate dose calculations using an accessible interface. This tool is suitable for virtual clinical trials and system performance evaluation, and allows further extension to advanced imaging techniques such as contrast-enhanced or phase-contrast mammography. Code: <span><span>https://github.com/PREDICO-Project/MIMAC</span><svg><path></path></svg></span></div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"135 ","pages":"Article 104995"},"PeriodicalIF":3.3,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144203169","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}