Physica Medica-European Journal of Medical Physics最新文献

{"title":"Dose distribution of secondary radiation in a water phantom for a spatially fractionated proton beam","authors":"A. Tobola-Galus ,&nbsp;L. Stolarczyk ,&nbsp;I. Ambrožová ,&nbsp;M.A. Caballero-Pacheco ,&nbsp;M. Davídková ,&nbsp;C. Domingo ,&nbsp;M. De Saint-Hubert ,&nbsp;Ž. Knežević ,&nbsp;M. Liszka ,&nbsp;M. Majer ,&nbsp;I. Martinez Rovira ,&nbsp;N. Mojżeszek ,&nbsp;A. Wochnik ,&nbsp;R. Kopeć ,&nbsp;J. Swakoń ,&nbsp;R. Harrison ,&nbsp;P. Olko","doi":"10.1016/j.ejmp.2025.105204","DOIUrl":"10.1016/j.ejmp.2025.105204","url":null,"abstract":"<div><h3>Objective</h3><div>3D mapping of scattered radiation doses in water after grid proton irradiation using a dedicated brass collimator was performed within the EURADOS experiment at the scanning gantry of the Cyclotron Centre Bronowice at IFJ PAN. The goal of this paper was to determine to what extent the dedicated grid collimators would increase secondary doses administered to patients compared to Pencil Beam Scanning (PBS) techniques.</div></div><div><h3>Methods</h3><div>A broad set of passive point-like detectors including thermoluminescence (TLD), radio-photoluminescence (RPL) and track detectors (PADC) positioned in a dedicated water phantom was applied to determine gamma and neutron doses. The dose assessment was supported by Monte Carlo (MC) radiation transport calculations.</div></div><div><h3>Results</h3><div>The results show that the highest absorbed dose values were measured in the proximal area of the proton beam field and in the Spread out Bragg Peak (SOBP). Applying the same treatment plan the beam formation with PBS + grid collimator caused a 5-fold increase in the absorbed out-of-field dose compared to irradiation with the PBS and in the case of fast neutrons, the increase was around a factor of 10. These doses are comparable to unwanted exposure to scattered radiation arising from conventional photon radiotherapy.</div></div><div><h3>Conclusions</h3><div>The spatial distribution of the measured dosimetric quantities supports the thesis that in spatially fractionated proton radiotherapy, in which the beam is formed using a grid collimator, the main source of gamma radiation and neutrons is the collimator. Despite this, grid collimators remain a viable option due to their adaptability to various proton systems.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"139 ","pages":"Article 105204"},"PeriodicalIF":2.7,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145417698","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":"Knowledge-based automated radiation therapy treatment planning utilizing dose prediction with a 2.5D-U-Net","authors":"H. Oppitz ,&nbsp;M. Eckl ,&nbsp;K. Siebenlist ,&nbsp;J. Boda-Heggemann ,&nbsp;Y. Abo-Madyan ,&nbsp;F.A. Giordano ,&nbsp;J. Hesser ,&nbsp;J. Fleckenstein","doi":"10.1016/j.ejmp.2025.105199","DOIUrl":"10.1016/j.ejmp.2025.105199","url":null,"abstract":"<div><h3>Purpose</h3><div>Inverse treatment planning (ITP) in intensity modulated radiation therapy (IMRT) involves the specification of dose constraints as objective functions. These are manually and iteratively adjusted during planning to achieve patient-specific optimal outcomes. We propose a knowledge-based treatment planning (KBP) solution using deep learning to automate ITP.</div></div><div><h3>Methods</h3><div>KBP is tested for prostate and breast volumetric modulated arc therapy. A 2.5D-U-Net is optimized for dose prediction using 72/66 treatment plans obtained from manual planning (MP). The dose prediction model is then used to derive personalized optimization parameters to control ITP for 12 test patient datasets each (<span><math><mn>60</mn><mo>/</mo><mn>50</mn><mspace></mspace><mi>G</mi><mi>y</mi></math></span> prescription dose). For inference, MP and KBP outcomes are compared using DVH metrics, plan quality metric (<span><math><mrow><mi>PQM</mi></mrow></math></span>) and blinded expert rating.</div></div><div><h3>Results</h3><div>Median differences (<span><math><mrow><mi>MD</mi></mrow></math></span>) between MP and KBP are maximum <span><math><mn>0.5</mn><mspace></mspace><mi>G</mi><mi>y</mi></math></span> in absolute values for prostate organs at risk (OAR) mean doses. <span><math><mrow><mi>MD</mi></mrow></math></span> in <span><math><msub><mi>V</mi><mrow><mn>56</mn><mi>G</mi><mi>y</mi></mrow></msub></math></span> is <span><math><mn>0.4</mn><mspace></mspace><mi>c</mi><mi>c</mi></math></span> for rectum and bladder. For breast treatment, absolute <span><math><mrow><mi>MD</mi></mrow></math></span> values for OAR mean doses are maximum <span><math><mn>0.4</mn><mspace></mspace><mi>G</mi><mi>y</mi></math></span>. <span><math><mrow><mi>MD</mi></mrow></math></span> in <span><math><msub><mi>V</mi><mrow><mn>20</mn><mi>G</mi><mi>y</mi></mrow></msub></math></span> of the ipsilateral lung is <span><math><mo>-</mo><mn>1.0</mn><mspace></mspace><mo>%</mo></math></span>. <span><math><mrow><mi>MD</mi></mrow></math></span> in <span><math><mrow><mi>PQM</mi></mrow></math></span> is <span><math><mn>0.2</mn><mspace></mspace><mo>%</mo></math></span> and <span><math><mn>2.9</mn><mspace></mspace><mo>%</mo></math></span> for prostate and breast, respectively. According to expert rating, in none of the test cases KBP provides a markedly worse plan than MP.</div></div><div><h3>Conclusion</h3><div>We developed a KBP solution for ITP of IMRT that is able to automatically generate treatment plans with similar quality when compared to MP. This has the potential to facilitate and accelerate ITP while ensuring high treatment plan quality.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"139 ","pages":"Article 105199"},"PeriodicalIF":2.7,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145417700","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":"Lung cancer screening CT acquisition protocols for three generations of CT systems conforming to German legislation","authors":"Stefan Sawall ,&nbsp;Joscha Maier ,&nbsp;Christian H. Ziener ,&nbsp;Heinz-Peter Schlemmer ,&nbsp;Thuy D. Do ,&nbsp;Hans-Ulrich Kauczor ,&nbsp;Stefan O. Schoenberg ,&nbsp;Matthias F. Froelich ,&nbsp;Marc Kachelrieß","doi":"10.1016/j.ejmp.2025.105208","DOIUrl":"10.1016/j.ejmp.2025.105208","url":null,"abstract":"<div><h3>Objective</h3><div>Develop a computed tomography (CT) acquisition protocol for lung cancer screening compliant with German legislation across three CT system generations, addressing standardization of image quality and radiation dose amid technical variability.</div></div><div><h3>Materials and methods</h3><div>Three CT systems, a first-generation dual-source energy-integrating (EID) CT (Somatom Flash), a second-generation dual-source EID CT (Somatom Force), and a photon-counting CT (Naeotom Alpha), were evaluated. An anthropomorphic thorax phantom with fat rings was used to simulate small, medium, and large patients and included lesions with 150 HU contrast. Image quality was quantified via contrast-to-noise ratio (CNR) at multiple dose levels. Focus was placed on the system-specific adaptation of acquisition and reconstruction parameters, reflecting the challenges faced in harmonizing imaging protocols across diverse hardware generations.</div></div><div><h3>Results</h3><div>At matched CTDI, CNR varied markedly, with newer systems performing best. Thicker slices improved CNR. To reach the defined target of a CNR of 2.2 on 3.0 mm slices, the required CTDI were, in the small phantom, Flash and Force about 0.37 mGy and Alpha 0.26–0.19 mGy. In the medium phantom, Flash 1.30 mGy, Force about 0.96 mGy, and Alpha 0.46–0.24 mGy. In the large phantom, Flash 3.34 mGy, Force 5.15 mGy, and Alpha 2.08–0.69 mGy. Required dose increased with phantom size and differed by system generation, underscoring the clinical difficulty of “one-size-fits-all” dose specifications.</div></div><div><h3>Conclusions</h3><div>Uniform protocol implementation across CT platforms is challenged by hardware and reconstruction disparities. Patient-size-adapted and system-specific protocols are essential to balance diagnostic performance and radiation safety for future lung cancer screening programs.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"139 ","pages":"Article 105208"},"PeriodicalIF":2.7,"publicationDate":"2025-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145363783","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":"Radiography for in-flight health assessment in the framework of astronauts’ healthcare: a new field for medical physics?","authors":"Laura Antonia Cerbone","doi":"10.1016/j.ejmp.2025.105197","DOIUrl":"10.1016/j.ejmp.2025.105197","url":null,"abstract":"<div><h3>Objective</h3><div>The recent acquisition of the first-ever hand radiography in low Earth orbit marked a milestone for X-ray imaging in space, motivating further research for the development of space-adapted devices. This review intends to provide an overview of the current state of X-ray imaging technologies for space applications, analysed within the framework of astronauts’ healthcare assessment, highlighting the role of medical physicists in advancing this field.</div></div><div><h3>Methods</h3><div>An initial search was conducted on PubMed using keywords related to radiography and spaceflight. A further selection was performed by screening the reference lists of pertinent papers that emerged in the initial search.</div></div><div><h3>Results</h3><div>This review shows medical conditions that may pose risks to astronauts during spaceflight and could benefit from X-ray imaging for diagnosis or treatment. Currently available technology for in-flight X-ray imaging is presented. Gender-specific aspects have been considered. Critical aspects identified include device limitations, sources of image deterioration, the need for quality assessment and dosimetry studies.</div></div><div><h3>Conclusions</h3><div>A strong interest in the use of radiography in space emerged. However, to date, only one radiographic image has been acquired in low Earth orbit. Further research is needed to identify adequate hardware and to investigate the feasibility, image quality, and radiation dose for in-flight radiographic imaging. Quality assurance procedures should possibly be adapted to the space environment. The role of medical physicists in this context is central, and specific attention to this field is desirable to address the challenges outlined.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"139 ","pages":"Article 105197"},"PeriodicalIF":2.7,"publicationDate":"2025-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145363847","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 simplified numerical model for Compton cameras efficiency and spatial resolution estimation","authors":"Aicha Bourkadi Idrissi,&nbsp;Ilenia D’Adda,&nbsp;Giacomo Borghi,&nbsp;Marco Carminati,&nbsp;Carlo Fiorini","doi":"10.1016/j.ejmp.2025.105190","DOIUrl":"10.1016/j.ejmp.2025.105190","url":null,"abstract":"<div><h3>Background and objective:</h3><div>One of the main advantages of Compton Cameras (CC) with respect to mechanically collimated gamma cameras is a potentially higher efficiency, which is a key feature for imaging devices developed for applications such as emission tomography in nuclear medicine or radioactive environmental monitoring. Several Monte Carlo (MC) simulation toolkits are available to study the optimal detector configuration with good accuracy but generally low computational efficiency.</div></div><div><h3>Methods:</h3><div>Here, we propose a simplified numerical model of the classical two-tier CC for multi-parameter optimization via stochastic simulations. Designed as a user-friendly, low-cost alternative to traditional Monte Carlo tools, it helps estimate system efficiency and reduce the need for extensive simulations. The model calculates scatter and absorber efficiencies, both geometrical and intrinsic, based on inputs that include detector dimensions, distances, material density, and cross-sections, and outputs partial and total detection efficiencies.</div></div><div><h3>Results:</h3><div>The impact of the principal geometrical and physical parameters on the total efficiency has been analyzed for a heterogeneous CC for hadron therapy featuring GAGG and LYSO scintillators as scatter and absorber detectors, respectively. The results were validated through ANTS2 simulation package (Morozov et al., 2016) and a GATE (Allison et al., 2016) simulated data of a CC available in literature (Barrientos et al., 2023), showing good agreement, confirming the model’s reliability.</div></div><div><h3>Conclusion:</h3><div>The developed tool estimates the impact of various parameters on system efficiency in just a few minutes per CC configuration, significantly faster than conventional Monte Carlo simulations, which typically take several hours.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"139 ","pages":"Article 105190"},"PeriodicalIF":2.7,"publicationDate":"2025-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145363784","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":"On the robustness of the Transit-Guided Radiation Therapy technique against variations in linac operating conditions","authors":"Artur Latorre-Musoll ,&nbsp;Sergi Serrano-Rueda ,&nbsp;Núria Jornet ,&nbsp;Josep Sempau","doi":"10.1016/j.ejmp.2025.105206","DOIUrl":"10.1016/j.ejmp.2025.105206","url":null,"abstract":"<div><h3>Purpose</h3><div>To evaluate the robustness of the Transit-Guided Radiation Therapy (TGRT) technique against variations in linac operating conditions using Monte Carlo simulations.</div></div><div><h3>Methods</h3><div>End-to-end simulations using PRIMO and PENELOPE/penEasy software were conducted to simulate radiation beams and transit portal images (TPIs) of ten clinical plans under unaltered and modified scenarios (including changes in output dose, beam symmetry, EPID strip sensitivity, and MLC positions). The TGRT technique was used to estimate patient position errors from the TPIs with known errors introduced. Residual errors post-TGRT correction, relative to the magnitude of the known errors, served as a figure of merit for TGRT performance. Results from the modified scenarios were compared to unaltered ones to assess the impact of the modifications on TGRT performance.</div></div><div><h3>Results</h3><div>TGRT performance was impaired at rates ranging from 0.0135 to 0.0439 per percentage change in output dose, beam symmetry and EPID strip sensitivity. For changes in MLC positions the impairing rate was 0.28/mm. Given that the TGRT performance was 0.44 ± 0.19 under reference conditions, minor changes in linac operating conditions (within typical machine QA tolerances) resulted in negligible impairment of TGRT performance. No overcorrections were observed within these tolerances.</div></div><div><h3>Conclusions</h3><div>The TGRT technique demonstrates high resilience to variations in linac operating conditions, maintaining performance within clinically acceptable limits. These findings support the robustness of TGRT for clinical application, ensuring reliable patient position monitoring and correction in radiotherapy treatments.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"139 ","pages":"Article 105206"},"PeriodicalIF":2.7,"publicationDate":"2025-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145363782","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":"Automatic target delineation for online adaptive H&N IMPT with a plan library approach – A feasibility study","authors":"M.K. Giżyńska ,&nbsp;M. Oud ,&nbsp;S. Breedveld ,&nbsp;B.J.M. Heijmen ,&nbsp;M. Hoogeman","doi":"10.1016/j.ejmp.2025.105191","DOIUrl":"10.1016/j.ejmp.2025.105191","url":null,"abstract":"<div><h3>Purpose</h3><div>Plan library (PL) based, online adaptive intensity modulated proton therapy (IMPT) was recently proposed for head-and-neck (HN) cancer. In this approach, a set of robust treatment plans is generated prior to the fractionated treatment, each with a different setup robustness (SR) setting. Each fraction, one of the plans is automatically selected for treatment, based on target coverage in the daily repeat-CT (rCT). For clinical implementation, fast and accurate automated target delineation is required. We tested feasibility of using clinically available auto-contouring methods.</div></div><div><h3>Methods</h3><div>For 15 HN patients with in total 67 rCTs with manually generated ground truth (GT) CTV₇₀₀₀ and CTV₅₄₂₅ contours, these contours were also generated with 19 auto-contouring approaches available in commercial software. Auto-contouring was compared to GT regarding contour metrics, selected plans, achieved target coverage and predicted Normal Tissue Complication Probabilities (NTCP).</div></div><div><h3>Results</h3><div>With the five most promising auto-contouring methods, in 66–72 % of rCTs the same plan was selected as for GT contours, while in 19–26 % of other rCTs, plans with a larger SR were selected, assuring uncompromised target coverage. The 90-percentile near-minimum V_95% for CTV₇₀₀₀ was 96.9 %/&gt;97.6 % for selection based on GT/five best performing auto-contouring methods. For 1/15 patients target coverage was reduced. Auto-contour usage in PL-based on-line adaptive IMPT resulted in small NTCP increases, but these were much smaller than the reported NTCP reductions comparing PL-based on-line adaptive with current off-line adaptive IMPT.</div></div><div><h3>Conclusions</h3><div>Carefully selected commercially available auto-contouring for plan library based on-line adaptive IMPT generally resulted in adequate patient dose.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"139 ","pages":"Article 105191"},"PeriodicalIF":2.7,"publicationDate":"2025-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145363848","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":"Point cloud dosimetry framework for preclinical microbeam radiation therapy","authors":"Jack Humphreys ,&nbsp;Christopher White ,&nbsp;Florian Mentzel ,&nbsp;David Bolst ,&nbsp;Jason Paino ,&nbsp;Ah Chung Tsoi ,&nbsp;Lorenzo Arsini ,&nbsp;Franco Scarselli ,&nbsp;Carlo Mancini-Terracciano ,&nbsp;Anatoly Rosenfeld ,&nbsp;Moeava Tehei ,&nbsp;Stéphanie Corde ,&nbsp;Michael Lerch ,&nbsp;Susanna Guatelli ,&nbsp;Markus Hagenbuchner","doi":"10.1016/j.ejmp.2025.105198","DOIUrl":"10.1016/j.ejmp.2025.105198","url":null,"abstract":"<div><h3>Background:</h3><div>Microbeam Radiation Therapy (MRT) is an emerging radiotherapy technique which is currently at the research stage. In order to further progress from research, toward clinical deployment, it is essential to develop a reliable and accurate dose engine such as Monte Carlo (MC) simulations.</div></div><div><h3>Purpose:</h3><div>MC execution times are far too long for practical, clinical applications. In previous studies, we used a 3D U-Net, trained with Geant4 MC simulations, to calculate the dose in digital rat phantoms. This choice of model imposes significant scalability challenges in the case of larger geometries. Casting MRT dose prediction as a 3D point cloud regression problem is a flexible and extensible solution to overcoming many of these hurdles. This problem formulation requires the use of point-based models which are unproven for the task of MRT dose prediction.</div></div><div><h3>Methods:</h3><div>In order to assay the viability of this family of models on this task, the SphereFormer is trained to accurately replicate the gold standard MC dosimetry on uniform voxel grids.</div></div><div><h3>Results:</h3><div>Furthermore, the benefits of the scalability of this method are demonstrated by the utilisation of out-of-field information to significantly improve over the existing state-of-the-art results on valley dose prediction, being accurate to within 3% for at least 84.1% of voxels compared with 78.2% for the baseline.</div></div><div><h3>Conclusion:</h3><div>This paper serves as a proof-of-concept study for the application of 3D point cloud methods to MRT dose prediction and marks the first time such a method have been applied to dosimetry in general.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"139 ","pages":"Article 105198"},"PeriodicalIF":2.7,"publicationDate":"2025-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145350170","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":"Effect of gadolinium-based contrast media on intravoxel incoherent motion (IVIM) MRI parameters in brain imaging","authors":"Lei Wang ,&nbsp;Qiyong Ai ,&nbsp;Weitian Chen ,&nbsp;Zongyou Cai ,&nbsp;Ziqiang Yu ,&nbsp;Jill Abrigo ,&nbsp;Tiffany Y So","doi":"10.1016/j.ejmp.2025.105172","DOIUrl":"10.1016/j.ejmp.2025.105172","url":null,"abstract":"<div><h3>Purpose</h3><div>Current intravoxel incoherent motion (IVIM) MRI protocols typically involve acquiring IVIM images before the injection of intravenous contrast media. The effect of contrast on IVIM model parameters remains unclear. This study aimed to assess the effect of intravenous gadolinium-based contrast media on IVIM parameters (f, D*, and D) in brain MRI.</div></div><div><h3>Materials and methods</h3><div>Thirty-one participants in the experimental contrast group (age 38.8 ± 8.81, 22 females, 9 males) and 31 participants in the control group (age 34.7 ± 9.68, 17 females, 14 males) were prospectively recruited. Pre-contrast, immediate post-contrast, and delayed post-contrast IVIM with 14b values following administration of gadoteric acid at 0.1 ml per kg body mass were performed in a 3.0 T MRI scanner. The IVIM parameters, and the nominal signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated and compared between scans using repeated measures analysis of variance and paired t-tests.</div></div><div><h3>Results</h3><div>No baseline differences in IVIM parameters were observed in the control group across the three scans (p = 0.077 to 0.866). In the contrast group, there were reductions in regional f, D*, D, and ADC values between the pre-contrast to post-contrast scan, followed by a return towards baseline in the delayed phase (p &lt; 0.050). SNR (p = 0.056 to 0.513) and CNR (p = 0.359 to 0.999) were not significantly different before and after contrast.</div></div><div><h3>Conclusion</h3><div>Potential alterations in f, D*, D, and ADC are observed following administration of gadolinium-based contrast media. These changes may require consideration when performing IVIM after other contrast sequences.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"139 ","pages":"Article 105172"},"PeriodicalIF":2.7,"publicationDate":"2025-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145322449","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":"Timing or criteria to trigger adaptive radiotherapy (ART) for nasopharyngeal carcinoma (NPC): A systematic review","authors":"Jia Ding Wong ,&nbsp;Aik Hao Ng ,&nbsp;Li Kuo Tan ,&nbsp;Jeannie Hsiu Ding Wong","doi":"10.1016/j.ejmp.2025.105203","DOIUrl":"10.1016/j.ejmp.2025.105203","url":null,"abstract":"<div><h3>Introduction</h3><div>Nasopharyngeal carcinoma (NPC), prevalent in Southern China and Southeast Asia, is primarily treated with radiation therapy (RT) and concurrent chemoradiotherapy (CCRT). Due to its anatomical complexity and changes during treatment, adaptive radiotherapy (ART) is employed to adjust plans mid-course. However, ART is time-consuming and labor intensive. This systematic review aims to summarize and analyze the timepoints and criteria used to trigger replanning in NPC patients undergoing ART.</div></div><div><h3>Methods</h3><div>A systematic search was conducted in PubMed and Scopus to identify studies reporting on the timing or criteria for replanning in NPC patients treated with ART. Eligible studies were screened, and relevant data were extracted.</div></div><div><h3>Results</h3><div>51 studies met the inclusion criteria. Among these, 42 recommended a single replanning session, 3 suggested one or two sessions depending on individual factors, 4 proposed two sessions, and 2 recommended three. Week 5 was the most frequently reported timepoint for initiating ART, followed by weeks 4 and 3. Tumor volume reduction was a common criterion. Changes in parotid gland anatomy and dosimetric parameters were frequently cited due to their relevance as organs at risk. Body weight loss was a triggering factor in eleven studies, while four studies highlighted ill-fitted masks as indicators for ART initiation.</div></div><div><h3>Conclusion</h3><div>There is notable variability in the timing or criteria for initiating ART in NPC patients. Prospective studies are necessary to develop evidence-based ART guidelines and protocols.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"139 ","pages":"Article 105203"},"PeriodicalIF":2.7,"publicationDate":"2025-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145322450","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}