Medical physics最新文献

{"title":"Quantifying the dosimetric accuracy of expiration-gated stereotactic lung radiotherapy","authors":"Daan Hoffmans,&nbsp;Isabel Remmerts de Vries,&nbsp;Max Dahele,&nbsp;Wilko Verbakel","doi":"10.1002/mp.17743","DOIUrl":"10.1002/mp.17743","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>In stereotactic body radiotherapy, a form of motion management is often applied to mobile lung tumors. Gated radiotherapy is such form of motion management in which the radiation beam is switched on or off depending on the actual tumor position. Compared to inspiration, the tumor position is typically more stable during expiration. Also, the tumor spends more time in expiration position. Therefore, we often consider expiration-gating for patients with relatively large tumor motion.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>We validated dosimetric accuracy of expiration-gated stereotactic lung radiotherapy by means of phantom measurements and modeling the effects of residual motion in patients.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Dose profiles from film measurements in a respiratory-motion phantom were compared to dose calculations, for different expiration gating methods. Fluoroscopic real-time tumor tracking was used to produce a convolution kernel which was applied to the calculated dose distribution to model dosimetric effects of residual motion. This convolution method was validated against film measurements and then retrospectively applied to clinical tumor tracking data of five patients. In addition, clinical tumor motion data was manipulated to simulate the effect of a short breathing period of 2 s and prolonged gating latency of 500 ms.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>A good agreement between calculated and measured dose was found when amplitude gating was used (100% gamma pass rate, 3%/2 mm). For phase gating, good agreement required a stable breathing period. Measurements showed good performance of the convolution method (gamma pass rate &gt; 99%). For the clinical data, we found a maximal dose shift of 2.4 mm, introduced by residual tumor motion or respiratory drift. For all patients, the size of the ITV was adequate to account for this dose shift. Simulating higher breathing speed in combination with large latency values resulted in dosimetric shifts that were larger than the PTV margin.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>Amplitude gating is robust for irregular breathing patterns. Expiration-gating is a dosimetrically accurate method of treatment delivery provided that during delivery there is a prompt reaction to respiratory drift and the latency of the gating system is short.</p>\u0000 </section>\u0000 </div>","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 5","pages":"2773-2784"},"PeriodicalIF":3.2,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mp.17743","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143652898","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Flexible and modular PET: Evaluating the potential of TOF-DOI panel detectors","authors":"Gašper Razdevšek,&nbsp;Georges El Fakhri,&nbsp;Thibault Marin,&nbsp;Rok Dolenec,&nbsp;Matic Orehar,&nbsp;Yanis Chemli,&nbsp;Alberto Giacomo Gola,&nbsp;David Gascon,&nbsp;Stan Majewski,&nbsp;Rok Pestotnik","doi":"10.1002/mp.17741","DOIUrl":"10.1002/mp.17741","url":null,"abstract":"&lt;div&gt;\u0000 \u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Background&lt;/h3&gt;\u0000 &lt;p&gt;Panel detectors have the potential to provide a flexible, modular approach to Positron Emission Tomography (PET), enabling customization to meet patient-specific needs and scan objectives. The panel design allows detectors to be positioned close to the patient, aiming to enhance sensitivity and spatial resolution through improved geometric coverage and reduced noncollinearity blurring. Parallax error can be mitigated using depth of interaction (DOI) information.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Purpose&lt;/h3&gt;\u0000 &lt;p&gt;One of the key questions the article addresses is: Do panel detectors offer viable clinical imaging capabilities, or does limited angular sampling restrict their utility by causing image distortions and artifacts? Additionally, this article explores the scalability of panel detectors for constructing scanners with a long axial field of view (LAFOV).&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Methods&lt;/h3&gt;\u0000 &lt;p&gt;Monte Carlo simulations using GATE software were used to assess the performance of panel detectors with various DOI resolutions and Time-of-Flight (TOF) resolutions as fine as 70 ps. The 30 &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mo&gt;×&lt;/mo&gt;\u0000 &lt;annotation&gt;$times$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; 30 cm panels comprised pixelated 3 &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mo&gt;×&lt;/mo&gt;\u0000 &lt;annotation&gt;$times$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; 3 &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mo&gt;×&lt;/mo&gt;\u0000 &lt;annotation&gt;$times$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; 20 mm LSO crystals. Simulations were run on large high-performance computing clusters (122,000 CPU cores). Open-source CASToR software was used for (TOF MLEM) image reconstruction. The image quality of the scanners was assessed using a range of phantoms (NEMA, Derenzo, XCAT, and a high-resolution brain phantom). The Siemens Biograph Vision PET/CT scanner served as the reference model. The performance of larger 120 &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mo&gt;×&lt;/mo&gt;\u0000 &lt;annotation&gt;$times$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; 60 cm panels was also evaluated.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Results&lt;/h3&gt;\u0000 &lt;p&gt;Sensitivity increases over threefold when panel-panel distance is reduced from 80 to 40 cm. The noise equivalent count rate, unmodified by TOF gain, of the panel detectors matches that of the reference clinical scanner at a distance of app","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 5","pages":"2845-2860"},"PeriodicalIF":3.2,"publicationDate":"2025-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mp.17741","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143639919","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stable and discriminating OCT-derived radiomics features for predicting anti-VEGF treatment response in diabetic macular edema","authors":"Sudeshna Sil Kar,&nbsp;Hasan Cetin,&nbsp;Sunil K. Srivastava,&nbsp;Anant Madabhushi,&nbsp;Justis P. Ehlers","doi":"10.1002/mp.17695","DOIUrl":"10.1002/mp.17695","url":null,"abstract":"&lt;div&gt;\u0000 \u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Background&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;Radiomics-based characterization of fluid and retinal tissue compartments of spectral-domain optical coherence tomography (SD-OCT) scans has shown promise to predict anti-VEGF therapy treatment response in diabetic macular edema (DME). Radiomics features are sensitive to different image acquisition parameters of OCT scanners such as axial resolution, A-scan rate, and voxel size; consequently, the predictive capability of the radiomics features might be impacted by inter-site and inter-scanner variations.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Purpose&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;The main objective of this study was (1) to develop a more generalized classifier by identifying the OCT-derived texture-based radiomics features that are both stable (across multiple scanners) as well as discriminative of therapeutic response in DME and (2) to identify the relative stability of individual radiomic features that are associated with specific spatial compartments (e/g. fluid or tissue) within the eye.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Methods&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;A combination of 151 optimal responders and rebounders of anti-VEGF therapy in DME were included from the PERMEATE (imaged using Cirrus HD-OCT scanner) and VISTA clinical trials (imaged using Cirrus HD-OCT and Spectralis scanners). For each patient within the study, a set of 494 texture-based radiomics features were extracted from the fluid and the retinal tissue compartment of OCT images. The training set (&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;S&lt;/mi&gt;\u0000 &lt;mi&gt;t&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;annotation&gt;${{S}_t}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;) included 76 patients and the independent test set &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;(&lt;/mo&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;S&lt;/mi&gt;\u0000 &lt;mi&gt;v&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt;$({{S}_v}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;) comprised of 75 patients. Features were ranked based on (i) only discriminability criteria, that is, maximizing area under the receiver operating characteristic curve (AUC) and (ii) both stability and discriminability criteria. The subset of radiomic features for which the feature expression remained relatively consistent between the two datasets, as assessed by Wilcoxon rank-sum test, were considered to be stable. Different machine learning (ML) classifiers (such as k","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 5","pages":"2762-2772"},"PeriodicalIF":3.2,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mp.17695","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143627343","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Demonstration of virtual imaging trial applications for optimization and education of dento-maxillofacial CBCT imaging","authors":"Karen Merken,&nbsp;Nicholas Marshall,&nbsp;Johan Nuyts,&nbsp;Rodrigo T Massera,&nbsp;Reinhilde Jacobs,&nbsp;Hilde Bosmans","doi":"10.1002/mp.17708","DOIUrl":"10.1002/mp.17708","url":null,"abstract":"&lt;div&gt;\u0000 \u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Background&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;A number of studies have suggested that there is a need for improved understanding of dento-maxillofacial cone beam computed tomography (CBCT) technology, and to establish optimized imaging protocols. While several ex vivo/in vitro studies, along with a few in vivo studies, have addressed this topic, virtual imaging trials could form a powerful alternative but have not yet been introduced within the field of dento-maxillofacial imaging.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Purpose&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;To introduce and illustrate the potential of utilizing a virtual imaging trial (VIT) platform for dento-maxillofacial CBCT imaging through a number of case studies.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Methods&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;A framework developed in-house, simulating an existing CBCT scanner, and the necessary digital patient phantoms were prepared for the following potential studies: I) the impact of intracanal material type (Ni-Cr alloy, fiberglass, gutta-percha) and acquisition settings (tube current (mA), tube voltage (kVp)) on root fracture (RF) visibility; II) image artefact levels from candidate new restorative materials, such as graphene; III) the effect of patient rigid motion on image artifacts; IV) the effect of a metal artifact reduction algorithm on RF visibility in a tooth treated endodontically and restored with a metal post. In addition, features not available on the real system, including automatic exposure control and extended tube current and tube voltage ranges, were added to study the impact of these parameters. Patient dose levels were also quantified.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Results&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;The generated images showed the influence of different restorative materials, dose levels, rigid motion, and image processing on the quality of the final images. Results of these simulated conditions were consistent with findings in the literature. Patient effective dose levels ranged between 22 and 138 &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;μ&lt;/mi&gt;\u0000 &lt;mi&gt;Sv&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt;$mu{rm Sv}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; for all simulated scenarios. Images were considered sufficiently realistic according to an experienced oral radiologist. Furthermore, the platform was able to simulate scenarios that are difficult or impossible to replicate physically in a controlled and repeatable way.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 ","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 5","pages":"3487-3497"},"PeriodicalIF":3.2,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mp.17708","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143618044","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"MR-Linac is a better choice for adaptive therapy compared to cone-beam CT","authors":"Filippo Alongi,&nbsp;Dandan Zheng,&nbsp;Indra J. Das","doi":"10.1002/mp.17706","DOIUrl":"10.1002/mp.17706","url":null,"abstract":"","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 5","pages":"2702-2706"},"PeriodicalIF":3.2,"publicationDate":"2025-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143582426","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cover","authors":"","doi":"10.1002/mp.17201","DOIUrl":"https://doi.org/10.1002/mp.17201","url":null,"abstract":"","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 3","pages":"C1"},"PeriodicalIF":3.2,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mp.17201","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143554433","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"List of Advertisers","authors":"","doi":"10.1002/mp.17202","DOIUrl":"https://doi.org/10.1002/mp.17202","url":null,"abstract":"","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 3","pages":"1969"},"PeriodicalIF":3.2,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mp.17202","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143554663","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimization of Low-Contrast Detectability in Abdominal Imaging: A Comparative Analysis of PCCT, DECT, and SECT Systems","authors":"Jessica D. Flores,&nbsp;Erik Wåhlin,&nbsp;Louise Blomkvist,&nbsp;Rebecca Titternes,&nbsp;Antonios Tzortzakakis,&nbsp;Bryan Connolly,&nbsp;Adrian Szum,&nbsp;Johan Lundberg,&nbsp;Patrik Nowik,&nbsp;Tobias Granberg,&nbsp;Gavin Poludniowski","doi":"10.1002/mp.17717","DOIUrl":"10.1002/mp.17717","url":null,"abstract":"&lt;div&gt;\u0000 \u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Background&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;Clear representation of anatomy is essential in the assessment of pathology in computed tomography (CT). With the introduction of photon-counting CT (PCCT) and more advanced iterative reconstruction (IR) algorithms into clinical practice, there is potential to improve low-contrast detectability in CT protocols. As such, it is necessary to perform task-based assessments to optimize protocols and compare image quality between PCCT and energy-integrating CT, like dual-energy CT (DECT) and single-energy CT (SECT).&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Purpose&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;This work aimed to assess low-contrast detectability in abdominal protocols used in clinical PCCT, DECT, and SECT, using both model and human observers.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Methods&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;Data were acquired with the standard resolution scan mode on a PCCT (NAEOTOM Alpha, Siemens Healthineers, Forchheim, Germany) and a DECT/SECT (SOMATOM Force, Siemens Healthineers, Forchheim, Germany). Detectability was investigated in the CTP 515 low-contrast module of the Catphan 600 phantom, which was surrounded by a fat annulus to simulate an abdomen and resulted in a water equivalent diameter of 298 mm. Supra-slice contrast rods with a nominal 1.0% contrast and diameters of 4, 6, 9, and 15 mm were used. Factory abdominal protocols were adjusted to acquire images with various tube potentials (70, 90, 120, and 140 kV in PCCT; 70/150Sn and 80/150Sn kV in DECT; 100 and 120 kV in SECT), virtual monoenergetic image (VMI) energy levels (40 to 140 keV in PCCT and DECT), doses (5, 10 mGy in PCCT; 10 mGy in DECT and SECT), and IR settings (Br40 kernel, no quantum IR (QIR) and QIR levels 1 to 4 in PCCT; advanced modeled IR (ADMIRE) level 3 in DECT and SECT). Mixed DECT (linear blending of the images at two tube voltages) images were also reconstructed. The noise power spectrum and task transfer function of each scan protocol were quantified; the detectability index for each protocol was also determined using in-house implementations of model observers (non-prewhitening matched filters with internal noise, NPWI, and with an eye filter and internal noise, NPWEI) and human observers (in-house four-alternative forced choice, scoring with 95% confidence intervals).&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Results&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;Results show that the image noise is minimized at a VMI energy corresponding to the applied spectrum's mean energy in PCCT and with VMI settings of 70 and 80 keV for 70/150Sn and 80/150Sn tube potential pairs, respectively, in DECT. With respect to the human observer d","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 5","pages":"2832-2844"},"PeriodicalIF":3.2,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mp.17717","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143545262","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Domino volumetric metamaterial resonator for very-low-field MRI","authors":"Yu Liu,&nbsp;Xia Xiao,&nbsp;Xiangzheng Kong,&nbsp;Guoquan Chen,&nbsp;Jiannan Zhou,&nbsp;Fuqiang Lu,&nbsp;Pengfei Zhao,&nbsp;Yanwei Pang,&nbsp;Zhenchang Wang","doi":"10.1002/mp.17726","DOIUrl":"10.1002/mp.17726","url":null,"abstract":"&lt;div&gt;\u0000 \u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Background&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;Very-low-field magnetic resonance imaging (VLF-MRI) plays a significant role in medical imaging diagnosis due to its low cost and light weight. High-quality MR images are essential for accurate medical diagnosis. It is urgent to explore a low-cost, simple and convenient approach to boost the signal-to-noise ratio (SNR) of VLF-MRI system to make medical diagnosis more accurate.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Purpose&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;The aim of this study was to evaluate the effect of the proposed metamaterial resonator on enhancing the performance of the 70 mT VLF-MRI system. The domino volumetric metamaterial resonator (DVMR), which consisted of an array of rectangular plan spiral resonator cell, was designed to work at the Larmor frequency of the 70 mT VLF-MRI system. When placed around the realistic multi- tissue voxel human wrist phantom, the DVMR improved the SNR in the region of interest (ROI).&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Methods&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;The equivalent circuits of DVMR cell and radio frequency (RF) coil were analyzed by the coupling mode theory and circuit model theory. The non-dominated sorting genetic algorithm II (NSGA-II) was used to optimize the structure of the DVMR cell. The DVMR was composed of multiple coaxial DVMR cells stacked. The 10 g-averaged specific absorption rate (SAR&lt;sub&gt;av.&lt;/sub&gt;10g), the &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;|&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;msubsup&gt;\u0000 &lt;mi&gt;B&lt;/mi&gt;\u0000 &lt;mn&gt;1&lt;/mn&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;/msubsup&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;|&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt;$| {{mathrm{B}}_{mathrm{1}}^{mathrm{ - }}} |$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; field enhancement factor, and the SNR enhancement factor were analyzed. The enhancement effect of the DVMR on the performance of the VLF-MRI system was assessed by comparing the cases with and without the DVMR. The proposed DVMR was compared with the identically-sized solenoid coil. To further verify the performance of the proposed DVMR, the preliminary experiments are performed.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Results&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;Due to the introduction of the proposed DVMR, the SNR enhancement factor for the cuboid phantom reached up to 5.06 by comparing with using the RF coil alone. For the radial direction of the realistic human wrist phantom, the SNR using the DVMR was higher than ","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 5","pages":"2874-2886"},"PeriodicalIF":3.2,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143525747","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Breast cancer detection from ultrasound computed tomography imaging using radiomic analysis: in silico trial","authors":"Andres Vargas,&nbsp;Nicole Hernandez,&nbsp;Ana B. Ramirez,&nbsp;Said Pertuz","doi":"10.1002/mp.17710","DOIUrl":"10.1002/mp.17710","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Ultrasound computed tomography (USCT) is an imaging modality currently under development for its clinical use in breast imaging. In order to justify clinical trials on imaging prototypes, further research is required to investigate uses and limitations of USCT.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>We investigate the potential of USCT for the detection of breast lesions through the computerized analysis of speed-of-sound (SOS) images of the breast.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>We conducted an in silico study with a set of 116 virtual breast phantoms (VBPs). We simulated US acquisition and reconstructed 2D SOS slices of the breast via the full waveform inversion (FWI) technique. Subsequently, we conducted breast lesion detection based on computerized texture features (i.e., radiomic features) of the SOS slices. We compare the performance in cancer detection against radiomic analysis of mammograms in terms of the area under the curve (AUC) of the receiver operating characteristic (ROC) curve with 95% confidence intervals estimated using five-fold cross-validation. Statistical analysis involved the Wilcoxon rank-sum test to evaluate significant differences in detection scores, with a significance level of <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>p</mi>\u0000 <mo>&lt;</mo>\u0000 <mn>0.05</mn>\u0000 </mrow>\u0000 <annotation>$p&lt;0.05$</annotation>\u0000 </semantics></math>. AUCs were compared using DeLong's test, and the significance level was adjusted with Bonferroni's correction to account for multiple comparisons.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The AUC for lesion detection from reconstructed SOS images and mammography were 0.87 (95% CI: 0.81-0.94) and 0.77 (95% CI: 0.68-0.86), respectively. Detection of breast lesions using the multimodal approach combining SOS images and mammograms, yielded an AUC of 0.89 (95% CI: 0.83-0.95), with statistically significant differences with respect to the use of mammograms alone (<i>p</i> = 0.0112).</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Our in silico experimental results demonstrate the feasibility of using USCT for breast lesion detection using fully automatic analysis of reconstructed SOS images. The multimodal approach, that combines radio-density and acoustic properties of the breast, outperforms the analysis using a single modality.</p>\u0000 </section>\u0000 </div>","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 4","pages":"2465-2474"},"PeriodicalIF":3.2,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143525745","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}