Medical physics最新文献

{"title":"Characterization of silicon carbide diodes as cost-effective active detectors for proton UHDR dosimetry","authors":"Ivan Lopez Paz, Celeste Fleta, Paula Ibáñez, Ángela Henao, Daniel Sanchez-Parcerisa, Adrián Zazpe, Ines del Monte-Garcia, Consuelo Guardiola","doi":"10.1002/mp.17986","DOIUrl":"https://doi.org/10.1002/mp.17986","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Proton therapy allows for better localization of the dose distribution in the tumor. In addition, the FLASH effect can be exploited to reduce the toxicity to healthy tissue by using short-pulsed treatment at ultra-high dose rates (UHDR). Such intense radiation conditions have limited options for active detectors for dosimetry.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>Silicon carbide-based diodes are proposed as a cost-effective alternative to diamond detectors for dosimetry in UHDR.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Two new SiC diodes designed and fabricated at the Institute of Microelectronics of Barcelona (IMB-CNM) were exposed to 20 <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>μ</mi>\u0000 <mi>s</mi>\u0000 </mrow>\u0000 <annotation>$mu{rm s}$</annotation>\u0000 </semantics></math> proton low-energy pulses with up to 25 Gy per pulse to verify the capability of this technology to function under UHDR radiation at the Center for Microanalysis of Materials (CMAM) facility. The response of a single diode was correlated to the dose per pulse measured with calibrated EBT4 radiochromic films. Likewise, a 2 <span></span><math>\u0000 <semantics>\u0000 <mo>×</mo>\u0000 <annotation>$times$</annotation>\u0000 </semantics></math> 2 dosimeter matrix mounted on a motorized stage system was used as a proof-of-concept for a large array dose monitor under construction, by scanning the response of each of its pixels as a function of position with respect to the beam, compared against calibrated radiochromic films. Finally, the same device was exposed to varying pulse lengths, while connected to a current-to-voltage amplifier and an oscilloscope in order to measure the pulse structure.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>First, the single diode showed a good dose rate linearity. No indication of saturation was observed even at the highest dose per pulse (DPP) of 25 Gy. This was observed even after over-exposure of 52 kGy of 7 MeV protons, although its response lowered to 31% of the initially measured value. Second, the beam profiles observed by the pixelated detector were consistent with those of the reference measurements. Finally, the full width half maximums of the pulses observed by the pixels show good correlation with the pulse width of the beam.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>The SiC detectors developed at ","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 7","pages":""},"PeriodicalIF":3.2,"publicationDate":"2025-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144635421","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":"Noise-aware system generative model (NASGM): positron emission tomography (PET) image simulation framework with observer validation studies","authors":"Suya Li, Kaushik Dutta, Debojyoti Pal, Kooresh I. Shoghi","doi":"10.1002/mp.17962","DOIUrl":"https://doi.org/10.1002/mp.17962","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Simulation of positron emission tomography (PET) images is critical in dynamic imaging protocol optimization, quantitative imaging metric development, deep learning applications, and virtual imaging trials. These applications rely heavily on large volumes of simulated PET data. However, the current state-of-the-art PET image simulation platform is time-prohibitive and computationally intensive. Although deep learning-based generative models have been widely applied to generate PET images, they often fail to adequately account for the differing acquisition times of PET images.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>This study seeks to develop and validate a novel deep learning-based method, the noise-aware system generative model (NASGM), to simulate PET images of different acquisition times.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>NASGM is based on the conditional generative adversarial network and features a novel dual-domain discriminator that contains a spatial and a frequency branch to leverage information from both domains. A transformer-based structure is applied for the frequency discriminator because of its ability to encode positional information and capture global dependencies. The study is conducted on a simulated dataset, with a public PET/CT dataset as the input activity and attenuation maps, and an analytical PET simulation tool to simulate PET images of different acquisition times. Ablation studies are carried out to confirm the necessity of adopting the dual-domain discriminator. A comprehensive suite of evaluations, including image fidelity assessment, noise measurement, quantitative accuracy validation, task-based assessment, texture analysis, and human observer study, is performed to confirm the realism of generated images. The Wilcoxon signed-rank test with Bonferroni correction is applied to compare the NASGM with other networks in the ablation study at an adjusted <i>p</i>-value <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>≤</mo>\u0000 <mn>0.01</mn>\u0000 </mrow>\u0000 <annotation>$ le 0.01$</annotation>\u0000 </semantics></math>, and the alignment of features between the generated and target images is measured by the concordance correlation coefficient (CCC).</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The quantitative accuracy measured by the correlation of mean recovery coefficients of tumor groups, and the NASGM-generated images ","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 7","pages":""},"PeriodicalIF":3.2,"publicationDate":"2025-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mp.17962","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144624751","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":"Comparison of three reconstruction algorithms for low-dose phase-contrast computed tomography of the breast with synchrotron radiation","authors":"Sandro Donato,&nbsp;Simone Caputo,&nbsp;Luca Brombal,&nbsp;Bruno Golosio,&nbsp;Renata Longo,&nbsp;Giuliana Tromba,&nbsp;Raffaele G. Agostino,&nbsp;Gianluigi Greco,&nbsp;Benedicta Arhatari,&nbsp;Chris Hall,&nbsp;Anton Maksimenko,&nbsp;Daniel Hausermann,&nbsp;Darren Lockie,&nbsp;Jane Fox,&nbsp;Beena Kumar,&nbsp;Sarah Lewis,&nbsp;Patrick C. Brennan,&nbsp;Harry M. Quiney,&nbsp;Seyedamir T. Taba,&nbsp;Timur E. Gureyev","doi":"10.1002/mp.17950","DOIUrl":"https://doi.org/10.1002/mp.17950","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Phase-contrast breast CT imaging holds promise for improved diagnostic accuracy, but an optimal reconstruction algorithm must balance objective image quality metrics with subjective radiologist preferences.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>This study systematically compares three reconstruction algorithms—filtered back projection (FBP), unified tomographic reconstruction (UTR), and customized simultaneous algebraic reconstruction technique (cSART)—to identify the most suitable approach for phase-contrast breast CT imaging.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Fresh mastectomy samples were scanned at the Australian synchrotron using monochromatic 32 keV X-rays, a mean glandular dose of 2 mGy, flat-panel detectors with 0.1 mm pixels, and 6-m distance between the rotation stage and the detector. Paganin's phase retrieval method was used in conjunction with all three CT reconstruction algorithms. Objective metrics, including spatial resolution, contrast, signal-to-noise, and contrast-to-noise, were evaluated alongside subjective assessments by seven experienced radiologists. Ratings included perceptible contrast, sharpness, noise, calcification visibility, and overall quality.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>cSART excelled in objective metrics, outperforming UTR and FBP. However, subjective evaluations favored FBP due to its higher image contrast, revealing a discrepancy between objective and subjective assessments.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>The findings highlight the contrast-focused nature of radiologists’ subjective assessments and the potential of cSART for delivering superior objective image quality. These insights inform the development of hybrid evaluation tools and guide clinical translation for future live patient imaging studies.</p>\u0000 </section>\u0000 </div>","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 7","pages":""},"PeriodicalIF":3.2,"publicationDate":"2025-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mp.17950","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144624758","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":"Analysis of quantitative angiography in intracranial aneurysm using projection foreshortening correction and injection bias removal","authors":"Parmita Mondal,&nbsp;Allison Shields,&nbsp;Mohammad Mahdi Shiraz Bhurwani,&nbsp;Kyle A. Williams,&nbsp;Sricharan S. Veeturi,&nbsp;Swetadri Vasan Setlur Nagesh,&nbsp;Adnan H. Siddiqui,&nbsp;Ciprian N. Ionita","doi":"10.1002/mp.17965","DOIUrl":"https://doi.org/10.1002/mp.17965","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;In neurovascular disease applications, 2D quantitative angiography (QA) based on digital subtraction angiography (DSA), is an intraoperative methodology used to assess disease severity and guide treatment. However, despite DSA's ability to produce detailed 2D projection images, the inherent dynamic 3D nature of blood flow and its temporal aspects can distort key hemodynamic parameters when reduced to 2D. This distortion is primarily due to biases such as projection-induced foreshortening and variability from manual contrast injection.&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 study aims to mitigate these biases and enhance QA analysis by applying a path-length correction (PLC) correction, followed by singular value decomposition (SVD)-based deconvolution, to angiograms obtained through both in-silico and in-vitro methods.&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;We utilized DSA data from in-silico and in-vitro patient-specific intracranial aneurysm models. To remove projection bias, PLC for various views were developed by co-registering the pre-existing 3D vascular geometry mask with the DSA projections, followed by ray tracing to determine paths across 3D vessel structures. These maps were used to normalize the logarithmic angiographic images, correcting for projection-induced foreshortening across different angles. Subsequently, we focused on eliminating injection bias by analyzing the corrected angiograms under varied projection views, injection rates, and flow conditions. Regions of interest at the aneurysm dome and inlet were placed to extract time density curves for the lesion and the arterial input function, respectively. Using three standard SVD methodologies, we extracted the aneurysm impulse response function (IRF) and its associated parameters peak height (PH&lt;sub&gt;IRF&lt;/sub&gt;), area under the curve (AUC&lt;sub&gt;IRF)&lt;/sub&gt;, and mean transit time (MTT). The effectiveness of PLC and SVD in eliminating injection bias is assessed by examining the slope of MTT versus injection duration.&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;Our findings revealed that projection and injection parameters significantly affect key quantitative angiographic parameters such as PH&lt;sub&gt;IRF&lt;/sub&gt;, AUC&lt;sub&gt;IRF&lt;/sub&gt;, and MTT. Our approach utilizing PLC followed by SVD-based deconvolution consistently reduced these effects from a slope of 0.363 ± 0.179–0.015 ± 0.017 across in-silico and from 0.842 ± 0.07–0.031 ± 0.015 in-vitro settings, yielding stable and reliable measurements which were correlated only with the hemodynamic conditions.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 ","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 7","pages":""},"PeriodicalIF":3.2,"publicationDate":"2025-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144624761","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":"Beam field guided diffusion model for liver cancer radiotherapy dose distribution prediction","authors":"Xiangxu Cao,&nbsp;Yuqian Zhao,&nbsp;Shuzhou Li,&nbsp;Fan Zhang,&nbsp;Zhen Yang,&nbsp;Xiaoyu Yang","doi":"10.1002/mp.17989","DOIUrl":"https://doi.org/10.1002/mp.17989","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;Deep learning has been widely applied to the design of cancer radiotherapy treatment planning for dose distribution prediction. However, the significant variability in tumor size, quantity, and location poses substantial challenges for accurate dose distribution prediction in liver cancer radiotherapy.&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;Given that the clinical effectiveness and accuracy of the predicted dose distribution directly impact the quality of treatment plans generated by automatic radiotherapy planning methods, this study aims to develop a novel and precise dose prediction method based on diffusion models.&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;We propose a beam field (BF) guided diffusion model (BeamDiff) consisting of a forward and a reverse process for liver cancer radiotherapy dose distribution prediction. In the forward process, noise is progressively added to the actual dose distribution map until it transforms into a standard Gaussian noise map. In the reverse process, a noise predictor is used to estimate the noise and iteratively generate the desired dose distribution map. To effectively leverage patient-specific clinical features, we design a multi-branch hybrid encoder to extract features from BF and clinical structural information, with their relationships captured by a designed multi-condition aggregation module (MAM). Given that our inputs consist solely of 2D slices, which inherently lack inter-slice dependencies and similarity features, we integrate the multi-head attention (MHA) module into the encoder to re-establish connections between slices. In the decoder, we design an asymmetric fusion module (AFM) to integrate high-level feature maps from the encoder with low-level ones from the decoder, mitigating information loss caused by downsampling while preserving fine details and contextual information.&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;We evaluate the proposed method on a clinical liver cancer radiotherapy dataset. In terms of prediction accuracy, our model achieves an average Dose score of 1.27 Gy and a DVH score of 0.28 Gy. The mean absolute error (MAE) is 1.97 Gy for the planning target volume (PTV), 2.21 Gy for the liver, 1.14 Gy for the spinal cord, and 1.16 Gy for the stomach. Regarding clinical effectiveness, the predicted results of our method are the closest to meeting clinical requirements across the evaluated metrics.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Conclusions&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;We develop a method specifically tailored for liver cancer radiotherapy dose pred","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 7","pages":""},"PeriodicalIF":3.2,"publicationDate":"2025-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144635145","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":"Dosimetric characterization for the flat-panel x-ray source: An electronic brachytherapy unit","authors":"Mengke Qi,&nbsp;Sifu Luo,&nbsp;Wangjiang Wu,&nbsp;Jing Kang,&nbsp;Ting He,&nbsp;Jiancong Dai,&nbsp;Song Kang,&nbsp;Jun Chen,&nbsp;Ting Song,&nbsp;Yongbao Li,&nbsp;Bin Ouyang,&nbsp;Linghong Zhou,&nbsp;Yuan Xu","doi":"10.1002/mp.17988","DOIUrl":"https://doi.org/10.1002/mp.17988","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>The flat-panel x-ray source (FPXS) is an innovative x-ray source comprising millions of micro sources that emit low-energy x-rays. To date, the dosimetric characteristics of FPXS remain unclear, limiting its clinical applications.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>This study aims to characterize the physical and dosimetric characteristics of FPXS through Monte Carlo (MC) dose calculation and experimental dosimetry measurements and to analyze the feasibility of FPXS as an electronic brachytherapy (EB) unit.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>A measurement setup and two specialized measurement platforms were developed. By using an energy spectrometer, ionization chamber, and Gafchromic film, a measurement procedure for physical beam characteristics and dosimetric characteristics of FPXS was established, and a series of experimental measurements were conducted. A previously in-house developed MC simulation toolkit, designated gFPDMC, was employed to perform FPXS structure simulation and parallel dose calculation. The measured dose distributions were compared with the gFPDMC-calculated dose distributions, thereby validating the accuracy of gFPDMC.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The measured energy spectra are consistent with the MC-simulated spectra with mean relative error (MRE) values &lt; 9% and an average energy difference &lt; 1.40%. The measured surface dose rate of FPXS increases exponentially with the operating voltage, with a maximum dose rate of 2.45 Gy/min at 40 kV; the depth dose rate decreases exponentially with the measurement depth and increases with the operating voltage. The doses calculated by gFPDMC, DOSXYZnrc, and Geant4 exhibit excellent consistency, with mean absolute error (MAE) values of 0.31% and 0.40%. The gFPDMC-calculated percentage depth dose (PDDs) exhibit identical voltage-dependent depth dose characteristics as measured PDDs, with deviations &lt; 4%.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>The precision of gFPDMC was rigorously validated through comparison with DOSXYZnrc, Geant4, and experimentally measured dose. Adequate operating voltage and suitable dose rate demonstrate the feasibility of FPXS as an EB unit.</p>\u0000 </section>\u0000 </div>","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 7","pages":""},"PeriodicalIF":3.2,"publicationDate":"2025-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144635146","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":"A novel uniform-spaced fast rescanning method for carbon-ion radiotherapy","authors":"Jun Zhang,&nbsp;Xiaoyan An,&nbsp;Ningning Chai,&nbsp;Qiang Li,&nbsp;Pengbo He","doi":"10.1002/mp.17994","DOIUrl":"https://doi.org/10.1002/mp.17994","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Phase-controlled Rescanning (PCR) technique has been used in clinical practice. The feature of the phase-controlled rescanning (PCR) method is that the beam intensity is adjusted by the accelerator actively. In this work, we developed a simplified fast rescanning method, called uniform-spaced rescanning (USR), which does not require the active adjustment of the beam intensity by the accelerator.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>The motion compensation effectiveness of the USR was verified by comparing the four-dimensional dose distributions (4DDDs) between the USR and PCR methods. Furthermore, 4D treatment plans based on the range-adapted internal target volume (raITV) and four-dimensional robust optimization (4DRO) under the beam delivery of USR were also evaluated.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>4DCT datasets and respiratory curves from 25 lung tumor patients were used. The beam delivery simulations included the following scenario combinations: six prescription doses (2, 5, 10, 15, 20, 25 Gy (RBE)) under a single fraction, five beam intensities (1, 2, 3, 4, 5 × 10⁸ particles per second (pps)), and three motion management techniques (no gating, gating with 30% duty cycle (DC), and gating with rescanning (2, 4, 6× USR/PCR)). Similarly, the 4DDDs of the two-field raITV and 4DRO plans were calculated with the same beam delivery parameters. Dose metrics such as the target dose coverage of D₉₅ and homogeneity index (HI) were analyzed.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The D₉₅ of the 4× USR was greater than 95% for all the beam intensity scenarios. The D₉₅, HI and beam delivery time under the USR method were very similar to the PCR method with the increase of rescanning number. Under the 2, 4, 6× USR, the average CTV-D₉₅ values of the raITV plans were higher than that of the 4DRO plans (94.9%/94.4%; 96.9%/96.4%; 97.7%/96.7%), and smaller HI values were observed for the raITV plans (11.7%/21.2%; 9.1%/17.7%; 7.9%/17.4%). For the organ at risks (OARs) sparing, the 4DRO plans could provide a better protection of the ipsilateral lung than the raITV plans.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>The USR method could achieve the similar motion compensation effects to the PCR method, but the complexity of beam control is simplified. The raITV plans could provide a better target dose coverage but lower OARs sparing effects than the 4DRO plans.</p>\u0000 </section>\u0000 </div>","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 7","pages":""},"PeriodicalIF":3.2,"publicationDate":"2025-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144635149","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":"Radiotherapeutic efficacy of gold nanoparticles for high dose-rate brachytherapy compared to conventional radiotherapy: An in vitro study","authors":"Daniel Cecchi,&nbsp;Nolan Jackson,&nbsp;Mehran Goharian,&nbsp;Wayne Beckham,&nbsp;Devika Chithrani","doi":"10.1002/mp.18006","DOIUrl":"https://doi.org/10.1002/mp.18006","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;Radiation therapy is a pivotal part of the treatment plan for many cancer patients. Effective dose escalation in the tumour is required to achieve optimal curative results but is hindered by normal tissue toxicity. Gold nanoparticles (GNPs) as radiosensitizers to improve the radiation cross-section of malignant tissue is one avenue currently being explored to improve therapeutic results. It is hypothesized that at lower incident photon energies, dose enhancement from GNPs should be significantly greater compared to high-energy irradiations due to a greater photoelectric cross-section.&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 assess GNP radiosensitization in vitro during low-energy, high-dose-rate brachytherapy (HDR-BT) irradiations and compare to the measured radiosensitization from a 6MV photon beam from a clinical linear accelerator (LINAC).&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 novel Solid Water Phantom was developed for uniform irradiations from a common HDR-BT source (192-Ir) and verified using EBT-4 radiochromic film. HeLa (cervical) and PC3 (prostate) monolayer cell cultures were used to represent common HDR-BT treatment sites. The cells were dosed at 10 µg/mL concentration with functionalized 12 nm spherical GNPs. GNP uptake in the cellular membrane was quantified using live-cell imaging and a trace element analysis technique. Cell cultures with or without GNPs were irradiated from the 192-Ir source or clinical 6 MV photon beam from a LINAC to a 200 cGy dose prescription. Cellular viability was measured using a clonogenic assay and DNA double-strand break (DSB) assay.&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;Endocytosis of spherical GNPs was confirmed 24 h post-incubation, resulting in an average of 8.7 × 10&lt;sup&gt;5&lt;/sup&gt; GNPs/cell and 6.0 × 10&lt;sup&gt;5&lt;/sup&gt; GNPs/cell for HeLa and PC3 cell cultures, respectively. The incorporation of GNPs induced 183% (&lt;i&gt;p &lt;&lt;/i&gt; 0.001) and 364% (&lt;i&gt;p =&lt;/i&gt; 0.01) greater DNA DSBs with HDR-BT irradiations compared to LINAC irradiations for HeLa and PC3 cells, respectively, after the 200 cGy prescription. GNPs reduced the survival fraction of HeLa and PC3 cells after 2 weeks post-irradiation by 4.6% (&lt;i&gt;p &lt;&lt;/i&gt; 0.05) and 8.5% (&lt;i&gt;p &lt;&lt;/i&gt; 0.05), respectively, with HDR irradiations compared to LINAC irradiations.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Conclusions&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;Our results suggest GNP incorporation into HDR-BT is a viable and effective treatme","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 7","pages":""},"PeriodicalIF":3.2,"publicationDate":"2025-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mp.18006","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144635288","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":"Impact of intracellular radionuclide distribution in a Monte Carlo biophysical 3D multi-cellular model for targeted alpha therapy","authors":"Victor Levrague,&nbsp;Mario Alcocer-Ávila,&nbsp;Sarah Leilla Otmani,&nbsp;Lydia Maigne,&nbsp;Etienne Testa,&nbsp;Michaël Beuve,&nbsp;Rachel Delorme","doi":"10.1002/mp.17917","DOIUrl":"https://doi.org/10.1002/mp.17917","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;To understand and predict the therapeutic efficacy of targeted alpha therapy (TAT), nano- and microdosimetry are needed to consider the very heterogeneous dose deposition at cellular and subcellular levels.&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 objective of this study is to theoretically evaluate the importance of cell internalization of alpha-emitters on relevant dosimetric and biological endpoints.&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;Isolated cells and realistic 3D multi-cellular geometries (spheroids modeled with CPOP) were generated as well as distributions of alpha-emitters corresponding to various cellular internalization cases. The alpha particles emitted were tracked with Geant4 (Monte Carlo) simulations. We calculated mean specific energies deposited into each cell nucleus (&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;Z&lt;/mi&gt;\u0000 &lt;mi&gt;n&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;annotation&gt;$Z_n$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;), cell survival fractions using the NanOx biophysical model, values of relative biological effectiveness (RBE) and tumor control probabilities (TCP) for each scenarios. The impact of spheroid compaction and size, alpha particle energy and radionuclide daughter diffusion was studied. The impact of the heterogeneous distribution of a number of alpha particles per cell was also studied, using a lognormal probability law.&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;For a given activity per cell (APC), the radionuclide distribution had a critical influence on &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;Z&lt;/mi&gt;\u0000 &lt;mi&gt;n&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;annotation&gt;$Z_n$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; in isolated cancerous cells or small spheroids (&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mo&gt;&lt;&lt;/mo&gt;\u0000 &lt;annotation&gt;$&lt;$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;50 &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;m&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt;$mu{rm m}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; radius), while its impact was relatively low in larger and more comp","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 7","pages":""},"PeriodicalIF":3.2,"publicationDate":"2025-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mp.17917","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144635364","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":"An image-free method of elbow external fixation surgery based on computer-assisted navigation: A cadaveric study","authors":"Teng Zhang,&nbsp;Junqiang Wang,&nbsp;Hui Ding,&nbsp;Yejun Zha,&nbsp;Guangzhi Wang,&nbsp;Wei Han","doi":"10.1002/mp.17974","DOIUrl":"https://doi.org/10.1002/mp.17974","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Identifying the elbow flexion-extension (FE) motion axis is crucial for the precise placement of an elbow external fixator. Traditional x-ray fluoroscopy has high radiation exposure, low accuracy, poor repeatability, and is greatly influenced by individual experience.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>This study aimed to assess the feasibility and accuracy of a novel image-free method for elbow external fixation surgery based on computer-assisted navigation.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>An optical positioning system was employed to track the motion trajectory of the forearm relative to the upper arm. This system works by emitting infrared signals detected by cameras to determine the spatial positions of markers attached to the limbs. The 3D principal components analysis (PCA) was used to determine the orientation of the elbow's rotation axis by analyzing the trajectory data. The 2D circle fitting method involved fitting a circle to the projected data points on a plane perpendicular to the identified axis, ensuring precise calculation of the rotation plane and axis. A custom graphical user interface (GUI) was developed to visualize the kinematics data and guide the placement of an axis pin for the external fixator.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The kinematics data of elbow FE movements showed high repeatability with RMS-radius within 1 mm, RMS-coplane less than 2 mm, Deviation-center no more than 2 mm, and deviation angle within 1.5°.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>The proposed image-free method improves the accuracy and repeatability of elbow external fixation surgery, increasing feasibility and security.</p>\u0000 </section>\u0000 </div>","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 7","pages":""},"PeriodicalIF":3.2,"publicationDate":"2025-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144635390","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}