Physics in medicine and biology最新文献

{"title":"Patient-specific uncertainty calibration of deep learning-based autosegmentation networks for adaptive MRI-guided lung radiotherapy.","authors":"Moritz Rabe, Ettore F Meliadò, Sebastian N Marschner, Claus Belka, Stefanie Corradini, Cornelis A T van den Berg, Guillaume Landry, Christopher Kurz","doi":"10.1088/1361-6560/add640","DOIUrl":"10.1088/1361-6560/add640","url":null,"abstract":"<p><p><i>Objective.</i>Uncertainty assessment of deep learning autosegmentation (DLAS) models can support contour corrections in adaptive radiotherapy (ART), e.g. by utilizing Monte Carlo Dropout (MCD) uncertainty maps. However, poorly calibrated uncertainties at the patient level often render these clinically nonviable. We evaluated population-based and patient-specific DLAS accuracy and uncertainty calibration and propose a patient-specific post-training uncertainty calibration method for DLAS in ART.<i>Approach.</i>The study included 122 lung cancer patients treated with a low-field MR-linac (80/19/23 training/validation/test cases). Ten single-label 3D-U-Net population-based baseline models (BM) were trained with dropout using planning MRIs (pMRIs) and contours for nine organs-at-riks (OARs) and gross tumor volumes (GTVs). Patient-specific models (PS) were created by fine-tuning BMs with each test patient's pMRI. Model uncertainty was assessed with MCD, averaged into probability maps. Uncertainty calibration was evaluated with reliability diagrams and expected calibration error (ECE). A proposed post-training calibration method rescaled MCD probabilities for fraction images in BM (calBM) and PS (calPS) after fitting reliability diagrams from pMRIs. All models were evaluated on fraction images using Dice similarity coefficient (DSC), 95th percentile Hausdorff distance (HD95) and ECE. Metrics were compared among models for all OARs combined (<i>n</i> = 163), and the GTV (<i>n</i> = 23), using Friedman and posthoc-Nemenyi tests (<i>α</i> = 0.05).<i>Main results.</i>For the OARs, patient-specific fine-tuning significantly (<i>p</i> < 0.001) increased median DSC from 0.78 (BM) to 0.86 (PS) and reduced HD95 from 14 mm (BM) to 6.0 mm (PS). Uncertainty calibration achieved substantial reductions in ECE, from 0.25 (BM) to 0.091 (calBM) and 0.22 (PS) to 0.11 (calPS) (<i>p</i> < 0.001), without significantly affecting DSC or HD95 (<i>p</i> > 0.05). For the GTV, BM performance was poor (DSC = 0.05) but significantly (<i>p</i> < 0.001) improved with PS training (DSC = 0.75) while uncertainty calibration reduced ECE from 0.22 (PS) to 0.15 (calPS) (<i>p</i> = 0.45).<i>Significance.</i>Post-training uncertainty calibration yields geometrically accurate DLAS models with well-calibrated uncertainty estimates, crucial for ART applications.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144039959","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":"TOPAS-nBio-Reg: a regression testing system for track structure simulations in TOPAS-nBio.","authors":"Thongchai A M Masilela, Naoki D-Kondo, Wook-Geun Shin, Ramon Ortiz, Isaac Meyer, Jay A LaVerne, Bruce Faddegon, Jan Schuemann, José Ramos-Méndez","doi":"10.1088/1361-6560/add4b9","DOIUrl":"10.1088/1361-6560/add4b9","url":null,"abstract":"<p><p><i>Objective.</i>To develop a regression testing system for TOPAS-nBio: a wrapper of Geant4-DNA, and the radiobiological extension of TOPAS-a Monte Carlo code for the simulation of radiation transport. This regression testing system will be made publicly available on the TOPAS-nBio GitHub page.<i>Approach.</i>A set of seven regression tests were chosen to evaluate the suite of capabilities of TOPAS-nBio from both a physical and chemical point of view. Three different versions of the code were compared: TOPAS-nBio-v2.0 (the previous version), TOPAS-nBio-v3.0 (the current public release), and TOPAS-nBio-v4.0 (the current developer version, planned for future release). The main aspects compared for each test were the differences in execution times, variations from other versions of TOPAS-nBio, and agreement with measurements/in silico data.<i>Main results.</i>Execution times of nBio-v3.0 for all physics tests were faster than those of nBio-v2.0 due to the use of a new Geant4 version. Mean point-to-point differences between TOPAS-nBio versions across all tests fell largely within 5%. The exceptions were the radiolytic yields (<i>G</i>values) ofH2andH2O2, which differed moderately (16% and 10% respectively) when going from nBio-v3.0 to nBio-v4.0. In all cases a good agreement with other experimental/simulated data was obtained.<i>Significance.</i>From a developer point of view, this regression testing system is essential as it allows a more rigorous reporting of the consequences of new version releases on quantities such as the LET or<i>G</i>values of chemical species. Furthermore, it enables us to test 'pushes' made to the codebase by collaborators and contributors. From an end-user point of view, users of the software are now able to easily evaluate how changes in the source code, made for their specific application, would affect the results of known quantities.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144036893","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":"Therapeutic enhancement effects using a lower energy 2.5 MV photon beam combined with gold nanoparticles on the BxPC-3 pancreatic cancer cell line,<i>in vitro</i>.","authors":"Xiao Qing Yao, Sarah A Sabatinos, Eric Da Silva, Amandeep Taggar, Diana Ha, Rao Khan, Raffi Karshafian, James Gräfe","doi":"10.1088/1361-6560/add4b8","DOIUrl":"10.1088/1361-6560/add4b8","url":null,"abstract":"<p><p><i>Objective</i>. This study investigates the feasibility of using a clinically relevant lower energy 2.5 megavoltage (MV) photon beam in combination with gold nanoparticles (GNPs).<i>Approach.</i>Pancreatic cancer cell line, BxPC-3 impregnated with GNPs were exposed<i>in vitro</i>to 2.5 MV photon beam and compared with orthovoltage 225 kV and clinical 6 MV photon beam. Bare, 50 nm diameter, spherical GNPs were introduced in the cell culture 24 h prior to irradiation at a concentration of either 10<i>μ</i>g ml^-1or 50<i>μ</i>g ml^-1. GNP uptake was determined using inductively coupled plasma optical emission spectroscopy. The cells were irradiated with doses between 0 Gy to 8 Gy. Cell survival curves were obtained via clonogenic assay using immediate or delayed plating (24 h) methods 12 d after irradiation. The terminal deoxynucleotidyl transferase dUTP nick end labeling assay was used to evaluate DNA damage at two time points post irradiation, immediate and 24 h for 1 Gy and 6 Gy.<i>Main results</i>. The enhancement factor (EF) in BxPC-3 cells was greatest for cells incubated with 50<i>μ</i>g ml^-1of GNPs analyzed immediately post irradiation. Cells irradiated with 225 kV showed greatest EF (1.57 ± 0.15), followed by 2.5 MV (1.51 ± 0.04). The lowest EF was seen for 6 MV, immediate plating (1.10 ± 0.04). A significant increase in the number of DNA double strand breaks (DSB) was observed in cells incubated with 50<i>μ</i>g ml^-1of GNPs irradiated at 6 Gy with 225 kV and 2.5 MV. There was no significant increase in DSBs for the cells irradiated with 6 MV.<i>Significance.</i>These results suggest that the 2.5 MV could be a compromise between an orthovoltage energy beam and a clinical 6 MV beam, showing comparable reduction in cell survival to the 225 kV beam. Future GNP radiation enhancement research may focus on intermediate energy beams.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144036163","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 coil-channel multiplexer for high-density receive arrays compatible with the MR-linac.","authors":"Tom Bosma, Jan G M Kok, Pim T S Borman, Cornelis A T van den Berg, Martin F Fast","doi":"10.1088/1361-6560/add3b7","DOIUrl":"https://doi.org/10.1088/1361-6560/add3b7","url":null,"abstract":"<p><p><i>Objective.</i>We present a prototype add-on multiplexer for retro-fitting high-channel count receive coils onto systems with analog readout chains, such as the MR-linac. This particular system is currently equipped with two coil elements, containing only four channels each.<i>Approach.</i>We developed a 4:1 multiplexer board based on time-division. CMOS-based single-pole double-throw switches were used to accommodate for fast switching and adequate encoding bandwidths. Coil-channel images were separated after reconstruction by solving a system of equations based on the square-wave modulation imposed by the multiplexer. The prototype was tested at a 1.5 T scanner on an image-quality phantom and a slice of bovine muscle using four coil channels from a previously characterized 16-channel anterior coil prototype.<i>Main results.</i>The image data received through multiplexing could be reliably divided into separate coil-channel images, preserving the coil sensitivity maps. Leakage between channels remained below -30 dB. In each coil channel the signal-to-noise ratio was penalized by a factor of two compared to direct digitization due to the inflicted data compression. Furthermore, it was shown that the<i>g</i>-factor for parallel imaging remained largely unaffected by multiplexing. Imaging speedup is expected with this multiplexer, since a fourfold channel-count increase typically yields<i>g</i>-factor improvements that are superior to the signal-quality reduction.<i>Significance.</i>A 4:1 coil-channel add-on multiplexer was developed and its functionality demonstrated in the MR readout chain at 1.5 T. We expect that this solution will enable significant imaging speedup for clinical MR systems that suffer from compatibility with a limited number of channels for the receive coil array.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":"70 10","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144028769","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 robust framework with knowledge-guided planning and fiducial-based registration for bronchoscopy navigation system.","authors":"Haixing Zhu, Zhongjie Shi, Wenbo Zhai, Yifei Liu, Yuan Wang, Zimo Bai, Zhanxiang Wang, Rining Wu, Weipeng Liu","doi":"10.1088/1361-6560/add8dc","DOIUrl":"https://doi.org/10.1088/1361-6560/add8dc","url":null,"abstract":"<p><strong>Objective: </strong>Bronchoscopy is a valuable minimally invasive examination in clinical practice and is widely used in the diagnosis of suspected peripheral lung lesions. However, this device has difficulty in accessing peripheral areas from lack of inadequate guidance and heavily relies on intraoperative X-ray or computerized tomography (CT) scan.</p><p><strong>Approach: </strong>In order to overcome these limitations, we propose a robust navigation framework with knowledge-guided planning and fiducial-based registration for bronchoscopy navigation, which makes three notable contributions that have been experimentally verified to be of practical value. Firstly, we propose a preoperative path-planning algorithm with anatomical prior knowledge to generate a feasible and accurate trajectory. Secondly, a fiducial-based patient-image registration scheme is&#xD;introduced to align virtual images with the patient's actual anatomy, building a robust rigid relationship and enabling real-time updates. Thirdly, we establish a position sensing approach to present precise positions and track the movement of the bronchoscope.</p><p><strong>Main results: </strong>Extensive experiments on the 3D-printed airway tree model and in vivo porcine lung are conducted to evaluate comprehensive capabilities. Qualitative and quantitative results manifest that our framework can achieve excellent&#xD;performance, reaching a success rate of 100% in the path-planning stage, achieving robust registration precision with a fiducial registration error (FRE) of 0.998 ± 0.074 mm, and obtaining the standard deviation of 0.017 mm, 0.206 mm and 0.013 mm in the tracking stage.</p><p><strong>Significance: </strong>Our results demonstrate the feasibility and effectiveness and further has potential prospects as an auxiliary tool to extend the capabilities of clinical bronchoscopy.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144079571","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":"Carotid pulse wave velocity estimation based on incident waves using coherent plane wave compounding ultrasound.","authors":"Li Xiong, Yufeng Zhang, Xiaoxu Wang, Bingbing He, Zhiyao Li, Jingying Zhu","doi":"10.1088/1361-6560/add3b8","DOIUrl":"https://doi.org/10.1088/1361-6560/add3b8","url":null,"abstract":"<p><p><i>Objective</i>. Local pulse wave velocity (PWV) plays a crucial role in assessing the regional arterial elasticity. Accurate estimation of local PWV is beneficial for the risk assessment and early diagnosis of cardiovascular diseases. In this study, a method involving incident waves based on coherent plane wave compounding ultrasound (IWCU) is proposed to suppress reflected waves in pulse waves (PW) and improve the performance of transit time (TT)-based local PWV estimation.<i>Approach</i>. The ultrasonic radio frequency echo signals are collected and coherently compounded, and the PWs and central blood flow velocities at 128 beam positions are calculated, from which the incident waves (IWs) are estimated based on the Kelvin-Voigt model. Then, the time delays (TDs) of the IWs propagating are calculated, and the local PWV is finally estimated. The mean and standard deviations (MSD) of the normalized root mean squared errors NRMSEs between the presupposed and estimated TDs and PWVs were calculated for quantitatively evaluating the performance of the proposed IWCU method, and compared with those of the PWs based on coherent plane wave compounding ultrasound and the regional upstroke tracking methods in simulation experiments. The relative errors, Bland-Altman analysis and coefficient of variation (CV) were measured to further assess the accuracy, reproducibility and variability of IWCU method in<i>in vitro</i>and<i>in vivo</i>experiments.<i>Main results</i>. The IWCU method yields higher accuracy, reproducibility and lower variability for local PWV estimation. The MSD of the NRMSEs for TDs and local PWVs are 11.78 ± 0.52% and 4.10 ± 2.25%. Additionally, the mean relative error and CV are 6.10% and 12.56%, respectively.<i>Significance</i>. The IWCU method provides improved TT-based local PWV estimation, and has the potential to support future clinical diagnoses of arterial stiffness.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":"70 10","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143978622","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":"Monte Carlo calculation of¹¹⁹Sb microscale absorbed dose using cascaded and averaged Auger electron spectra.","authors":"Andrew Vincent Zwaniga, Raffi Karshafian, Humza Nusrat, Eric Da Silva, James L Gräfe","doi":"10.1088/1361-6560/add851","DOIUrl":"https://doi.org/10.1088/1361-6560/add851","url":null,"abstract":"<p><p>Radionuclides decaying by electron capture or internal transition produce a large number of Auger electrons in a cascade that follows their radioactive decay. A shortlist of the most potent Auger electron-emitters has appeared in the literature including^103mRh,¹⁰³Pd,¹¹¹In,¹¹⁹Sb,¹²³I,¹²⁵I,¹⁶⁵Er, and¹⁹⁷Hg. Among them,¹¹⁹Sb has been identified as the most potent for targeting micrometastases, yielding several tens of Auger electrons per decay with energies from a few eV up to 30 keV. In this paper, we recalculate Auger, Coster-Kronig, and super Coster-Kronig yields and transition probabilities as subshell-normalized relative transition probabilities and develop a new method to create radionuclide sources in TOPAS Monte Carlo, the code for which has been made publicly available. We then apply our method to encode the Auger electron spectra of¹¹⁹Sb from MIRD RADTABS and EADL into TOPAS and calculate the absorbed dose to water volumes of radius 10 nm up to 10 μm, finding that the averaged MIRD Auger electron spectrum underestimates the absorbed dose by a factor of 20 to 50 on this scale. We show that this result is not isolated to¹¹⁹Sb and conclude that either the cascaded MIRD or EADL spectrum should be used for accurate microscale dosimetry. We compare with results obtained using the built-in Geant4 Atomic Relaxation for¹¹⁹Sb in TOPAS and find an unexpected continuum of low-energy electrons but no excess absorbed dose relative to either MIRD or EADL. We show that¹¹⁹Sb does not produce more absorbed dose in microscale volumes than^103mRh,¹⁰³Pd,¹¹¹In,¹²³I,¹²⁵I,¹⁶⁵Er, or¹⁹⁷Hg, warranting future microdosimetry calculations of RBE and DNA damage to understand whether¹¹⁹Sb is the most potent Auger electron-emitter, as claimed in the literature.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143994167","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":"Lightweight and universal deep learning model for fast proton spot dose calculation at arbitrary energies.","authors":"Bo Pang, Shuoyan Chen, Yiling Zeng, Muyu Liu, Qi Zhang, Hong Quan, Yu Chang, Zhiyong Yang","doi":"10.1088/1361-6560/add3b9","DOIUrl":"https://doi.org/10.1088/1361-6560/add3b9","url":null,"abstract":"<p><p><i>Objective.</i>To better integrate into processes like rapid adaptive planning and quality assurance, this study aims to propose a lightweight and universal proton spot dose calculation model suitable for arbitrary energies.<i>Approach.</i>Given the alignment between the characteristics of proton spot dose deposition and the sequence learning capabilities of the long short-term memory (LSTM) network, the lightweight model, multi-energy dose LSTM (MED-LSTM), is proposed. To comprehensively investigate the effectiveness of model, we trained and evaluated it on prostate, nasopharynx, and lung cases consistently.<i>Main results</i>. Regarding the results for spot dose, the prostate, nasopharynx, and lung models achieved average gamma passing rates of 99.93%, 99.81%, and 99.89% respectively under the (1%, 3 mm) criterion. Under the (1%, 1 mm) criterion, the rates were 99.06%, 97.18%, and 98.32%, respectively. For the intensity-modulated proton therapy plan dose, the prostate model achieved optimal performance with gamma passing rates of 99.88% and 98.52% under the (1%, 3 mm) and (1%, 1 mm) criteria, respectively. Following this, the lung model achieved rates of 99.22% and 93.41%. The nasopharynx model exhibited the poorest performance, with rates of 99.56% and 88.95%, respectively. It is evident that the MED-LSTM model demonstrates extremely high dose calculation accuracy in most cases. However, visible deviations occur in some spot samples for the nasopharynx and lung cases due to structural tissue differences.<i>Significance.</i>The MED-LSTM model can rapidly and accurately determine the proton spot dose at any energy with relatively low number of parameters. This exciting outcome holds broad prospects for applications and research directions.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":"70 10","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143994185","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":"Evaluating photon-counting computed tomography for quantitative material characteristics and material differentiation in radiotherapy.","authors":"Didier Lustermans, Gabriel Paiva Fonseca, Cécile Jeukens, Vicki Trier Taasti, Katia Parodi, Guillaume Landry, Frank Verhaegen","doi":"10.1088/1361-6560/add3ba","DOIUrl":"https://doi.org/10.1088/1361-6560/add3ba","url":null,"abstract":"<p><p><i>Objective.</i>Photon-counting computed tomography (PCCT) counts the individual photons and measures their energy, which allows for energy binning and thereby multi-energy CT imaging. It is expected that quantitative data can be accurately extracted from the images and enable accurate material separation, yet its potential in radiotherapy is mostly unexplored. In this study, PCCT was assessed by evaluating estimation accuracies for relative electron density (RED), effective atomic number (<i>Z</i>_eff), and proton stopping-power ratio (SPR), as well as the potential for material differentiation.<i>Approach.</i>PCCT images of a Gammex Advanced Electron Density phantom (Sun Nuclear) with tissue-equivalent materials were acquired in a small and large phantom setup on a NAEOTOM Alpha PCCT scanner (Siemens Healthineers). The scans were performed at 120 and 140 kVp, and virtual monoenergetic images (VMIs) were generated. These VMIs were used to estimate RED,<i>Z</i>_eff, and SPR based on two calibration methods for each of the two phantom sizes. These results were compared to findings obtained based on dual-energy CT (DECT) scans acquired on a SOMATOM Confidence scanner (Siemens Healthineers) at 80 and 140 kVp, by using the low and high energy pair and VMIs. Calibration accuracy was quantified by the root-mean-squared error. Additional, material differentiation was assessed for both tissue-equivalent and calcium/iodine inserts by creating [RED/<i>Z</i>_eff]-space plots.<i>Main results.</i>There was minimal differences between the two PCCT x-ray spectra, with SPR errors below 0.8% for the large phantom and 0.7% for the small phantom, which was comparable to DECT using VMIs. Material differentiation showed similar results for DECT and PCCT using VMIs, and resulted in less<i>Z</i>_effspread, than the regular DECT kVp pair, possibly due to denoising.<i>Significance.</i>This study showed the ability of PCCT to retrieve material characteristics and possibility for material differentiation between tissue-equivalent material and calcium/iodine, with results comparable to DECT.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":"70 10","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144012588","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":"Optimization and evaluation of liver deformation modeling under microwave ablation based on ex vivo data.","authors":"Hui Che, Juntu Lyu, Erjiao Xu, Jian Wu","doi":"10.1088/1361-6560/add07c","DOIUrl":"https://doi.org/10.1088/1361-6560/add07c","url":null,"abstract":"<p><p><i>Objective</i>. Microwave ablation (MWA) has emerged as a crucial therapeutic technique for treating hepatocellular carcinoma. Despite its effectiveness, temperature-dependent structural modifications in liver tissues can adversely affect outcomes. Numerical modeling and simulations are essential tools for predicting tissue temperature and deformation prediction. However, existing methods lack comprehensive consideration of deformation-causative factors and fail to validate accuracy throughout the ablation zone.<i>Approach</i>. To overcome these limitations, we analyzed the gap between the<i>ex vivo</i>ablation deformation results and numerical simulations, and combined them to optimize the physical fields of thermally induced deformation across the entire liver tissue ablation zone. Specifically, we employed a grid marker arrangement with delayed computed tomography (CT) imaging in<i>ex vivo</i>experiments to capture high-resolution global deformation data. The optimization of the simulation was based on updating the coefficient for protein denaturation shrinkage and incorporating vapor diffusion influence in the mechanical model. The effect of vapor diffusion was thoroughly investigated and modeled into the stress-strain equation.<i>Main results</i>. Evaluation results demonstrate that our method significantly improves simulation alignment with observed experimental data, enhancing prediction accuracy of tissue deformation by 30%-90%. Additionally, our model exhibits enhanced capability for expansion representation to describe localized region deformation, resulting in increases of 2.2%-10.0% in dice similarity coefficient (<i>DICE</i>) and 4.2%-19.0% in intersection over union (<i>IoU</i>) when quantifying morphological differences with<i>ex vivo</i>experimental results.<i>Significance</i>. The improved simulation modeling could benefit the planning and optimization of MWA procedures, potentially enhancing treatment efficacy.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":"70 10","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144015754","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}