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  • IOP Publishing  (104)
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  • IOP Publishing  (104)
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  • Biology  (104)
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  • 1
    In: Physics in Medicine and Biology, IOP Publishing, Vol. 58, No. 6 ( 2013-03-21), p. 1739-1758
    Type of Medium: Online Resource
    ISSN: 0031-9155 , 1361-6560
    RVK:
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2013
    detail.hit.zdb_id: 1473501-5
    SSG: 12
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  • 2
    Online Resource
    Online Resource
    IOP Publishing ; 2015
    In:  Physics in Medicine and Biology Vol. 60, No. 14 ( 2015-07-07), p. 5359-5380
    In: Physics in Medicine and Biology, IOP Publishing, Vol. 60, No. 14 ( 2015-07-07), p. 5359-5380
    Type of Medium: Online Resource
    ISSN: 0031-9155 , 1361-6560
    RVK:
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2015
    detail.hit.zdb_id: 1473501-5
    SSG: 12
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  • 3
    In: Physics in Medicine & Biology, IOP Publishing, Vol. 67, No. 22 ( 2022-11-21), p. 225003-
    Abstract: Objective. Adaptive radiation therapy (ART) could protect organs at risk (OARs) while maintain high dose coverage to targets. However, there is still a lack of efficient online patient quality assurance (QA) methods, which is an obstacle to large-scale adoption of ART. We aim to develop a clinically relevant online patient QA solution for ART using daily CT scans and EPID-based in vivo dosimetry. Approach. Ten patients with rectal cancer at our center were included. Patients’ daily CT scans and portal images were collected to generate reconstructed 3D dose distributions. Contours of targets and OARs were recontoured on these daily CT scans by a clinician or an auto-segmentation algorithm, then dose-volume indices were calculated, and the percent deviation of these indices to their original plans were determined. This deviation was regarded as the metric for clinically relevant patient QA. The tolerance level was obtained using a 95% confidence interval of the QA metric distribution. These deviations could be further divided into anatomically relevant or delivery relevant indicators for error source analysis. Finally, our QA solution was validated on an additional six clinical patients. Main results. In rectal cancer, the 95% confidence intervals of the QA metric for PTV Δ D 95 (%) were [−3.11%, 2.35%], and for PTV Δ D 2 (%) were [−0.78%, 3.23%]. In validation, 68% for PTV Δ D 95 (%), and 79% for PTV Δ D 2 (%) of the 28 fractions are within tolerances of the QA metrics. one patient’s dosimetric impact of anatomical variations during treatment were observed through the source of error analysis. Significance. The online patient QA solution using daily CT scans and EPID-based in vivo dosimetry is clinically feasible. Source of error analysis has the potential for distinguishing sources of error and guiding ART for future treatments.
    Type of Medium: Online Resource
    ISSN: 0031-9155 , 1361-6560
    RVK:
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2022
    detail.hit.zdb_id: 1473501-5
    SSG: 12
    Location Call Number Limitation Availability
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  • 4
    Online Resource
    Online Resource
    IOP Publishing ; 2023
    In:  Physics in Medicine & Biology Vol. 68, No. 5 ( 2023-03-07), p. 055018-
    In: Physics in Medicine & Biology, IOP Publishing, Vol. 68, No. 5 ( 2023-03-07), p. 055018-
    Abstract: Objective. Radiomics contains a large amount of mineable information extracted from medical images, which has important significance in treatment response prediction for personalized treatment. Radiomics analyses generally involve high dimensions and redundant features, feature selection is essential for construction of prediction models. Approach. We proposed a novel multi-objective based radiomics feature selection method (MRMOPSO), where the number of features, sensitivity, and specificity are jointly considered as optimization objectives in feature selection. The MRMOPSO innovated in the following three aspects: (1) Fisher score to initialize the population to speed up the convergence; (2) Min-redundancy particle generation operations to reduce the redundancy between radiomics features, a truncation strategy was introduced to further reduce the number of features effectively; (3) Particle selection operations guided by elitism strategies to improve local search ability of the algorithm. We evaluated the effectiveness of the MRMOPSO by using a multi-institution oropharyngeal cancer dataset from The Cancer Imaging Archive. 357 patients were used for model training and cross validation, an additional 64 patients were used for evaluation. Main results. The area under the curve (AUC) of our method achieved AUCs of 0.82 and 0.84 for cross validation and independent dataset, respectively. Compared with classical feature selection methods, the AUC of MRMOPSO is significantly higher than the Lasso (AUC = 0.74, p -value = 0.02), minimal-redundancy-maximal-relevance criterion (mRMR) (AUC = 0.73, p -value = 0.05), F-score (AUC = 0.48, p -value 〈 0.01), and mutual information (AUC = 0.69, p -value 〈 0.01) methods. Compared to single-objective methods, the AUC of MRMOPSO is 12% higher than those of the genetic algorithm (GA) (AUC = 0.68, p -value = 0.02) and particle swarm optimization algorithm (AUC = 0.72, p -value = 0.05) methods. Compared to other multi-objective feature selection methods, the AUC of MRMOPSO is 14% higher than those of multiple objective particle swarm optimization (MOPSO) (AUC = 0.68, p -value = 0.02) and nondominated sorting genetic algorithm II (NSGA2) (AUC = 0.70, p -value = 0.03). Significance. We proposed a multi-objective based radiomics feature selection method. Compared to conventional feature reduction algorithms, the proposed algorithm effectively reduced feature dimension, and achieved superior performance, with improved sensitivity and specificity, for response prediction in radiotherapy.
    Type of Medium: Online Resource
    ISSN: 0031-9155 , 1361-6560
    RVK:
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2023
    detail.hit.zdb_id: 1473501-5
    SSG: 12
    Location Call Number Limitation Availability
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  • 5
    In: Physics in Medicine & Biology, IOP Publishing, Vol. 68, No. 19 ( 2023-10-07), p. 195015-
    Abstract: Objective. Respiratory motion tracking techniques can provide optimal treatment accuracy for thoracoabdominal radiotherapy and robotic surgery. However, conventional imaging-based respiratory motion tracking techniques are time-lagged owing to the system latency of medical linear accelerators and surgical robots. This study aims to investigate the precursor time of respiratory-related neural signals and analyze the potential of neural signals-based respiratory motion tracking. Approach. The neural signals and respiratory motion from eighteen healthy volunteers were acquired simultaneously using a 256-channel scalp electroencephalography (EEG) system. The neural signals were preprocessed using the MNE python package to extract respiratory-related EEG neural signals. Cross-correlation analysis was performed to assess the precursor time and cross-correlation coefficient between respiratory-related EEG neural signals and respiratory motion. Main results. Respiratory-related neural signals that precede the emergence of respiratory motion are detectable via non-invasive EEG. On average, the precursor time of respiratory-related EEG neural signals was 0.68 s. The representative cross-correlation coefficients between EEG neural signals and respiratory motion of the eighteen healthy subjects varied from 0.22 to 0.87. Significance. Our findings suggest that neural signals have the potential to compensate for the system latency of medical linear accelerators and surgical robots. This indicates that neural signals-based respiratory motion tracking is a potential promising solution to respiratory motion and could be useful in thoracoabdominal radiotherapy and robotic surgery.
    Type of Medium: Online Resource
    ISSN: 0031-9155 , 1361-6560
    RVK:
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2023
    detail.hit.zdb_id: 1473501-5
    SSG: 12
    Location Call Number Limitation Availability
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  • 6
    Online Resource
    Online Resource
    IOP Publishing ; 2022
    In:  Physics in Medicine & Biology Vol. 67, No. 24 ( 2022-12-21), p. 245007-
    In: Physics in Medicine & Biology, IOP Publishing, Vol. 67, No. 24 ( 2022-12-21), p. 245007-
    Abstract: Accurate T -staging is important when planning personalized radiotherapy. However, T -staging via manual slice-by-slice inspection is time-consuming while tumor sizes and shapes are heterogeneous, and junior physicians find such inspection challenging. With inspiration from oncological diagnostics, we developed a multi-perspective aggregation network that incorporated various diagnosis-oriented knowledge which allowed automated nasopharyngeal carcinoma T -staging detection (TSD Net). Specifically, our TSD Net was designed in multi-branch architecture, which can capture tumor size and shape information (basic knowledge), strongly correlated contextual features, and associations between the tumor and surrounding tissues. We defined the association between the tumor and surrounding tissues by a signed distance map which can embed points and tumor contours in higher-dimensional spaces, yielding valuable information regarding the locations of tissue associations. TSD Net finally outputs a T 1– T 4 stage prediction by aggregating data from the three branches. We evaluated TSD Net by using the T1-weighted contrast-enhanced magnetic resonance imaging database of 320 patients in a three-fold cross-validation manner. The results show that the proposed method achieves a mean area under the curve (AUC) as high as 87.95%. We also compared our method to traditional classifiers and a deep learning-based method. Our TSD Net is efficient and accurate and outperforms other methods.
    Type of Medium: Online Resource
    ISSN: 0031-9155 , 1361-6560
    RVK:
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2022
    detail.hit.zdb_id: 1473501-5
    SSG: 12
    Location Call Number Limitation Availability
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  • 7
    Online Resource
    Online Resource
    IOP Publishing ; 2023
    In:  Physics in Medicine & Biology Vol. 68, No. 13 ( 2023-07-07), p. 135006-
    In: Physics in Medicine & Biology, IOP Publishing, Vol. 68, No. 13 ( 2023-07-07), p. 135006-
    Abstract: Objective. High-resolution multi-modal magnetic resonance imaging (MRI) is crucial in clinical practice for accurate diagnosis and treatment. However, challenges such as budget constraints, potential contrast agent deposition, and image corruption often limit the acquisition of multiple sequences from a single patient. Therefore, the development of novel methods to reconstruct under-sampled images and synthesize missing sequences is crucial for clinical and research applications. Approach . In this paper, we propose a unified hybrid framework called SIFormer, which utilizes any available low-resolution MRI contrast configurations to complete super-resolution (SR) of poor-quality MR images and impute missing sequences simultaneously in one forward process. SIFormer consists of a hybrid generator and a convolution-based discriminator. The generator incorporates two key blocks. First, the dual branch attention block combines the long-range dependency building capability of the transformer with the high-frequency local information capture capability of the convolutional neural network in a channel-wise split manner. Second, we introduce a learnable gating adaptation multi-layer perception in the feed-forward block to optimize information transmission efficiently. Main results . Comparative evaluations against six state-of-the-art methods demonstrate that SIFormer achieves enhanced quantitative performance and produces more visually pleasing results for image SR and synthesis tasks across multiple datasets. Significance . Extensive experiments conducted on multi-center multi-contrast MRI datasets, including both healthy individuals and brain tumor patients, highlight the potential of our proposed method to serve as a valuable supplement to MRI sequence acquisition in clinical and research settings.
    Type of Medium: Online Resource
    ISSN: 0031-9155 , 1361-6560
    RVK:
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2023
    detail.hit.zdb_id: 1473501-5
    SSG: 12
    Location Call Number Limitation Availability
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  • 8
    Online Resource
    Online Resource
    IOP Publishing ; 2022
    In:  Physics in Medicine & Biology Vol. 67, No. 22 ( 2022-11-21), p. 225012-
    In: Physics in Medicine & Biology, IOP Publishing, Vol. 67, No. 22 ( 2022-11-21), p. 225012-
    Abstract: Objective . Open magnetic induction tomography (MIT) is a promising technique for detecting the intracranial hemorrhage due to the non-radioactive, non-invasive and portable features. However, severe inhomogeneity of the sensitivity distribution under the open MIT sensor array and the ill-conditioned nature of MIT inverse problem limit the imaging quality in hemorrhage reconstruction. More accurate and robust imaging algorithms are urgently needed in clinical diagnosis. Approach. In this study, the space-constrained optimized Tikhonov regularization (SOTR) method is proposed for 3D hemorrhage reconstruction by open MIT. The sensitivity matrix is optimized according to the characteristics of sensitivity distribution under the open MIT sensor array. To test the performance of the SOTR method, 3D anatomical head models with hemorrhages in different volumes and locations were established. The images of the hemorrhages were reconstructed by the Tikhonov regularization (TR), total variation (TV) regularization, isotropic SOTR, and anisotropic SOTR method. Correlation coefficient C C , localization error L E , and volume error V E were calculated to evaluate the hemorrhage imaging quality. Main results . Compared with the traditional sensitivity matrix, the optimized sensitivity matrix has smaller column number and better uniformity, which alleviates the under-determined and ill-conditioned problem of MIT. The imaging results indicate that both the isotropic and anisotropic SOTR methods can effectively improve the reconstruction accuracy for the location and volume of the hemorrhages. Moreover, compared with the TR and TV methods, the two SOTR methods are more robust against the measurement noise. Significance . The proposed method improves the imaging quality of the intracranial hemorrhage, which promotes the clinical applications of open MIT.
    Type of Medium: Online Resource
    ISSN: 0031-9155 , 1361-6560
    RVK:
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2022
    detail.hit.zdb_id: 1473501-5
    SSG: 12
    Location Call Number Limitation Availability
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  • 9
    Online Resource
    Online Resource
    IOP Publishing ; 1994
    In:  Physics in Medicine and Biology Vol. 39, No. 11 ( 1994-11-01), p. 2073-2090
    In: Physics in Medicine and Biology, IOP Publishing, Vol. 39, No. 11 ( 1994-11-01), p. 2073-2090
    Type of Medium: Online Resource
    ISSN: 0031-9155 , 1361-6560
    RVK:
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 1994
    detail.hit.zdb_id: 1473501-5
    SSG: 12
    Location Call Number Limitation Availability
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  • 10
    Online Resource
    Online Resource
    IOP Publishing ; 2012
    In:  Physics in Medicine and Biology Vol. 57, No. 5 ( 2012-03-07), p. 1283-1308
    In: Physics in Medicine and Biology, IOP Publishing, Vol. 57, No. 5 ( 2012-03-07), p. 1283-1308
    Type of Medium: Online Resource
    ISSN: 0031-9155 , 1361-6560
    RVK:
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2012
    detail.hit.zdb_id: 1473501-5
    SSG: 12
    Location Call Number Limitation Availability
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