- 标题
- 摘要
- 关键词
- 实验方案
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Can Realistic Liver Tissue Surrogates Accurately Quantify the Impact of Reduced-kV Imaging on Attenuation and Contrast of Parenchyma and Lesions?
摘要： To assess if a liquid tissue surrogate for the liver (LTSL) can emulate contrast-enhanced liver parenchyma and lesions and quantify the impact of reduced-kV imaging as a function of lesion contrast, phase of enhancement, and phantom size.
关键词： Liquid tissue surrogate,Computed tomography,Lesion,Tube potential,Liver
更新于2025-09-19 17:15:36
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Image quality and dose evaluation of MVCT TomoTherapy acquisitions: A phantom study
摘要： Background: The aim of this study is to evaluate the dose delivered and the image quality of pre-treatment MVCT images with Hi-Art TomoTherapy system, varying acquisition and reconstruction parameters. Materials and methods: Catphan 500 MVCT images were acquired with all acquisition pitch and reconstruction intervals; image quality was evaluated in terms of noise, uniformity, contrast linearity, contrast-to-noise ratio (CNR) and spatial resolution with the Modulation Transfer Function (MTF). Dose was evaluated as Multi Slice Average Dose (MSADw) and measurements were performed with the Standard TomoTherapy? Quality Assurance Kit composed by the TomoTherapy Phantom, the Exradin A1SL ion chamber and TomoElectrometer. For each pitch-reconstruction interval, acquisitions were repeated 5 times. Results: Differences in noise and uniformity, though statistically significant in some cases, were very small: noise ranged from 2.3% for Coarse – 3 mm to 2.4% for Coarse – 6 mm, while uniformity passed from 99.5% for Coarse – 6 mm to 99.8% for Normal – 4 mm. No differences at all were found for CNR for high and low density inserts, while MTF was higher for pitch Coarse, even if no differences in spatial resolution were observed visually (spatial resolution was up to 4 lp/cm for all combinations of pitch and reconstruction interval). Dose was dependent on pitch, being 1.0 cGy for Coarse, 1.5 cGy for Normal and 2.85 cGy for Fine. Conclusions: We observed negligible differences in image quality among different pitch and reconstruction interval, thus, considerations regarding pre-treatment imaging modalities should be based only on dose delivered and on the desired resolution along the cranio-caudal axis for image-guided radiotherapy and adaptive radiotherapy purposes.
关键词： Image guided radiotherapy,Pre-treatment imaging,Tomotherapy,Image quality,Megavoltage computed tomography
更新于2025-09-19 17:15:36
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Low-dose single-energy material decomposition in radiography using a sparse-view computed tomography scan
摘要： Dual-energy material decomposition (DEMD) is a well-established theoretical x-ray technique that uses low- and high-kilovoltage radiographs to separate soft tissue and bone in radiography and computed tomography (CT). However, it requires double exposures that result in increased patient radiation doses, causes increases in the execution time, and generates errors due to misregistration attributed to the patient motion between two scans. In this study, we investigated a low-dose, single-energy material decomposition (LSEMD) method in radiography using a sparse-view computed tomography scan where the attenuation length in the object was estimated from the CT image. We performed a systematic simulation and an experiment to demonstrate the feasibility of use of the LSEMD method in radiography. Only 60 projections, far fewer than those required by the Nyquist sampling theory, were acquired at an x-ray tube voltage of 80 kVp, and were used to reconstruct a sparse-view CT image with a state-of-the-art dictionary-learning (DL) algorithm. We investigated the image performance of the LSEMD and compared the elicited results with those obtained with the use of DEMD (80 kVp and 120 kVp were used). Our results indicate that the DL algorithm produced high-quality sparse-view CT images. Accordingly, the LSEMD method yielded material decomposition results that were very similar to the results elicited by the conventional DEMD method in radiography.
关键词： dictionary-learning,low-dose single-energy material decomposition,Computed tomography,dual-energy material decomposition
更新于2025-09-19 17:15:36
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Filter-based energy-resolved X-ray computed tomography with a clinical imager
摘要： Filter-based energy-resolved X-ray computed tomography (CT) is an approach for implementing energy-resolved CT imaging using a flat-panel-detector-based cone-beam system. In this study, we performed experiments with a 20-cm-diameter phantom on a clinical X-ray imager. The material density results showed good agreement with the ideal values. We also propose an improved method for obtaining the detector response function and the X-ray spectrum, which requires fewer measurements and will be practical for future clinical use. Issues such as scatter and image noise remain to be addressed.
关键词： computed tomography,energy-resolved CT,material distinction,X-ray
更新于2025-09-19 17:15:36
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A low-rank estimation method for CTIS image reconstruction
摘要： The computed tomography image spectrometer (CTIS) is a snapshot hyperspectral imaging technique, which enables hyperspectral image acquisition in a dynamic scene. However, traditional image reconstruction methods with no explicit constraints will introduce high-frequency noise. The low-rank property has been used in hyperspectral image denoising and achieved great effects. We develop an effective method of low-rank estimation (LRE) for CTIS image reconstruction, which shows significant improvements in both the image quality and the spectral quality of the reconstructed image. Compared with the traditional methods, the peak signal-to-noise ratio of the LRE hyperspectral image can be increased by 8 dB, and the spectral-angular mapping can be decreased by 4 times.
关键词： computed tomography image spectrometers,image reconstruction,low-rank estimation,hyperspectral image
更新于2025-09-19 17:15:36
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CT/MRI-Guided Synergistic Radiotherapy and X-ray Inducible Photodynamic Therapy Using Tb-Doped Gd-W-Nanoscintillators
摘要： The use of X-rays instead of UV/Vis light to trigger photodynamic therapy, named X-ray inducible photodynamic therapy, holds tremendous promise due to a high penetration capacity in tissues and is worthy of in-depth study. In this study, a novel multifunctional nanoagent based on Merocyanine 540-coupled Gd2(WO4)3:Tb nanoscintillators and the vitalization of its abilities for dual-modal computed tomography and the magnetic-resonance-imaging-guided synergistic radio-/X-ray inducible photodynamic therapy of tumors is reported. Synergistic therapies show a higher tumor growth inhibition efficiency at a lower X-ray dose than radiotherapy alone. Through this proof-of-concept work, a way to tactfully understand and utilize nanoscintillators for cancer theranostics is shown.
关键词： magnetic resonance imaging,nanoscintillators,computed tomography,X-ray inducible photodynamic therapy,radiotherapy
更新于2025-09-19 17:15:36
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Mechanisms limiting the release of TiO2 nanomaterials during photocatalytic cement alteration: the role of surface charge and porous network morphology
摘要： Nanomaterials have been widely used in a wide range of manufactured products in order to improve / add new properties. Photocatalytic cement maintains clean and white wall fronts and also provide interesting air pollution-reducing properties due to photocatalytic activity of incorporated TiO2-NMs. However, despite these environmental benefits, there is evidence of the release of TiO2-NMs during cement use. Therefore, it is crucial to understand the parameters controlling TiO2-NMs release. Zêta potentials of TiO2-NMs were investigated from the unaltered core to the cement altered surface using simulated cement pore waters. The mineralogy and chemical composition of the altered layer were investigated using X-ray Diffraction (XRD) and micro X-ray fluorescence spectroscopy (micro-XRF). Finally, pore network morphology was fully analyzed using X-ray computed tomography at both micro and nano-scales (micro and nano-CT) and quantified using 3D morphological software (i-Morph). This study provides evidence that the TiO2-NMs release comes from a very thin “active surface layer” (thickness less than 20 μm) where both cement surface chemistry and the pore network appears to be favorable for the TiO2-NMs diffusion. The pore volume connected to the surface with a throat size ≥1016 nm appears to control and be used as a predictor for TiO2-NMs release.
关键词： Life cycle,exposure,3D imaging,pore throat size,micro and nano X-ray computed tomography (micro and nano-CT)
更新于2025-09-19 17:15:36
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[SPIE Computer-Aided Diagnosis - Houston, United States (2018.2.10-2018.2.15)] Medical Imaging 2018: Computer-Aided Diagnosis - Convolutional neural networks for the detection of diseased hearts using CT images and left atrium patches
摘要： Cardiovascular disease is a leading cause of death in the United States. The identification of cardiac diseases on conventional three-dimensional (3D) CT can have many clinical applications. An automated method that can distinguish between healthy and diseased hearts could improve diagnostic speed and accuracy when the only modality available is conventional 3D CT. In this work, we proposed and implemented convolutional neural networks (CNNs) to identify diseased hearts on CT images. Six patients with healthy hearts and six with previous cardiovascular disease events received chest CT. After the left atrium for each heart was segmented, 2D and 3D patches were created. A subset of the patches were then used to train separate convolutional neural networks using leave-one-out cross-validation of patient pairs. The results of the two neural networks were compared, with 3D patches producing the higher testing accuracy. The full list of 3D patches from the left atrium was then classified using the optimal 3D CNN model, and the receiver operating curves (ROCs) were produced. The final average area under the curve (AUC) from the ROC curves was 0.840 ± 0.065 and the average accuracy was 78.9% ± 5.9%. This demonstrates that the CNN-based method is capable of distinguishing healthy hearts from those with previous cardiovascular disease.
关键词： Deep learning,Heart disease,Classification,Cardiovascular disease (CVD),Convolutional neural networks,Computer-aided diagnosis,3D Computed tomography
更新于2025-09-19 17:15:36
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Root canal morphology of permanent teeth in a Malaysian subpopulation using cone-beam computed tomography
摘要： Background: To determine the root canal morphology of human permanent maxillary and mandibular teeth in a Malaysian subpopulation using cone-beam computed tomography (CBCT). Methods: A total of 208 CBCT images were examined retrospectively. Prevalence of an extra root/canal and internal morphology based on Vertucci’s classification were observed in human maxillary and mandibular permanent teeth. Variations in the external and internal morphology were compared in relation to gender and tooth side (left vs right) using Pearson Chi-square and Fisher’s exact tests with significance level set at p < 0.05. Results: In the maxillary arch, the prevalence of three canals were observed in 0.3% of first premolars and two canals in 46.5% of second premolars. Males displayed significantly higher prevalence of two canals in maxillary second premolars than females (p < 0.05). The prevalence of a second mesiobuccal canal in maxillary first and second molars were 36.3 and 8.5%, respectively. Males displayed significantly higher prevalence of a second mesiobuccal canal in maxillary second molars than females (p < 0.05). The prevalence of a second palatal canal in maxillary first and second molars were 0.9 and 0.6%, respectively. In the mandibular arch, the prevalence of two canals were observed in 5.1% of central incisors, 12.3% of lateral incisors, 6.1% of canines, 18.7% of first premolars and 0.5% of second premolars. The prevalence of a middle mesial canal, second distal canal and extra root (radix entomolaris) were detected in 1.9, 19.5 and 21.4% of mandibular first molars, respectively. The prevalence of a C-shaped canal was observed in 48.7% of mandibular second molars. Females displayed significantly higher prevalence of a C-shaped canal in the right mandibular second molars than males (p < 0.05). No other statistically significant differences in root anatomy and root canal morphology were observed in relation to gender and tooth side. Conclusions: Wide variations in the root canal morphology exist among Malaysians. CBCT is a clinically useful tool in the identification of external and internal morphological variations in the human teeth.
关键词： Root canal,Cone-beam computed tomography,Malaysian,Morphology
更新于2025-09-19 17:15:36
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Dimensional accuracy of cone beam CT with varying angulation of the jaw to the X-ray beam
摘要： Objectives: CBCT machines do not always allow for patients to be scanned in the ideal position for image acquisition. This study aimed to investigate the influence of the position/angulation of the mandible relative to the x-ray beam of a CBCT machine. Methods: Five sequential CBCT scans were captured of a human mandible at each angulation. The 0° occlusal plane was captured as the reference followed by 10°, 20°, 30° and 40° using a coronal and sagittal positioning. Inspection software utilized a best fit alignment to automatically calculate the three-dimensional variation at 15 standardized points of interest. Results: Statistically significant differences were found between the dimensional accuracy of CBCT scans taken at 10° (0.0263mm) of coronal angulation, as well as those taken at 20° (-0.0173mm) and 30° (0.0352mm) of sagittal angulations (P <0.001, 0.016, and <0.001, respectively). The largest deviations in accuracy included an overall maximum deviation of 0.490mm. Conclusion: The position of the mandible with respect to the x-ray beam has a clinically insignificant effect on dimensional accuracy, up to the maximum angle of 40° assessed.
关键词： Imaging,Three-Dimensional,Dimensional Measurement Accuracy,Cone-Beam Computed Tomography
更新于2025-09-19 17:15:36