- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Multiphoton Tomography with Linear Optics and Photon Counting
摘要： Determining an unknown quantum state from an ensemble of identical systems is a fundamental, yet experimentally demanding, task in quantum science. Here we study the number of measurement bases needed to fully characterize an arbitrary multimode state containing a definite number of photons, or an arbitrary mixture of such states. We show this task can be achieved using only linear optics and photon counting, which yield a practical though nonuniversal set of projective measurements. We derive the minimum number of measurement settings required and numerically show that this lower bound is saturated with random linear optics configurations, such as when the corresponding unitary transformation is Haar random. Furthermore, we show that for N photons, any unitary 2N design can be used to derive an analytical, though nonoptimal, state reconstruction protocol.
关键词： photon counting,linear optics,quantum state tomography,multiphoton states,quantum information
更新于2025-09-04 15:30:14
-
Deformation analysis of the spongious sample in simulated physiological conditions based on in-situ compression, 4D computed tomography and fast readout detector
摘要： In this work, an in-house designed table top loading device equipped with a bioreactor is used for the in-situ compression of a spongious sample in simulated physiological conditions. On-the-fly 4D computed tomography is used as a tool for the advanced volumetric analysis of the deforming microstructure of the specimen. The loading device with the bioreactor was placed directly onto the rotational stage of a modular X-ray scanner. As the loading device is equipped with a slip-ring cable system, it can perform an unlimited number of revolutions during the on-the-fly scanning procedure. A complementary metal-oxide-semiconductor flat panel detector with a fast readout was used for the acquisition of the X-ray images. The specimen was compressed with a low loading velocity. A set of the volumetric data capturing the deformation of the specimen during the experiment was prepared from the images acquired by the detector. A digital volume correlation algorithm was used for the evaluation of the volumetric strain fields in the specimen.
关键词： Computerized Tomography (CT) and Computed Radiography (CR),Detection of defects,Inspection with x-rays
更新于2025-09-04 15:30:14
-
Role of Tractional Forces and Internal Limiting Membrane in Macular Hole Formation: Insights from Intraoperative Optical Coherence Tomography
摘要： We report the case of a 69-year-old patient who underwent vitrectomy for vitreomacular traction (VMT) and developed a postoperative macular hole that was observed 1 week after surgery. The hole did not close by in-office fluid-gas exchange alone, but was achieved after repeat surgery with internal limiting membrane (ILM) peeling. Intraoperative OCT (iOCT) images from the first surgery revealed an occult macular hole that formed after VMT release. We discuss how iOCT findings provide insight into the role of the ILM in macular hole formation and emphasize the importance of carefully inspecting iOCT images in real time to avoid missing small but important findings.
关键词： Macular hole,Optical coherence tomography,Internal limiting membrane,Vitreomacular traction
更新于2025-09-04 15:30:14
-
Spectral-Domain Optical Coherence Tomography Features in Open-Angle Glaucoma With Diabetes Mellitus and Inadequate Glycemic Control
摘要： PURPOSE. To evaluate spectral-domain optical coherence tomography (SD-OCT) features according to glycemic control status in open-angle glaucoma with diabetes mellitus. METHODS. Subjects underwent comprehensive ocular examination, visual ?eld testing, and SD-OCT imaging (Cirrus HD-OCT). The relationship between glycosylated hemoglobin (HbA1c) and OCT measurements was compared between diabetic nonglaucomatous eyes and diabetic glaucomatous eyes. Glaucoma-discriminating ability was assessed using the area under the receiver operating characteristic curves (AUCs) for OCT parameters and compared between groups relative to the glycemic control group. RESULTS. Analysis was performed on 69 nonglaucomatous and 87 glaucomatous eyes in the nondiabetic group, and on 72 nonglaucomatous and 56 glaucomatous eyes in the diabetic group. Average, inferonasal, inferior, and inferotemporal ganglion cell–inner plexiform layer (GCIPL) thicknesses were positively correlated with HbA1c in diabetic nonglaucomatous eyes (P ? 0.040, 0.037, 0.025, and 0.013, respectively). The AUC of the average cup-to-disc area ratio (CDR), vertical CDR, and cup volume in diabetic eyes with poor glycemic control was signi?cantly higher than those in nondiabetic eyes (P ? 0.011, 0.003, and 0.043, respectively). The AUC of cube volume, cube average thickness, and minimal GCIPL thickness in diabetic eyes with poor glycemic control was lower than those in nondiabetic eyes (P ? 0.006, 0.007, and 0.004, respectively). CONCLUSIONS. In this study, optic nerve head parameters had a superior ability to discriminate glaucoma in diabetic eyes with poor glycemic control. Conversely, the ability to discriminate glaucoma using macular parameters tended to be lower for diabetic eyes with inadequate glycemic control.
关键词： spectral-domain optical coherence tomography,diabetes mellitus,ganglion cell-inner plexiform layer,glaucoma
更新于2025-09-04 15:30:14
-
Comprehensive Three-Dimensional Analysis of the Neuroretinal Rim in Glaucoma Using High-Density Spectral-Domain Optical Coherence Tomography Volume Scans
摘要： To describe spectral-domain optical coherence tomography (OCT) methods for quantifying neuroretinal rim tissue in glaucoma and to compare these methods to the traditional retinal nerve fiber layer thickness diagnostic parameter. Neuroretinal rim parameters derived from three-dimensional (3D) volume scans were compared with the two-dimensional (2D) Spectralis retinal nerve fiber layer (RNFL) thickness scans for diagnostic capability. This study analyzed one eye per patient of 104 glaucoma patients and 58 healthy subjects. The shortest distances between the cup surface and the OCT-based disc margin were automatically calculated to determine the thickness and area of the minimum distance band (MDB) neuroretinal rim parameter. Traditional 150-lm reference surface–based rim parameters (volume, area, and thickness) were also calculated. The diagnostic capabilities of these five parameters were compared with RNFL thickness using the area under the receiver operating characteristic (AUROC) curves. The MDB thickness had significantly higher diagnostic capability than the RNFL thickness in the nasal (0.913 vs. 0.818, P ? 0.004) and temporal (0.922 vs. 0.858, P ? 0.026) quadrants and the inferonasal (0.950 vs. 0.897, P ? 0.011) and superonasal (0.933 vs. 0.868, P ? 0.012) sectors. The MDB area and the three neuroretinal rim parameters based on the 150-lm reference surface had diagnostic capabilities similar to RNFL thickness. The 3D MDB thickness had a high diagnostic capability for glaucoma and may be of significant clinical utility. It had higher diagnostic capability than the RNFL thickness in the nasal and temporal quadrants and the inferonasal and superonasal sectors.
关键词： neuroretinal rim,spectral-domain optical coherence tomography,glaucoma,optic disc,optic nerve
更新于2025-09-04 15:30:14
-
[IEEE 2018 IEEE 18th International Conference on Bioinformatics and Bioengineering (BIBE) - Taichung, Taiwan (2018.10.29-2018.10.31)] 2018 IEEE 18th International Conference on Bioinformatics and Bioengineering (BIBE) - SAR ADC with DAC and SC Low-Pass Filter for Positron Emission Tomography Application
摘要： For positron emission tomography (PET), successive approximation register (SAR) analog-to-digital converter (ADC) and switched-capacitor (SC) low-pass filter implemented in tsmc 0.18-um CMOS process is presented. To reduce DAC switching energy and layout size, a hybrid resistor-capacitor DAC is applied. To save energy, asynchronous control logic to drive the ADC is used. A pre-amplifier based comparator circuit is built to reduce the kickback noise from the dynamic latch. The proposed filter uses cascades of first-order and second-order biquad seting blocks. In order to reach the largest possible input dynamic range, the method of dynamic range scaling and minimum capacitor scaling is used.
关键词： SAR ADC,SC Low-Pass Filter,Positron Emission Tomography,DAC
更新于2025-09-04 15:30:14
-
Retinal and Choroidal Imaging With 870-nm Spectral-Domain OCT Compared With 1050-nm Spectral-Domain OCT, With and Without Enhanced Depth Imaging
摘要： The purpose of this study was to compare images of the retina and choroid obtained with Spectralis 1050-nm spectral-domain optical coherence tomography (SD-OCT) with and without enhanced depth imaging (EDI) to the commercially available 870-nm SD-OCT with and without EDI. Methods: Full-length 308 line scans were obtained with both 870- and 1050-nm Spectralis OCT instruments, with and without EDI. Two trained retina physicians masked to wavelength and EDI status assessed the ability to visualize the vitreoretinal interface and full-thickness choroid, and subfoveal choroidal thickness (SFCT) was measured. Results: Included in the study were 21 eyes. The vitreoretinal interface was visualized best with 870-nm OCT without EDI and was diminished with 1050-nm OCT. Graders preferred 1050 nm with EDI over 870 nm with EDI in qualitative comparisons of the choroid; 1050 nm without EDI was slightly preferred over 870 nm with EDI but was not statistically significant. SFCT measurements correlated well among the imaging modalities except for 870 nm without EDI. Conclusions: SD-OCT with EDI at 870 nm provides good visualization of both the vitreoretinal interface and choroid, whereas 1050-nm SD-OCT with or without EDI provides more choroidal detail at the expense of visualization of the vitreoretinal interface.
关键词： longer wavelength,optical coherence tomography (OCT),choroid,retina
更新于2025-09-04 15:30:14
-
Automated Analysis of Vitreous Inflammation Using Spectral-Domain Optical Coherence Tomography
摘要： Purpose: To develop an automated method for quantifying vitreous signal intensity on optical coherence tomography (OCT), with particular application for use in the assessment of vitreous inflammation. Methods: This retrospective, observational case-control series comprised 30 patients (30 eyes), with vitreous haze secondary to intermediate, posterior, or panuveitis; 12 patients (12 eyes) with uveitis without evidence of vitreous haze; and 18 patients (18 eyes) without intraocular inflammation or vitreoretinal disease. The presence and severity of vitreous haze was classified according to the National Eye Institute system; other inflammatory indices and clinical parameters were also documented. Spectral-domain OCT images were analyzed using custom VITreous ANalysis software (termed ‘VITAN’), which is fully automated and avoids the need for manual segmentation. Results: VITAN performed accurate segmentation in all scans. Automated measurements of the vitreous:retinal pigment epithelium (RPE) signal ratio showed a moderate correlation with clinical vitreous haze scores (r ? 0.585, P , 0.001), comparable to that reported using manual segmentation in our previous study (r ? 0.566, P ? 0.0001). The novel parameter of vitreous:RPE textural ratio showed a marginally stronger correlation (r ? 0.604, P , 0.001) with clinical vitreous haze scores than the Vitreous:RPE signal ratio. Conclusions: The custom OCT image analysis software (VITAN) allows rapid and automated measurement of vitreous parameters, that is comparable to our previously reported vitreous:RPE index, and correlates with clinically measured disease activity. Such OCT-based indices may provide the much needed objective markers of vitreous activity, which may be used in both clinical assessment, and as outcome measures in clinical trials for intermediate, posterior, and panuveitis.
关键词： optical coherence tomography,vitreous inflammation,uveitis automated segmentation
更新于2025-09-04 15:30:14
-
Virtual Averaging Making Nonframe-Averaged Optical Coherence Tomography Images Comparable to Frame-Averaged Images
摘要： Developing a novel image enhancement method so that nonframe-averaged optical coherence tomography (OCT) images become comparable to active eye-tracking frame-averaged OCT images. Twenty-one eyes of 21 healthy volunteers were scanned with noneye-tracking nonframe-averaged OCT device and active eye-tracking frame-averaged OCT device. Virtual averaging was applied to nonframe-averaged images with voxel resampling and adding amplitude deviation with 15-time repetitions. Signal-to-noise (SNR), contrast-to-noise ratios (CNR), and the distance between the end of visible nasal retinal nerve fiber layer (RNFL) and the foveola were assessed to evaluate the image enhancement effect and retinal layer visibility. Retinal thicknesses before and after processing were also measured. All virtual-averaged nonframe-averaged images showed notable improvement and clear resemblance to active eye-tracking frame-averaged images. Signal-to-noise and CNR were significantly improved (SNR: 30.5 vs. 47.6 dB, CNR: 4.4 vs. 6.4 dB, original versus processed, P , 0.0001, paired t-test). The distance between the end of visible nasal RNFL and the foveola was significantly different before (681.4 vs. 446.5 lm, Cirrus versus Spectralis, P , 0.0001) but not after processing (442.9 vs. 446.5 lm, P ? 0.76). Sectoral macular total retinal and circumpapillary RNFL thicknesses showed systematic differences between Cirrus and Spectralis that became not significant after processing. The virtual averaging method successfully improved nontracking nonframe-averaged OCT image quality and made the images comparable to active eye-tracking frame-averaged OCT images. Virtual averaging may enable detailed retinal structure studies on images acquired using a mixture of nonframe-averaged and frame-averaged OCT devices without concerning about systematic differences in both qualitative and quantitative aspects.
关键词： optical coherence tomography,retina,image processing
更新于2025-09-04 15:30:14
-
Evaluation of a Region-of-Interest Approach for Detecting Progressive Glaucomatous Macular Damage on Optical Coherence Tomography
摘要： Purpose: To evaluate a manual region-of-interest (ROI) approach for detecting progressive macular ganglion cell complex (GCC) changes on optical coherence tomography (OCT) imaging. Methods: One hundred forty-six eyes with a clinical diagnosis of glaucoma or suspected glaucoma with macular OCT scans obtained at least 1 year apart were evaluated. Changes in the GCC thickness were identified using a manual ROI approach (ROIM), whereby region(s) of observed or suspected glaucomatous damage were manually identified when using key features from the macular OCT scan on the second visit. Progression was also evaluated using the global GCC thickness and an automatic ROI approach (ROIA), where contiguous region(s) that fell below the 1% lower normative limit and exceeded 288 lm2 in size were evaluated. Longitudinal signal-to-noise ratios (SNRs) were calculated for progressive changes detected by each of these methods using individualized estimates of test–retest variability and age-related changes, obtained from 303 glaucoma and 394 healthy eyes, respectively. Results: On average, the longitudinal SNR for the global thickness, ROIA and ROIM methods were (cid:2)0.90 y(cid:2)1, (cid:2)0.91 y(cid:2)1, and (cid:2)1.03 y(cid:2)1, respectively, and was significantly more negative for the ROIM compared with the global thickness (P ? 0.003) and ROIA methods (P ? 0.021). Conclusions: Progressive glaucomatous macular GCC changes were optimally detected with a manual ROI approach. Translational Relevance: These findings suggests that an approach based on a qualitative evaluation of OCT imaging information and consideration of known patterns of damage can improve the detection of progressive glaucomatous macular damage.
关键词： progression,optical coherence tomography,macula,glaucoma
更新于2025-09-04 15:30:14