Target detection in turbid medium using polarization-based range-gated technology

ObjectivesTo investigate the prevalence of incidental findings and need for further dental treatment and analyse the influence of size of field-of-view (FOV) and age in cone beam computed tomography (CBCT) for pre-implant planning.Methods404 CBCT scans were examined retrospectively for incidental findings and need for further dental treatment. Incidental finding-frequencies and need for further treatment were assessed for different age (< 40 years, 40–60 years, > 60 years) and FOV groups (small, medium, large). Intraexaminer and interexaminer agreements were evaluated.ResultsIn 82% of the scans at least one incidental finding was found, with a total of 766 overall. More incidental findings were found in scans with large FOV (98% vs. 72%, OR = 22.39 large vs. small FOV, p < 0.0001) and in scans of patients > 60 years (OR = 5.37 patient’s age > 60 years vs. < 40 years, p = 0.0003). Further dental treatment due to incidental findings was needed in 31%. Scans with large FOV were more likely to entail further treatment (OR = 3.55 large vs. small FOV, p < 0.0001). Partial edentulism and large FOV were identified as risk factors for further treatment (p = 0.0003 and p < 0.0001). Further referral of the patient based on incidental findings was judged as indicated in 5%. Intra- and inter-examiner agreements were excellent (kappa = 0.944/0.805).ConclusionsA considerable number of incidental findings with need for further dental treatment was found in partially edentulous patients and in patients > 60 years. In pre-implant planning of elderly patients, the selection of large FOV CBCT scans, including dentoalveolar regions not X-rayed recently, help to detect therapeutically relevant incidental findings.

Purpose: To develop a methodology for development of 3D planning of obese patients larger than CT field of view (FOV) using PHILIPS Pinnacle 3 treatment planning system. Material & Methods: Obese patient larger than CT FOV was scanned on Siemens Emotion Duo CT simulator in two laterally shifted positions. The Patient had appropriate BBs (central and lateral CT markers) on the central plane. The patient was first positioned such that one side of the patient's contour is fully visible in the reconstructed image. Another similar data set was acquired by shifting the patient laterally. A new composite CT data set with a larger FOV was generated by mapping the left and right halves of the two data sets using the indigenously developed software. Typically the images were joined at a user selectable sagittal plane. In this way, it was possible to fuse the above image sets to makeup the full patient for target/structures delineation. A traditional 3D planning on Pinnacle3 was carried out. Results: An acceptable 3D plan data set was generated and dose distribution along with DRR was obtained using Pinnacle3. The DRRs were compared with AP and LAT simulation films and acceptable results were obtained. Similarly, the plan SSDs and depths were compared with data from patient setup with satisfactory results. Conclusion: A methodology has been developed, tested and implemented for the obese patients with larger CT FOV for 3D planning on Pinnacle3. Essentially using this method, the 50 cm diameter FOV limitation of our scanner has been increased to 70 cm FOV. This was useful for a few selected individual cases in our clinic. While the composite data set is dependent upon the accuracy of patient positioning, several improvements are planned for the future.

Contrast-enhanced (CE) breast imaging involves the injection contrast agents (i.e., iodine) to increase conspicuity of malignant lesions. CE imaging may be used in conjunction with digital mammography (DM) or digital breast tomosynthesis (DBT) and has shown promise in improving diagnostic specificity. Both CE-DM and CE-DBT techniques require optimization as clinical diagnostic tools. Physical factors including x-ray spectra, subtraction technique, and the signal from iodine contrast, must be considered to provide the greatest object detectability and image quality. We developed a cascaded linear system model (CLSM) for the optimization of CE-DM and CE-DBT employing dual energy (DE) subtraction or temporal (TE) subtraction. We have previously developed a CLSM for DBT implemented with an a-Se flat panel imager (FPI) and filtered backprojection (FBP) reconstruction algorithm. The model is used to track image quality metrics - modulation transfer function (MTF) and noise power spectrum (NPS) - at each stage of the imaging chain. In this study, the CLSM is extended for CE breast imaging. The effect of x-ray spectrum (varied by changing tube potential and the filter) and DE and TE subtraction techniques on breast structural noise was measured was studied and included as a deterministic source of noise in the CLSM. From the two-dimensional (2D) and three-dimensional (3D) MTF and NPS, the ideal observer signal-to-noise ratio (SNR), also known as the detectability index (d'), may be calculated. Using d' as a FOM, we discuss the optimization of CE imaging for the task of iodinated contrast object detection within structured backgrounds. Increasing x-ray energy was determined to decrease the magnitude of structural noise and not its correlation. By performing DE subtraction, the magnitude of the structural noise was further reduced at the expense of increased stochastic (quantum and electronic) noise. TE subtraction exhibited essentially no residual structural noise at the expense of increased quantum noise, even over that of the DE case. For DE subtraction, optimization of dose weighting to the HE view (fh ) results in the minimization of quantum noise. Both subtraction weighting factor (wSub ) and the iodine contrast signal were dependent on the LE and HE x-ray spectra. To best detect a 5 mm Gaussian lesion with 5 mg/ml of iodine within a 4 cm thick breast, it was found that the high energy (HE) view should be acquired with a tube potential of 47 kVp (W/Ti spectrum) and the low energy (LE) view with a potential of 23 kVp (W/Rh spectrum). Due to the complete removal of structural noise, TE subtraction produced much higher d' than DE subtraction both as a function of mean glandular dose and iodine concentration. We have shown the effect of increasing x-ray energy as well as projection domain subtraction on breast structural noise. Further, we have exhibited the utility of the CLSM for DE and TE subtraction CE imaging in the optimization of imaging parameters such as x-ray energy, fh , and wSub as well as guiding the understanding of their effects on image contrast and noise.

The objectives of this pilot study were to develop a video fluoroscopy kinematics method for the assessment of the coxofemoral joint in cats with and without osteoarthritis (OA)-associated disability. Two non-OA cats and four cats affected by coxofemoral OA were evaluated by video fluoroscopy. Video fluoroscopic images of the coxofemoral joints were captured at 120 frames/s using a customized C-arm X-ray system while cats walked freely on a treadmill at 0.4 m/s. The angle patterns over time of the coxofemoral joints were extracted using a graphic user interface following four steps: (i) correction for image distortion; (ii) image denoising and contrast enhancement; (iii) frame-to-frame anatomical marker identification; and (iv) statistical gait analysis. Reliability analysis was performed. The cats with OA presented greater intra-subject stride and gait cycle variability. Three cats with OA presented a left-right asymmetry in the range of movement of the coxofemoral joint angle in the sagittal plane (two with no overlap of the 95% confidence interval, and one with only a slight overlap) consistent with their painful OA joint, and a longer gait cycle duration. Reliability analysis revealed an absolute variation in the coxofemoral joint angle of 2º-6º, indicating that the two-dimensional video fluoroscopy technique provided reliable data. Improvement of this method is recommended: variability would likely be reduced if a larger field of view could be recorded, allowing the identification and tracking of each femoral axis, rather than the trochanter landmarks. The range of movement of the coxofemoral joint has the potential to be an objective marker of OA-associated disability.

In view of urgent demand high resolution and large field of view on three-line array airborne mapping camera, the paper proposes an airborne mapping camera optical system with large field of view and high resolution, which consists of single telecentric lens, RGB multispectral prism and field splicing prism. In order to solve RGB multispectral splitting problem in system, a new multispectral splitting prism based on a close distance confocal plane linear array sensor is proposed, which successfully solves RGB multispectral splitting problem of confocal plane linear array sensor with a close distance (B band and G band are only 4 pixels apart, and G band and R band are 2.2mm apart). The telecentric optical system is designed, focal length is 130mm, field of view (FOV) is 77&deg; (working field of view is 60&deg;), and image elecentricity is less than 0.1&deg; across full field of view. There are four multispectral bands which are panchromatic, R, G, B band. The optical system has excellent imaging quality and compact structure.

Depth of interaction (DOI) errors in commonly employed crystal detectors cause severe degradation of off-axis resolution in current positron emission tomography (PET) scanners used for small animal or single organ imaging. We propose a PET camera design that uses low cost, easily fabricated, lead-walled straw (LWS) detectors. Photons converted in Pb generate photoelectrons that escape into the straw interior producing an avalanche whose position can be readily measured with high precision. Straws can be of considerable length (up to 50 cm), but small in diameter (2 mm), and can be packed to form scanners with high sensitivity and large fields of view (FOV). The rigorous three-dimensional position encoding eliminates DOI errors encountered in crystal detectors, and provides submillimeter resolution and sensitivity response that is uniform over the full extent of the FOV. We present preliminary results of the operation of a prototype 200-straw module. We then propose a PET scanner design that consists of two rotating trapezoidal detector panels, each panel containing fourteen 200-straw modules (a total of 5600 straws). The FOV has a diameter of 5 cm and extends axially to 15 cm. This unique geometry affords a long field of view, with near constant axial sensitivity of 4.7%, and uniform resolution of 0.9 times 0.9 times 1.0 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> maintained over the entire extent of the FOV, as determined in Monte Carlo simulations.

Optical imaging through complex media has many important applications. Although research progresses have been made to recover optical image through various turbid media, the widespread application of the technology is hampered by the recovery speed, requirement on specific illumination, poor image quality and limited field of view. Here we demonstrate that above-mentioned drawbacks can be essentially overcome. The realization of high speed color imaging through turbid media is successfully carried out by taking into account the media memory effect, the point spread function, the exit pupil of the optical system, and the optimized signal to noise ratio. By retrieving selected speckles with enlarged field of view, high quality image is recovered with a responding speed only determined by the frame rates of the image capturing devices. The immediate application of the technique is expected to register static and dynamic imaging under human skin to recover information with a wearable device.

Background and Objectives Given the substantial increase in dental implant procedures, the significance of precise linear measurements and the factors influencing them has been underscored by cone-beam computed tomography (CBCT). This study aimed to evaluate the impact of field of view (FOV) on the accuracy of linear measurements. Subjects and Methods The study was performed on 6 human mandibles. FOVs used included: Small FOV 80 × 80 mm / Large FOV: 120 × 80 mm, each with two different resolutions. Digital caliper measurements were considered as the gold standard. Measurements were reviewed by two observers using NNT Viewer software. Results The buccolingual dimension measured using a digital caliper, serving as the gold standard, averaged 7.02 ± 1.84 mm. CBCT measurements of the same dimension yielded mean values of 7.02 ± 1.87 mm for 80x80 FOV with high resolution, 6.97 ± 1.67 mm for 80x80 FOV with normal resolution, 6.87 ± 1.63 mm for 120x80 FOV with high resolution, and 6.93 ± 1.64 mm for 120x80 FOV with normal resolution (p = 1.000). The vertical dimension measured using a digital caliper, serving as the gold standard, averaged 18.08 ± 3.62 mm. CBCT measurements of the same dimension yielded mean values of 18.02 ± 3.65 mm for 80x80 FOV with high resolution, 18.10 ± 3.67 mm for 80x80 FOV with normal resolution, 18.09 ± 3.65 mm for 120x80 FOV with high resolution, and 18.09 ± 3.65 mm for 120x80 FOV with normal resolution (p = 1.000). Conclusion Statistical analysis revealed no significant difference in measurement accuracy between FOVs with varying resolutions.

It is difficult to realize large field of view (FOV) and high-resolution at the same time. How to achieve high-resolution measurement under the premise of large FOV imaging is an important research issue. Aiming at the problem of single point target recognition, especially the angle measurement of single light source, this paper proposes a high-resolution measurement method with array FOV and coded apertures. A mask is added in front of the image sensor. The coded apertures on the mask divide the large FOV into several sub fields of view (sub-FOV). Different sub-FOV are time-sharing multiplexed on the image sensor. Apertures encoded by position information are arranged on the sub-FOV. When a single light source irradiates the apertures, the diffraction spot is imaged on the image sensor. The centroid method can accurately determine the centroid of light spot to submicron scale or even nanoscale. Analyzing the coded information contained in the imaging can realize the recognition of sub-FOV, and then calculate the incident angle of light to realize the target recognition. A mask is designed to realize the method. Through experiments, this mask can achieve a large FOV of 1200×120° with an angle measurement accuracy of 0.003°(3 σ).

Despite the recent development of advanced ophthalmic imaging techniques, volumetric fluorescence angiography (vFA) over a large field of view is still lacking. Fundus photography techniques have significant limitations due to the lack of 3D imaging capability. Scanning laser ophthalmoscopy (SLO) and confocal SLO (cSLO) use confocal gating to remove diffused light, resulting in crisper image quality. However, the volumetric imaging of SLO requires to compile z stacks, which can be challenging and time-consuming. Adaptive optics SLO (AOSLO) allows diffraction-limited resolution in both axial and lateral resolution. This technique is limited however, by its small field of view (FOV) and also the necessity of z stacks for volumetric imaging. To fill the technical void of vFA over a large field of view (FOV), we developed a novel retinal imaging modality called oblique scanning laser ophthalmoscopy (oSLO) for in vivo volumetric fluorescence retinal imaging. By using oblique illumination and detection, oSLO essentially allows "OCT-like" cross-sectional images contributed solely by the fluorescent contrast, without the need for z stacking. We will demonstrate 3D vFA over a 30˚x30˚ FOV in vivo in mouse retina. We will further report a high-speed oSLO in imaging capillary hemodynamics. The new capability allows the calculation of capillary hematocrit and blood speed in 3D, which can be potentially valuable in diabetic retinopathy and macular degeneration.

Grating-based X-ray differential phase contrast imaging provides excellent image contrast for low-Z objects that cannot be acquired by conventional X-ray imaging, which has great potential applications in the early diagnosis of cancer and non-destructive detections of low-Z materials and devices. Large field of view imaging is a crucial factor for this technology from the laboratory to practical application. For the objective need of large field of view, on the basis of the Fresnel diffraction theory and the structure characteristics of gratings, we establish a quantitative physical model to analyze the factors that affect the imaging field of view and give a feasible way for large imaging field of view. This work provides a theoretical basis for the large field of view grating-based X-ray differential phase contrast imaging in the future.

The first fast-neutron scintillation block detector has been developed for use in neutron imaging applications. The low-cost, large field of view (FOV) block detector consists of a 10 × 10 array of plastic scintillator crystals, each with a size of approximately 1 × 1 × 5 cm3. To achieve both low cost and fast response time, the detector uses a 2 × 2 array of photomultiplier tubes (2-in. Photonis XP20D0) optically coupled to the array of scintillation crystals through a custom-made light guide. The light guide is segmented in such a way that all scintillator crystals can be resolved, including the edge crystals, to fully utilize the entire FOV of the detector. The thickness and depth of the light-guide segments were also optimized to maintain nearly uniform linearity between the true pixel locations and the reconstructed positions. Flood images from simulation and experiment show that each of the 100 pixels is resolved with an average peak-to-valley ratio for 14 MeV neutrons of 9:1. A mean deviation of 3.3 mm is obtained between the resolved image peaks and the respective true positions demonstrating good linearity. A coincidence measurement performed using a deuterium-tritium neutron generator, in which the neutrons were measured with the block detector and the corresponding alpha particles were measured with another scintillation detector revealed a total time resolution of 1.3 ns full width at half maximum.

Imaging probe for breast cancer localization

Image quality in light-sheet fluorescence microscopy is strongly affected by the shape of the illuminating laser beam inside embryos, plants or tissue. While the phase of Gaussian or Bessel beams propagating through thousands of cells can be partly controlled holographically, the propagation of fluorescence light to the detector is difficult to control. With each scatter process a fluorescence photon loses information necessary for the image generation. Using Arabidopsis root tips we demonstrate that ballistic and diffusive fluorescence photons can be separated by analyzing the image spectra in each plane without a priori knowledge. We introduce a theoretical model allowing to extract typical scattering parameters of the biological material. This allows to attenuate image contributions from diffusive photons and to amplify the relevant image contributions from ballistic photons through a depth dependent deconvolution. In consequence, image contrast and resolution are significantly increased and scattering artefacts are minimized especially for Bessel beams with confocal line detection.

Two-dimensional intraoral radiography is the most common tool for diagnosing root fractures (RFs). Cone beam CT (CBCT) is widely used to depict RFs in endodontically treated teeth. Beam hardening and other artefacts caused by gutta percha may result in an incorrect diagnosis when using CBCT only. A comparison of two CBCT machines with photostimulated phosphor (PSP) plate images enhanced with the equalization tool was carried out to detect RFs in endodontically treated teeth. 66 roots were collected, decoronated and treated endodontically using the same technique with gutta percha. 33 of these roots were randomly selected and fractured; the 2 root fragments were glued together with 1 layer of methyl methacrylate and placed randomly in 8 prepared beef rib fragments. Large fields of view (FOVs) were acquired with one CBCT unit and small FOVs with the second CBCT unit. Periapical radiographs (using intraoral PSP plates) were also acquired. A contrast enhancement tool was used when evaluating the PSP plate images. Small FOV images had significantly higher accuracy (area under the receiver operating characteristic curve) and sensitivity in detecting RFs than PSP plates and large FOV images. The specificity of the enhanced PSP images was higher than, although not significantly higher than, the small FOV images and was significantly higher than the large FOV images. CBCT small FOVs should be acquired for depicting RFs of endodontically treated teeth. Images obtained using PSP plates had the lowest rate of false-positive results and their use can save the patient a radiation dose.