Optimal Field Of View Research Articles

Cone Beam Computed Tomography - An Inevitable Diagnostic Aid in Dentistry

Cone Beam Computed Tomography (CBCT) has emerged as a pivotal imaging modality across various disciplines, providing three-dimensional visualisation with significant applications in dentistry, medical diagnostics, and industrial fields. This article presents a comprehensive overview of key aspects in CBCT imaging, encompassing the critical topics of Field of View (FOV), Resolution, Dose Considerations, and Artefacts. The Field of View (FOV) is a fundamental parameter influencing the scope and application of CBCT. This article explores the impact of different FOV settings on image acquisition, highlighting considerations for selecting an optimal FOV based on the specific diagnostic requirements of diverse clinical scenarios. Resolution plays a pivotal role in defining the clarity and precision of CBCT images. The article delves into the nuances of spatial and contrast resolution in CBCT, addressing the technological advancements and challenges associated with achieving high-resolution imaging while minimizing radiation exposure. Dose considerations are paramount in any medical imaging technique, and CBCT is no exception. This article provides an analysis of radiation dose management strategies in CBCT, emphasizing the importance of balancing diagnostic efficacy with patient safety. It explores dose optimization techniques, dose monitoring, and advancements in technology aimed at minimizing radiation exposure. Artefacts are inherent challenges in CBCT imaging that can compromise diagnostic accuracy. Understanding artefacts is crucial for practitioners to enhance the reliability and interpretability of CBCT images. Key Words: CBCT, Cone Beam Computed Tomography, 3-D imaging, Diagnostic imaging, Radiation dose.

Optimal uniform guide star catalog using a geneticalgorithm.

To achieve optimal and reliable star sensors and overcome some onboard hardware and software limitations, this study aimed to make an optimal uniform guide star catalog. For this purpose, the objective function was defined by the field of view (FOV) and magnitude threshold, and then design variables were optimized. The optimal uniform guide star catalog was obtained by a genetic algorithm alongside the Latinized stratified sampling method and by a novel, to the best of our knowledge, spherical density determination algorithm based on the minimum number of stars required for a star identification algorithm. Finally, Monte Carlo simulation was used to validate the results, which indicate a dramatic improvement, including a reduction in the number of stars in the uniform catalog and an increase in the probability of observing the minimum required stars for the star identification algorithm (at least 5 stars) in 98.34% of all possible optimal FOVs (about 12°).

Dual-channel snapshot imaging spectrometer with wide spectrum and high resolution.

The comprehensive analysis of dynamic targets brings about the demand for capturing spatial and spectral dimensions of visual information instantaneously, which leads to the emergence of snapshot spectral imaging technologies. While current snapshot systems face major challenges in the development of wide working band range as well as high resolution, our novel dual-channel snapshot imaging spectrometer (DSIS), to the best of our knowlledge, demonstrates the capability to achieve both wide spectrum and high resolution in a compact structure. By dint of the interaction between the working band range and field of view (FOV), reasonable limits on FOV are set to avoid spectral overlap. Further, we develop a dual-channel imaging method specifically for DSIS to separate the whole spectral range into two parts, alleviating the spectral overlap on each image surface, improving the tolerance of the system for a wider working band range, and breaking through structural constraints. In addition, an optimal FOV perpendicular to the dispersion direction is determined by the trade-off between FOV and astigmatism. DSIS enables the acquisition of 53×11 spatial elements with up to 250 spectral channels in a wide spectrum from 400 to 795nm. The theoretical study and optimal design of DSIS are further evaluated through the simulation experiments of spectral imaging.

Autonomous Laparoscope Control for Minimally Invasive Surgery With Intuition and RCM Constraints

The automated laparoscope control can ensure the stability of the laparoscopic image and enhance the performance of surgeons during surgical operations. The letter presented a method that autonomously adjusted the laparoscope pose to obtain the optimal field of view (FOV). An optimization problem was constructed to generate the laparoscope pose, which provided the optimal FOV, based on the domain knowledge extracted from expert surgeons’ experience. Furthermore, an image-based algorithm to perceive the position of the surgical instruments’ tool-tips in real-time was developed. Because the RCM constraint of the laparoscope can cause image misorientation as the laparoscope moves around, we presented a new intuition criterion to minimize the misorientation of FOV. We presented a new intuition criterion to minimize the misorientation of FOV. Finally, a control framework that could accomplish the autonomous laparoscope control with the RCM constraint and the intuition constraint was proposed. The simulation and experiment results demonstrated the validity of our method for automated laparoscope control.

Distance effects on visual search and visually guided freehand interaction on large displays

Different from mouse-based and touch-based interactions at a static distance, motion-sensing interaction on a large display is typically performed at varying distances ranging from an arm's length to several metres. To investigate the effect of distance on visual search and freehand interaction performance, an empirical experiment was conducted; 30 participants were recruited to complete a series of target search and freehand selection tasks on large displays, which were 1.6 and 2.4 m wide, respectively. The results indicated that (1) the user-preferred viewing distance was positively related to the physical size of the display: a larger display size corresponded to a larger viewing distance. (2) The viewing distance had a two-sided effect on the visual search time efficiency. At a close range, increasing distance improved the search time efficiency; but at a farther range, the efficiency decreased. (3) An optimal field of view at which visual search was most efficient was found; (4) however, increasing the distance lowered freehand interaction efficiency and accuracy. Changing the distance also caused variations in the performance on divided large display areas: (5) the visual search efficiency on the upper area was higher than that on the lower area, increasing the distance reduced the difference; (6) freehand interaction efficiency and accuracy on the lower area outperformed that on the upper area, increasing the distance also reduced the difference. Implications were discussed for building more efficient and user-friendly large display-based user interfaces.

A novel method for VR sickness reduction based on dynamic field of view processing

In this paper, we proposed a novel method for virtual reality (VR) sickness reduction based on dynamic field of view (FOV) processing. Dynamic FOV processing is performed based on the estimated VR sickness for each video frame. The level of sickness is estimated using VR sickness model, which is obtained by defining the relationship between the motion information and the measured VR sickness. For motion information analysis, subregion-based correspondence points tracking is used to efficiently remove outliers and prevent prediction error propagation. Amount of head dispersion is used as a quantitative VR sickness measure, which can be calculated from inertial measurement unit sensor in VR devices. The optimal FOV range was determined by experimentally validating a minimum FOV that can effectively reduce VR sickness with almost negligible loss in presence. The simulation results show a significant decrease of 37% compared to full FOV viewing, when FOV is dynamically varied between full and 60°.

Study on Distortion and Field of View of Contents in VR HMD

Recently, VR HMD (virtual reality head mounted display) has been utilized for virtual training, entertainment, vision therapy, and optometry. In particular, virtual reality contents are increasingly used for vision therapy and optometry. Accordingly, high-quality virtual reality contents such as a natural vision of life is required. Therefore, it is necessary to study the content production according to the optical characteristics of the VR HMD. The purpose of this paper is to suggest a proper FOV (field of view) of contents according to the distortion rate. We produced virtual reality contents and obtained distorted images by virtual camera. The distortion rate is calculated by using the distorted image. It is proved that the optimal FOV of the VR content with the minimum distortion is 90 ~ 100°. The results of this study are expected to be applied to the production of high quality contents.

Low-dose whole-body CT for staging multiple myeloma

Purpose Differentiating asymptomatic (smouldering) from symptomatic myeloma requiring active treatment is essential. Symptomatic myeloma occurs when there is organ or tissue impairment (CRAB: hyperCalcaemia, Renal insufficiency, Anaemia, Bone lesions). Current guidelines recommend a skeletal survey (SS) to screen for bone lesions but whole-body low-dose computed tomography (WBLDCT) can be considered as an alternative. WBLDCT increases detection of bone lesions and is a useful screen for mechanical complications. We aim to evaluate radiation exposure and artefacts encountered on setting up a WBLDCT service for myeloma staging. Methods and materials WBLDCTs were performed using established protocols and data for the first 15 patients analysed; the effective radiation dose for each patient was calculated and artefacts documented. Results Other than minimal streak artefact not affecting diagnostic quality, there were no artefacts. Median effective dose = 4.37 milliSievert (mSv) – equivalent to 2 SS and half that of a CT-thorax abdomen pelvis (TAP). It was noted that arms down was more comfortable than arms up in this elderly population and hands placed in front rather than along the body allowed optimum field of view (FOV) coverage. Conclusion WBLDCT is an effective alternative to the more traditional SS and is now routinely performed at our institution for patients with a new diagnosis of myeloma and in the assessment of complications. It is faster, better tolerated than an SS and can be performed at a satisfactory radiation dose with no artefacts.

Nano- and Micro-Corrugations in Photo-Aligned Polymer Thin-Films; Correlations Between Topologies and Directional Light Scattering

Isotropic and anisotropic nano- and micro-corrugations in polymer thin-films are shown to be independently tunable via photo-controlled diffusion of liquid crystalline pre-polymer molecules on substrate surfaces. Amplitude and shape of MC-topologies are quantitatively correlated with light scattering. Scattering from monomer corrugated (MC)-topologies is correlated with the averaged power spectral density (PSD) function of MC-height fluctuations and shown to be proportional to PSD. Paper-white MC-diffusers with optimal field of view, minimal glare and brightness enhancement exceeding 25 are demonstrated. Photo-patterning of MC-topologies is shown to render multidirectional diffusers and diffuse reflectors feasible. Generation of ultra thin MC-reflectors does not require micro tools and renders integration into flat panel displays feasible.