• Journal of the Korean Society for Precision Engineering
• /
• v.16 no.3 s.96
• /
• pp.198-207
• /
• 1999

This paper presents an accurate algorithm for geometric calibration of X-ray imaging system. Calibration is a very important process for improving an imaging system performance. There has been a lot of previous works using linear camera modeling technique, where lens distortion is neglected and/or center of distortion is assumed to be known. Geometrical distortion of image intensifier, however, is very large and its center of distortion should be calculated. This paper presents a new calibration method to estimate the intensifier position and orientation, scale factor, distortion coefficient, magnification factor, and center of distortion using the least square method. We investigate the properties of the algorithm by computer simulation. Simulation results show that the parameters can be estimated accurately using the proposed algorithm.

• Medical Lasers
• /
• v.10 no.1
• /
• pp.1-6
• /
• 2021

Intravital microscopy is a high-resolution imaging technique based on laser-scanning two-photon and confocal microscopy, which allows dynamic 3D cellular-level imaging of various biological processes in a living animal in vivo. This unique capability allows biomedical researchers to directly verify a hypothesis in a natural in vivo microenvironment at the cellular level in a physiological setting. During the last decade, intravital microscopy has become an indispensable technique in several fields of biomedical sciences such as molecular and cell biology, immunology, neuroscience, developmental, and tumor biology. The most distinct advantage of intravital microscopy is its capability to provide a longitudinal view of disease progression at the cellular-level with repeated intravital imaging of a single animal over time by saving the images after each session.

• The Korean Journal of Nuclear Medicine
• /
• v.38 no.2
• /
• pp.171-174
• /
• 2004

Angiogenesis, the formation of new capillaries from existing vessels, increases oxygenation and nutrient supply to ischemic tissue and allows tumor growth and metastasis. As such, angiogenesis targeting provides a novel approach for cancer treatment with easier drug delivery and less drug resistance. Therapeutic anti-angiogenesis has shown impressive effects in animal tumor models and are now entering clinical trials. However, the successful clinical introduction of this new therapeutic approach requires diagnostic tools that can reliably measure angiogenesis in a noninvasive and repetitive manner. Molecular imaging is emerging as an exciting new discipline that deals with imaging of disease on a cellular or genetic level. Angiogenesis imaging is an important area for molecular imaging research, and the use of radiotracers offers a particularly promising technique for its development. While current perfusion and metabolism radiotracers can provide useful information related to tissue vascularity, recent endeavors are focused on the development of novel radioprobes that specifically and directly target angiogenic vessels. Presently available proges include RGD sequence containing peptides that target ${\alpha}_v\;{\beta}_3$ integrin, endothelial growth factors such as VEGF or FGF, metalloptoteinase inhibitors, and specific antiangiogenic drugs. It is now clear that nuclear medicine techniques have a remarkable potential for angiogenesis imaging, and efforts are currently continuing to develop new radioprobes with superior imaging properties. With future identification of novel targets, design of better probes, and improvements in instrumentation, radiotracer angiogenesis imaging promises to play an increasingly important role in the diagnostic evaluation and treatment of cancer and other angiogenesis related diseases.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.20 no.12
• /
• pp.2363-2369
• /
• 2016

In this paper, we propose three-dimensional (3D) quick-response (QR) code generation technique using passive 3D integral imaging and computational integral imaging reconstruction technique. In our proposed method, we divide 2D QR code into 4 planes with different reconstruction depths and then we generate 3D QR code using synthetic aperture integral imaging and computational reconstruction. In this 3D QR code generation process, we use integral imaging which is one of 3D imaging technologies. Finally, 3D QR code can be scanned by reconstructing and merging 3D QR codes at 4 different planes with computational reconstruction. Therefore, the security level for QR code scanning may be enhanced when QR code is scanned. To show that our proposed method can improve the security level for QR code scanning, in this paper, we carry out the optical experiments and computational reconstruction. In addition, we show that 3D QR code can be scanned when reconstruction depths are known.

• Molecules and Cells
• /
• v.41 no.7
• /
• pp.676-683
• /
• 2018

Cilia are highly specialized antennae-like organelles that extend from the cell surface and act as cell signaling hubs. Intraflagellar transport (IFT) is a specialized form of intracellular protein trafficking that is required for the assembly and maintenance of cilia. Because cilia are so important, mutations in several IFT components lead to human disease. Thus, clarifying the molecular functions of the IFT proteins is a high priority in cilia biology. Live imaging in various species and cellular preparations has proven to be an important technique in both the discovery of IFT and the mechanisms by which it functions. Live imaging of Drosophila cilia, however, has not yet been reported. Here, we have visualized the movement of IFT in Drosophila cilia using time-lapse live imaging for the first time. We found that NOMPB-GFP (IFT88) moves according to distinct parameters depending on the ciliary segment. NOMPB-GFP moves at a similar speed in proximal and distal cilia toward the tip (${\sim}0.45{\mu}m/s$). As it returns to the ciliary base, however, NOMPB-GFP moves at ${\sim}0.12{\mu}m/s$ in distal cilia, accelerating to ${\sim}0.70{\mu}m/s$ in proximal cilia. Furthermore, while live imaging NOMPB-GFP, we observed one of the IFT proteins required for retrograde movement, Oseg4 (WDR35), is also required for anterograde movement in distal cilia. We anticipate our time-lapse live imaging analysis technique in Drosophila cilia will be a good starting point for a more sophisticated analysis of IFT and its molecular mechanisms.

• Journal of the Optical Society of Korea
• /
• v.20 no.2
• /
• pp.228-233
• /
• 2016

In this paper, we propose a nonlinear maximum average correlation height (MACH) filter for information authentication of photon counting double random phase encryption (DRPE). To enhance the security of DRPE, photon counting imaging can be applied because of its sparseness. However, under severely photon-starved conditions, information authentication of DRPE may not be implemented successfully. To visualize the photon counting DRPE, a three-dimensional imaging technique such as integral imaging can be used. In addition, a nonlinear MACH filter can be utilized for helping the information authentication. Therefore, in this paper, we use integral imaging and nonlinear MACH filter to implement the information authentication of photon counting DRPE. To verify our method, we implement optical experiments and computer simulation.

• Journal of information and communication convergence engineering
• /
• v.8 no.5
• /
• pp.581-585
• /
• 2010

A grid was sandwiched between two cascaded imaging plates. Using a fan-beam X-ray tube and a single exposure scheme, the two imaging plates, respectively, recorded grid-less and grid type information of the object. Referring to the mathematical model of the Grid-less and grid technique, it was explained that the collected components whereas that of imaging plates with grid was of high together with large scattered components whereas that of imaging plate with grid was of low and suppressed scattered components. Based on this assumption and using a Gaussian convolution kernel representing the effect of scattering, the related data of the imaging plates were simulated by computer. These observed data were then employed in the developed post-processing estimation and restoration (kalman-filter) algorithms and accordingly, the quality of the resultant image was effectively improved.

• Current Optics and Photonics
• /
• v.3 no.3
• /
• pp.220-226
• /
• 2019

A novel speckle-shifting ghost imaging (SSGI) technique is proposed in this paper. This method can effectively extract the edge of an unknown object without achieving its clear ghost image beforehand. However, owing to the imaging mechanism of SSGI, the imaging result generally contains serious noise. To solve the problem, we further propose a simple and effective method to remove noise from the speckle-shifting ghost image with a connected-region labeling (CRL) algorithm. In this method, two ghost images of an object are first generated according to SSGI. A threshold and the CRL are then used to remove noise from the imaging results in turn. This method can retrieve a high-quality image of an object with fewer measurements. Numerical simulations are carried out to verify the feasibility and effectiveness.

• Proceedings of the Korea Air Pollution Research Association Conference
• /
• 2010.04a
• /
• pp.475-476
• /
• 2010

• Proceedings of the Optical Society of Korea Conference
• /
• 2007.07a
• /
• pp.257-258
• /
• 2007

For objective evaluation of computational integral imaging reconstruction (CIIR) schemes, a framework with the computational pickup and the CIIR process using Gaussian images is presented and characteristics of CIIR along the distance between lenslet array and objects are investigated.