Diffuse Optical Molecular Imaging For Small Animal Model

Upon the entry into 21th century, main aims of observation on life course have been shifted toward probing into how each parts of organism acts as a complicated system. At present optical molecular imaging, which is a rising issue, is recognized widely as one of mainstream means for research on molecular events. And it is well accepted that the imaging will play momentous role of study for life science.There are two kinds of modality for Optical Molecular Imaging (OMI), planar projection imaging and tomography. Because it is easy relatively to implement, the planar imaging is adopted widely such as Whole-body Fluorescence Optical Imaging (WFOI). Excitation light source,which is a laser or source with high power and broad spectrum generally, is one of essential components for WFOI. A WFOI system with the two kinds of sources is costly and inconvenient. After replaced a mercury lamp by Light Emitting Diodes (LEDs), a power-LED-based WFOI system was presented. For two sources'replacement it is commonly to ignore the influence of excitation or absorption spectrum of fluorescent substance. The ignoring results in that the fluorescence intensity various with the replacement. Therefore, the required luminous flux of LED was probed into by analyzing spectrum of the sources discussed firstly and a WFOI system was developed then.The required flux is for the same intensive fluorescence excited by mercury lamp in various wavelengths range. With the system, dynamic courses were monitored of green fluorescence protein expressing tumors development and medication of the tumor in the same intact nude mice. In WFOI, auto-fluorescence pulls down image contrast.Previously the contrast was reported to be enhanced by a multi-spectrum imaging. But the multi-spectrum imaging augmentes cost of the imaging system's hardware and increases complexity for imaging course. In this paper the signal of autofluorescence was trailed off according to the chroma of autofluorescence. Then an image with enhanced contrast was obtained by image fusion. Experiments indicated that the power-LED-based WFOI system was low cost and easy operation. For light sources'replacement, it is necessary to take into account influence of the wavelength-dependent excitation efficiency if the sources differ in their spectrum distribution within the selected range. The image contrast can be enhanced via software for replacing the multi-spectrum imaging at some extents.In contrast with the planar imaging, it is more complex to implement a tomography such as Diffuse Optical Tomography (DOT). However issues about optical tomography are a hotspot for merits of optical imaging and that the tomography can supply with 3-D information. The reported DOT systems are mainly based on fibers and their sources-detectors are with slab geometry by and large. Structure of those systems with fiber is complex and it is difficult to alter configuration of their optical module. And it is inconvenience to remodel their scan precision. In a word flexibility of those systems with fibers is badly. To those systems whose geometry is slab, it is necessary to compress sample that results in deforming of the sample. In order to fulfill a DOT system with better flexibility, issues about DOT were discussed in rest part of this paper. A DOT system without fiber is presented and its geometry is circular fan-beam. Without fiber light is focused directly onto surface of the sample and at the other side of the sample the detector captures photonics traversing the sample. The rotation stage carries the source and the detector and circles round the sample while the detector acquires images at different angle. It is easy to alter interval angle for acquiring image by changing interval angle for rotation of the stage. Dispensing with fiber the system is more flexible to samples with various sizes. And for the presented system's geometry, it is not demanded to compress sample.Reconstruction process is absolutely necessary for DOT. In this paper Genetic Algorithm (GA) was utilized. GA is one of the main kinds of intelligent computing technology. But, the mutation of standard GA is nondirectional regulator. Thus the mutation operation contributes less for convergence of GA. In order to accelerate convergence a method was proposed to assist mutation of GA. Individuals were initialized and fine-tuned with projection information for diffuse optics. Experiments showed that the proposed method accelerates convergence of GA to some extent.