We can consider the absorber as a collection of light-missing points if the light is diffused well at the depth of the absorbing structure. The scattered light goes through the absorbing structure and projects the shadow on the surface of the scattering medium. In transillumination imaging, homogeneous light is irradiated from outside of the scattering medium. Therefore, its applicability to the transillumination image of an absorbing structure must be examined. This PSF was obtained as the light image from a point light source observed at the scattering medium surface. Geometry for PSF as light distribution observed at the scattering medium surface. In this paper, we propose the 3D imaging of internal absorbing structure of a small experimental animal from 2D NIR transillumination images using new scatter-suppression techniques. Therefore, we could expect to realize the 3D imaging from the transillumination images if we were able to apply this light-source PSF to the absorbing structure and thereby solve the problem of the depth-dependence of the PSF. With the known depth of the light source in a diffuse medium, we can recover the fluorescent distribution clearly through an interstitial tissue by the deconvolution with this PSF. We have derived the PSF for the fluorescent light source by applying the diffusion approximation to the equation of transfer. They require much simpler and more compact device as well as much less computational effort.įor scattering suppression, the deconvolution technique using the point spread function (PSF) is effective.

We would be able to reconstruct the 3D structure with a common filtered back-projection algorithm and with a CCD or CMOS camera if we were able to suppress the scattering effect in transillumination images effectively. However, current techniques require great computational effort such as finite element method calculation, and large devices such as numerous fiber bundles around the object body. Once the cross-sectional images become available, 3D imaging is possible. Using this technique, cross-sectional imaging of human breasts and infant heads was achieved.

The typical technique for a macroscopic structure is diffuse optical tomography (DOT). To overcome this problem, great effort has been undertaken to develop optical computed tomography (optical CT) techniques. In transillumination images, the deeper structure is blurred and cannot be differentiated from the shallower and less-absorbing structure. The major reason for that relative lack of use is the difficulty of the strong scattering in tissues. The possibility and the potential of the NIR transillumination technique were pointed out early, but the technique has not been used widely. With specific contrast media, the usefulness of NIR imaging is expanded significantly. Functional imaging is also possible using spectroscopic principles. In transillumination imaging using near-infrared (NIR) light, we can visualize the location of internal bleeding, infection, and angiogenesis.

The number of experimental animals killed for experimentation would be reduced if we were able to visualize the animals’ internal structures non-invasively. Three-dimensional imaging with X-ray or MRI has contributed greatly not only to medical diagnosis, but also to life science.

Kappa saphir deconvolution