Abstract
Transillumination with non-ionizing radiation followed by the observation of transmitted and diffused light is the simplest, and probably the oldest method to obtain qualitative information on the internal structure of tissues or body sections. Although scattering precludes formation of high-definition image (unless complex techniques are employed), low resolution pictures complemented by information on the functional condition of the living sample can be extracted. In this context, we have investigated a portable optoelectronic instrumental configuration for efficient transillumination and image detection, even in ambient day-light, of in vivo samples with thickness up to 5 cm, sufficient for visualizing macroscopic structures. Tissue illumination is obtained with an extended source consisting in a matrix of 36 near infrared Vertical Cavity Surface Emitting Lasers (VCSELs) that is powered by a custom designed low-voltage current driver. In addition to the successful acquisition of morphological images of the hand dorsal vein pattern, functional detection of physiological parameters (breath and hearth rate) is achieved non-invasively by means of a monochrome camera, with a Complementary Metal Oxide Semiconductor (CMOS) sensor, turned into a wavelength selective image detector using narrow-band optical filtering.
Highlights
Optical imaging methods have been successfully applied in biomedical and clinical applications and reviewed in several recent publications [1,2,3]
Tissue illumination is obtained with an extended source consisting in a matrix of 36 near infrared Vertical Cavity Surface Emitting Lasers (VCSELs) that is powered by a custom designed low-voltage current driver
With thethe transillumination system; (b) photo of the hand taken with a color transillumination system; (b) photo of the hand taken with a color Complementary Metal Oxide Semiconductor (CMOS)
Summary
Optical imaging methods have been successfully applied in biomedical and clinical applications and reviewed in several recent publications [1,2,3]. Optical transillumination is a non-invasive diagnostic technique based on the use of a light source placed underneath the tissue under test, to identify internal structural abnormalities. For all the reasons mentioned so far, transillumination followed by the observation of diffused light, though probably the oldest and simplest method to obtain qualitative information on the internal structure of tissues or of a body section [10,11,12,13], is not yet considered a reliable diagnostic method It is only exploited as a first approach to a diagnostic suspicion, in view of more detailed and invasive tests [14,15].
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