Venous translucence

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Overview
Venous translumination or translucence, has been applied in phlebology since 1996 by the surgeon Pedro Fernandes Neto, during ambulatory clinical exams (Brazil). The results were registered in annals of national and international congresses of angiology. It is a process of reflective image visualization of veins by the incidence of light, which reaches up to the superficial venous system. It is an exam of static nature, however it is also a non-invasive method. For being a procedure of easy application and of low cost exam, it can be repeated when it is necessary, what becomes the process useful in the attendance of several pathological situations. Therefore, the use of this process for the obtaining of images with the generation of inconographic files, revealed to be of great importance for the attendance of several stages of venous diseases, beside this facilitating the several treatment conducts, guiding with this, the choice of the best procedure. It is a new diagnostic procedure, still in phase of investigation and a deeper analysis is necessary, in relation to certain technical patterns of this new method. Another aspect is the optical physics. The venous translumination is due to the refraction, absorption and reflection of light, whose principle is the dispersion and absorption of light colors. The color that is not absorbed is reflected and is the one that we can see. Therefore, the venous translumination is based on the incidence of a luminous focus on the vein, where part of the light is absorbed and another reflected, supplying an image of the silhouette of the studied sanguine vase.

Considerations on technical aspects
Some technical considerations, deserve to be described for better understanding of the process that served as a base for this study. Same questions are following related:

How to avoid artifacts or luminous pollution, during the venous translumination ?
Certain beginnings of the reflection and refraction of the light are importants, for the understanding the distorted images that can appear during a scanning. Many of these can be due to inappropriate sources, that would provoke light loss similar to luminous pollution. We reminded that when a light ray happens on a surface, it leaves across the reflection and part enters as a ray refracted in the second middle, from where can or not to be absorbed.

During the venous translumination, the amount of reflected light depends on the relationship among the indexes of refraction of both means that can be altered as in the venous thrombosis or in the dermatolipoesclerose. Considering this technical parameter, we verified that certain types of lamps process more dispersion than reflection and therefore they favor the formation of artifacts. The luminous pollution in compensation, appears for the use of appropriate components.

Focalizing on this question, another aspect that is observed, it the inability to be obtain translumited images with a fiber optic source due to the irradiation frequency being greater than necessary. It is also known that the reflection in an optic fiber source is initially processed, internally. Certain instruments as the venoscopy are not specific for the obtaining of reflected images. The illumination of the skin for distanced infrared light of the area without there being the impression of the source on the skin, doesn't reveal diagnostic images. The handling of the translumination transductor has to be in direct contact with the skin. The process exam should be similar to the accomplished by the doppler ultrasonography.

The tissue
The tissue translumineted by a white light has a refraction index in agreement with its texture. By the impression of the camera on the skin, the red and yellow color is observed. The red color is soon disperses in the skin and the yellow surroundingit begins, to alter its tonality with the change in souce direction. A shade with the change of the direction of the source arises. It is know that the refraction index charge in agreement with the spectrum of transmitted light and when the white light is projected and finds an obstacle, becomes separated in the three elementary colors (RGB). It leaves of this light during the translumination can suffer larger dispersion or reflection depending on the way with that the source is put on the examined area. This handling can define the better image or to harm her interpretation. Everything will depend on the examiner's experience.

Interaction of the light with the one of the color's skin.
The skin is opaque the light. In physics light reception, heat or other type of radiant energy on the part of the molecules, is called absorption. In this case when the tissues are illuminated in the process of translumination, it happens that it leaves of this light is absorbed and the other is reflected. It is known that an object that absorbs the whole radiation that happens on him is known as black body and, therefore the pigments that give color to the skin and the other tissues, absorb certain wavelengths of the white light and they contemplate as well as they transmit radiant energy. This is one of the aspects of the color sensation that captured by our vision. However it is not known the mechanism well by the which certain substances absorb more light than other, presumably that process depends on his molecular structure. Another observed fact is that the light when reaching more pigmented areas or in patients with dermolipoesclerose, she disperses and it suffers the reflection more easily, being prejudiced absorption tends in view that in that situation the refraction index and smaller, for the difficulty that the white light has to penetrate to the subdermic plans.Several studies about the distribution of the elastin and of the collagen fibers in the patients bearers of dermal lesions during CIV, they should be analyzed so that she can verify as the same ones come in these situations and the influence of as it is processed those alterations. Considering this aspect is that a study of the tissues consistences using the translumination and the dermatoscopy could supply important data to complement the diagnosis of some collagen diseases of the and to study the aging of the tissues. The interaction and the relationship of skin color during the translumination is important. like this that individuals of white skin has a better venous visualization during the translumination, than the mulatto or black man.

Influence of the viscosity and of the blood flow
The erythrocytes absorb more light because they are oxygenated. Considering that aspect we can deduce that the venous blood has a light absorption different from arterial blood in which sanguine viscosity is greater due to the higher concentration of CO2 and to the factor of the stasis. In that sense the venous circulation has greater power to reflect the light. When we proceeded the translumination in an arterial-venous fistulae, we didn’t usually observe reflected images also due to the flow velocity is higher and the fact that the sanguine viscosity in the arterial section is less than in the venous segment. The truth is that it is not possible to visualize arterial vases by translumination, because they don’t supply a reflection due to their accelerated inflow. Another considered aspect is that the iron that participates in the composition of hemosiderin and others mine existent in the blood, emit light of several wavelengths when stimulated

Histogram of colors
In the translumination, the spectrum of white light is decomposed of different wavelengths colors, in agreement with the incident area. The histogram represents the graphic visualization of these colors and the luminescence of the obtained images. In a histogram, the intensity of the luminescence is accompanied by the gray baseline that decreases as the source approaches, where the red scale is more intense and it is represented by a line in ascension. The scales of blue and green colors represent in this situations, the refraction indexes of the light in the occasion that the transluminator is positioned in contact with the studied area. In the histogram, when we disable the selection of a scale, for example the green scale, we can map the intensity of luminescence of whole captured images. Bollinger and collaborators remind an exam of their experience, denominated fluorescence videomiscroscopy, based on the video capture of images and study of the luminescence of the same, through the light emission stimulated by the 20% sodium-fluorocein (0.3 ml/l of blood).The principles of spectrographic analysis of this test are similar to that we use to evaluate the intensity of luminescence of captured images by venous translumination, and the histogram that we use also evaluate the scales of red, blue and green (RGB). Finally, we remind that all organic components are composed by several chemical elements that emit light according with its wavelength. This is why the analysis of histogram by the spectrum of colors of transluminated images could be applied, to define a certain organic element in relation to the quality and amount of their components.