Application of Photometric Stereo in Dermatology - Essay Example

Dermatology Running head: APPLICATION OF PHOTOMETRIC STEREO IN DERMATOLOGY Application of photometric stereo in dermatology Write here Write the name of the institution here The advent of new technology has always been the main driving force behind the development of new diagnostic and treatment methods in the medical profession. PhotoDerm represents one of the various technologies that are used in medicine to treat and detect various diseases. It is used in dermatology to treat various conditions like facial blood vessels and redness, leg veins, an elevated scar, a port wine stain, a spider vein and even tattoos. PhotoDerm has been used worldwide since 1995 and its full potential has gained recognition during the last few years. The treatment and diagnostic method known in medicine as PhotoDerm is actually based in a concept in physics known as photometric stereo, which gives the ability to estimate local surface orientation by using several images of the same surface taken from the same viewpoint but under illumination from different directions. Woodham first introduced it. The light sources are ideally point sources some distance away in different directions, so that in each case there is a well-defined light source direction from which to measure surface orientation. Therefore, the change of the intensities in the images depends on both local surface orientation and illumination direction. Photometric stereo is a way in which the ill-posed problems in shading from shading can be resolved. It uses several images of the same surface under different illumination directions. The advantages of photometric stereo are: 1) Unlike single image shape from shading algorithms, photometric stereo makes no assumption of the smoothness of the surface, which it makes it quite useful in determining surfaces so individual as the skin. 2) It also requires only additional lighting and can be easily implemented at a reasonable computational cost. 3) Each image brings along its own unique reflectance map, therefore each image will define a unique set of possible orientations for each point, making a better analysis of the skin. 4) Photometric stereo can recover not only surface orientation but also surface albedo. The system triggers up to 16 lights, one at a time, synchronized with a high-speed video camera to capture views of a surface under various lighting directions. Photometric stereo is used to extract surface normals, and reflectance transformations to relight objects by introducing specular highlights. In the past, PhotoDerm has been the recommended treatment for patients who have extensive broken blood vessels, chronic facial redness or who have severe, long lasting facial blushing. It can be as a result of an abnormal functioning of blood vessels (altered responsiveness to substances delivered via the blood stream, altered responsiveness to neurotransmitters released from nerves, altered responsiveness to substances released from the epidermis or dermis) or in the chronic stages, structural damage to blood vessels and abnormal blood vessel growth in response to the chronic inflammatory environment. In mild cases, there are mild abnormalities in blood vessel function and structure. In more severe cases, there is extensive damage and dysfunction of these blood vessels. As the blood vessels become more abnormal and more leaky, one experiences more triggers. When the blood vessels are irritated and damaged, it changes the resting state of the blood vessel (length tension characteristic of the muscle layer of the blood vessel) making it much more responsive to many substances and triggers (i.e., able to open up much more easily to deliver more blood to the facial skin). Photoderm treatments act in a way that they remove the damaged and functionally abnormal blood vessels. These blood vessels will be replaced by smaller, stronger blood vessels. When treatment with PhotoDerm, several guidelines should be followed: 1. A patient should never stop the treatment after only the first, the second or even the third treatment. This only removes the obvious structurally damaged blood vessels. The patient should follow up with 4, 5, 6 or even more treatments. In addition, they are finding out that by inducing a facial flush prior to treatment has an extremely beneficial effect on the outcome of the treatment. 2. Individual patients have individual settings. Skin tone, the thickness of skin, the depth of the vessels, the orientation of the vessels, the vessels involved (blue veins, red arterioles, or both) should be taken into consideration. More important then the initial settings are the follow up treatments. The physician should be extremely aggressive and adjust the control settings after each session -- in order to get different size vessels, different vessel types, and different depths of vessels. 3. If the nose of the patients is involved, the physician should treat underneath the tip of the nose and underneath the sides of the nose where a great majority of blood enters the area. 4. EMLA anaesthetic crme or any other crme should not be used. Some scientists claim that EMLA is a topical vasoconstrictor and will limit the success of the treatment. In addition, any topical crme or makeup can potentially alter the penetration of the light treatment. This was already proven. The patient can use a topical 2 or 4% lidocaine gel (which is also a vasodilator -- great) or the patient should ask the physician about oral pain killers prior to Photoderm. 5. Patients will experience swelling if the crystal is placed to close to the delicate under eye area, so the physician should be especially careful. 6. Treatment of the nose should be with the smaller crystals to allow better contact with the curves of the nose. 7. Some of the tougher vessels respond better to double pulses (and even triple pulses). At present, there are 3 different types of PhotoDerm treatments- Multilight VL, Pigmented Lesion Removal (PL) and Epilight Hair Removal (HR). Multilight VL takes the advantageofadiscoverytermed SelectivePhotoThermolysistospecificallytargetcertain tissueswithIntensePulsedLight.Intense Pulsed Lightis similarto laser technology,butemits a broader,andthus more controllable,spectrum of light, which allows computer manipulation totargetspecifictissuecomponents ofthe skin. In the case of lesions of the vascular system,such as spider veins of the face or legs,vascular birthmarks, small varicose veins, prominent facial and neck veins, and blood vessellesions of the trunk,the target tissue is haemoglobin in the blood.A computeris then used to selectivelypulse thelightsource inaspecific wavelengthrange, heating visible bloodvessels, whilesparing allthesurrounding normal skin.This techniquecontrolsdepth ofpenetration, and degree of heating,eliminating the need for tedious and potentially painful needle vein sclerosis, and eliminating the need for electric spark cauterywhich can leave scars. This technique iseffective for mostpatients,butmustnotbe usedin patientswithrecentlytanned skin,orthose with darker complexions,due tocross - reactivity withthe skin's naturalmelaninpigment.Representative patient photos fromourSkin Care Suite are shownbelow. The Pigment lesion removal allows the removalofall mostvarieties ofbenign pigmented lesions includingand similar lesions. This technology takes advantage of the Pigment lesion removal, and the abilityto computer-manipulate the wavelengthsemitted,to specifically target melanin,the brown pigmentinmostoftheselesions. This amazing technology will heat the melanin, destroying it, while sparing thesurrounding normal skin. Selected cases are shown below, and more will follow shortly. The Epilight process is purely used for cosmetic purposes for long-term removal of unwanted hair. This system uses a broad range of light waves,manipulatedbyspecial filters,andcomputer- controlled,to focuslightenergyondeeperhairfollicles, whilesparingtheoverlyingskin,taking advantage of the concept of Selective PhotoThermolysis. In this instance the target tissueisthe melaninpigmentationassociatedwith hair follicles,andthus the heat can be localized to the hair itself and the cells of hair production deep within the follicles. Because onlyacertain proportion ofthe hair at any given site is undergoing active growth at any given time,and that proportion varies with the location,there is often a need for more than one treatment. This allowseradication of most oftheactively growinghair,butwhenthedormant hair beginstoemerge,asecondorthird treatmentmaybeneeded to obtain an optimal result. This approach to hair removalhas a much wider latitudethansinglewavelength laser techniques,and it allows not only a broader spectrum of hair colour response, but also a deeper penetration of the skin, to more thoroughly destroy the follicles,eliminating the unwanted hair. Afurtherbenefitistherelativelypainless sensation oftheEpiLight,alongwiththe avoidanceof the post-treatmentburning pain sensation often seen withlaser methods. This treatment should not be applied to recently tannedskin,anddespite some claims,isnotsuitablefor darkly pigmented patients at the present time. Research is currently underwayto allowbroadening ofthe applicability of the techniquetoincludeAfrican-Americans,andother darklypigmentedpatients. The strengthof EpiLight is the avoidance of endless waxing andits tendencytoingrownhair,andthe avoidance of tedious,painful, andcostly electrolysis hair removal, which is often ineffective,and may leave scarring or discoloration. As we have seen, PhotoDerm is the frontrunner in the diagnosis and treatment of dermatological diseases. It is clearly seen that this technology will only be improved further and that quite some time will pass before it is replaced. References: Frequently Asked Questions about PhotoDerm Hair Removal; Retrieved (7 March 2007) http://www.dermlaser.com/hairfaq.html Skin Care Review: Intense Pulsed Laser (IPL) - Photoderm; (2007) Retrieved (7 March 2007); http://www.smartskincare.com/reviews/product/lighten_ninvproc_na_ip-laser_20020910.html Ancevski, Gocev, Pavlova, Petrova; (2005) Dermatovenerologija; Skopje, Macedonia; Kultura. Read More