Reflectance Feedback During Laser Irradiation of Blood

University of Arizona
posted on 06/05/2010

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Background:  In recent years, the use of lasers for treatment of dermatological conditions and other conditions involving blood vessels has rapidly gained acceptance by the medical community. Lasers delivering light in the green and yellow regions of the visible spectrum are of particular importance for their effectiveness to treat vascular disorders because hemoglobin preferentially absorbs in these regions. This allows hemoglobin to be selectively targeted by the radiation in treatment known as photothermolysis. Resulting absorbed light, induces necrosis of blood vessels in the treated area. The coagulated or necrotized vessels are eventually reabsorbed by the body.

One problem encountered in applying laser treatment is determining a light dosage sufficient to effect the required coagulation, but not so intense to cause undesirable side effects. Coagulation can vary from patient to patient depending on factors such as melanin content of the skin, the size of blood vessels being treated and the depth of the blood vessels in the skin. Extending dosage beyond that required to effect coagulation can lead to complications including scarring, scabing, edema and epidermal damage or extravasation of red blood cells.

Invention:  The invention relates in particular to methods of detecting onset of coagulation in blood vessels, induced by the absorbtion of laser irradiance. During irradiation with a long pulse laser, blood has a characteristic reflectance curve. This reflectance curve has features that correspond to the state of the blood. During irradiation of blood, an increase in the reflectance value corresponds to the onset of coagulation of the blood. A sharp increase to a high level of reflectance corresponds to vaporization of blood. Said reflectance signatures can be effectively used to monitor laser irradiation and its impact on blood and vessels.

Advantages: Automatic feedback for laser irradiation of blood vessels, patient specific laser treatment, increase efficacy of treatment while minimizing side effects.

State of Development:  This invention is reduced to practice. A issued patent US Utility Patent No. 6,766,187 issued on July 20, 2004. University of Arizona seeks licensing partners in the fields of laser treatment of skin, eyes, and vasulature.

Lead Inventor:  Jennifer Barton

UA ID:  UA00-045

 

 

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Automatic feedback for laser irradiation of blood vessels, patient specific laser treatment, increase efficacy of treatment while minimizing side effects.