Abstract: A dermatology handpiece delivers a treatment beam of optical energy to a lesion. The handpiece has the ability to selectively determine whether or not the treatment beam is delivering optical energy to a lesion or to healthy tissue. This is achieved without visual inspection of the skin surface by the physician. Slight variations in tissue, not readily discernable by the human eye, can be detected and treated. A base line, or threshold, is established for the treatment area. Normal tissue, falling below the base line, does not receive a dose of optical energy. A threshold or base line signal is created by taking a reading of healthy skin. The dermatology handpiece is adjusted so that the treatment beam is not delivered until a threshold or base line signal is exceeded. Substantially all of a lesion receives the proper amount of optical energy in the treatment beam, while healthy tissue does not receive a dosage of optical energy.