Development of a coherent optical imaging system for clinical dermatology

Abstract

The abnormal structure of cutaneous capillaries is associated with many skin diseases including skin cancer and port wine stain. Consequently, the demand for an imaging modality that can provide non-invasive visualization of capillary level blood flow is high. The major challenge in such imaging is to achieve high resolution and great flow sensitivity over a sufficient depth. Numerous imaging techniques derived from optical coherence tomography have provided a technical breakthrough and produced promising images of capillary networks of retina and brain tumors. However, these modalities have never been applied in clinical dermatological studies. This thesis illustrates the process of design and complete construction of an optical frequency domain imaging (OFDI) system for dermal vasculature imaging that can be used in a clinical environment. The system consists of optical hardware, electronics, and a microscope; every part is contained in a portable cart that can be readily carried to a clinic. The optical subsystem includes a wavelength-swept laser source, a fiber optic interferometer with a delay stage and a polarization-sensitive balanced receiver. All power supplies, control drivers and monitoring circuits are integrated and enclosed in a case with a control interface. The microscope is attached to an articulating arm to be positioned as desired while the patient sits at ease. The system performance is summarized as 10 [mu]m resolution with frame rate of 100 frames per second. Further studies, in collaboration with dermatologists, will involve imaging the vascular structure of port wine stain lesions and investigating their correlation to laser treatment.