Dual-Illumination Ultrasound/Photoacoustic Endoscopic System

Abstract

The high mortality rate of cervical cancer can be minimized by early-stage cancer detection or providing functional information about the tissue to provide an effective treatment. Such clinical procedures require the need for a safe, low-cost, and high-resolution functional diagnostic system. Previously, we proposed a dual-modal ultrasound and photoacoustic imaging endoscope with a miniaturized footprint for imaging the cervical tissue through the cervical canal. Since the light delivery system in our endoscope can carry a limited amount of light fluence (restricted to ANSI safety limits), we proposed to develop a dual, co-planar illumination system to irradiate cervical tissue both from inside and outside. The proposed endoscopic system was developed by coupling the external illumination system to the developed US/PA imaging endoscope. The external illumination system can provide additional illumination to the cervical tissue through the vaginal fornix area. The total diameter of the external illumination system is 4.2 mm and comprises of seven optical fibers. The performance of the system was evaluated through a tissue-mimicking phantom. Results indicated that the combined dual-illumination system enabled PA imaging to provide a higher consistent signal amplitude. In addition, an enhanced signal to noise ratio and contrast to noise ratio was achieved throughout the whole mimicked tissue phantom thickness while complying with the safety limits for light fluence.