Development of a Customized Endoscopic Dual-Diffusing Optical Fiber Probe for Pancreatic Cancer Therapy: Toward Clinical Use.

We developed a dual-diffusing optical fiber probe (DDOFP), capable of uniformly illuminating the anatomical structure of pancreatic duct for photodynamic therapy (PDT) of pancreatic cancer in clinical settings. Optical fiber presents a unique route for pancreatic PDT by enabling access to the pancreatic duct. For effective pancreatic PDT, the optical fiber should produce a uniform illumination covering of the pancreatic duct, while maintaining its transmission property under thermomechanical stresses in surgical environments. The transmission profiles of DDOFP were measured using a charge-coupled device (CCD) camera at two directions: front-spherical and side-cylindrical areas of the optical fiber. We simulated the change in transmission property by curved tube structures using optically transparent phantom. DDOFP was integrated with 19-gauge needle catheter that is commercially used as an optical guide to treat pancreatic cancer. The temperature of DDOFP was measured at the end face using a thermistor probe in the bovine tissue, while delivering laser energy of over 200 and 500 J. DDOFP was customized to secure the inner diameter of the 19-gauge needle catheter of 686 μm to be integrated as a clinical device. The round ball lens fiber tip minimized the back-burn effect caused by blood carbonization during surgery and induced front-spherical diffusion. DDOFP produced uniform light illumination with intensity difference of <10%. When DDOFP was bent with a small curvature <15 mm, the transmission intensity was consistent. Under high-power laser transmission, DDOFP was found to be robust to cracking or deformation. DDOFP was customized for pancreatic PDT with superior thermomechanical property and uniform light illumination at both the front-spherical and side-cylindrical areas. This is the smallest clinically available optical fiber per our knowledge and officially approved by the Korea Food and Drug Administration (item approval number: 17-516). DDOFP can contribute immensely toward the efficient delivery of pancreatic PDT and photothermal therapy.