Incident Angle Study for Designing an Endoscopic Tool for Intraoperative Brain Tumor Detection

In neurosurgical procedures maximizing the resection of tumor tissue while avoiding healthy tissue is of paramount importance and a difficult task due to many factors, such as surrounding eloquent brain. Swiftly identifying tumor tissue for removal could increase surgical outcomes. The TumorID is a laser-induced fluorescence spectroscopy device that utilizes endogenous fluorophores such as NADH and FAD to detect tumor regions. With the goal of creating an endoscopic tool for intraoperative tumor detection in mind, a study of the TumorID was conducted to assess how the angle of incidence (AoI) affects the collected spectral response of the scanned tumor. For this study, flat and convex NADH/FAD gellan gum phantoms were scanned at various AoI (a range of 36 degrees) to observe the spectral behavior. Results showed that spectral signature did not change significantly across flat and convex phantoms, and the Area under Curve (AUC) values calculated for each spectrum had a standard deviation of 0.02 and 0.01 for flat and convex phantoms, respectively. Therefore, the study showed that AoI will affect the intensity of the spectral response, but the peaks representative of the endogenous fluorophores are still observable and similar. Future work includes conducting an AoI study with a longer working-distance lens, then incorporating said lens to design an endoscopic, intraoperative tumor detection device for minimally invasive surgery, with first applications in endonasal endoscopic approaches for pituitary tumors.