Poster Presentation – Abstracts Archive
UK & Ireland Prostate Brachytherapy Conference 2017
Abstract number 20
Fabry-Pérot based optical fiber sensor for real time measurement of oxygen level in hypoxic tumors for prostate cancer during radiation therapy
Viphavakit C*; O’Keeffe S*; Andersson-Engels S** ; Lewis E*
*Optical Fibre Sensors Research Centre, University of Limerick **Irish Photonic Integration Centre, Tyndall National Institute, Cork
The hypoxia detecting sensors described in this article are developed to assist clinicians in diagnosis and real-time monitoring of radiation dose in radiotherapy of hypoxic tumors, which are tumors with a lower oxygen level compared to the surrounding tissues, especially in the case of prostate cancer. An optical fi ber sensor based on a Fabry-Pérot interferometer is described as a new and innovative sensor. The sensors have an outer diameter of 220µm with a 20-30µm length air-cavity and a 30µm thickness end cap located at the tip of the sensor. They are made entirely of silica glass optical fi ber, which is a passive material, and coated with gold, which is a biocompatible material. Therefore, the sensor can be used as an invasive tool to access within the tumors while receiving the radiation treatment by integrating within biopsy or Brachytherapy needles. Partial pressure of oxygen (pO2) level is a key parameter used to differentiate the hypoxic tumors from surrounding healthy tissues. The pO2 level is related to the hemoglobin level which can be interpreted from the change of the refractive index in red blood cells in this work. The sensors are used to measure the phase change in the received optical spectrum when there is a change in refractive index using a Fast Fourier Transform based analysis method. The FFT method is independent of signal amplitude allowing a simple phase based measurement as the amplitude (intensity) control and wavelength evolution tracking are not required. The device is able to detect the changes when there is a very small change of the refractive index in the blood solution which is in a range between 1.343 and 1.348. The resolution of the device is in order of 10-3 refractive index units (RIU) with a sensitivity of 9.44 rad/RIU.