Improved Dosimetry in Radiotherapy with Gold-Coated Fiber Optics

Abstract Background: Patients receiving radiotherapy, a clinical treatment process in which radiation ‎is used for the treatment of various types of cancer, utilize a variety of radiation sources with ‎unique characteristics and procedures. In vivo dose measurements can help identify systematic ‎and random errors in delivery of the treatment and therefore play an important role in quality ‎assurance. Recently, the photon response of optical fibers has been investigated by many research ‎groups. The small diameters of optical fibers increase the possibility of producing a dosimeter ‎with high spatial resolution, important in the sense that an accurate value for the absorbed dose in ‎the surrounding tissue of the dosimeter can be more accurately reported. Another important ‎advantage of optical fibers as radiation dosimeters is that, unlike conventional TLDs, optical ‎fibers are impervious to water. The aim of this study is to verify the dosimetric use of fiber ‎optics in interface dosimetry and to investigate a novel enhanced dose technique using different ‎gold thicknesses as a coating for fiber optics.‎ Methods: To achieve this goal, commercially available Ge-doped SiO2 optical fibers (Cor Active, ‎Canada) with a core diameter of 50.9 ± 4.1 µm were irradiated using a 250 kVp superficial X-ray ‎machine and a dose of 3 Gy. Before irradiation, fiber optics were prepared, and the following ‎steps, preheat annealing and reading, were performed.‎ Results: The results show enhancement with increasing gold (Au) thickness, with the highest ‎percentage dose enhancement of approximately 160% obtained at 80 nm. A slight deviation from ‎the enhancement was obtained at 20 nm, the first thickness of gold. Encouraging results from ‎such studies have paved the way for the development of optical fiber radiation dosimeters ‎specifically tailored to the task of dosimetry in radiotherapy.‎ ‎ Conclusion: An optical fiber dosimeter can be placed within the tissue of interest, which is ‎applicable due to its flexibility.‎