Collapsed-Hole Ge-Doped Photonic Crystal Fiber as a Diagnostic Radiation Dosimeter

A new type of microstructured optical fiber, fabricated by collapsing down the entire array of holes formed by a Photonic Crystal Fiber (referred to herein as PCF-collapsed), is used in this study as an ionizing radiation dosimeter. The performance of the optical fiber is evaluated for diagnostic applications, covering doses from a fraction of 1 mGy up to 10 Gy. The effect of different x-ray beam accelerating potentials from 40 up to 125 kVp photon beam, 6 MeV electrons, and 6 MV photons are demonstrated. The performance of the PCF-collapsed is compared with the uncollapsed PCF (PCF-structured) and a conventional 20-μm-core-diameter optical fiber, all three types of fiber being fabricated from the same Ge-doped-preforms. It is shown that while a PCF-structured has relatively low sensitivity, by collapsing all of the holes in the PCF, the TL response of the fiber is increased by more than 16 times, being also more than four times greater than that of the conventional form optical fiber. The PCF-collapsed can detect a minimum dose as low as 0.6 mGy measured and 5.75 ± 0.11 mGy calculated. The TL analysis suggests that a collapsed-hole-PCF enhances structural defects in an uncollapsed-hole-PCF, highly desirable for dosimeter applications.