| With the application of nuclear technology and the development of radiotherapy technology,radiation measurement and monitoring technology is also developing.Due to the unique size advantage of optical fiber,optical fiber dosimeter has been widely studied.In order to apply the optical fiber dosimeter to small radiation field radiotherapy and narrow space for X-ray detection,the probe size of the optical fiber dosimeter should be as small as possible.In recent years,researchers have been consciously reducing the volume of optical fiber dosimeter.Compact volume is of great significance to improve the integration and spatial resolution of optical fiber dosimeter.Based on this background,a quartz optical fiber X-ray probe smaller than the traditional plastic fiber X-ray probe is designed and fabricated.A capillary filled with Gd2O2S:Tb powder works as the sensing probe and connects to a length of quartz optical fiber.Compared with the traditional optical fiber dosimeter,the optic-fiber X-ray probe with this structure further reduces the size and improves the spatial resolution of the probe.In this article,theoretical model was established to describe that the fluorescent light from the scintillator was received by the optical fiber,and calculated by simulation software.The quartz fiber X-ray sensor under high-energy and low-energy X-rays were tested.The results show that,the dose-rate linearity of the probe was 0.999996 at 6 MV X-ray,and the highest response was 11315 Counts.The dose-rate linearity at 50 kV X-ray was 0.9999,and the highest response was 731448 Counts.The repeatability of the probe was measured at 6MV,600 MU/min,50 kV and 12W,and the relative errors of the maximum repeatability were6.2%and 0.028%,respectively,indicating that the probe has better repeatability at 50 kV X-ray.In addition,the sensitivity of the probe at 6 MV and 50 kV X-ray were analyzed.Therefore,fiber optic X-ray dosimeter has greater application potential in low-energy X-ray dose-rate detection.In order to explore the influence of different structures on the response of quartz fiber X-ray probe under high energy X-ray and the reasons,probes with different structures were designed and fabricated,such as different filling methods,conical structure,coating and different sealing materials.And the dose linearity of each probe was tested under high-energy X-ray,which also reflects its response.Finally,the effects of different structures on the probe response and dose linearity and the reasons are discussed combined with simulation results. |
