Département de Physique, de Génie Physique et d'Optique, Université Laval, Québec, QC G1V 0A6, Canada.
Centre de Recherche sur le Cancer, Université Laval, Québec, QC G1R 3S3, Canada.
Sensors (Basel). 2023 Jan 12;23(2):886. doi: 10.3390/s23020886.
The interest in fiber Bragg gratings dosimeters for radiotherapy dosimetry lies in their (i) submillimeter size, (ii) multi-points dose measurements, and (iii) customizable spatial resolution. However, since the radiation measurement relies on the thermal expansion of the surrounding polymer coating, such sensors are strongly temperature dependent, which needs to be accounted for; otherwise, the errors on measurements can be higher than the measurements themselves. In this paper, we test and compare four techniques for temperature compensation: two types of dual grating techniques using different coatings, a pre-irradiation and post-irradiation temperature drift technique, which is used for calorimetry, and finally, we developed a real-time interpolated temperature gradient for the multi-points dosimetry technique. We show that, over these four tested techniques, the last one outperforms the others and allows for real-time temperature correction when an array of 13 fiber Bragg gratings spatially extending over the irradiation zone is used. For a 20 Gy irradiation, this technique reduces the measurement errors from 200% to about 10%, making it suitable for a radiotherapy dose range. Temperature correction for medical low-dose range dosimetry is a first in our field and is essential for clinical FBG dosimetry applications.
光纤布拉格光栅剂量计在放射治疗剂量学中的应用引起了人们的兴趣，这主要基于其（i）亚毫米级尺寸、（ii）多点剂量测量和（iii）可定制的空间分辨率。然而，由于辐射测量依赖于周围聚合物涂层的热膨胀，因此这种传感器强烈依赖于温度，需要对此进行补偿；否则，测量误差可能会高于测量本身。在本文中，我们测试并比较了四种温度补偿技术：两种使用不同涂层的双光栅技术、一种预辐照和后辐照温度漂移技术，该技术用于量热法，最后，我们为多点剂量测量技术开发了实时插值温度梯度。我们表明，在这四种测试技术中，最后一种技术表现最佳，当使用空间上延伸到照射区域的 13 个光纤布拉格光栅阵列时，它允许实时温度校正。对于 20Gy 的照射，该技术将测量误差从 200%降低到约 10%，使其适用于放射治疗剂量范围。该技术是我们在医疗低剂量范围剂量学领域的首次应用，对于临床光纤布拉格光栅剂量学应用至关重要。
