Two-Dimensional Dose Distribution Measurement Based On Rotational Optical Fiber Array: A Monte Carlo Simulation Study

Quality assurance is particularly important for modulated radiotherapies which improve dose conformity and involve complex processes of dose delivery. This work proposes a dose measurement method based on a rotational optical fiber array and the Cherenkov effect as an alternative pretreatment quality assurance method. Monte Carlo simulation toolkit Geant4 is used to study the accuracy and influencing factors of this method. Four different shapes of radiation field are designed to explore the influence of different reconstruction algorithms, fiber spacing, rotation angles, and radiation types on the accuracy of dose field measurement. The results show that the difference between the reconstructed dose field and the reference dose field is within 8% under the irradiation of uniform radiation field. To obtain high-precision reconstructed images, the fiber spacing should be within 2 mm, and at least 60 angles of projection data should be acquired when the fiber array is rotated 180?. In conclusion, the proposed new method using a rotating fiber array can reconstruct the radiation field distribution rapidly, and provides accurate information on the shape and intensity distribution of the radiation field. Further studies are needed to improve the accuracy and feasibility in real clinical practice.