Position and Deformation-Checking Method Based on Structured Illumination. External Radiotherapy Use

Abstract

The main goal of a radiotherapy treatment is to provide the prescribed radiation dose to the tumor while minimizing healthy tissue irradiation. During every fraction of treatment, correct placement of the patient on the treatment couch as well as early detection of any shape changes that the patient´s body may undergo are crucial, because both affect the dose distribution. Structured illumination by fringe projection is typically used for finding an object’s spatial dimensions by projecting a pattern on it and taking a photo from a specific location. In this paper we propose a different approach for this technique: given an object’s 3D surface, an image can be computed and projected with the objective of locating this object at a specific location; only when the object is at the exact previously chosen position and preserves its original shape and form, an undistorted fringe pattern will be observed. Verification of patient’s correct position on the treatment couch and the detection of shape changes nearby the radiation field are feasible using the structured illumination based method presented in this work, a potentially useful tool for external radiotherapy treatments.