Heitger, K. (2022). Correction of detector panel deflection for accurate intra-fraction motion monitoring in a radiotherapy linear accelerator [Diploma Thesis, Technische Universität Wien]. reposiTUm. https://doi.org/10.34726/hss.2022.77509
Radiotherapy is used to cure cancer by applying ionising radiation, mostly hog energy photon beams. One the most common devices for treatment in radiotherapy is the linear accelerator (Linac). It has a treatment head and a detector that are both mounted on a gantry. The detector is used for patient position verication. Measurements have shown that during a rotation of the gantry the detector of the Linac experiences a displacement because of gravity. Due to the displacements the resulting images are distorted. A foregoing work measured the displacement of the iViewGT detector used by the Elekta Versa HD, which is used for this work. In this work a corrective algorithm is established to correct the distortion in the images. For this, the measured displacements are taken into account to calculate the necessary transformation matrix, which is then applied to original images. Images acquired at the iViewGT at gantry angles 0° and 180° as well as a simulated image are then used to validate the algorithm. The application of this algorithm results in a decrease of the distortion in these images. The remained distortion in the simulated image is 20%. In a further work the corrective algorithm should be extended for the includingkV-imaging system as it is expected to experience a deection as well.
en
Additional information:
Abweichender Titel nach Übersetzung der Verfasserin/des Verfassers