Verificação das etapas de registro e delineamento em planejamentos de radiocirurgia estereotáxica

Abstract

Some requirements in the quality assurance process are necessary to perform special treatments, such as stereotaxic cranial radiosurgery (CR). Among some points of attention, it is possible to mention small-field dosimetry; validation of the planning system; assessment of IGRT systems; teams training, end-to-end test; periodic quality controls definition and others. The goals of this work were to verify the steps of image acquisition, registration and delineation of structures in a radiosurgery plan, bringing greater security to the process. Using Sun Nuclear's StereoPHAN phantom, computed tomography, magnetic resonance imaging and planar images obtained from a angiography device were acquired from the phantom and imported into the treatment planning system (SPC) iPlan. The images were visually and quantitatively inspected, using metrics such as the Target Registration Error (TRE), internal cavities dimensions evaluation and variations between the edges of the volumes delineated between the different series of images. The results were satisfactory for the analysis of the TRE, being smaller than the size of one voxel in the fusion process, the superposition of the delineation of the spheres, did not present a difference in the edges greater than 1 mm, but the calculated volumes were superior to the smaller spheres when delineated using the planar images. This fact is related to the low contrast of the planar images obtained, causing the delineation to be slightly larger than expected. It is concluded, therefore, that the SPC used is adequate for the processes tested in CR and the SteroPHAN phantom contributed to an independent verification, even though the institution already has established quality controls for the practice of CR.