Tumor-site specific geometric distortions in high field integrated magnetic resonance linear accelerator radiotherapy

Forfattere Hasler SW, Bernchou U, Bertelsen A, van Veldhuizen E, Schytte T, Hansen VN, Brink C, Mahmood F
Kilde Phys Imaging Radiat Oncol . 2020 Aug 19;15:100-104 Publiceringsdato 01 jan 0001


Magnetic resonance imaging (MRI) has exquisite soft-tissue contrast and is the foundation for image guided radiotherapy (IGRT) with integrated magnetic resonance linacs. However, MRI suffers from geometrical distortions. In this study the MRI system- and patient-induced geometric distortion at four different tumor-sites was investigated: adrenal gland (7 patients), liver (4 patients), pancreas (6 patients), prostate (20 patients). Maximum level of total distortion within the gross-tumor-volume (GTV) was 0.96 mm with no significant difference between abdominal patients (adrenal gland, liver, pancreas) and pelvic patients (prostate). Total tumor-site specific distortion depended on location in the field-of-view and increased with the distance to MRI iso-center.

Keywords: Adaptive radiotherapy; Geometric distortion; MR guided radiotherapy; MR-linac; MRI; QA.