Image–based dosimetry in 90Y radioembolization

• Main Author: Χριστοδούλου, Μαρία
• Other Authors: Christodoulou, Maria
• Language: English
• Published: 2023
• Subjects: Radioembolization; Yttrium-90; Treatment planning; Monte Carlo simulations; Liver cancer; Ραδιοεμβολισμός; Ύττριο-90; Σχεδιασμός θεραπείας; Προσομοιώσεις Μόντε Κάρλο; Καρκίνος στο ήπαρ

Liver cancer is the sixth most usual form of cancer in the world and remains the third leading cause of death. The most effective treatment method is surgery. Radioembolization with 90Y microspheres is a modern form of treatment that combines elements of brachytherapy and embolization for the treatment of liver cancer. Although it has no contraindications as a treatment method, it is at the center of attention of medical research due to its therapeutic effectiveness. The treatment is based on dosimetric models which are in clinical application. However, the distribution of microspheres is wrongly assumed to be homogeneous. Through the biodistribution of the surrogate 99mTc-MAA, which is available from the imaging protocol of radioembolization. There are significant discrepancies in clinical indications in the distribution between 99mTc-MAA and 90Y microspheres, probably due to the morphological difference such as the size of the beads and the number of particles, in the way of their administration and due to imaging limitations, such as imaging noise. This thesis aims to improve the estimation of the therapeutic dose deposited by 90Y microspheres during radioembolization of the liver to develop personalized dosimetry based on Monte Carlo (MC) simulations. The 3D model developed was based on the use of Dose Voxel Kernels (DVKs) and was tested on data from two patients (the first for post-treatment 90Y PET/CT scans and the second for pre-treatment 99mTc-MAA SPECT/CT scans). The comparison results against direct MC simulations. The results of comparing the measured absorbed dose using DVKs and the direct MC simulation showed a small difference of the order of 2% for the liver and 4%-7% for the water