Optimisation of 90Y Selective Internal Radiation Therapy (SIRT) Procedures: towards improved personalised dosimetry

Selective internal radiation therapy (SIRT) is a well-established therapy for treating unresectable hepatocellular carcinoma (HCC). The current PhD research, identified and quantified uncertainties in the dosimetric process for 90Y SIRT treatments and developed new methods for improved accuracy in the dose estimation and delivery. Current planar nuclear medicine imaging methods often overestimate the Lung Shunt Fraction (LSF). A new scatter correction method was developed, improving LSF accuracy which is easily implementable in any standard nuclear medicine department. The improved accuracy of SPECT/CT LSF estimation was demonstrated using realistic 4D anatomical phantoms. The corrected planar method from the first study also showed comparable accuracy, offering a simpler alternative. The implications of tumour delineation among different radiologists on the dosimetric accuracy in SIRT was investigated. Post-treatment 90Y PET/CT is challenging due to the decay characteristics of 90Y which makes dose verification challenging. This study optimised imaging parameters for 90Y PET/CT following SIRT. The irregular shape of liver tumours make dose quantification challenging. Radiomic analysis of SIRT patient data was used to 3D-print tumour models and imaged to assess the uncertainties non-spherical objects have on quantitative 90Y PET/CT. The work presented in this thesis has addressed some of the challenges associated with the dosimetric accuracy in SIRT therapies and provides a means for correcting for some of these limitations.