Personalized Radiotherapy Clinical Target Volume from a novel DTI-derived Tumour Spread Index (TSI) map

Motivation: GBM patients suffer from poor treatment outcome. The current radiotherapy planning (i.e. GTV, CTV, PTV) does not adjust the CTV margin to account for the microscopic spread of the glioma tumour cells along white matter fiber tracts. Goal(s): Utilizing DTI MRI to tailor the CTV margin to each patient's unique tumour progression pathway. Approach: Pre-surgical DTI-based tractography was used to quantify tumor spread probability, producing the Tumour Spread Index (TSI) map, which was used to generate a personalized CTV. Results: This proof-of-concept study showed that using DTI-based tractography with a TSI map to personalize CTV improved coverage of recurrent regions in follow-up imaging. Impact: Utilizing tractography to map the probable path of tumour spread and use this to direct radiation is a new paradigm in targeted radiotherapy which may lead to improved progression free survival in GBM patients.