1. PhD Research Project Non-linear determination of planning treatment volume growth margins in radiotherapy Researcher: Bon Mzenda Supervisors: David Brown, Alex Gegov & Mir Hosseini-Ashrafi

2. Purpose Use of novel computational techniques to derive margins for use in cancer treatment with external beam radiotherapy, based on the radiobiological effects of organ motion, patient set-up variations and delineation errors.

3. Fuzzy logic-based margin derivation Why fuzzy logic? Parameters for tumour control (TCP), damage to healthy tissues (NTCP), organ motion, set-up errors and required margin cannot be easily combined using mathematical methods FL offers linguistic rules and membership functions that allow linking of these variables

4. Fuzzy model results Good agreement between fuzzy results and current margin formulations Advantage of FL is that it shows acceptable maximum usable limit of margin sizes

5. Fuzzy network Under investigation to improve transparency of initial fuzzy system Results also show acceptable margins for clinical use