Physics Bucharest 2017

Linear – Quadratic Model • Quantitative explanation of many aspects of radiotherapy observed at the macroscopic (clinical) level, e.g. fractionation and dose-rate effects, divergence of response between tumours and normal tissues, etc.

• Model continues to be developed, e.g. to incorporate effect of oxygen effects, tumour repopulation, etc.

• Limitations • Response at low doses per fraction (<2Gy) – underestimates biological response • Response at high dose per fraction (>10Gy) – not modelled well • Brachytherapy– steep dose gradients