Radiosensitivity and radiobiology

Contours on a geographical map show elevation; without the contours we know which place is where but we won’t know how high is each place. In radiotherapy, contoured dose maps take centre stage. Patients need to wait for the physicist to complete treatment planning before they can receive treatment — because the physicist needs time to optimise the dose contours. We like high dose gradients. That is, rapid dose fall-off as we move out from the tumour (our target) to the surrounding healthy tissues. Depending on tissue type, some tissues can withstand more radiation than the rest. We call this attribute radiosensitivity, of a subject called radiobiology (radiation biology).