Currently, there is great interest in incorporating biological information into intensity-modulated radiotherapy (IMRT) treatment planning with the aim of selectively boosting high-risk tumor subvolumes - a concept that has also been called 'dose painting'. However, conventional IMRT optimization utilizes dose-volume based objective functions, which have inherent limitations such as pursuing homogeneous dose distributions and assuming linear-dose-response curves. In this book we present a dose painting IMRT optimization-framework in which nonlinear biological objective functions are utilized....