My general interest is imaging in radiotherapy, and specifically the use of imaging to improve the precision of radiotherapy. My career started out with the development of imaging detectors for radiotherapy verification. Soon after, image processing and in particular image registration became the focus of my research. Because of my connection to the AMC (I work there one day a week), the application of imaging tools in radiology is also included. Image guided radiotherapy is the modern name of my activities. The combination of image processing and image registration has allowed us to develop advanced image guidance solutions that are also implemented by industry. Because imaging is used to measure and improve the precision of irradiation, also statistical aspects of patient motion and deformation and the safety margin needed to cover these have my interest. The latest development is research into radiotherapy planning systems that work without margins but directly utilize knowledge of geometrical uncertainties in combination with biological models.