Technical radiotherapy progress drive the practices towards increasingly more precise irradiations. The recent developments of the various imaging methods and specialized software made more controls possible. The fields of investigations relate to the quality assurance of the irradiation, the reproducibility of positioning, the movements evaluations and real time dosimetry. Radiotherapy finds, in the images exploitation, a strong potential in improving quality treatments, however it is conditioned by the implementation of ambitious programs, time consuming, but essential to grant the precision of virtual simulations and the daily practice. If all the existing technical devices and software offer higher tools than the current practices, the recommendations can be limited to the insurance of a sufficient precision and reproducibility of the whole treatments. It is thus fundamental to be able to filter the errors, the systematic deviations and to control the statistics of positioning and movements. Each radiotherapy department must apply an adapted program to each site and exploit the imaging chain to maintain its results.