Development and availability of multislice CT modifies quickly procedures for diagnostic and pretherapeutic explorations. This new technology provides many advantages such as: to reduce time of examination and to facilitate exploration of larger anatomical volumes, to reduce partial volume effects, to enhance the ratio signal/noise, to improve intravascular concentration of contrast product and then to better identify arterial or venous phases. Use of multislice CT for exploration with respiratory gating is also discussed. On the other hand, multislice CT requires new requirements as medical time occupation and handling of important number of images. Active collaboration between radiologists and radiation oncologists is needed to define new acquisition modalities and practical ways of co-interpretation.