In patients with cancer the correct diagnosis is the basis for the correct treatment. Ultrasound, CT, MRI, SPECT and PET/CT are used for primary diagnosis, staging, evaluation of treatment effect, control, in patients with relapse and for planning of radiation therapy. The choice is made after diagnostic strategies based on sensitivity, specificity, side effects and price. Due to radiation ultrasound and MRI are preferred in children and adolescents. Denmark has a low use of diagnostic imaging, the challenge of tomorrow is to offer our patients the correct diagnostic imaging without delay and with high quality for both protocol and image interpretation.