Background: Radioactive material and ionising radiation play a central role in medical diagnostics and therapy. The benefit of ionising radiation is opposed by the risk of irreparable damage of the human organism. This risk, especially for developing malign neoplasms, has particularly been investigated in the population surviving the atomic bombing of Hiroshima and Nagasaki, but also increasingly in persons with occupational or medical exposure to ionising radiation. Methods: We conducted a systematic search for publications in English and German in relevant databases in March 2016. Retrievals were screened by two independent reviewers. We included examinations using imaging procedures with ionising radiation. The assessment of methodological quality was done concerning representativeness, risk of bias, and further limitations, and reporting quality was assessed using the RECORD checklist. Results: The systematic searches identified seven cross-sectional, one register, and four cohort studies. An increase in collective effective doses analogue to the increase of computed tomography (CT) examinations could be observed. An increased risk of brain tumours in children after exposition to head CT and by an increase of the number of examinations was shown. For children with predisposing factors, an increased risk of tumours of the central nerve system, leukemia, and lymphoma was found. Furthermore, a general risk for malign neoplasms or haemoblastoma, and a specific risk for lymphoma after CT examinations of different parts of the body could be observed. Discussion: Taking into consideration a mostly unclear representativeness of studies and an unclear or high risk of bias as well as lack of comparability due to different research questions, the validity of results is limited. Conclusion: The risk of bias due to a large number of reference sources must be reduced in studies leading to realistic estimates of collective radiation doses. The risk of CT-induced radiation exposure for children should be investigated by further studies with a follow-up of at least ten years.