More recently , contradictory data have been reported . Lemon et al . [ 52 ] investigated cancer development and longevity of cancer - prone Trp53 + /− mice exposed to a single 10 - mGy CT scan or gamma irradiation . CT - scanned mice lived longer than the control mice , and CT caused a significant increase in the latency of sarcoma and carcinoma . In another experiment from the same group , 4 Gy was administered first to the same mice and weekly CT scans were repeated 10 times [ 53 ] . The overall lifespan was about 8 % longer in mice exposed to multiple CT scans after 4 - Gy irradiation than the control mice receiving 4 Gy alone . Increased latency periods for lymphoma and sarcoma progression contributed to the overall lifespan increase . Thus , conflicting data exist regarding the oncogenicity of CT radiation exposure . However , it should be noted that the former study suggesting the bionegative effect used only 20 mice per group , whereas the latter two studies employed about 100 or 200 mice per group . than the control mice receiving 4 Gy alone . Increased latency periods for lymphoma and sarcoma progression contributed to the overall lifespan increase . Thus , conflicting data exist regarding the oncogenicity of CT radiation exposure . However , it should be noted that the former study suggesting the bionegative effect used only 20 mice per group , whereas the latter two studies employed about 100 or 200 mice per group .