From 1985 to 1995, the field of radiation oncology changed dramatically, primarily due to the improvements in computers. Updates to treatment planning systems enabled the move from 2D treatment planning to 3D treatment planning with far more accurate contours of both targets and healthy tissue. Conventional simulation equipment was replaced with spiral CT systems, supporting the move from 2D to 3D planning. As targets were better defined, treatment techniques shifted toward conformal therapy, utilizing multileaf collimation systems to shape fields and create nonuniform fluences used for intensity-modulated radiation therapy. The concept of tomotherapy, intensity-modulated radiation therapy-treated slice by slice, was introduced. Dose constraints for healthy tissue were studied in more depth. Major discoveries occurred in radiation biology, which led to improved treatment outcomes. However, accidents occurred too. Overall, the computer revolution greatly impacted radiation oncology during these years, pushing it toward modern treatment techniques.