The RTK project emerged in June 2010 at the International Conference on the use of Computer in Radiation Therapy when Gregory Sharp and Simon Rit discussed the lack of open-source solutions for cone-beam CT reconstruction. At that time, Plastimatch could perform filtered backprojection reconstruction on CPU and GPU but the architecture of the software did not allow easy evolution towards new iterative algorithms. They decided then to develop a new platform based on the already famous ITK.

The initial developments were based on existing codes and the platform rapidly allowed efficient filtered backprojection reconstruction using the raw data of several cone-beam CT scanners used in radiation therapy. These developments attracted the interest of the Université Catholique de Louvain and the company Ion Beam Application (IBA) who were developing the first cone-beam CT scanner in a proton therapy treatment room. RTK is now used in IBA scanners.

Today, these partners are gathered in the RTK consortium. The RTK platform provides an efficient platform for continuous developments whiile benefiting from the new features of ITK.