Thanks to the power it delivers, Bull's NovaScale supercomputer has helped to support a major step forward in cancer treatment, by enabling the extremely precise calculation of the dose of photons and electrons for external radiotherapy treatments. The aim of the project is to improve the precision of radiotherapy treatments, thus increasing recovery chances with reduced risks for the patient. The selected solution is built on the Monte-Carlo type probability models included in the calculation code algorithms. They take into account all the physical effects of the irradiation and enable to increase the precision of radiation doses. Together with the precision of current imaging systems (scanners, MRI...), this innovation is an important step forward in radiotherapy treatment. One of the first countries to benefit from the latest technological advances, and take full advantage of supercomputing power in the form of 'on-demand service' In order to deliver the necessary computing power for the levels of precision required by this new technique, Bull's High-Performance Computing (HPC) Centers of Expertise have developed a pioneering supercomputer, consisting of a cluster of NovaScale R422 servers equipped with Intel Xeon processors capable of evolving to include up to 80 processing cores. In addition, the implementation of a Service-Oriented Architecture (SOA) infrastructure for the HPC architecture has enabled an 'on-demand service' to be set up, giving all medical establishments involved in anti-cancer treatments access to these new technologies. The SOA infrastructure includes the JOnAS application generator, combined with the Bonita workflow engine and a Web application. The system is secured using data encryption, checking data integrity, a Virtual Private Network (VPN), as well as by integrity verification and a directory of access rights. The success of the project has been the result of a close and exemplary collaboration between Bull's Java Enterprise Middleware Center of Expertise (JOnAS, Bonita and JCA connector), the Bull HPC Center for the HPC infrastructure (batch processing and resources management), the Bull Benchmarking Center (performance optimization), and Bull's Services teams who developed the Web application. The chosen radiation physics codes originate from the University of Barcelona, and have been parallelized and optimized by CEA LIST, which has also been responsible for metrological validation on the project. The dose calculation service, developed by DOSISOFT, is in the course of being validated by a number of organizations involved in cancer treatment in France, including the Gustave Roussy Institute in Villejuif and the Curie Institute in Paris. Bull has acted as the co-coordinator of this project, which has been partly funded by the French national network for healthcare technologies, the RNTS (Reseau National des Technologies pour la Sante). It is due to be fully operational and open to all healthcare establishments in early 2009.