Abstract : This paper presents the architecture of the Virtual Imaging Platform sup- porting the execution of medical image simulation workflows on multiple comput- ing infrastructures. The system relies on the MOTEUR engine for workflow execu- tion and on the DIRAC pilot-job system for workload management. The jGASW code wrapper is extended to describe applications running on multiple infrastruc- tures and a DIRAC cluster agent that can securely involve personal cluster re- sources with no administrator intervention is proposed. Grid data management is complemented with local storage used as a failover in case of file transfer errors. Between November 2010 and April 2011 the platform was used by 10 users to run 484 workflow instances representing 10.8 CPU years. Tests show that a small per- sonal cluster can significantly contribute to a simulation running on EGI and that the improved data manager can decrease the job failure rate from 7.7% to 1.5%.