Radiotherapy techniques deliver ionizing radiations (X-rays, photons, electrons, protons, etc.) inside cancerous tissues to kill the abnormal cells. Radiotherapy-related activities such as the optimization of the therapeutic radiation dose to patients, workers' radioprotection, linear accelerator commissioning, quality assurance processes and technical innovations of linear accelerators are strongly based on the ability to predict the dose distribution. Monte Carlo based simulations are so far the most accurate tool for the calculation of dosimetric parameters, with the drawback of requiring extensive computing resources to achieve statistically meaningful results in a reasonable time frame. In the last years, advanced cancer treatment clinical and research communities have used e-Infrastructures to support their activities. The present paper reports on the development of a computing facility for helping clinical researchers in using modern R&E networking and distributed computing and storage resources for a new radiotherapy technique: the Intra-Operative Electron Radiotherapy. The web application developed addresses some technical and clinical needs as the design of linear accelerators' collimation systems and the optimization of the patient therapeutic dose distribution.