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24/04/2009Intraoperative radiotherapy equipment based on a 12 mev race-track microtron

Telstar is taking part in a project to develop a piece of Intraoperative Radiotherapy (IORT) equipment based on a Race-Track electron Microtron (RTM). 

The main part of the RTM is located within a vacuum chamber that forms the head of the equipment and this head is moved into position using a robotic arm.  Specifically, Telstar is responsible for carrying out the process engineering and detailing, for drawing up the technical specifications and for manufacture of the vacuum chamber. The electron beam dynamics have been simulated using RTMTRACE code.  For the 2D design of the magnetic system, POISSON code has been used, with the definitive design of the 3D magnets being carried out using ANSYS software. Based on the calculations and the simulation of the movement of the electrons in the RTM, a magnetic system structure consisting of 4 poles has been chosen, and its dimensions and the characteristics of its materials have been defined.

Intraoperative Radiotherapy (IORT) using electrons is a treatment method that aims to combine the work of two disciplines, surgery and radiotherapy, in order to improve local tumour control rates. It consists in the administration, directly into the surgical site, of a high dose of radiation within a certain tumour volume delimited by the radiotherapist during the course of a surgical procedure. This makes it possible to reduce errors in the estimation of the treatment volume, as well as protecting the anatomical structures of the normal tissue by segregating or protecting them.

The main advantages of the race-track microtron proposed by the project over existing equipment dedicated to intraoperative radiotherapy are that, with the same output beam energy, the weight and dimensions of the race-track microtron are reduced and the power consumption is several times lower than that of the linac. The energy of the output beam electrons is determined, with high precision, by the magnetic field of the magnets used to bend the beam, meaning that it is necessary to calibrate the beam each day.  As such, the dose of radiation administered in the operating theatre can be reduced and the number of operations permitted per year can be increased. The output beam energy exchange principle is very simple (extraction from another orbit) for which reason the transverse dimensions of the beam and its energy spectrum do not change.  Furthermore, no uncontrolled currents, known as "dark currents", are generated.

The project, in which Telstar is participating, involves collaboration between a group of companies, research centres and hospitals, led and managed by the Universitat Politècnica de Catalunya (UPC), and carried out at the Institute of Energy Technologies (INTE) at UPC.