C. Peroni

MATRIX: AN INNOVATIVE PIXEL IONIZATION CHAMBER FOR ON-LINE BEAM MONITORING IN HADRONTHERAPY

The control of beam position and dose delivery are key issues in the treatment of tumours using hadron beams, especially in the case of active dose distribution systems. In this framework, an innovative pixel ionization chamber has been designed and constructed for 2-D control of beam position, shape and intensity. This chamber is characterized by a 21 × 21 cm sensitive area subdivided in 1024 pixels of 6.5 × 6.5 mm. The 1024 channels are read-out by 8 boards based on 16 TERA06 chips. The sensitivity can be adjusted in the range 100800 fC. The tested minimum read-out time of the full chamber is 1 ms. After some preliminary measurements with X-rays, tests have been performed on the proton beam of the cyclotron of the Joint Research Centre in Ispra, Italy. In March 2005, MATRIX has been successfully tested on several beam lines for proton-therapy at the Loma Linda University Medical Center, US. The very positive results of these tests are presented. Figure 1: Schematic view of the MATRIX pixel ionization chamber.