A dosimetry system for fast measurement of 3D depth-dose profiles in charged-particle tumor therapy with scanning techniques

The high complexity and high instantaneous dose rates of the intensity modu lated treatment plans performed using carbon beams at GSI require a good gr anularity of the dose verification procedures. As a consequence, a new dete ctor system was developed in order to obtain a 3D reconstruction of the rel ative depth-dose distributions in a short time, with high granularity and o ver large volumes. The system takes advantage of the active beam delivery s ystem operative in the therapy facility of GSI and consists of one position sensitive detector with a stack of ionization chambers and a range-shifter . After a technical description of the apparatus, the procedure to reconstr uct the 3D measurements is explained and the possible sources of errors in the measurements are analyzed. Finally, the results of the measurement of s ome treatment plans are shown. (C) 2000 Elsevier Science B.V. All rights re served.