Speaker
Giacomo Bartesaghi
(INFN Mailand)
Description
Radiotherapy, together with chemiotherapy and surgery, is one of the main
methods applied in the fight against cancer; in order to increase the chances
of a successful radiotherapy treatment the dose delivery to the tumour
areas and the surrounding normal tissues has to be computed with high
accuracy. Standard dosimeters are accurate but too small (ionization
chambers and diodes) or non real time (radiographic films). At present there
is no device that can perform real time and bidimensional measurements of
a dose distribution. This article will describe the development of a real-time
dosimeter based on scintillating fibers for photon and electron beams (each
one of few mm 3); the fibers are made of polystyrene, that is water
equivalent and thus tissue equivalent, allowing a direct dose calculation. The
small scintillators are inserted in a PMMA phantom; the light produced is
collected by white fibers and readout by a multichannel photomultiplier tube.
Several prototypes (single and multi channel) have been assembled; they
have passed successfully the tests of reliability, linearity response and
comparison with standard dosimeters. The paper will describe the prototypes
and the readout electronics, together with the results of the measurements
with electron and photon beams with energy up to 20 MeV (Varian Clinac
1800), and the status of the 2D dosimeter development.
Author
Giacomo Bartesaghi
(INFN Mailand)
