Speaker
Monica Scaringella
(University of Florence)
Description
Proton radiation therapy is one of the most precise techniques for conformal radiation therapy in the treatment of cancer. One of the aspects that limits this medical approach is the relatively low accuracy of the stopping power (SP) maps inside the tissue, which are required for treatment planning and patient positioning, that today are derived from X-ray CT scans by converting the relative absorption coefficient (“Hounsfield values”) to relative SP.
In this framework proton Computed Tomography (pCT) is an imaging technique based on the use of proton beams with kinetic energies of the order 200 MeV to directly and precisely measure SP distributions.
A pCT system which aims to improve the accuracy on the SP map with respect to the ones obtained by conventional X-ray CT should be able to, at least, partially overcome the problems introduced by the intrinsic effect of the Multiple Coulomb Scattering on charged particles crossing matter. A viable solution to this problem is to measure the trajectory of each single proton both upstream and downstream the object under test. Furthermore the residual kinetic energy of the proton completes the ‘single event’ information. Having measured the trajectory entry and exit points and directions the most likely proton internal path (MLP) could be estimated. Assigning the proton energy loss to each single MLP an initial measurement data set can be constructed to be converted into 3-dimensional SP maps using tomographic reconstruction algorithms.
Subject of this talk will be the description of the pCT scanners developed by the INFN PRIMA/RDH collaboration which are based on a tracker and a calorimeter to measure single protons trajectory and residual energy, respectively.
The tracker is composed by four x-y planes of silicon microstrip detector. Residual energy is measured by a calorimeter composed by YAG:Ce scinitillating crystals.
A first prototype of pCT scanner, with an active area of about 5x5 cm${^2}$ and a data rate capability of 10 kHz, has been constructed and characterized with 60 MeV protons at Laboratori Nazionali del Sud – Catania (Italy) and with 180 MeV protons at Svedberg Laboratory – Uppsala (Sweden). Results of these measurements, including tomographic reconstructions and radiographies of test phantoms, will be shown and discussed.
To enter in a pre-clinical test phase the collaboration has designed a new pCT scanner with an extended field of view (up to ~ 5x20${^2}$cm) and an increased event rate capability up to one MHz. This system will make use of the same technologies of the small one with an improved architecture to cope with the new requirements in terms of event rate and detector complexity. This pCT system, presently under construction, will be also described.
Author
Monica Scaringella
(University of Florence)
Co-authors
Carlo Civinini
(INFN - Florence Division)
Cinzia Talamonti
(University of Florence and INFN - Florence Division)
Concetta Stancampiano
(INFN - Laboratori Nazionali del Sud)
Cristina Pugliatti
(University of Catania and INFN Catania Division)
Domenico Lo Presti
(University of Catania and INFN -Catania Division)
Eleonora Vanzi
(Azienda Ospedaliera Universitaria Senese)
Francesco Romano
(INFN - Laboratori Nazionali del Sud)
Giacomo Cuttone
(INFN - Laboratori Nazionali del Sud)
Mara Bruzzi
(University of Florence and INFN - Florence Division)
Margherita Zani
(University of Florence and INFN - Florence Division)
Marta Bucciolini
(University of Florence and INFN - Florence Division)
Massimo Carpinelli
(University of Sassari and INFN - Cagliari Division)
Nunzio Randazzo
(INFN - Catania Division)
Pablo Cirrone
(INFN - Laboratori Nazionali del Sud)
Stefania Pallotta
(University of Florence and INFN - Florence Division)
Valeria Sipala
(University of Sassari and INFN - Cagliari Division)
