Biomedical Physics: BNCT
The group of Boron Neutron Capture Therapy (BNCT) studies the application of this treatment to tumours that are not operable due to their dissemination or infiltration, and to tumours that are resistant to the conventional therapies. Malignancies like spread hepatic metastases, disseminated lung tumours, mesothelioma, osteosarcoma are often fatal for the patients, and usually are highly disabling. BNCT consists in administrating to the patient a drug able to concentrate the isotope 10-B in the tumour more than in the healthy tissues. Afterwards, the tumour is irradiated with low energy neutrons, causing the neutron capture in boron, occurring with a cross section of 3837 b at thermal energies. This reaction releases two high LET charged particles (α and 7-Li), with a range comparable to the cell size, that deposit all their energy inside the cell where they are produced. The higher boron concentration in tumour comparing to normal cells, guarantees that the damages are selectively confined in the tumour with a substantial sparing of the healthy tissue. The research nuclear reactor TRIGA Mark II at the University of Pavia is an adequate neutron source to perform preclinical experiment and clinical trials of BNCT. In 2001 and 2003, two patients affected by disseminated hepatic metastases from colon adenocarcinoma, were treated applying the protocol of autotransplantation. After boron administration, the liver of the patients was explanted, irradiated in the reactor for about 10 minutes and finally re-implanted. The clinical outcomes, different for the two patients, proved the selective therapeutic effect and the possibility of sparing the normal tissue even irradiating a whole organ. Afterward, new research lines have been started to demonstrate the feasibility of BNCT using external neutron beams to treat disseminated pulmonary tumours and osteosarcoma. In particular, an important point is the study of boron distribution in tumour and in normal cells using in vitro and in vivo models and the demonstration of BNCT effectiveness in terms of tumour evolution as a function of the administered dose. The group is active also in mixed field dosimetry (neutrons and gamma rays, also with microdosimetric techniques), and in Monte Carlo simulations (MCNP, SRIM, GEANT4) for the calculation of treatment plans in radiotherapy.
Recently, the group is working on two new research lines. The first one concerns the project of installing a Radiofrequency Quadrupole accelerator (RFQ) at CNAO. This accelerator, built by INFN, is able to deliver a 5 MeV, 30 mA proton beam that impinges on a Be detector producing a high flux neutron beam suitable for clinical BNCT. The studies focus on the optimization of the neutron beam, the dosimetry, the radioprotection, the treatment planning. Moreover, to perform online the patient dosimetry during the neutron irradiation by imaging, it is possible to exploit a de-excitation gamma emitted by 7-Li following the neutron capture in 10-B. In Pavia, the group is currently building a new detector based on CdZnTe crystals, having excellent characteristics of efficiency and resolution, to obtain a SPECT detection system dedicated to BNCT.
For further information, see the website.
Staff: Saverio Altieri, Francesca Ballarini, Silva Bortolussi, Mario Carante, Nicoletta Protti, Ian Postuma.