[Particle radiotherapy for malignant gliomas].

Particle radiations using protons or carbons, and boron neutron capture therapy are emerging as a therapeutic modality for malignant gliomas. Some non-randomized prospective studies found favorable results; however, the advantageous method of advantage of conformal radiation using protons or carbon ions and tumor cell-selective radiation using boron neutron capture therapy have not been confirmed. In a recent clinical trial involving 20 newly diagnosed glioblastomas at the Proton Medical Research Center at Tsukuba, the median overall survival time and the 1- and 2-year survival rates were 21.6 months, 71.1% and 45.3%, respectively. In the clinical trial of boron neutron capture therapy of 15 newly diagnosed glioblastomas at Tsukuba, the median overall survival time and the 1- and 2-year survival rates were 25.7 month, 80.0% and 53.3%, respectively. The rationale, history, and clinical results of particle radiotherapy for glioblastoma were also discussed.

Progress in the use of gadolinium for NCT.

The evaluation of possible improvement in the use of Gd in cancer therapy, in reference to gadolinium in cancer therapy (GdNCT), has been analysed. At first the problem of the gadolinium compounds toxicity was reviewed identifying the Motexafin Gadolinium as the best. Afterwards, the spectrum of IC and Auger electrons was calculated using a special method. Afterwards, this electron source has been used as input of the PENELOPE code and the energy deposit in DNA was well defined. Taking into account that the electron yield and energy distribution are related to the neutron beam spectrum and intensity, the shaping assembly architecture was optimised through computational investigations. Finally the study of GdNCT was performed from two different points of view: macrodosimetry using MCNPX, with calculation of absorbed doses both in tumour and healthy tissues, and microdosimetry using PENELOPE, with the determination of electron RBE through the energy deposit. The equivalent doses were determined combining these two kinds of data, introducing specific figures of merit to be used in treatment planning system (TPS). According to these results, the GdNCT appears to be a fairly possible tumour therapy.