ABSTRACT
Glioblastoma is considered the most common malignant primary tumor of central nervous system. In spite of the current standard and multimodal treatment, the prognosis of glioblastoma is poor. For this reason, new therapeutic approaches need to be developed to improve the survival time of the glioblastoma patient. In this study, we performed a preclinical experiment to evaluate therapeutic efficacy of 166Ho microparticle suspension administered by microbrachytherapy on a minipig glioblastoma model. Twelve minipigs were divided in 3 groups. Minipigs had injections into the tumor, containing microparticle suspensions of either 166Ho (group 1; n = 6) or 165Ho (group 2; n = 3) and control group (group 3; n = 3). The survival time from treatment to euthanasia was 66 days with a good state of health of all minipigs in group 1. The median survival time from treatment to tumor related death were 8.6 and 7.3 days in groups 2 and control, respectively. Statistically, the prolonged life of group 1 was significantly different from the two other groups (p < 0.01), and no significant difference was observed between group 2 and control (p=0.09). Our trial on the therapeutic effect of the 166Ho microparticle demonstrated an excellent efficacy in tumor control. The histological and immunohistochemical analysis showed that the efficacy was related to a severe 166Ho induced necrosis combined with an immune response due to the presence of the radioactive microparticles inside the tumors. The absence of reflux following the injections confirms the safety of the injection device.
ABSTRACT
The aim of this work is quantifying the radionuclidic impurities of the irradiated [(18)O]water originated by the [(18)F]FDG synthesis process, and characterizing, from a radioprotection point of view, the waste streams produced. Two samples of 2.4ml [(18)O]H(2)O, contained in two different target cells, have been irradiated with a proton current of 37µA in a PETtrace cyclotron for about one hour each; after irradiation, without performing any chemical purification process but waiting only for the (18)F decay, they have been transferred in two vials and measured by HPGe gamma spectrometry and, subsequently, by Liquid Scintillation Counting. Previously, Monte Carlo calculations had been carried out in order to estimate the radionuclides generated within the target components ([(18)O]H(2)O, silver body and Havar® foil), with the aim to identify the nuclides expected to be found in the irradiated water. Experimental results for the two samples, normalized to the same irradiation time, show practically the same value of tritium concentration (about 36kBq/ml) while gamma emitters activity concentrations exhibit a greater spread. Considering that tritium derives from water activation while other pollutants are caused by activated cell materials released into water through erosion/corrosion mechanisms, such a spread is likely to be attributable to differences in the proton beam shape and position (production of different natural circulation patterns inside the target and different erosion mechanisms of the target cell walls). Both tritium and the other radioactive pollutants exhibit absolute values of activity and activity concentrations below the exemption limits set down in EURATOM Council Directive 96/29.
ABSTRACT
A new dual MRI/SPECT pH-responsive agent where the SPECT active moiety acts as reporter of the concentration making it possible to exploit the responsiveness of the MRI probe.
