A significant proportion of the normal brain tissue is spared when the doses of radiation deposited by the microbeams is in the order of thousands of grays (Figure 1) [1,2].
Figure 1: Photo of a stained horizontal brain tissue section after the passage of micro beams, showing the destruction of cells in the path of the beams while other tissues remain intact (image from: Laissue et al.).
The purpose of our work was to develop this technique at the ESRF by (i) repeating the experiment performed by Laissue et al. ; (ii) optimising the experimental parameters, and (iii) comparing the technique with other synchrotron-based therapy techniques. Survival curves obtained after irradiation are plotted in Figure 2.
Figure 2: Survival curves obtained after irradiation. Details of the series are presented in Table 1, below.
|Series||Cells type||Protocol of implantation||Spacing||Rats per series|
|1||9L||104 c in 1 µl||200 µm||23|
|2||9L||104 c in 1 µl||200 µm||11|
|3||9L||104 c in 1 µl||100 µm||12|
|7(seam)||9L||104 c in 1 µl||no spacing||12|
|Ctrl||9L||104 c in 1 µl||no irradiation||6|
Table 1: The irradiation protocol.
Although the survival time obtained in this experiment is smaller than the one obtained by Laissue , there is the same proportion of rats showing a complete ablation of the tumour after irradiation. Future experiments will be devoted to finding the best compromise between tumour destruction and preservation of normal brain tissue in order to improve the survival curves.
P. Regnard, G. Le Duc, E. Brauer, I. Troprès, L. Lamalle, S. Bouvier, C. Clair, H. Bernard, A. Joubert, F. Lopes, J. Gastaldo, D. Dallery, J. Laissue and A. Bravin.
 Zeman, Curtis et al. 1961.
 Curtis 1967.
 Laissue et al., 1998.
 Laissue, Geiser et al. 1998.