TY - JOUR
T1 - A narrow microbeam is more effective for tumor growth suppression than a wide microbeam
T2 - An in vivo study using implanted human glioma cells
AU - Uyama, Atsushi
AU - Kondoh, Takeshi
AU - Nariyama, Nobuteru
AU - Umetani, Keiji
AU - Fukumoto, Manabu
AU - Shinohara, Kunio
AU - Kohmura, Eiji
N1 - Copyright:
Copyright 2011 Elsevier B.V., All rights reserved.
PY - 2011/7
Y1 - 2011/7
N2 - The tumoricidal mechanisms of microbeam radiation therapy, and the more recently proposed minibeam radiation therapy, for the treatment of brain tumors are as yet unclear. Moreover, from among the various parameters of beam geometry the impact of changing the beam width is unknown. In this study, suppression of tumor growth in human glioma cells implanted in mice was evaluated experimentally using microbeams of two different widths: a conventional narrow beam (20 μm width, 100 μm center-to-center distance) and a wide beam (100 μm width, 500 μm center-to-center distance). The tumor growth ratio was compared and acute cell death was studied histologically. With cross-planar irradiation, tumor growth was significantly suppressed between days 4 and 28 after 20 μm microbeam irradiation, whereas tumor growth was suppressed, and not significantly so, only between days 4 and 18 after 100 μm microbeam irradiation. Immunohistochemistry using TUNEL staining showed no increase in TUNEL-positive cells with either microbeam at 24 and 72 h post-irradiation. The 20 μm microbeam was found to be more tumoricidal than the 100 μm microbeam, and the effect was not related to apoptotic cell death. The underlying mechanism may be functional tissue deterioration rather than direct cellular damage in the beam path.
AB - The tumoricidal mechanisms of microbeam radiation therapy, and the more recently proposed minibeam radiation therapy, for the treatment of brain tumors are as yet unclear. Moreover, from among the various parameters of beam geometry the impact of changing the beam width is unknown. In this study, suppression of tumor growth in human glioma cells implanted in mice was evaluated experimentally using microbeams of two different widths: a conventional narrow beam (20 μm width, 100 μm center-to-center distance) and a wide beam (100 μm width, 500 μm center-to-center distance). The tumor growth ratio was compared and acute cell death was studied histologically. With cross-planar irradiation, tumor growth was significantly suppressed between days 4 and 28 after 20 μm microbeam irradiation, whereas tumor growth was suppressed, and not significantly so, only between days 4 and 18 after 100 μm microbeam irradiation. Immunohistochemistry using TUNEL staining showed no increase in TUNEL-positive cells with either microbeam at 24 and 72 h post-irradiation. The 20 μm microbeam was found to be more tumoricidal than the 100 μm microbeam, and the effect was not related to apoptotic cell death. The underlying mechanism may be functional tissue deterioration rather than direct cellular damage in the beam path.
KW - co-planar microbeam
KW - cross-planar microbeam
KW - microbeam radiation therapy
KW - narrow microbeam
KW - wide microbeam
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U2 - 10.1107/S090904951101185X
DO - 10.1107/S090904951101185X
M3 - Article
C2 - 21685685
AN - SCOPUS:79959557882
VL - 18
SP - 671
EP - 678
JO - Journal of Synchrotron Radiation
JF - Journal of Synchrotron Radiation
SN - 0909-0495
IS - 4
ER -