Inactivation of individual mammalian cells by single alpha-particles.
OBJECTIVE
To measure clonogenic death of Chinese hamster V79 cells following exposure to a defined number of 4.3 MeV alpha-particles (track-averaged LET = 105 keV/micron).


METHODS
Cells were irradiated at the radiobiological facility installed at the TTT-3 Tandem accelerator in Naples by using a 'Biostack' approach, which allows the positions of incident tracks relative to cells to be carefully determined. Subcellular structure was identified by fluorescence microscopy, while tracks were visualized by LR-115 solid state nuclear track detectors.


RESULTS
Particle hits in the cytoplasm did not significantly affect cell survival, yet survival probability decreased exponentially as a function of the number of nuclear traversals. Measured probability of surviving to exactly one 4.3 MeV alpha-particle traversal in the cell nucleus was 0.67 +/- 0.10. Inactivation cross-section was substantially higher than expected from conventional survival curves. However, folding of the data with Poisson statistics showed that survival level expected if a mean of one alpha-particle goes through a nucleus is higher than the measured value after exactly one particle traversal.


CONCLUSIONS
V79 cells have about 67% probability to survive a single alpha-particle traversal in the cell nucleus. Single-particle survival curves are consistent with conventional dose-survival relationships, once Poisson distribution of traversals is taken into account.
Pugliese
M
M
Servizio di Radioprotezione, Università Federico II, Mostra d'Oltremare, Napoli, Italy.
Durante
M
M
Grossi
G F
GF
Monforti
F
F
Orlando
D
D
Ottolenghi
A
A
Scampoli
P
P
Gialanella
G
G
D000512:Alpha Particles / Q000009:adverse effects*; D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000528:radiation effects; D002470:Cell Survival / Q000528:radiation effects; D006224:Cricetinae; D003412:Cricetulus; D003600:Cytosol / Q000528:radiation effects; D005347:Fibroblasts / Q000166:cytology / Q000528:radiation effects*; D007091:Image Processing, Computer-Assisted; D018499:Linear Energy Transfer; D008432:Mathematical Computing; D008856:Microscopy, Fluorescence; D009010:Monte Carlo Method