Purpose: Compared to photons, using particle radiation in radiotherapy reduces the dose and irradiated volume of normal tissues, potentially reducing side effects. The biological effect of dose deposited by particles such as carbon ions, however, differs from that of dose deposited by photons. The inaccuracy in models to estimate the biological effects of particle radiation remains the most important source of uncertainties in particle therapy. Improving this requires high-precision studies on biological effects of particle radiation. Therefore, the authors aimed to develop a facility for reproducible and high-precision carbon-ion irradiation of cells in culture. The combined dose non-uniformity in the lateral and longitudinal direction should not exceed +/- 1.5%. Dose to the cells from particles than other carbon ions should not exceed 5%.
Methods: A uniform lateral dose distribution was realized using a single scatter foil and quadrupole magnets. A modulator wheel was used to create a uniform longitudinal dose distribution. The choice of beam energy and the optimal design of these components was determined using GEANT4 and SRIM Monte Carlo simulations. Verification of the uniformity of the dose distribution was performed using a scintillating screen) lateral) and a water phantom) longitudinal) . The reproducibility of dose delivery between experiments was assessed by repeated measurements of the spatial dose distribution. Moreover, the reproducibility of dose-response measurements was tested by measuring the survival of irradiated HEK293 cells in three independent experiments.
Results: The relative contribution of dose from nuclear reaction fragments to the sample was found to be
Conclusions: With the new facility, high-precision carbon-ion irradiations of biological samples can be performed with highly reproducible results. (C) 2011 American Association of Physicists in Medicine. [DOI: 10.1118/1.3528164)]
- particle radiotherapy
- carbon ions
- RELATIVE BIOLOGICAL EFFECTIVENESS
- RAT SPINAL-CORD