Uncertainty evaluation in simulation study on range-shift estimation due to statistical noise in secondary electron bremsstrahlung from a small number of carbon ions

Abstract Secondary electron bremsstrahlung (SEB) has been proposed for range verification in particle therapy. However, the uncertainty in range-shift estimation due to high statistical noise under small numbers of carbon ion irradiation remains unclear. This simulation study evaluated the uncertainty of SEB-based range-shift estimations under conditions with limited numbers of carbon ions. The SEB images were generated by irradiating an acrylic target with monoenergetic carbon-ion beams and calculating the energy deposited onto a cadmium telluride pixel detector in simulation. Estimated range shifts were derived from the obtained SEB images using our proposed range-shift estimation method. As a result, the uncertainty was 1.4 mm for 10 8 ions and 4.4 mm for 10 7 ions. The results suggested that improving the sensitivity of the detector is effective in reducing the uncertainty.