Fig. 6: Radioactive washout.

Top: individual activity data recorded after the end of irradiation in Supplementary Fig. 5 are grouped (left: 5 Gy (n = 7 animals), middle: 20 Gy (n = 8 animals), right: comparison of fit functions assuming the physics decay of the beam containing 96% ¹¹C, 3% ¹⁰C and 0.5% ¹⁵O ions). Filled circles represent the total measured activity while the crosses correspond to the activity normalized for a physical decay. As a fit function, a double-exponential decay function was chosen over a single-exponential decay following the results of the F test (ratio of the fit χ² with one or two parameters) with number of degrees of freedom d.f. >100. F(5 Gy) = 1126 (≫1), F(20 Gy) = 63 (≫1). The fit functions are depicted separately on the top left. Orange and blue lines are the fits of the 20 Gy and 5 Gy data, respectively. Dashed lines correspond to the fit of the full decay data, while the solid lines represent the fits of the biological washout data only. Bottom: double-exponential decay rates (k_s for the slow washout constant and k_f for the fast washout constant) and the weight of the slow component (W_s) from equation (1) for 5 Gy and 20 Gy. Box plots display the median (line), interquartile range (box spanning the 25th–75th percentiles) and whiskers extending to the furthest data points within 1.5× the interquartile range. Circles display the individual data points, and colours represent treatment groups (blue for 5 Gy, orange for 20 Gy). Significance of the differences was assessed by two-sided unpaired t-test assuming equal variances. Effect size and confidence intervals were not computed. Data visualization and analysis were performed in Python 3.10 using the Seaborn and SciPy libraries.