Fig. 2.

Dose-response relationship between rate of myocardial infarction and mean whole heart dose. The regression line is the best fitting linear dose response relationship (RR = κ[1.18 + 0.06389*MWHD]; P = .006). This results in an ERR of 6.4%/Gy (95% CI, 1.3-16.0). Squares indicate point estimates for dose categories (no RT, <2 Gy, 2-9 Gy, 10-19 Gy, ≥20 Gy; Table 2) and are plotted at the mean MWHD of each dose category. No significant departure from linearity was identified. The sum of the squared distances between the point estimates for dose categories was used to find the best fit of the linear dose-response to the categorical estimates, resulting in a linear RR of 1.18 at 0 Gy. Abbreviations: CI = confidence interval; ERR = excess rate ratio; MWHD = mean whole heart dose; RR = rate ratio; RT = radiation therapy.