Pdf creator version 1.4.xx is mapping 2 specific greek char to the wrong char set. It maps symbol Δ (delta) του 8710 witch happen to be the char for mathematic D and symbol Ω (omega) to 8486 which is also a mathematic symbol. The correct mapping for delta is charset 916 and the correct mapping for omega is charset 937
if((int)b == 8710) { stringToReplace.Add(b.ToString(), "Δ"); }
elseif ((int)b == 8486) { stringToReplace.Add(b.ToString(), "Ω"); }