Coincidences->Draw("sinogramTheta:sinogramS>>h2(128, -300.0, 300.0, 128, 0.0, 3.1)");

int x = h2->GetXaxis()->GetNbins();  
int y = h2->GetYaxis()->GetNbins();  
int val = 0;

ofstream output_file("sinogram.csv");

for(int yi=0; yi<y; yi++){
  for(int xi=0; xi<x; xi++){

    val = h2->GetBinContent(xi,yi);
    output_file<<val;

    if(xi != x-1){
      output_file<<",";
    }

  }
  output_file<<"\n";
}
output_file.close()