Fig. 4. Digital radiogram
of three different boluses and of one transpon-der: from the left, 72 g, 70 g and 20 g boluses, respectively. The differencein radiopacity of the cases (Al2O3of 72 g bolus vs. zirconia-ceramic of 70 gand 20 g boluses) together with the impossibility to screen the presenceof the inner transponder in 70 g and 20 g boluses is pointed out.