Petrovic B et al. / Verification of EDW in three ways 201 4x4 cm2, 15deg ( field edge 2 cm) 10x10 cm2, 30deg (field edge 5 cm) 15x15 cm2, 45deg (field edge 7.5 cm) Position of detector in relation to Central axis (mm) Position of detector in relation to Central axis (mm) 100 1.63 5.65 CA 24 EPID CA 24 EPID CA 24 EPID CA 24 EPID Position of detector in relation to Central axis (mm) 80 85 90 95 100 105 110 115 120 26.21 10.32 7.25 4.92 4.19 4.04 3.48 3.01 2.74 16.24 14.27 12.92 11.79 10.74 9.86 9.04 8.25 7.64 20x20 cm2, 60deg, (field edge 10 cm) Position of detector in relation to Central axis (mm) 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 68.4 65.96 63.53 61.05 58.53 56.34 54.11 49.82 43.59 21.59 8.34 5.9 4.91 4.5 3.84 3.38 3.14 70.32 67.95 65.59 63.17 60.81 58.67 56.08 52.97 24.67 14.52 13.08 11.99 11.24 10.43 9.63 9.11 8.70 (STT). The EDW provides seven wedge angles (10°, 15°, 20°, 25°, 30°, 45°, and 60°) for both symmetric and asymmetric field sizes. The upper independ- ent jaws, assigned to as Y1 and Y2, can travel from a full open position to 10 cm across the central axis, thus allowing field sizes up to 30 cm along the wedged direction. Two wedge orientations are available: Y1-IN and Y2-OUT, indicating the mov- ing jaw. The EDW needs only one reference STT for each photon energy. This so called ”Golden” STT represents the full field width of 30 cm and a wedge angle of 60°. Intermediate wedge angles can be derived by means of weighted averaging of an ”open field STT” and the Golden STT (ratio of tan- gens method). The individualized treatment STT is then obtained by the truncation to the desired field size and normalization so that the final number of monitor units is the total number of monitor units needed to deliver a certain dose to the reference point. These individualized STTs are created au- tomatically by the linac computer, as the operator types in the energy, wedge angle, monitor units, etc. In order to deliver a dynamically wedged field, the length of the treatment field is divided into 20 segments, and the speed of the moving jaw and the dose rate within each segment are controlled based on a calculated segmented treatment table (STT) generated by the linear accelerator computer. The implementation of dynamic wedges in the various radiation therapy planning (RTP) systems has already been described.1,2 As with any other commissioning activity, great care must be taken to ensure that enhanced dynamic wedges are cor- rectly modelled in the treatment planning system. To directly verify the computational accuracy of a treatment planning system, measurements need to be made with the accelerator setup to the same identical specifications as already planned.3 This work was aimed to verify EDW (described in details in literature)4 in the treatment planning system (TPS) and use patient set up equipment to compare dosimetrical and calculation results with electronic portal imaging device (EPID) measure- ments. In addition, comparison with hard wedges was also presented. The electronic portal imaging device is very so- phisticated gadget, accessory at the stand of the ac- celerator, which has an amorphous silicon detector remaining resistant to irradiation after the applica- tion of very high doses, and has certain dosimetri- cal characteristics which were also investigated here but also well described in literature.5-10 Radiol Oncol 2010; 44(3): 199-206.