The effect of dynamic wedge angle in breast cancer's absorbed radiation dose

Abstract

A Wedge is well known as one of medical equipment to homogenize the dose distribution received by the target during treatment process. This project aims to analyze the effect of wedge angle dependence on absorb irradiation dose received by the Planning Target Volume (PTV) utilizing Dose Volume Histogram (DVH) result. The variations of wedge angle are 15°, 30°, 45° and 60°. This study involved 3 data on breast cancer patients with prescribe dose 25x2 Gy. The radiation dose of PTV was evaluated at D5% and D95%. The average D5% of PTV at a wedge angle of 15° was (53.80±0.02) Gy, wedge 30° was (57.01±0.02) Gy, wedge 45° was (60.54±0.02) Gy, and wedge 60° for (63.88±0.02) Gy. The D95% of PTV at a wedge angle of 15° was (35.00±0.02) Gy, wedge 30° was (36.15±0.02) Gy, wedge 45° was (37.54±0.02) Gy, and wedge 60° for (41.49±0.02) Gy. The average comparison value of Homogeneity Index (HI) with wedge variation is (1.53±0.05) for wedge 15°, for wedge 30° for (1.57±0.05), for wedge 45° for (1.61±0.06), and for a 60° wedge (1.54±0.01). Statistical test results showed that the HI values on wedges 15°, 30°, 45°, and 60° were not significantly different (P = 0.34). However, the HI value which was close to ideal was equal to 1 and could give a homogeneous and optimal dose distribution to PTV. Therefore, wedge angle 15° could give a more homogeneous and optimal dose distribution.