부산대학교 도서관

Aim: Hypofractionation in breast radiotherapy is gaining increasing relevance in routine clinical practice; however, gray areas remain on its safety. Majority of data regarding the same pertains to the treatment of the conserved breast. This study aimed to compare the use of standard wedge-based tangentials (two-dimensional [2D] TW) versus 3D conformal radiotherapy field in the field (3DCRT FIF) with the intent of evaluating if the latter would provide a dosimetric advantage. Materials and Methods: Twenty-six postmastectomy patients were enrolled in this study. Comparative plans using 2D TW and 3DCRT FIF were generated to deliver 50 Gy in 25 fractions. Dosimetric parameters pertaining target dose, Homogeneity Index (HI), Conformity Index, and dose to normal structures were compared and analyzed. The parameters that achieved significance were evaluated using the hypofractionated plan. Results: The 3DCRT FIF plan showed better planning target volume coverage, V95% (P < 0.001) and less cardiac dose (V30 and MD) as well as lung V20, V30, MD, and V5 for both lungs (P < 0.001). The dose to the left descending coronary artery (LAD) was also less with a trend toward significance (P = 0.07). The 3DCRT FIF plan also improved HI (P = 0.02). However, the high-dose volume V107% and radiation exposure were not higher. The significant parameters were evaluated in the hypofractionated schedule of 40 Gy/15 Fr. The MD to the heart was 8.96 Gy in FIF plan versus 20.16 Gy in TW plan. The average V20 to the ipsilateral lung was 37.8% versus 65.2%. The average dose to the contralateral breast was 50% less, i.e., 3.92 Gy versus 8.96 Gy. Conclusion: The results of this study suggest that there would be a significant benefit of using 3DCRT FIF plans for patients being considered for hypofractionated radiotherapy in the postmastectomy setup.