Determination and comparison of dosimetric parameters of three-dimensional conformal radiotherapy, field in field, and intensity-modulated radiotherapy techniques in radiotherapy of breast conserving patients.

Purpose: Three radiation therapy techniques for breast are common, namely three-dimensional conformal radiotherapy (3D-CRT), Field-in-Field (FIF), and Intensıty-Modulated Radıotherapy (IMRT). The purpose of this study was to determine and compare dosimetric parameters of three different treatment planning planning types; 3D-CRT, FIF, and IMRT in target and normal tissues after breast-conserving surgery.

Methods: One hundred patients with left or right breast cancer cooperated in this study. They were divided into three categories (small, medium, and large size) based on breast volume. Three treatment planning techniques were carried out by planner for each patient in Prowess® 5.2 Treatment Planning System. The dosimetric parameters were obtained from dose-volume histograms using the CERR software (MATLAB Company, Washington, USA), which runs as an add-on in MATLAB software.

Results: 3D-CRT technique with the highest value of D_max creates more hot spots than the other techniques in the tumor region (P = 0.013). IMRT and FIF showed the best uniformity compared to 3D-CRT in all groups with respect to the values of the parameters D₉₈ and D₂. IMRT provided the best coverage in the tumor compared to other methods (P < 0.001). 3D-CRT technique yielded a high volume receiving ≥107% of the prescription dose (P < 0.001). Among the three methods, the FIF method results in a lower dose to the lung for treatment based on the V₅ and V₂₀ parameters (P < 0.001). Homogeneity index for IMRT was better than FIF, as well as, conformity index (CI) for IMRT and FIF was better than 3D-CRT.

Conclusion: IMRT and FIF plans offered excellent target coverage and uniformity, whereas FIF had better protection of healthy tissues. Thus FIF method is an efficient method to improve the quality of treatment for breast cancer patients.