Conformity Index and Homogeneity Index of the Postoperative Whole Breast Radiotherapy

BACKGROUND The treatment of breast cancer involves a multidisciplinary approach in which radiotherapy plays a key role. AIM The conformity index and the homogeneity index are two analysis tools of a treatment plan using conformal radiotherapy. The purpose of this article is an analysis of these two parameters in the assessment of the treatment plans in 58 patients undergoing postoperative radiotherapy of the whole breast. MATERIALS AND METHODS All 58 patients participating in the study had a conservatively treated early-stage breast cancer. The treatment was performed using a standard regimen of fractionation in 25 fractions up to a total dose of 50 Gy. Dose-volume histograms were generated for both plans with and without segmental fields. RESULTS Pair samples t-test was used. The technique with segmental fields allowed us more homogeneity distribution when compared to standard two tangential field techniques. The HI values were 1.08 ± 0.01 and 1.09 ± 0.01 for segment and technique with two tangential fields (p < 0.001). The DHI values were 0.92 ± 0.02 and 0.901 ± 0.01 for segment and technique with two tangential fields (p < 0.001). The CI values were 1.38 ± 0.02 and 1.43 ± 0.3 for segment and technique with two tangential fields (p = 0.0018). CONCLUSION The results showed that the conformity and the homogeneity index are important tools in the analysis of the treatment plans during radiation therapy in patients with early-stage breast cancer. Adding segment fields in the administration of radiotherapy in patients with conservatively treated breast cancer can lead to improved dosage homogeneity and conformity.