[Comparison of the whole breast target volume delineated according to surface marks, palpation and glandular tissue on CT images after breast-conserving surgery].

ABSTRACT

OBJECTIVE: To compare the methods of delineating the whole breast target volume based on surface marks, palpation and glandular tissue on CT images, and to explore the contouring criteria after breast-conserving surgery. METHODS: In 15 patients with breast cancer after breast-conserving surgery, the whole breast target was delineated in 3D CT simulation images each by three different methods. The target volume delineated according to anatomical marks were named CTVan, according to breast palpation named CTVpa, and according to glandular mammary tissue showing by CT images named CTVgl. The volumes of CTVan, CTVpa and CTVgl, and the degree of inclusion (DI) and conformal index (CI) between the targets were measured. RESULTS: The mean volumes of CTVan, CTVpa and CTVgl were (792.23 ± 282.25) cm(3), (618.33 ± 295.90) cm(3) and (196.83 ± 117.62) cm(3), respectively. The differences among the three methods were statistically significant (P < 0.001). The difference between CTVan and CTVpa had no statistical significance (P = 0.08), and both the differences between CTVan and CTVgl, and between CTVpa and CTVgl had statistical significance (both P < 0.001). The CI between CTVan and CTVpa (0.644 ± 0.122) was significantly larger than the CI between CTVan and CTVgl (0.264 ± 0.108), and the CI between CTVpa and CTVgl (0.328 ± 0.115)(P < 0.001). The DI of CTVan to CTVpa was 0.709 ± 0.144,DI of CTVgl to CTVan was 0.994 ± 0.005 and DI of CTVgl to CTVpa was 0.989 ± 0.008. The differences of inner, outer, upper and lower boundaries of CTVpa and CTVan were (3.35 ± 7.23) mm, (5.57 ± 13.37) mm, (1.75 ± 11.62) mm, and (11.25 ± 4.07)mm, respectively. The cranial and medial boundaries had a negative correlation with CTVpa (P < 0.05 for all). CONCLUSIONS: The differences among the three methods in the delineation of whole breast target volume are statistically significant. The target volume delineated according to the glandular mammary tissue displayed by CT scan is significantly smaller than that by the other two methods. Combination of breast palpation and anatomical marks may be helpful in delineating the whole breast target volume is relatively reasonable at present.