2. Department of medical physics, South Egypt Cancer Institute, University of Assiut, Egypt.
Background: Comprehensive radiation therapy fields used in the management of early-stage breast cancer. Our aim to determine the variability of the depth of supraclavicular (SCV) & infraclavicular (ICV) nodes, to estimate the actual radiation dose received by these regions in a series of patients treated in the traditional technique, and to compare these doses with those received by using an optimized dosimetric technique.
Methods: In 20 patients undergoing treatment-planning computed tomography (CT) scanning in the treatment position, the maximum depth of the SCV and ICV lymph nodes and brachial plexus were measured on CT images. Doses received at the 90% isodose surface for the SCV and ICV volumes were then estimated by using traditional dose calculations and optimized planning. A repeated measures analysis of covariance was used to compare the SCV and ICV depths and to compare the doses achieved with the traditional and optimized methods.
Results: We found that SCV nodes > 3 cm and ICV nodes > 4.5 cm will not be covered by 90% isodose surface. However, as the depth to the SCV and ICV nodes increases, the percentage of the SCV volume encompassed within the 90% isodose surface significantly decreases for cases of therapy planned by using traditional planning versus the conformal optimized plan (p< 0.05%).
Conclusion: Conformal optimized planning provided improved dosimetric coverage compared with traditional techniques.
Keywords: Breast, conformal radiotherapy, supraclavicular irradiation