An integrated design of fields in IMRT for post-radical mastectomy

Objective: To investigate the dosimetry differences of target and OARs of an integrated design of fields in IMRT and the mainstream IMRT technique for post-radical mastectomy. Methods: A total of 41 patients with post-radical mastectomy who received IMRT were eligible, the conventional fixing two-degrade collimator and the integrated IMRT fields were designed respectively. The dosimetry parameters of target and OARs, monitor units and delivery time of both plans were compared. Results: The dose distribution for targets and OARs of both plans met clinical requirements. The dosimetry parameters of target of both plans showed no statistically significant difference (P > 0.05). Compared with the conventional technique, the integrated IMRT plans showed significant advantages, the ipsilateral lung V₅ decreased by 9.7% (t = 2.407, P < 0.05), V₁₀ 11.2% (t = 2.160, P < 0.05), V₂₀ 17.3% (t = 2.465, P < 0.05), V₃₀ 13.4% (t = 2.119, P < 0.05), D_mean 13.8% (t = 2.258, P < 0.05). And the heart V₃₀ decreased by 28.4% (t = 2.589, P < 0.05), D_mean 23.2% (t = 2.409, P < 0.05). The dosimetric differences of other OARS were not statistically significant (P > 0.05). Conclusions: The new method can effectively reduce exposed volume and exposed dose of ipsilateral lung and heart without affecting the target dose coverage. The method has universal applicability to patients with post-radical mastectomy who received IMRT, with important clinical significance. (authors)