| [Objective]To evaluate the effects of intensity modulated radiotherapy (IMRT) in improving target coverage and sparing all appropriate normal tissues after the plan was generated for each postmastectomy patient.[Methods]Two plans, including IMRT and partially wide tangent fields (PWTFs), were generated using an in-house optimization system for ten female breast cancer patients who underwent surgical mastectomy. And the two plan techniques were compared using dose-volume histogram (DVH) analysis. Metrics for plan comparisons included minimal, maximal, and mean doses.[Results]IMRT resulted in more uniform chest wall (CW) coverage than did PWTFs. The average chest wall(CW) minimal dose was 35.35±7.85 Gy for IMRT and 29.33 ±5.98 Gy for PWTFs (P= 0.04). The average internal mammary node(MN) minimal dose was 51.05 ±1.61 Gy for IMRT and 48.85±1.70 Gy for PWTFs (P = 0.02). The volume of ipsilateral lung receiving 20Gy(V2O) and the volume of heart receiving 30Gy (V30) for left-side patient were greatly lower for IMRT. But the mean dose of ipsilateral lung and heart were greater for IMRT (7.27 ± 1.52Gy and 8.40±2.72Gy) than for PWTFs (5.92±2.16Gy and 3.70±3.89Gy)( P≤0.05).And the average contralateral breast mean dose was 4.80±1.70 Gy for MRT, but a greater breast volume was exposed compared with PWTFs.[Conclusions]A new IMRT technique achieves full target coverage while maintaining similar doses to heart and ipsilateral lung as conventional techniques. However, contralateral lung and breast volumes exposed to low doses were increased with IMRT and will need to be reduced in future studies. |
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