Dosimetric Analysis of Forward Planned IMRT, Conformal and Conventional Wedge Planned Techniques for Intact Breast Radiotherapy

Purpose: The aim of this study is to make a quantitative comparison between the new forward planned intensity mod¬ulated radiation therapy technique (FP-IMRT), 3-D conformal radiotherapy technique (CRT) and the classic conventional wedge technique (CW) for whole breast radiation therapy.Patient and Methods: Between June 2007 and May 2008, 18 patients with early-stage breast cancer were treated at King Abdul Aziz Hospital and Oncology Center, Jeddah, after breast- conserving therapy (BCT), using FP-IMRT technique. All those patients were retrospectively analyzed and all were replanned with CRT technique and CW technique. The data were compared as resulted of the three techniques. The parameters used for comparison were the clinical target volume (CTV) enclosed by the 95%, 105% and 110% isodose (CTV95%, ctv105% CTV110%), CTV maximum dose (CTVmax), target volume coverage (CTV95_io5%), CTV conformity index (CI) and the mean doses to the surrounded organs at risk.Results: The V95% for the FP-IMRT was 92.05% of the prescribed dose, which was statistically significant higher than the other two techniques. The V105% and VI10% for FP-IMRT was 2.05% and 0% respectively, which was significantly less than that from CRT and CW techniques. There is also a significant improvement in the V95-105% and the CI with the FP-IMRT technique. The mean dose to the heart and ipsilateral lung was significantly low with FP-IMRT.Conclusion: The use of FP-IMRT technique with multiple static multileaf collimator (MLC) segments for breast radio-therapy is an efficient and effective method for achieving uniform dose throughout the breast and reducing the dose to organs at risk (OARs) and it is superior to CRT and CW techniques.