The Function of Forward Planned Intensity-modulated Radiotherapy Technique in Radiotherapy of the Intact Breast Dose Distribution Optimization

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ABSTRACT Objective: The recommended course of treatment for early-stage breast cancer is breast-conserving surgery followed by adjuvant whole-breast radiation. It is challenging to obtain homogeneous dose distribution using standard procedures because of breast irregularities. Currently, it is possible to use different breast irradiation techniques such as a field in field (FIF) which produces a more homogenous distribution of doses within the target volumes while sparing the organs at risk, leading to a better treatment outcome. Materials and Methods: The present study aimed to compare the conformal and the FIF techniques dosimetrically. In this retrospective dosimetric study, we evaluate 20 patients with early-stage breast cancer who underwent computed tomography. For each patient, two different treatment plans were created, three-dimensional conformal radiotherapy and a FIF plan. A dose of 50 Gy in 25 fractions was prescribed to the planning target volume (PTV). Results: The plans were compared with each other on volume coverage (conformity and homogeneity) and OAR sparing. The dosimetric parameters and monitor components were compared with paired sample t-test. The FIF technique obtained a significantly lower dose homogeneity index, lower maximum doses, and higher median doses in PTV (P < 0.05). In ipsilateral lungs, FIF significantly reduced the maximum and mean doses (P < 0.05). In patients with left-sided breast cancer, minimum and maximum doses and V40 of the heart were significantly decreased in FIF plans (P < 0.05). Doses to the contralateral lung differ to a little degree as well. Conclusion: The use of forward intensity-modulated radiation therapy (RT) technique for RT of high-risk node-positive breast cancer patients provides an efficient and reliable method for achieving superior dose uniformity, conformity, and homogeneity in the breast chest wall volume with minimal doses to the OAR. Monitor units were less in FIF, with less time on the machine and less machine consumption.