A dosimetric comparison of 3D-CRT, IMRT, and static tomotherapy with an SIB for large and small breast volumes

作者：Michalski Andrea; Atyeo John^*; Cox Jennifer; Rinks Marianne; Morgia Marita; Lamoury Gillian

来源：Medical Dosimetry, 2014, 39(2): 163-168.

DOI：10.1016/j.meddos.2013.12.003

• Breast cancer
• 3D-CRT
• IMRT
• Tomotherapy
• Simultaneous integrated boost

Radiation therapy to the breast is a complex task, with many different techniques that can be employed to ensure adequate dose target coverage while minimizing doses to the organs at risk. This study compares the dose planning outcomes of 3 radiation treatment modalities, 3 dimensional conformal radiation therapy (3D-CRT), intensity-modulated radiation therapy (IMRT), and static tomotherapy, for left-sided whole-breast radiation treatment with a simultaneous integrated boost (SIB). Overall, 20 patients with left-sided breast cancer were separated into 2 cohorts, small and large, based on breast volume. Dose plans were produced for each patient using 3D-CRT, IMRT, and static tomotherapy. All patients were prescribed a dose of 45 Gy in 20 fractions to the breast with an SIB of 56 Gy in 20 fractions to the tumor bed and normalized so that D-98% > 95% of the prescription dose. Dosimetric comparisons were made between the 3 modalities and the interaction of patient size. All 3 modalities offered adequate planning target volume (PTV) coverage with D-98% > 95% and D-2% < 107%. Static tomotherapy offered significantly improved (p = 0.006) dose homogeneity to the PTVboost eval (0.079 +/- 0.011) and breast minus the SIB volume (Breast(StB)) (p < 0.001, 0.15 +/- 0.03) compared with the PTVboost eval (0.085 +/- 0.008, 0.088 +/- 0.12) and Breastsm (0.22 +/- 0.05, 0.23 +/- 0.03) for IMRT and 3D-CRT, respectively. Static tomotherapy also offered statistically significant reductions (p < 0.001) in doses to the ipsilateral lung mean dose of 6.79 +/- 2.11 Gy compared with 7.75 +/- 2.54 Gy and 8.29 +/- 2.76 Gy for IMRT and 3D-CRT, respectively, and significantly (p < 0.001) reduced heart doses (mean = 2.83 +/- 1.26 Gy) compared to both IMRT and 3D-CRT (mean = 3.70 +/- 1.44 Gy and 3.91 +/- 1.58 Gy). Static tomotherapy is the dosimetrically superior modality for the whole breast with an SIB compared with IMRT and 3D-CRT. IMRT is superior to 3D-CRT in both PTV dose conformity and reduction of mean doses to the ipsilateral lung.

• 出版日期2014