Field-in-field IMRT versus 3D-CRT of the breast. Cardiac vessels, ipsilateral lung, and contralateral breast absorbed doses in patients with left-sided lumpectomy: a dosimetric comparison.

PURPOSE

This study evaluated dose distribution and homogeneity of field-in-field intensity-modulated radiation treatment (FIF-IMRT) compared with standard wedged tangential-beam 3D conformal radiotherapy (CRT) of the left breast in patients who have undergone lumpectomy. Our aim was to improve dose-distribution homogeneity in the breast and decrease the dose to organs at risk (OAR), i.e, heart and vessels, ipsilateral lung, and contralateral breast.

MATERIALS AND METHODS

FIF-IMRT and wedge plans of 3D-CRT were carried out for 18 patients with cancer of the left breast. Plans were compared according to cumulative dose-volume histogram (c-DVH) analysis in terms of planned treatment volume (PTV), homogeneity index (HI), and conformity index (CI), as well as dose and volume parameters of OARs.

RESULTS

When the targeted volumes receiving 105 % and 110 % of the prescribed dose in the PTV were compared, significant decreases were found with the FIF-IMRT technique. With the 105 % dose to the OARs, monitor unit (MU) counts were significantly lower with the FIF-IMRT technique. V2 of pulmonary artery, left atrium, and aorta and V1 for the contralateral breast were statistically significantly lower with FIF-IMRT plans (p = 0.001). PTV showed a better HI and CI with FIF-IMRT.

CONCLUSIONS

FIF-IMRT enables better dose distribution in the PTV and reduces dose to OARs in breast cancer radiotherapy.