The Study Of Dosimetric Comparision Between 3D-conformal Radiotherapy (3D-CRT) And Field-in-field Intensity Modulated (FIF-IMRT) For The Intact Breast Radiotherapy

OBJECTIVE: This study was to evalutate the potential dosimetric benefits and optimal indications of 3D-conforrmal radiotherapy(3D-CRT) and field-in-field intensity modulated radiotherapy(FIF-IMRT) for the intact breast radiotherapy.MATERIALS AND METHOD: Ten patients who received breast-concerving surgery were selected for this study(left 5 cases and right 5 cases). For each of randomly chosen patients,2 plans were designed in Adac Pinnacle system. The total prescribed dose was 46Gy/25fractions, 2Gy/fraction. A dosimetric comparision of 3D-conforrmal radiotherapy(3D-CRT) and field-in-field intensity modulated radiotherapy (FIF-IMRT) was performed on each patients. We compared the dose distribution, dose volume histograms(DVH), dose uniformity in t he planning target volume(PTV)and dose received by organs at risk(OARs).RESULTS:The PTV coverage in 3D-CRT plan was similar to that of in FIF-IMRT plan. A better dose uniformity throughout the whole breast in FIF-IMRT plan was achieved. In FIF-IMRT plan, the Dmax was decreased,the percentage of PTV receiving more than 103% prescribed dose(V103) decreased from 31.71% to 20.93% (P=0.039), V105 from 10. 97% to 4. 16% (P=0.004), V107 from 2.42% to 0.28% (P=0. 004) , and there is no region which received more than 110% prescribed dose. The Dmean and V20 of ipsilateral lung, Dmax and Dmean of heart, Dmean of liver were similar in two plans. The Dmean of contralateral lung and the Dmean of contralateral breast were increased a little.CONCLUSION: Compared to 3D-CRT ,FIF-IMRT improves the dose uniformity throughout the whole breast, decreases the Dmax of PTV and the percentage of PTV receiving more than 103%, 105%, 107% prescribed dose. FIF-IMRT is a better choice for the selected patients.