A dosimetric comparison of the tangential beams IMRT with multifield beams IMRT of the chest wall in postmastectomy breast cancer recurrent patients / 中华放射医学与防护杂志

ABSTRACT

Objective To compare the dose distribution of reserved planned tangential beam IMRT(2-field IMRT) with multifields beams IMRT(6-field IMRT) of the bulk-recurrent chest wall in postmastectomy breast cancer patients.Methods For 8 patients with chest wall in postmastectomy breast cancer bulk-recurrence,2-field IMRT and 6-field IMRT plans were generated on PTV in Pinnacle Planning System.The prescribed dose of PTV was 50 Gy in 25 fractions and GTV was 66-70 Gy which irradiated incrementally by subsequent plan in 8-10 fractions.The conformal index (CI) and homogeneity index (HI) of 95％ of prescribed dose over PTV were compared,while the dose distribution on ipsilateral lung and heart were evaluated.Results The CI of PTV by 6-field IMRT (0.66 ± 0.08) was higher than that of the2-field IMRT (0.53±0.10)(t=7.99,P＜0.05).The HI ofPTV by6-field IMRT (1.36±0.08)waslower than that of 2-field IMRT (2.19 ±0.78) (t =9.04,P ＜0.05).There was no statistical difference in V5,V10,V20 and V35 for ipsilateral lung and in D V35 and D for heart between two plans.Conclusions Compared with 2-field IMRT,6-field IMRT might have a better dose distribution on planning target volume(PTV) for chest wall in postmastectomy breast cancer bulk-recurrence patients,butthere is no significant difference in dose-volume of ipsilateral lung and heart between two plans.