Dosimetric comparison of three techniques in treatment of accelerated partial breast irradiation / 中华放射医学与防护杂志

ABSTRACT

Objective To dosimetrically compare three delivery techniques of VMAT,IMRT and 3D-CRT in the treatment of accelerated partial breast irradiation (APBI).Methods Twenty patients with T1/2N0M0breast cancer were treated with VMAT.These cases were subsequently re-planned using static gantry IMRT and 3D-CRT technology to evaluate dosimetric differences.Dosimetric parameters including dose conformity index (CI),dose volume histogram (DVH) analysis of normal tissue coverage,dose parameters of PTV and normal tissues were evaluated,the delivery parameters including MU and delivery time were also analyzed.Results The IMRT and VMAT plans provided lower maximum dose,better mean dose and more conformal target dose distributions than the 3D-CRT plans (F =14.86,8.57,18.23,P ＜0.05).The volume of ipsilateral breast receiving 5 Gy for VMAT technique was significantly less than that of3D-CRTor IMRT(F=5.83,P＜0.05).The ipsilateral lung volume receiving 20 Gy (V20),5 Gy(V5) and the 5％ volume dose (D5) of IMRT were superior to those of 3D-CRT and VMAT(F =16.39,3.62,4.81,P ＜ 0.05).The low volume dose distributions of D5 in contralateral lung for IMRT was better than that of VMAT and 3D-CRT(F =3.99,3.43,P ＜ 0.05).The total mean MUs for VMAT,3D-CRT and IMRT were 621.0 ± 111.9,707.3 ± 130.9 and 1161.4 ± 315.6,respectively (F =31.30,P ＜ 0.05).The average machine delivery time was(1.5 ± 0.2)min for the VMAT plans,(7.0 ± 1.6)min for the 3D-CRT plans and (11.5 ± 1.9)min for the IMRT plans.Conclusions VMAT and IMRT techniques offer improved dose conformity as compared with 3D-CRT techniques without increasing dose to the ipsilateral lung.In terms of MU and delivery time,VMAT is more efficient for APBI than conventional 3D-CRT and static beam IMRT.