Abstract
The study is to investigate a Hybrid IMRT/VMAT technique which combines intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) for the treatment of nonsmall cell lung cancer (NSCLC). Two partial arcs VMAT, 5-field IMRT, and hybrid plans were created for 15 patients with NSCLC. The hybrid plans were combination of 2 partial arcs VMAT and 5-field IMRT. The dose distribution of planning target volume (PTV) and organs at risk (OARs) for hybrid technique was compared with IMRT and VMAT. The monitor units (MUs) and treatment delivery time were also evaluated. Hybrid technique significantly improved the target conformity and homogeneity compared with IMRT and VMAT. The mean delivery time of IMRT, VMAT, and hybrid plans was 280 s, 114 s, and 327 s, respectively. The mean MUs needed for IMRT, VMAT, and hybrid plans were 933, 512, and 737, respectively. Hybrid technique reduced V 5, V 10, V 30, and MLD of normal lung compared with VMAT and spared the OARs better with fewer MUs with the cost of a little higher V 5, V 10, and mean lung dose (MLD) of normal lung compared with IMRT. Hybrid IMRT/VMAT can be a viable radiotherapy technique with better plan quality.
Highlights
Treatment of nonsmall cell lung cancer (NSCLC) remains one of the major challenges for radiotherapy
Three-dimensional conformal radiotherapy (3D-CRT) has proved to be a promising treatment method for NSCLC allowing higher doses to be delivered to the target by improved shaping of radiation portals and conformal avoidance of normal structures compared with the conventional radiotherapy [1]
Several studies suggested that V5 [11,12,13,14], V10 [12, 14, 15], and mean lung dose (MLD) [14, 15, 17, 18] were correlated with radiation pneumonitis, the determination of the contributors to radiation pneumonitis was challenging, since a variety of treatment/patient-related factors appeared to influence this risk
Summary
Treatment of nonsmall cell lung cancer (NSCLC) remains one of the major challenges for radiotherapy. Three-dimensional conformal radiotherapy (3D-CRT) has proved to be a promising treatment method for NSCLC allowing higher doses to be delivered to the target by improved shaping of radiation portals and conformal avoidance of normal structures compared with the conventional radiotherapy [1]. Compared to 3DCRT, intensity modulated radiation therapy (IMRT) further significantly improved the dose conformity and sparing of organs at risk [2]. Volumetric modulated arc therapy (VMAT) provided more conformal target coverage and better sparing of organs at risk (OARs), with shorter treatment delivery time and fewer MUs than IMRT in treating cancers of different sites [5,6,7,8,9]. A larger volume of lung receiving lower dose (V5 and V10) in VMAT has been reported [10]. Dose volume histogram parameters of V5 [11,12,13,14] and V10 [12, 14, 15] have been showed to be the predictors of the radiation pneumonitis
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