RESUMEN
Objective To investigate the significance of computed tomography(CT)and 3.0 T magnetic resonance imaging(MRI)in intensity-modulated radiotherapy(IMRT)for esophageal carcinoma. Methods Thirty-five patients newly diagnosed with esophageal carcinoma who received radical radiotherapy in our hospital from November 2013 to April 2015 were enrolled as subjects. Target volume was delineated on the CT images and MRI images(T2-weighted and diffusion-weighted fusion images). The MRI-and CT-based IMRT plans were designed using the same dose prescription and dose constraints for organs at risk(OAR). The target volume,prescribed dose,and doses for OAR were compared between the two plans. Results In the two plans, dose distribution and planning parameters met the clinical requirement. The length of lesion,gross tumor volume (GTV),and planning target volume(PTV)defined by 3.0 T MRI were significantly smaller than those defined by CT(P=0.00,0.03,0.03). There were no significant differences in the D 2%,D 98%,D 50%,homogeneity index,or conformity index for primary GTV(PGTV)and PTV-PGTV between the two plans(all P>0.05). Compared with the CT-based plan,the 3.0 T MRI-based plan had a significantly smaller mean dose to the lungs and an insignificantly smaller actual dose to the lungs(P=0.00;P>0.05).There were no significant differences in maximum doses tolerated by the spinal cord or heart between the two plans. Conclusions In terms of target volume delineation and dosimetric parameters, both CT-and 3.0 T MRI-based plans meet the clinical requirement. The 3.0 T MRI-based plan may provide potential benefits for some OAR due to a smaller target volume compared with the CT-based plan.