Treating dose of target volume of nasopharyngeal carcinoma and contiguous organ at risk influenced by MRI and CT image difference in cranial base

Abstract

Objective To study the treating dose of target volume of nasopharyngeal carcinoma (NPC) and contiguous organ at risk influenced by magnetic resonance imaging (MRI) and computed tomography(CT) Image difference in cranial base. Methods 26 cases were performed from 101 patients of NPC with MRI and CT image difference in cranial base. We applied ARTP-TOP3D-TPS system to delineate target volume of NPC and contiguous organ at risk and develop the three-dimensional conformal radiotherapy (3-DCRT) plan, and compared the target volume of NPC by MRI (GTVMR) with the target volume of NPC by CT ( GTVCT) . Results There was statistic difference between GTVMT(47.0±16.3) cm3 and GTVCT (31.6±10.0) cm3 ( Z = 4.462, P < 0.01 ). Compared with CT based plan, the mean dose of brainstem, pituitary, temporal lobe and both eyes and the D5 mean dose of brainstem, spinal cord, pituitary, temporal lobe and both eyes in MRI based plan were larger. There was no statistic difference in the mean dose of spinal cord between two plans. Conclusions The dose of target volume in 3D-CRT plan based GTVMR is superior m GTVCT, but the dose of contiguous organ at risk in 3D-CRT plan based GTVMR is higher. Key words: Nasopharyngeal carcinoma; Target volume of primary tumor; Contiguous organ at risk influenced; Computed tomography ; Magnetic resonance imaging