Dosimetric comparison of tomotherapy and volumetric-modulated arc therapy for children with neuroblastoma

Abstract

Importance: Irradiation treatment for pediatric patients with neuroblastoma represents a major challenge due to the pediatric dose limits for critical structures and the necessity of sufficient dose coverage of the clinical target volume for local control. Objective: To investigate dosimetric differences between tomotherapy (TOMO) and volumetric-modulated arc therapy (VMAT) as retroperitoneal radiotherapy for children with neuroblastoma. Methods: Eight patients who received retroperitoneal radiotherapy for neuroblastoma were selected for comparison of TOMO and VMAT treatment plans. The Dmin, Dmax, Dmean, D95, D2, and D98 of planning target volume (PTV), conformity index (CI), heterogeneity index (HI), and organs at risk (OARs) parameters were compared. Delivery machine unit (MU) and image-guide radiotherapy solution results were also compared. Results: All patients received a cumulative dose of 19.5 Gy to the PTV. VMAT showed higher CI (0.93 ± 0.02), compared with TOMO (0.87 ± 0.03, P < 0.001). Notably, the average PTV HI was significantly better using TOMO (1.05 ± 0.01) than VMAT (1.08 ± 0.02, P = 0.003). Compared with VMAT, the Dmin, D95, and D98 all exhibited increases in TOMO; Dmax variation was less than 1% in TOMO. The D0.1cc for the spinal cord and D2cc for the small intestine were better in TOMO in terms of OARs. However, TOMO had more MUs and required a longer delivery time. Interpretation: Both planning techniques are capable of producing high- quality treatment plans. TOMO is superior for PTV coverage, but inferior for CI. TOMO requires extra treatment time; its cost is greater than the cost of VMAT.