Abstract

Info

Title:: Correlation between dose verification and plan complexity of volumetric modulated arc therapy for nasopharyngeal carcinoma

Author(s):: TENG Jianjian; SHI Jinping; ZHANG Liwen; XIE Qiuying; LIU Zhibin; Department of Radiation Oncology, Cancer Center, the First People’s Hospital of Foshan/Affiliated Foshan Hospital of Sun Yat-sen University, Foshan 528000, China

Keywords:: ; : nasopharyngeal carcinoma; volumetric modulated arc therapy; modulation complexity score; dose verification

Abstract:: Objective To study the correlations between gamma passing rate in dose verification and plan complexity of volumetric modulated arc therapy (VMAT) of nasopharyngeal carcinoma (NPC). Methods The VMAT plans of 106 NPC patients were selected. A two-dimensional ionization chamber array Matrixx was used for dose verification. The measured and planned dose distributions were compared and the gamma passing rates were evaluated under different criteria (3%/3 mm, 3%/2 mm, 3%/1 mm and 2%/2 mm). The modulation complexity score (MCS) of the treatment plan was calculated and used to quantitatively evaluate plan complexity. The correlation analysis between gamma passing rate and plan complexity was performed. Results If using the criteria of 3%/3 mm, 3%/2 mm, 3%/1 mm and 2%/2 mm, the gamma passing rate of VMAT plans was (98.49±0.95)%, (95.92±1.71)%, (89.74±2.44)% and (90.58±2.87)%, respectively. The mean MCS of plans was 0.210±0.019. Pearson’s correlation coefficient between the gamma passing rate (3%/3 mm, 3%/2 mm, 3%/1 mm and 2%/2 mm) and MCS were 0.333 (P<0.001), 0.303 (P=0.002), 0.347 (P<0.001) and 0.267 (P=0.006), respectively. Conclusion The gamma passing rate in the dose verification showed a weak correlation with MCS of VMAT of NPC.