Abstract

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Title:: Avoidance technique applied in volumetric modulated arc therapy for early-stage nasal natural killer/T-cell lymphoma: a dosimetric study

Author(s):: XU Tingting1; JIN Fu2; YANG Han2; 1. Department of Radiology, Fengdu Peoples Hospital of Chongqing, Chongqing 408299, China 2. Department of Radiation Oncology, Chongqing University Cancer Hospital/Chongqing Cancer Institute Chongqing Cancer Hospital, Chongqing 400030, China

Keywords:: Keywords: natural killer/T-cell lymphoma volumetric modulated arc therapy lens avoidance radiotherapy

Abstract:: Abstract: Objective To compare the dosimetric differences among 3 different volumetric modulated arc therapy (VMAT) plans, and to explore the dosimetric effects of VMAT avoidance technique on early-stage nasal natural killer/T-cell lymphoma. Methods Twenty patients with early-stage nasal natural killer/T-cell lymphoma were enrolled in the study, and 3 kinds of plans, namely no lens avoidance plan (VMAT-OFF), lens half-avoidance (VMAT-E) and lens avoidance plan (VMAT-E&E), were designed for each patients. The dosimetric parameters of planning target volume (PTV) and organs-at-risk were compared among 3 kinds of groups, and meanwhile, monitor units (MU) and SCIMOCA passing rate (3%/2 mm) were evaluated. Results The target dose distribution in 3 kinds of plans all met the prescribed dose requirements. There was no statistically difference in the D2%, D98%, V95%, homogeneity index and conformity index of PTV. MU was highest in VMAT-E&E, followed by VMAT-E and VMAT-OFF (P<0.05). The Dmax and Dmean to lens in VMAT-E&E were lower than those in VMAT-OFF (P<0.05) and VMAT-E (P<0.05), and no statistically difference was found in the Dmax and Dmean to other OAR. The SCIMOCA passing rate (3%/2 mm) of PTV, lens and plans were all higher than 95%, without statistical differences. Conclusion Although VMAT-E&E has relatively higher MU, it has more advantages in lens sparing.