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Abstract：
The purpose of this study was to compare hybrid intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (Hybrid IMRT/VMAT), with non-coplanar (nc) IMRT and nc-VMAT treatment plans for unresectable olfactory neuroblastoma (ONB). Hybrid IMRT/VMAT, nc-IMRT and nc-VMAT plans were optimized for 12 patients with modified Kadish C stage ONB. Dose prescription was 65 Gy in 26 fractions. Dose-volume histogram parameters, conformation number (CN), homogeneity index (HI), integral dose and monitor units (MUs) delivered per fraction were assessed. Equivalent uniform dose (EUD) and normal tissue complication probability (NTCP) based on the EUD model (NTCPLogit) and the Lyman-Kutcher-Burman model (NTCPLKB) were also evaluated. We found that the Hybrid IMRT/VMAT plan significantly improved the CN for clinical target volume (CTV) and planning treatment volume (PTV) compared with the nc-VMAT plan. In general, sparing of organs at risk (OARs) is similar with the three techniques, although the Hybrid IMRT/VMAT plan resulted in a significantly reduced Dmax to contralateral (C/L) optic nerve compared with the nc-IMRT plan. The Hybrid IMRT/VMAT plan significantly reduce EUD to the ipsilateral (I/L) and C/L optic nerve in comparison with the nc-IMRT plan and nc-VMAT plan, but the difference in NTCP between the three technique was <1%. We concluded that the Hybrid IMRT/VMAT technique can offer improvement in terms of target conformity and EUD for optic nerves, while achieving equal or better OAR sparing compared with nc-IMRT and nc-VMAT, and can be a viable radiation technique for treating unresectable ONB. However, the clinical benefit of these small differences in dosimetric data, EUD and NTCP of optic nerves may be minimal.
摘要：
这项研究的目的是比较混合调强放射治疗（IMRT）和体积调强放射治疗（混合IMRT/VMAT），非共面（nc）IMRT和nc-VMAT治疗不可切除的嗅神经母细胞瘤（ONB）。混合IMRT/VMAT，nc-IMRT和nc-VMAT计划优化为12例改良KadishC期ONB患者。剂量处方为65Gy，分为26个部分。剂量-体积直方图参数，构象数（CN），同质性指数(HI)，评估每个部分递送的积分剂量和监测单位(MU)。还评估了基于EUD模型（NTCPLogit）和Lyman-Kutcher-Burman模型（NTCPLKB）的等效均匀剂量（EUD）和正常组织并发症概率（NTCP）。我们发现，与nc-VMAT计划相比，混合IMRT/VMAT计划显着提高了临床目标体积（CTV）和计划治疗体积（PTV）的CN。总的来说,保存有风险的器官(OAR)与这三种技术相似，尽管与nc-IMRT计划相比，混合IMRT/VMAT计划导致对侧（C/L）视神经的Dmax显着降低。与nc-IMRT计划和nc-VMAT计划相比，混合IMRT/VMAT计划显着降低了同侧（I/L）和C/L视神经的EUD。但是三种技术之间的NTCP差异<1％。我们得出结论，混合IMRT/VMAT技术可以在视神经的目标一致性和EUD方面提供改进，与nc-IMRT和nc-VMAT相比，在实现相等或更好的OAR保留的同时，并且可以是用于治疗不可切除的ONB的可行的辐射技术。然而,剂量测定数据中这些微小差异的临床益处，视神经的EUD和NTCP可能最小。
