Xue Juan, Jin Sunian, Zhang Hongtao, Zou Kun, Sheng Junxiu, Tang Jinhai, Zhao Wanying, Yang Ping, Tang Lufan, Lv Xiupeng, Lv Li
The Department of Radiation Oncology, First Affiliated Hospital, Dalian Medical University, Dalian, Liaoning, China.
The Department of Pathology, Second Affiliated Hospital, Dalian Medical University, Dalian, Liaoning, China.
Front Oncol. 2023 Apr 17;13:1143564. doi: 10.3389/fonc.2023.1143564. eCollection 2023.
To evaluate the feasibility of using a simplified non-coplanar volumetric modulated arc therapy (NC-VMAT) and investigate its dosimetric advantages compared with intensity modulated radiation therapy (IMRT) and coplanar volumetric modulated arc therapy (C-VMAT) for hippocampal-avoidance whole brain radiation therapy (HA-WBRT).
Ten patients with brain metastase (BM) were included for HA-WBRT. Three treatment plans were generated for each case using IMRT, C-VMAT, and NC-VMAT, respectively.
The dosimetric results of the three techniques complied roughly with the RTOG 0933 criteria. After dose normalization, the V of whole brain planned target volume (WB-PTV) in all the plans was controlled at 95%. Homogeneity index (HI) of WB-PTV was significantly reduced in NC-VMAT (0.249 ± 0.017) over IMRT (0.265 ± 0.020, =0.005) and C-VMAT (0.261 ± 0.014, =0.020). In terms of conformity index (CI), NC-VMAT could provide a value of 0.821 ± 0.010, which was significantly superior to IMRT (0.788 ± 0.019, <0.001). According to D of WB-PTV, NC-VMAT could provide a value of 35.62 ± 0.37Gy, significantly superior to IMRT (36.43 ± 0.65Gy, <0.001). According to D of WB-PTV, NC-VMAT can achieve the lowest value of 33.18 ± 0.29Gy, significantly different from IMRT (33.47 ± 0.43, =0.034) and C-VMAT (33.58 ± 0.37, =0.006). Regarding D, D, and D of hippocampus, NC-VMAT could control them at 15.57 ± 0.18Gy, 8.37 ± 0.26Gy and 11.71 ± 0.48Gy, respectively. D and D of hippocampus for NC-VMAT was significantly lower than IMRT (D: 16.07 ± 0.29Gy, =0.001 D: 12.18 ± 0.33Gy, <0.001) and C-VMAT (D: 15.92 ± 0.37Gy, =0.009 D: 12.21 ± 0.54Gy, <0.001). For other organs-at-risk (OARs), according to D of the right optic nerves and the right lenses, NC-VMAT had the lowest values of 31.86 ± 1.11Gy and 7.15 ± 0.31Gy, respectively, which were statistically different from the other two techniques. For other organs including eyes and optic chiasm, NC-VMAT could achieve the lowest doses, different from IMRT statistically.
The dosimetry of the three techniques for HA-WBRT could roughly comply with the proposals from RTOG 0933. After dose normalization (D=30Gy), NC-VMAT could significantly improve dose homogeneity and reduce the D in the brain. Besides, it can reduce the D of the hippocampus, optic nerves, and lens. With this approach, an efficient and straightforward plan was accomplished.
评估使用简化非共面容积调强弧形放疗（NC-VMAT）的可行性，并研究其与调强放疗（IMRT）和共面容积调强弧形放疗（C-VMAT）相比在海马体避让全脑放疗（HA-WBRT）中的剂量学优势。
纳入10例脑转移瘤（BM）患者进行HA-WBRT。分别为每个病例生成使用IMRT、C-VMAT和NC-VMAT的三种治疗计划。
三种技术的剂量学结果大致符合RTOG 0933标准。剂量归一化后，所有计划中全脑计划靶区（WB-PTV）的V均控制在95%。NC-VMAT中WB-PTV的均匀性指数（HI）（0.249±0.017）显著低于IMRT（0.265±0.020，P=0.005）和C-VMAT（0.261±0.014，P=0.020）。在适形指数（CI）方面，NC-VMAT可提供0.821±0.010的值，显著优于IMRT（0.788±0.019，P<0.001）。根据WB-PTV的D，NC-VMAT可提供35.62±0.37Gy的值，显著优于IMRT（36.43±0.65Gy，P<0.001）。根据WB-PTV的D，NC-VMAT可达到最低值33.18±0.29Gy，与IMRT（33.47±0.43，P=0.034）和C-VMAT（33.58±0.37，P=0.006）有显著差异。关于海马体的D、D和D，NC-VMAT可分别将它们控制在15.57±0.18Gy、8.37±0.26Gy和11.71±0.48Gy。NC-VMAT的海马体D和D显著低于IMRT（D：16.07±0.29Gy，P=0.001；D：12.18±0.33Gy，P<0.001）和C-VMAT（D：15.92±0.37Gy，P=0.009；D：12.21±0.54Gy，P<0.001）。对于其他危及器官（OARs），根据右侧视神经和右侧晶状体的D，NC-VMAT的最低值分别为31.86±1.11Gy和7.15±0.31Gy，与其他两种技术有统计学差异。对于包括眼睛和视交叉在内的其他器官，NC-VMAT可达到最低剂量，与IMRT有统计学差异。
HA-WBRT的三种技术的剂量学大致符合RTOG 0933的建议。剂量归一化（D=30Gy）后，NC-VMAT可显著提高剂量均匀性并降低脑内的D。此外，它可降低海马体、视神经和晶状体的D。通过这种方法，完成了一个高效且直接的计划。
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