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1.5TMR 直线加速器肝脏立体定向放疗中磁场的影响及优化策略。

Influence and optimization strategy of the magnetic field in 1.5 T MR-linac liver stereotactic radiotherapy.

机构信息

Department of Oncology, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, China.

Department of Radiation Physics, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, 250117, China.

出版信息

Radiat Oncol. 2023 Oct 4;18(1):162. doi: 10.1186/s13014-023-02356-8.

DOI:10.1186/s13014-023-02356-8

PMID:37794505

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC10548616/

Abstract

OBJECTIVE

To compare intensity reduction plans for liver cancer with or without a magnetic field and optimize field and subfield numbers in the intensity-modulated radiotherapy (IMRT) plans designed for liver masses in different regions.

METHODS

This retrospective study included 62 patients who received radiotherapy for liver cancer at Shandong Cancer Hospital. Based on each patient's original individualized intensity-modulated plan (plan), a magnetic field-free plan (plan) and static intensity-modulated plan with four different optimization schemes were redesigned for each patient. The differences in dosimetric parameters among plans were compared.

RESULTS

In the absence of a magnetic field in the first quadrant, PTV D increased (97.75 ± 17.55 vs. 100.96 ± 22.78)%, D decreased (121.48 ± 29.68 vs. 119.06 ± 28.52)%, D increased (101.35 ± 7.42 vs. 109.35 ± 26.52)% and HI decreased (1.14 ± 0.14 vs. 1.05 ± 0.01). In the absence of a magnetic field in the second quadrant, PTV D increased (84.33 ± 19.74 vs. 89.96 ± 21.23)%, D decreased (105 ± 25.08 vs. 104.05 ± 24.86)%, and HI decreased (1.04 ± 0.25 vs. 0.99 ± 0.24). In the absence of a magnetic field in the third quadrant, PTV D decreased (110.21 ± 2.22 vs. 102.31 ± 26)%, L-P V decreased (10.66 ± 9.19 vs. 5.81 ± 3.22)%, HI decreased (1.09 ± 0.02 vs. 0.98 ± 0.25), and PTV D decreased (92.12 ± 4.92 vs. 89.1 ± 22.35)%. In the absence of a magnetic field in the fourth quadrant, PTV D increased (89.78 ± 6.72 vs. 93.04 ± 4.86)%, HI decreased (1.09 ± 0.01 vs. 1.05 ± 0.01) and D increased (99.82 ± 0.82 vs. 100.54 ± 0.84)%. These were all significant differences. In designing plans for tumors in each liver region, a total number of subfields in the first area of 60, total subfields in the second zone of 80, and total subfields in the third and fourth zones of 60 or 80 can achieve the dose effect without a magnetic field.

CONCLUSION

In patients with liver cancer, the effect of a magnetic field on the target dose is more significant than that on doses to organs at risk. By controlling the max total number of subfields in different quadrants, the effect of the magnetic field can be greatly reduced or even eliminated.

摘要

目的

比较有无磁场的肝癌强度降低计划，并优化不同区域肝脏肿块调强放疗（IMRT）计划中的场和子野数量。

方法

本回顾性研究纳入了在山东省肿瘤医院接受肝癌放疗的 62 例患者。基于每位患者的原始个体化调强计划（计划），为每位患者重新设计了无磁场计划（计划）和四个不同优化方案的静态调强计划。比较了计划之间的剂量学参数差异。

结果

在第一象限无磁场的情况下，PTV D 增加（97.75±17.55 比 100.96±22.78）%，D 减少（121.48±29.68 比 119.06±28.52）%，D 增加（101.35±7.42 比 109.35±26.52）%，HI 降低（1.14±0.14 比 1.05±0.01）。在第二象限无磁场的情况下，PTV D 增加（84.33±19.74 比 89.96±21.23）%，D 减少（105±25.08 比 104.05±24.86）%，HI 降低（1.04±0.25 比 0.99±0.24）。在第三象限无磁场的情况下，PTV D 减少（110.21±2.22 比 102.31±26）%，L-P V 减少（10.66±9.19 比 5.81±3.22）%，HI 降低（1.09±0.02 比 0.98±0.25），PTV D 减少（92.12±4.92 比 89.1±22.35）%。在第四象限无磁场的情况下，PTV D 增加（89.78±6.72 比 93.04±4.86）%，HI 降低（1.09±0.01 比 1.05±0.01），D 增加（99.82±0.82 比 100.54±0.84）%。这些都是显著差异。在设计每个肝区肿瘤的计划时，第一区总子野数为 60，第二区总子野数为 80，第三区和第四区总子野数为 60 或 80，可以在没有磁场的情况下达到剂量效果。