| 王海洋,戴相昆,牛保龙,等.Unity磁共振引导放疗中空腔勾画误差对靶区剂量学影响的研究[J].中华放射医学与防护杂志,2026,46(5):522-527.Wang Haiyang,Dai Xiangkun,Niu Baolong,et al.Effect of cavity structure delineation errors on target dosimetry in Unity MR-Linac radiotherapy[J].Chin J Radiol Med Prot,2026,46(5):522-527 |
| Unity磁共振引导放疗中空腔勾画误差对靶区剂量学影响的研究 |
| Effect of cavity structure delineation errors on target dosimetry in Unity MR-Linac radiotherapy |
| 投稿时间：2024-11-26 |
| DOI：10.3760/cma.j.cn112271-20241126-00456 |
| 中文关键词: 磁共振引导放疗 电子回旋效应 空腔 剂量学 |
| 英文关键词:MR-Linac Electron return effect Cavity Radiotherapy dosimetry |
| 基金项目:国家重点研发计划(2022YFC2409502,2022YFC2409503) |
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| 中文摘要: |
| 目的 探讨磁共振引导放射治疗(MRgRT)空腔边界勾画误差对患者肿瘤靶区剂量的影响,为临床应用提供参考。方法 在模体中建立位置相邻的虚拟靶区和空腔,将空腔与靶区毗邻一侧分别外扩1、2、4、6和8 mm模拟勾画误差。设计单野计划角度分别为0°、45°、90°、135°、180°、225°、270°和315°,多野计划采用角度均分(平均权重,包括两野对穿、均分3~8野),共28种计划,基于相同计划参数进行剂量计算。选取2例食管肿瘤与1例心脏内膜肉瘤患者的15个分次在线自适应计划,对靶区邻侧肺进行相同的勾画误差模拟与剂量再计算。对靶区剂量学参数进行分析。结果 模体单野情况下,勾画误差所致靶区剂量改变中有65%的变化幅度≥ 3%(5.63%±0.67%),其中0°、45°、90°、135°、180°、225°计划靶区最大剂量(Dmax)均随勾画误差的增大而增大。2野对穿情况下,起始角度为0°、45°、135°时部分靶区剂量变化幅度≥3%。随着射野数目的增加,靶区剂量的变化基本趋于稳定。患者模拟中,计划大体肿瘤靶体积(pGTV)_Dmax在勾画误差引入后有显著升高,4 mm时最大为1.31%(t=-2.886,P<0.05);同样,计划靶体积(PTV)_Dmax在6 mm时差异最大为2.22%(t=-6.66,P<0.05)。随着勾画误差的增大,靶区Dmax和平均剂量(Dmean)均呈现递增趋势,PTV_D95呈现递减趋势。结论 MR引导放疗时,在线靶区相邻空腔勾画误差会对靶区剂量造成影响,其中靶区最大剂量所受影响最为明显,实际临床应用中在尽可能保证空腔边界勾画精度的基础上,可通过适当增加射野数目的方式减弱由此带来的剂量计算不确定度。 |
| 英文摘要: |
| Objective To investigate the impact of MRgRT cavity delineation errors on tumor target dose in patients, in order to provide a reference for clinical applications. Methods A virtual target and adjacent cavity were modeled in a phantom. The cavity boundary adjacent to the target was expanded outward by 1, 2, 4, 6, and 8 mm to simulate delineation errors. Single-field plans were designed with beam angles of 0°, 45°, 90°, 135°, 180°, 225°, 270°, and 315°, while multi-field plans employed equally spaced beams (uniform weighting, including two opposed fields and 3-8 evenly distributed fields), totaling 28 plans. Dose calculations were performed based on identical planning parameters. Additionally, 15 online adaptive treatment fractions from two esophageal cancer patients and one cardiac sarcoma patient were selected, and the same delineation error simulations followed by dose recalculation were applied to the lung adjacent to the target. Dosimetric parameters of the target were analyzed. Results In the single-field phantom study, 65% of the dose variations caused by delineation errors exceeded 3% (5.63% ± 0.67%). Specifically, the target maximum dose (Dmax) increased with larger delineation errors for beam angles of 0°, 45°, 90°, 135°, 180°, and 225°. In the two-opposed-field scenario, only initial angles of 0°, 45°, and 135° exhibited dose variations ≥3%. As the number of beams increased, target dose variations stabilized. In patient simulations,pGTV_Dmaxsignificantly increased after introducing delineation errors, peaking at 1.31% for 4 mm (t=-2.88, P<0.05). Similarly,PTV_Dmax showed the largest difference (2.22%) at 6 mm (t=-6.66, P<0.05). With increasing delineation errors, target Dmax and man dose(Dmean) exhibited an upward trend, whilePTV_D95 demonstrated a downward trend. Conclusions In MR-guided radiotherapy, online delineation errors of cavities adjacent to the target can affect target dose distribution, with the Dmax being the most significantly impacted. To mitigate dose calculation uncertainties in clinical practice, maintaining high cavity boundary delineation accuracy is essential, and increasing the number of beams may help reduce such uncertainties. |
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