Yan Danfang, Ning Lihua, Chen Ying, Ke Shanbao, Huang Huijie, Wang Lihong, Yan Senxiang
Department of Radiation Oncology, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China.
Cancer Center, People's Hospital of Zhengzhou University, Zhengzhou, China.
Quant Imaging Med Surg. 2022 Aug;12(8):4239-4247. doi: 10.21037/qims-21-1101.
Radiation therapy is one of the essential treatment modalities for invasive thymomas. Clinically, respiratory motion poses a challenge for the radiotherapy of thoracic tumors. One method to address this issue is to train patients to hold their breath at the end of deep inspiration. The purpose of this retrospective cohort study was to investigate the dosimetric and clinical advantages of the deep inspiration breath-hold (DIBH) technique in postoperative intensity-modulated radiation therapy (IMRT) for thymomas.
Thymoma patients undergoing postoperative IMRT were included. Each patient underwent two computed tomography (CT) scans, one under free breath (FB) and the other under DIBH. Dosimetric parameters of organs at risk (OARs) were evaluated in three series plans. Dose analysis and volume comparisons were conducted during FB-3 mm (FB with 3 mm internal target volume margin), FB-10 mm (FB with 10 mm internal target volume margin), and DIBH and compared using a paired sample Student's test. Normal tissue complication probabilities (NTCP) for lungs and heart were calculated and compared.
The total lung volume significantly increased by 31% (4,216±198 2,884±166 mL) and the heart volume reduced by 12% (552±25 636±35 mL) between DIBH acquisitions compared to FB. A significant improvement was observed in all the dosimetric parameters (D, V20, V5) of the lung on DIBH compared to FB-3 mm (54%±2.85% 47%±2.90%, P<0.001; 15%±1.37% 12%±1.32%, P=0.004; and 10.28±0.58 8.76±0.57 Gy, P<0.001, respectively), as well as in the D and D2% of the esophagus and spine. The lung volume increment was related to a reduction in the mean dose of lungs, with a correlation coefficient of r=0.27, P=0.03. The NTCP values for pneumonitis significantly reduced with DIBH compared to the FB state (0.6% 1.1%, P<0.001).
The radiation dose to the OARs can be significantly reduced by using the DIBH technique in postoperative IMRT for thymomas. The increased volume of lungs using DIBH acquisitions can significantly reduce the incidence of pneumonitis.
放射治疗是侵袭性胸腺瘤的重要治疗方式之一。临床上，呼吸运动给胸部肿瘤的放射治疗带来了挑战。解决这一问题的一种方法是训练患者在深吸气末屏气。这项回顾性队列研究的目的是探讨深吸气屏气（DIBH）技术在胸腺瘤术后调强放射治疗（IMRT）中的剂量学和临床优势。
纳入接受术后IMRT的胸腺瘤患者。每位患者进行两次计算机断层扫描（CT），一次在自由呼吸（FB）状态下，另一次在DIBH状态下。在三个系列计划中评估危及器官（OARs）的剂量学参数。在FB-3mm（内部靶区体积边缘为3mm的FB）、FB-10mm（内部靶区体积边缘为10mm的FB）以及DIBH状态下进行剂量分析和体积比较，并使用配对样本t检验进行比较。计算并比较肺和心脏的正常组织并发症概率（NTCP）。
与FB相比，DIBH采集期间肺总体积显著增加31%（4216±198对2884±166mL），心脏体积减少12%（552±25对636±35mL）。与FB-3mm相比，DIBH状态下肺的所有剂量学参数（D、V20、V5）均有显著改善（分别为54%±2.85%对47%±2.90%，P<0.001；15%±1.37%对12%±1.32%，P=0.004；以及10.28±0.58对8.76±0.57Gy，P<0.001），食管和脊柱的D和D2%也有改善。肺体积增加与肺平均剂量降低相关，相关系数r=0.27，P=0.03。与FB状态相比，DIBH状态下肺炎的NTCP值显著降低（0.6%对1.1%，P<0.001）。
在胸腺瘤术后IMRT中使用DIBH技术可显著降低OARs的放射剂量。DIBH采集时肺体积增加可显著降低肺炎的发生率。
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