DIBH技术对纵隔淋巴瘤累及部位放疗靶区与OAR受量影响

Effect of deep inspiration breath-hold technique on dosimetry of target volume and organs at risk in mediastinal lymphoma irradiation

目的 探讨深吸气屏气（DIBH）技术对纵隔淋巴瘤放疗靶区和正常组织受量影响。方法 前瞻性采集连续收治的5例Ⅰ、Ⅱ期纵隔淋巴瘤病例。采用受累部位照射和蝴蝶野设野原则,对比DIBH和自由呼吸（FB）扫描时靶区绝对体积变化、重要OAR绝对剂量体积和相对剂量-体积差别。配对t检验差异。结果 5例中位年龄30岁。与FB相比DIBH时靶区绝对体积化疗前GTV缩减29.4 cm3（P=0.006）,PTV缩减322 cm3（P=0.005）;肺绝对体积平均增大1456 cm3（P=0.001）,心脏宽度缩小1.3 cm （P=0.012）。DIBH时心脏和肺Dmean显著降低（心脏为8.5 Gy∶11.6 Gy,P=0.022;肺为7.6 Gy∶11.6 Gy,P=0.000）。比较受一定水平照射的绝对体积时,心脏在高剂量水平V15及以上显著降低（P均〈0.05）。DIBH时肺和心脏相对百分比在所有剂量水平（V5—V35）均显著小于FB （P均〈0.05）。结论 纵隔淋巴瘤放疗,DIBH技术能显著缩小PTV,增加肺体积,且显著降低心肺Dmean和V5—V35水平的相对剂量-体积参数。

Objective Objective To evaluate the effect of deep inspiration breath-hold technique （DIBH） on the dosimetry of target volume and organs at risk （OARs） in mediastinal lymphoma irradiation. Methods This was a prospectively study and five patients with stage Ⅰ and Ⅱ mediastinal lymphomas were included continuously. The absolute target volume, the absolute OAR doses, and the relative doses to volume were compared between DIBH and free-breathing （FB） scans, based on the principles of the affected site irradiation and the “butterfly” field. The differences were analyzed using paired t test. Results The median age of these five patients was 30 years. Compared with FB scan, DIBH scan led to significant decreases in the gross tumor volume （GTV）（Δ=29.4 cm3, P=0.006） and the planning target volume （PTV）（Δ=322 cm3, P=0.005） before chemotherapy, while no significant difference in clinical target volume （CTV） was found. Meanwhile, the lung volume of DIBH scan was significantly increased （mean Δ=1456 cm3, P=0.001）, while the heart width of DIBH scan was significantly reduced （Δ=1.3 cm, P=0.012）, as compared with those of FB scan. The mean doses to the lung and heart were significantly lower in DIBH scan than in FB scan （heart：8.5±4.7 Gy vs. 11.6±4.7 Gy, P=0.022;lung：7.6±1.1 Gy vs. 11.6±1.4 Gy, P=0.000）. The absolute target volume of the heart was significantly reduced at V15 and above in DIBH scan than in FB scan （all P〈0.05）. Relative doses to volume of the lung and heart were significantly reduced at each dose level （from V5 to V35） in DIBH scan than in FB scan （all P〈0.05）. Conclusions DIBH technique can significantly reduce PTV, enlarge lung volume, and reduce the mean dose and relative doses to volume of the lung and heart at each level （from V5 to V35） compared with FB scan in mediastinal lymphoma radiation.