肺部小肿瘤射波刀与γ刀计划的剂量学比较

Dosimetry comparison between cyberknife and gamma knife plan for patients with small tumors of lung

目的 比较肺部小肿瘤的射波刀与γ刀照射计划的剂量学特点。方法 选择20例肺部小肿瘤患者,分别做射波刀计划1及γ刀计划2,分析各计划PTV的适形指数（CI）、均匀指数（HI）,肺接受5~30 Gy照射体积占全肺体积的百分比（V5、V10、V20、V30）,以及食管、脊髓最大受照剂量。结果 射波刀计划和γ刀计划的CI分别为0.67、0.58（t=1.58,P=0.100）;HI值分别为1.35、1.66（t=6.5,P=0.100）;双肺V5、V10、V20、V30在1计划中较2计划较大（t=5.12、4.67、5.73、6.12,P=0.000）;1、2计划的食管最大受量分别为（8.51±0.6）、（5.26±0.7）（t=-2.76,P=0.009）;脊髓最大受量分别为（9.1±1.2）、（3.4±1.4）（t=2.41、P=0.027）;每个计划食管、脊髓的剂量均不超过其限量。结论 射波刀照射计划在肺、食管、脊髓的受量大于γ刀计划,但靶区适形性、均匀性要高于γ刀计划。

Objective To compare dosimetry features between cyberknife and gamma knife plans for patients with small tumors of lung. Methods Twenty patients with small tumors of lung were selected and respectively treated with cyberknife plan（ named plan one） and gamma plan（ named plan two）. The conformity index（ CI） and homogeneity index（ HI） of PTV,the percentage of the irradiation volume exposed to 5 to 30 Gy accounting for the whole lung volume（ V5、V10、V20、V30） and the maximum exposure doses of esophagus and the spinal cord for each plan were analyzed. Results The CI of cyberknife and gamma knife plan were 0. 67 and 0. 58（ t = 1. 58,P = 0. 100）,while the HI were1. 35 and 1. 66 separately（ t = 6. 5,P = 0. 100）. The V5,V10,V20 and V30 of both lungs in plan one were bigger than those in plan two（ t = 5. 12,4. 67,5. 73,6. 12,P = 0. 000）. The maximum exposure doses of esophagus for two plans were（ 8. 51 ± 0. 6） and（ 5. 26 ± 0. 7） respectively（ t = 2. 41,P= 0. 027）. The maximum exposure doses of the spiral cord for two plans were（ 9. 1 ± 1. 2） and（ 3. 4± 1. 4） separately（ t = 2. 41,P = 0. 027）. The doses of esophagus and the spiral cord for each plan did not exceed those limits. Conclusion The exposure doses of lung,esophagus and the spiral cord are relatively higher for cyberknife plan for patients with small tumors of lung,but its CI and HI are better than those of gamma knife plan.