Wu Jianzhou, Li Huiling, Shekhar Raj, Suntharalingam Mohan, D'Souza Warren
Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
Radiother Oncol. 2008 Apr;87(1):35-43. doi: 10.1016/j.radonc.2008.02.010. Epub 2008 Mar 24.
To evaluate four planning techniques for stereotactic body radiation therapy (SBRT) in lung tumors.
Four SBRT plans were performed for 12 patients with stage I/II non-small-cell lung cancer under the following conditions: (1) conventional margins on free-breathing CT (plan 1), (2) generation of an internal target volume (ITV) using 4DCT with beam delivery under free-breathing conditions (plan 2), (3) gating at end-exhale (plan 3), and (4) gating at end-inhale (plan 4). Planning was performed following the RTOG 0236 protocol with a prescription dose of 54 Gy (3 fractions). For each plan 4D dose was calculated using deformable-image registration.
There was no significant difference in tumor dose delivered by the 4 plans. However, compared with plan 1, plans 2-4 reduced total lung BED by 1.9+/-1.2, 3.1+/-1.6 and 3.5+/-2.1 Gy, reduced mean lung dose by 0.8+/-0.5, 1.5+/-0.8, and 1.6+/-1.0 Gy, reduced V20 by 1.5+/-1.0%, 2.7+/-1.4%, and 2.8+/-1.8%, respectively, with p<0.01. Compared with plan 2, plans 3-4 reduced lung BED by 1.2+/-1.0 and 1.6+/-1.5 Gy, reduced mean lung dose by 0.6+/-0.5 and 0.8+/-0.7 Gy, reduced V20 by 1.2+/-1.1% and 1.3+/-1.5%, respectively, with p<0.01. The differences in lung BED, mean dose and V20 of plan 4 compared with plan 3 were insignificant.
Tumor dose coverage was statistically insignificant between all plans. However, compared with plan 1, plans 2-4 significantly reduced lung doses. Compared with plan 2, plan 3-4 also reduced lung toxicity. The difference in lung doses between plan 3 and plan 4 was not significant.
评估四种用于肺部肿瘤立体定向体部放射治疗（SBRT）的计划技术。
对12例I/II期非小细胞肺癌患者进行了四种SBRT计划，条件如下：（1）在自由呼吸CT上采用传统边界（计划1），（2）使用4DCT生成内部靶区（ITV）并在自由呼吸条件下进行射束投照（计划2），（3）呼气末门控（计划3），以及（4）吸气末门控（计划4）。按照RTOG 0236方案进行计划制定，处方剂量为54 Gy（分3次）。对于每个计划，使用可变形图像配准计算4D剂量。
4个计划所给予的肿瘤剂量无显著差异。然而，与计划1相比，计划2 - 4使全肺等效生物剂量（BED）分别降低了1.9±1.2、3.1±1.6和3.5±2.1 Gy，平均肺剂量分别降低了0.8±0.5、1.5±0.8和1.6±1.0 Gy，V20分别降低了1.5±1.0%、2.7±1.4%和2.8±1.8%，p<0.01。与计划2相比，计划3 - 4使肺BED分别降低了1.2±1.0和1.6±1.5 Gy，平均肺剂量分别降低了0.6±0.5和0.8±0.7 Gy，V20分别降低了1.2±1.1%和1.3±1.5%，p<0.01。计划4与计划3相比，在肺BED、平均剂量和V20方面的差异不显著。
所有计划之间肿瘤剂量覆盖在统计学上无显著差异。然而，与计划1相比，计划2 - 4显著降低了肺剂量。与计划2相比，计划3 - 4也降低了肺毒性。计划3和计划4之间的肺剂量差异不显著。
