Abstract
Objective This study evaluates dosimetric differences in Stereotactic Body Radiation Therapy (SBRT) for lung tumors using plans of Gamma Knife, and Volumetric Modulated Arc Therapy (VMAT), Dynamic Multileaf Collimator (DMLC) plans based on Linear Accelerator, aiming to inform the reader of appropriate treatment strategy selection.
Methods Ten patients with 23 lung tumor lesions treated with SBRT at Zhongshan Hospital of Dalian University were analyzed. Plans of Gamma Knife, and VMAT, DMLC plans based on Linear Accelerator were created for each lesion, totaling 18 plans per type. Lesions were treated with 30-50 Gy in 5-10 fractions. Dosimetric parameters, including gradient index (GI), heterogeneity index (HI), conformity index (CI), and doses to the plan target volumes (PTVs), the gross tumor volumes (GTVs) and organs at risk (OARs) were compared.
Results Plans of Gamma Knife showed superior HI and GI, higher PTV and GTV doses, and reduced doses to the ipsilateral and contralateral lungs, esophagus, spinal cord, and heart compared to VMAT and DMLC plans (p< 0.05). However, Plans of Gamma Knife required longer delivery times. When comparing VMAT and DMLC plans，VMAT plans had shorter delivery times than DMLC plans, but required more monitor units (MUs). Additionally, DMLC plans delivered a lower mean dose to the ipsilateral lung compared to VMAT plans.
Conclusions Gamma Knife SBRT plans achieves steeper dose falloff and minimizes radiation to normal lung tissue compared to VMAT and DMLC plans, but with longer delivery times. VMAT and DMLC plans displayed similar dose distributions for lung SBRT.