Feasibility of XXXX in stereotactic body radiation therapy for centrally located early stage non   small-cell lung cancer or lung metastases.

@entity1 @entity499 @entity5 @entity343 @entity358
PURPOSE: To investigate the ability of @entity499 ( @entity499 ) to spare critical organs immediately adjacent to the @entity5 target in stereotactic body radiation therapy (SBRT) for centrally located lung lesions. METHODS AND MATERIALS: @entity499 SBRT plans for 10 @entity1 with centrally located lesions or lesions immediately adjacent to a critical structure were generated. A total of 70 Gy in 10 fractions was prescribed to the planning target volume ( @entity343 ) to satisfy a target volume coverage of >= 95% @entity343 receiving 70 Gy and an established set of dose constraints for the organs at risk (OARs). Quality assurance (QA) of the @entity499 plans was performed with both ion chamber and film measurements. RESULTS: The @entity343 coverage criteria was met with 95% of the @entity343 receiving 70.68    0.33 Gy for all cases even though the OARs immediately adjacent to the @entity343 ranged from 0.38 to 0.85 cm away. The @entity358 ( @entity358 ), and V(20) were 7.15    1.44 Gy, and 11.93    3.24 % for the total lung, respectively. The dose parameters of @entity358 , V(5), V(10), and V(20) for the contralateral lung were significantly lower than those for the ipsilateral lung (p < 0.05). An average dose fall off from the @entity343 periphery to the edge of the immediately adjacent OAR was 47.6% over an average distance of 4.87 mm. Comparison of calculated and measured doses with the ion chamber showed an average of 1.85% point dose error, whereas an average mean gamma and the area with a gamma larger than 1 of 0.20 and 0.94% were observed, respectively. CONCLUSION: @entity499 allows the sparing of critical structures immediately adjacent to the @entity5 target, thus making SBRT for these centrally located lesions feasible.
