Fig. 2

Comparison of the dose distribution of non-block and block planning. a Non-block plan; (b) semi-circular plan for block 7. Each plan was made using the same target volume pertaining to a single patient. The dose gradient of block 7 was steeper than that of the non-block plan. Block 7: semi-circular virtual block that contoured the lungs outside a distance of 7 cm from the tracheal bifurcation