Figure 1.

Sample proton SBRT dose distributions. (A) Limitation of dose to central structures. Radiation dose to the right bronchial tree (yellow) was limited by using a two beam arrangement. The dose falloff of the anterior beam results in a relatively small dose deposition for the major airways immediately posterior. (B) Limitation of dose to a pace maker/defibrillator. A similar strategy to that shown in (A) was used to limit dose to a pacemaker, only in this case dose falloff of a posterior beam was critical.