In reply to Dr. Saini et al.

摘要

We thank Saini et al. for their interest in our article (1). The letter emphasizes the importance of lung V_5 by citing several references (2-4), which indicate that lung V_5 is a good predictor of pneumonitis. However, Wang et al. (2, 3) concluded that V_5 alone does not determine the onset of lung complications. Furthermore, lung data from these studies are from esophagus cancer patients undergoing a postsurgical procedure, which is believed to trigger postoperative complications in lung (4) and from non-small-cell lung cancer patients (3), who would have very different lung functions from the patients in our study.The following statement, "the errors in the dose-volume histogram of the normal lung can be up to 25% at dose levels of < 10 Gy" is misleading. Jang et al. (4) do show that a maximum of 25% difference in lung V_5 is observed between Monte Carlo simulations and treatment planning system calculations but only in mesothelioma patients. In those unusual plans, large fields delivering >1200 MU are used for a target dose of 180 cGy. In other plans, differences in lung V_5between Monte Carlo simulations and treatment planning system calculations are 1.0% to 7.2%.