van Luijk Peter, Faber Hette, Meertens Harm, Schippers Jacobus M, Langendijk Johannes A, Brandenburg Sytze, Kampinga Harm H, Coppes Robert P
Department of Radiation Oncology, University Medical Center, Groningen, The Netherlands.
Int J Radiat Oncol Biol Phys. 2007 Oct 1;69(2):552-9. doi: 10.1016/j.ijrobp.2007.05.065.
To test the hypothesis that heart irradiation increases the risk of a symptomatic radiation-induced loss of lung function (SRILF) and that this can be well-described as a modulation of the functional reserve of the lung.
Rats were irradiated with 150-MeV protons. Dose-response curves were obtained for a significant increase in breathing frequency after irradiation of 100%, 75%, 50%, or 25% of the total lung volume, either including or excluding the heart from the irradiation field. A significant increase in the mean respiratory rate after 6-12 weeks compared with 0-4 weeks was defined as SRILF, based on biweekly measurements of the respiratory rate. The critical volume (CV) model was used to describe the risk of SRILF. Fits were done using a maximum likelihood method. Consistency between model and data was tested using a previously developed goodness-of-fit test.
The CV model could be fitted consistently to the data for lung irradiation only. However, this fitted model failed to predict the data that also included heart irradiation. Even refitting the model to all data resulted in a significant difference between model and data. These results imply that, although the CV model describes the risk of SRILF when the heart is spared, the model needs to be modified to account for the impact of dose to the heart on the risk of SRILF. Finally, a modified CV model is described that is consistent to all data.
The detrimental effect of dose to the heart on the incidence of SRILF can be described by a dose dependent decrease in functional reserve of the lung.
验证心脏照射会增加有症状的放射性肺功能丧失（SRILF）风险这一假设，并且这种情况可以很好地描述为肺功能储备的调节。
用150兆电子伏特的质子对大鼠进行照射。获得了在照射全肺体积的100%、75%、50%或25%后呼吸频率显著增加的剂量反应曲线，照射野包括或不包括心脏。根据每两周对呼吸频率的测量，将6 - 12周后与0 - 4周相比平均呼吸频率的显著增加定义为SRILF。使用临界体积（CV）模型来描述SRILF的风险。采用最大似然法进行拟合。使用先前开发的拟合优度检验来测试模型与数据之间的一致性。
CV模型仅能一致地拟合肺照射的数据。然而，该拟合模型未能预测同时包括心脏照射的数据。即使将模型重新拟合到所有数据，模型与数据之间仍存在显著差异。这些结果表明，尽管CV模型描述了心脏未受照射时SRILF的风险，但该模型需要修改以考虑心脏剂量对SRILF风险的影响。最后，描述了一个与所有数据一致的修改后的CV模型。
心脏剂量对SRILF发生率的有害影响可以通过肺功能储备的剂量依赖性降低来描述。
