Radiation dose-effect relations and local recovery in perfusion for patients with non-small-cell lung cancer

Purpose: To determine local dose-effect relations for lung perfusion and de nsity changes due to irradiation for patients with non-small-cell lung canc er (NSCLC) and to quantify the effect of reperfusion. Methods and Materials: For 25 NSCLC patients and a reference group of 81 pa tients with healthy lungs, registered single photon emission computed tomog raphy (SPECT) lung perfusion and CT scans were made, before and after radio therapy. Average dose-effect relations for perfusion and CT-density changes were calculated and compared with the dose-effect relation of the referenc e group. On the basis of these dose-effect relations, the post-RT perfusion was predicted for each patient and compared to the measured post-RT perfus ion, Results: Well-perfused lung regions of the NSCLC patients showed the same d ose-effect relation as the reference patients. By comparing predicted and m easured post-treatment perfusion scans, regions of reperfusion could be det ermined for 18 of 25 NSCLC patients but for none of the reference patients. Conclusion: Well-perfused lung tissue of patients with NSCLC behaves like h ealthy lung tissue with respect to radiation. The dose-effect relation for perfusion and CT density was extended for doses up to 80 Gy, Radiation dama ge in poorly perfused lung regions was less than predicted as a consequence of local reperfusion. (C) 2000 Elsevier Science Inc.