The analysis of prognostic factors affecting post-radiation acute reaction after conformal radiotherapy for non-small cell lung cancer of patients in this study [6]. The group from St Louis described the risk of acute toxicity manifestation of grade 2 or higher in 14% of patients 6 months after radiotherapy. There were reported 4 deaths due to acute post-radiation pneumonitis [10]. Wang et al. reported the risk of acute lung toxicity of grade 3 or higher at a level of 6.7%. About 4% of patients died because of this complication after radiotherapy in this study [14]. The group from the Memorial Sloan Kettering Cancer Centre reported 18.3% of patients with acute lung toxicity of grade 3 or higher according to the RTOG/EORTC toxicity score. The percentage of deaths due to lung toxicity was 4%, similarly as in the Wang et al. study [15]. In our study the toxicity score modification consisted in changing the corticosteroid administration from grade 3 to grade 2 on the above-mentioned scale. The introduced change allowed us to single out a group of patients with indirect degree of post- radiation acute reaction course. The lack of uniform criteria for post-radiation pulmonary injury makes it difficult to compare the incidence and severity of post-radiation pneumonitis between published data. In comparing published data it is important to take into account that therapeutic indications for corticosteroid administration may be different in particular centres and departments. The results of our study, if we refer to the percentage of patients with clinical manifestation of grade 3 acute post- radiation pneumonitis according to RTOG/EORTC, are similar to published data from other centres [6, 10, 15]. A number of recently published reports evaluating toxicity after radiotherapy in patients with NSCLC are based on detailed analysis of dose-volume histograms. The purpose of these studies was to detect factors that increased the risk of acute post-radiation pneumonitis. Investigators have de- monstrated that the larger was the volume of lung tissue receiving some defined radiation dose, the higher was the risk of acute post-radiation lung injury. Some investigators have reported a similar relation to mean dose absorbed in the lung tissue. In the presented statistical analysis clinical manifestation of acute post-radiation pneumonitis revealed itself most often in patients who received low doses in a large volume of lung tissue, which was defined as ipsilateral, contralateral and total lung volume. The multivariate analysis conducted in the present study showed a strong relation between total lung volume receiving a dose of 10 Gy and the risk of acute lung injury. For lung volumes which received higher doses, in the range of 30-60 Gy, statistically significant differences were observed in total lung volume only. Similar results were reported by Graham et al. In their study the dose of 20 Gy and the mean dose in total lung volume were the factors of the risk of Arch Med Sci 5, October / 2010 Table III. Univariate analysis results of prognostic factors related to treatment technique Factors related to treatment technique V10 ipsilateral lung V10 contralateral lung V10 total lung V20 ipsilateral lung V20 contralateral lung V20 total lung V30 ipsilateral lung V30 contralateral lung V30 total lung V40 ipsilateral lung V40 contralateral lung V40 total lung V50 ipsilateral lung V50 contralateral lung V50 total lung V60 ipsilateral lung V60 contralateral lung V60 total lung Mean dose in ipsilateral lung Mean dose in contralateral lung Mean dose in total lung volume > 63% < 63% > 40% < 40% > 48% < 48% > 52% < 52% > 15% < 15% > 28% < 28% > 39% < 39% > 7% < 7% > 18% < 18% > 30% < 30% > 5% < 5% > 14% <14% >21% <21% > 3% < 3% > 10% < 10% > 13% < 13% > 1.3% < 1.3% > 6% < 6% > 32 Gy < 32 Gy > 12 Gy < 12 Gy > 18 Gy < 18 Gy 50% 50% 44% 56% 54% 46% 64% 36% 49% 51% 56% 44% 73% 27% 33% 67% 69% 31% 61% 39% 36% 64% 64% 36% 64% 36% 38% 62% 56% 44% 45% 55% 31% 69% 46% 54% 61% 39% 46% 54% 59% 41% P 0.005 0.01 < 0.001 0.007 0.090 < 0.001 0.057 0.618 < 0.002 0.229 0.998 0.005 0.148 0.830 0.062 0.169 0.658 0.05 0.061 0.220 0.063 761