Suggestion for a New Grading Scale for Radiation Induced Pneumonitis Based on Radiological Findings of Computerized Tomography: Correlation with Clinical and Radiotherapeutic Parameters in Lung Cancer Patients

Background: The objective of this research is the computed axial tomography (CT) imaging grading ofradiation induced pneumonitis (RP) and its correlation with clinical and radiotherapeutic parameters. Materialsand
Methods: The chest CT films of 20 patients with non-small cell lung cancer who have undergone threedimensionalconformal radiation therapy were reviewed. The proposed CT grading of RP is supported on solelyradiological diagnosis criteria and distinguishes five grades. The manifestation of RP was also correlated withany positive pre-existing chronic obstructive pulmonary disease (COPD) history, smoking history, the FEV1value, and the dosimetric variable V20.
Results: The CT grading of RP was as follows: 3 patients (15%) presentedwith ground glass opacity (grade 1), 9 patients (45%) were classified as grade 2, 7 patients (35%) presented withfocal consolidation, with or without elements of fibrosis (grade 3), and only one patient (5%) presented withopacity with accompanying atelectasis and loss of pulmonary volume (grade 4). Both univariate and multivariateanalysis revealed as prognostic factors for the radiological grading of RP the reduction of FEV1 and the V20(P=0.026 and P=0.003, respectively). There was also a significant (P<0.001) correlation of radiological gradingof RP with FEV1 and V20 (spearman rho 0.92 and 0.93, respectively).
Conclusions: The high correlation of theproposed radiological grading with the FEV1 and the V20 is giving a satisfactory clinical validity. Although theproposed grading scale seems relevant to clinical practice, further studies are needed for the confirmation of itsvalidity and reliability.