Radiation Pneumonitis and Fibrosis Following Split-Course Radiation Therapy for Lung Cancer: A radiologic and physiologic study

Radiographic signs of radiation pneumonitis and fibrosis were assessed and pulmonary function monitored in lung cancer patients after two different split-course radiation therapy schedules, one with a rest interval of 3 weeks and the other with a rest interval of 5 weeks, the total radiation dose being the same in both treatments (55 Gy/20 fractions/7 or 9 weeks). Post-mortem findings were analysed when available. Spirometric measurement of vital capacity, determination of diffusing capacity for carbon monoxide (DL) and alveolar volume with the single breath technique, and determination of regional distribution of lung perfusion by two different techniques, radiospirometry and gamma camera digital display following intravenous injection of 133Xe, were carried out before and at various times after the completion of irradiation. Of the physiologic parameters, only DL showed a significant decrease 6 as well as 9 months post-treatment (p