Radiation pneumonitis and radiation fibrosis

Several factors are reported in literature to be the cause of radiation pneumonitis and/or radiation fibrosis. They include total radiation dosage and duration of therapy, field size (total volume irradiated), type of energy source, age and general condition of the patients, preexisting or coexisting lung infections, blockage of lymphatic channels in the mediastinum, individual variation in response, and the correction factor for lung tissue. A few of the factors which are accepted as causes of lung injury in radiation therapy were examined. In order to keep the radiation pneumonitis and/or radiation fibrosis, damage at a minimum, comparison was made of the difference in dose distribution of single portal irradiation with that combining two-portal irradiation in opposition to the 60Co gamma rays and 10 MV x rays. The results obtained were as follows: Single portal irradiation was more favorable than two-portal irradiation in opposition regarding subjective complaints and lung injury, when irradiation technique, that is, total dosage and the duration of therapy, field size, and others, was the same. (auth.)