Purpose: The lung is the dose-limiting structure within the thorax. Radiation-induced lung damage resulting in either pneumonitis or pulmonary fibrosis limits the total dose of radiotherapy in the thoracic region. The paper reviewed and discussed the current knowledge of radiogenic pneumopathy.
Patients and methods: Analysis was done of experimental results and published data concerning lung reaction after radiotherapy.
Results: From a clinical point of view the radiation-induced lung damage can be described by 2 distinct phases: pneumonitis (4 to 6 weeks post radiationem) and pulmonary fibrosis (1 to 2 years post radiationem). Although there is increasing additional information on the etiology of radiation-induced lung damage up to now effective treatment based on these knowledges is available. The frequency of radiogenic pneumopathy detected by X-ray investigation after a radiation treatment demonstrates great difference between several investigators which is mainly caused by differences in the sequence of X-ray investigation. The ED50-value of pneumonitis after a conventional fractionated radiotherapy is about 35 Gy.
Conclusion: Minimizing the frequency of radiation-induced lung injury it ist necessary to check prior to radiotherapy the treatment ability of a patient concerning its lung function conditions, to remain a great untreated lung volume in treatment planning, to use smaller doses per fraction in the irradiated parts of the lung and to calculate the dose-distribution with the individual values of lung density of the patient. In cases of occurring pneumopathy with clinical signs only symptomatic treatment is possible.