Without imaging procedures a variety of chest diseases cannot be diagn
osed sufficiently. Examples are acute and chronic pneumonia, toxic eff
ects on the bronchial and alveolar system, immunologic and malignant c
hanges and cardiovascular disease involving the lung. Especially impor
tant are the types of disease that attack large sections of a populati
on, because a fath of infection may be hidden or because of short- or
long-term exposure to relevant concentrations of toxic or allergic age
nts - not necessarily recogniced as such - at work, in the general env
ironment or associated with certain types of behaviour or illness. All
this may have effects on biostatistical and socioeconomic data. Consi
dering available epidemiologic data on morbidity and mortality, then p
ulmonary tuberculosis, unspecific pneumonias, drug-induced and AIDS-as
sociated lung disease, pneumoconioses (silicosis and asbestosis) and p
rimary and secondary chest malignancies have to be included in this ca
tegory. Conventional chest radiography with high-kV technique and mode
rn film-screen combinations continues to be the imaging modality for i
nitial evaluation of chest disease worldwide. Low radiation exposure,
low cost and overall availability are major advantages. Conventional t
omography, however, has nowadays been largely replaced by CT, though a
few special indications remain. High-resolution CT (HRCT) and the spi
ral technique bring additional benefits. Periodic radiographic mass sc
reening of populations with certain disease prevalence still seems fea
sible, taking risk assessment, cost effectiveness and radiation exposu
re into account. The benefits of appropriate radiological examination
are very high: not only for the individual, but, in many instances, al
so for the population at large, especially when early detection might
prevent further spread of infection or when latent disease is detected
at an early stage. In the light the risk of damage due to radiation e
xposure seems quite negligible.