[Critical comment on enlargement techniques in diagnostic radiology (author's transl)].

Detail sharpness in radiographic magnification depends upon the properties of the focal spot, the screen and upon object motion. With direct magnification the finite size of the focal spot causes an increased penumbra. Uneven distribution of focal spot radiation leads to formation of false images. Radiographic magnification is rational when using a minute focal spot in combination with a poorly resolving (high speed) screen while the object remains stationary. Using high detail screens or non screen films there is no improved but possibly inferior resolution to non-magnified images, even though 0.1 mm x 0.1 mm foci are employed. Radiographic magnification performed with focal spots larger than 0.3 mm x 0.3 mm is not reasonable. Magnification procedures cause a considerable radiation exposure to the patient.