lähtekiirguse

Lähtekiirguse, often translated as "source radiation" or "primary radiation," refers to the radiation emitted directly from a source without any intermediate interaction or modification. This concept is fundamental in fields such as physics, astronomy, and medical imaging.

In physics, lähtekiirguse describes the initial electromagnetic waves or particles produced by a phenomenon, such as the light emitted by a star, the X-rays generated by an X-ray tube, or the gamma rays from a radioactive decay. It is the radiation that begins its journey from its origin.

In astronomy, the study of lähtekiirguse from celestial objects like stars and galaxies allows scientists to understand their composition, temperature, and physical processes. Telescopes are designed to capture and analyze this incoming radiation.

In medical imaging, such as in X-ray or CT scans, the X-rays produced by the machine are considered lähtekiirguse. This radiation then passes through the patient's body, and the attenuated radiation that emerges is detected to form an image. Understanding the properties of the initial source radiation is crucial for accurate diagnosis and minimizing patient exposure.

The term emphasizes the origin of the radiation, distinguishing it from secondary radiation, which is produced when primary radiation interacts with matter. For example, scattered X-rays are secondary radiation, while the X-rays coming directly from the tube are lähtekiirguse.