sädeannoksen

Sädeannos refers to the quantity of ionizing radiation absorbed by a substance or biological tissue. It is a crucial concept in radiation protection, medical imaging, and radiation therapy. The standard SI unit for absorbed dose is the gray (Gy), where one gray is defined as one joule of energy absorbed per kilogram of mass. Historically, the rad was used, with 1 Gy equal to 100 rad.

The absorbed dose itself does not fully describe the biological effect of radiation because different types of radiation have varying biological effectiveness. For example, alpha particles are more damaging than gamma rays for the same absorbed dose. To account for this, the equivalent dose is used, which is the absorbed dose multiplied by a radiation weighting factor. The SI unit for equivalent dose is the sievert (Sv).

In radiation therapy, the prescribed dose to a tumor is measured in grays. Medical imaging procedures also involve radiation doses, which are carefully managed to minimize patient exposure while achieving diagnostic quality. Understanding and quantifying radiation doses is essential for assessing risks and implementing appropriate safety measures.