Absorptiedosis

Absorptiedosis, in English usually called absorbed dose, is a physical quantity that measures the amount of energy from ionizing radiation deposited per unit mass of matter, typically tissue. It is defined by the equation D = E/m, where E is the energy imparted to the mass m. The SI unit of absorbed dose is the gray (Gy), equal to one joule per kilogram.

Absorptiedosis characterizes how much energy a body region receives but does not by itself describe biological risk. To compare risk across radiation types and tissues, dosimetry uses related quantities such as the equivalent dose (sievert) and the effective dose, which incorporate radiation quality factors and tissue weighting factors.

Measurement and estimation of absorbed dose use a variety of devices. Calorimeters determine energy deposition directly, while ionization chambers, thermoluminescent dosimeters (TLDs), optically stimulated luminescence (OSL) devices, and radiographic or radiochromic films estimate dose in practical settings. In radiotherapy, plan quality is assessed by spatial dose distributions within the target and surrounding tissues, with doses ranging from a few Gy in a single fraction to tens of Gy over many fractions; diagnostic procedures typically deliver mGy-scale doses.

Concepts of dose can be applied to any material but are most relevant to biological tissue. Dose distributions can be uniform or heterogeneous, and microdosimetry examines energy deposition on cellular and subcellular scales. The term absorptiedosis is standardized in radiological protection literature and is a component of international frameworks (e.g., ICRU, ICRP).