Röntgensugarakhoz

Röntgensugarakhoz, also known as the roentgen unit (symbol: R), is a historical unit of measurement for ionizing radiation exposure, specifically the absorbed dose of X-rays or gamma rays in air. The unit was named after Wilhelm Conrad Röntgen, the discoverer of X-rays, and was defined as the amount of radiation that produces one electrostatic unit of charge (approximately 2.58 × 10⁻⁴ coulombs per kilogram) in one kilogram of dry air under standard conditions.

The roentgen was widely used in the early 20th century to quantify radiation exposure in medical and industrial settings. However, it was gradually replaced by the gray (Gy), a unit of absorbed dose in the International System of Units (SI), which measures energy deposited per unit mass of any material, not just air. One roentgen is approximately equivalent to 0.00263 gray for air.

The roentgen unit was formally defined in terms of ionization in air, making it specific to X-rays and gamma rays. It did not account for the biological effects of radiation or the type of radiation beyond its ability to ionize matter. Due to its limitations, the roentgen was deprecated in favor of SI units in many scientific and medical contexts, though it remains occasionally referenced in historical or legacy documentation.

In modern practice, radiation exposure is typically measured using the sievert (Sv) for effective dose, which incorporates both the absorbed dose and the relative biological effectiveness of different types of radiation. The roentgen continues to appear in older literature but is no longer a standard unit in contemporary radiation safety or medical physics.