Radiation Dose Calculator

Radiation dose can describe different physical and biological quantities. Absorbed dose measures energy deposited per unit mass and is expressed in gray; this calculator displays milligray. Equivalent dose adjusts absorbed dose for the biological effectiveness of the radiation type, while effective dose applies an additional tissue weighting factor to represent the relative contribution of an exposed organ to overall stochastic health risk. Equivalent and effective dose are displayed in millisievert. The calculator starts with a dose rate specified at one meter from a point source. It multiplies that rate by exposure time, then divides by the square of the entered distance in meters. This inverse-square relationship means doubling distance reduces the idealized dose rate to one quarter, while tripling distance reduces it to one ninth. The approximation assumes an unobstructed point source. It may not represent broad beams, internal contamination, scattered radiation, shielding, geometry close to a source, or equipment whose displayed dose already applies at another reference position. Radiation weighting factors account for the different biological effects of ionizing radiation. Photons, gamma rays, X-rays, and beta particles use a factor of one in this simplified model. Alpha particles use twenty, and neutrons use a representative factor of ten even though official neutron factors vary with energy. Tissue factors here include whole-body exposure, lung, thyroid, and skin. They are educational values based on radiation-protection conventions and are not a substitute for a facility physicist's protocol or a current regulatory table. Time, distance, and shielding are the core practical controls behind the ALARA principle: keep exposure as low as reasonably achievable. Reduce the time near a source, increase distance when possible, and use shielding selected for the radiation energy and type. Medical imaging doses should not be judged solely from a generic calculation because scanner settings, patient size, scan length, administered activity, and organ distribution all matter. Occupational and public dose limits also depend on jurisdiction and monitoring period. Use calibrated dosimeters and approved software for compliance decisions. If an accidental or potentially significant exposure occurred, secure the area, follow the radiation safety plan, and contact the radiation safety officer or emergency authority rather than relying on this estimate.