Medical Radiation Calculator

Radiation dose describes energy deposited by ionizing radiation, while equivalent dose also reflects the differing biological effectiveness of radiation types. This calculator starts with a dose rate in milligray per hour and multiplies it by exposure time. It then adjusts for distance using the inverse-square relationship: dose intensity from an ideal point source changes with the square of the reference distance divided by the actual distance. Finally, it multiplies absorbed dose by a selected radiation weighting factor to provide a simplified equivalent-dose estimate in millisieverts. For X-rays and gamma rays, the radiation weighting factor is one, so a uniform whole-body absorbed dose expressed in mGy has the same numerical value as an equivalent dose in mSv under this simplified model. Alpha particles use a factor of 20. Neutron weighting is strongly energy dependent; this educational calculator uses a general factor of 10 and labels it accordingly. It should not be used when a facility-specific energy spectrum or dosimetry protocol provides a more appropriate factor. The inverse-square law is also an approximation. It applies best to an unobstructed point source in free space. Medical imaging systems, treatment beams, collimation, attenuation, scatter, shielding, patient geometry, field size, and source shape can make actual dose behavior substantially different. A dose-rate measurement is valid only under the conditions and at the location where it was determined. Do not use this calculator to replace a calibrated survey meter, personal dosimeter, scanner dose report, treatment-planning system, or medical physicist's calculation. Absorbed, equivalent, and effective dose are related but not interchangeable. Effective dose additionally applies tissue weighting factors and is designed mainly for population-level radiation-protection comparisons, not prediction of an individual's outcome. The displayed equivalent estimate assumes the entered absorbed dose is relevant to the exposed tissue and does not model tissue distribution. Medical benefits, organ sensitivity, age, pregnancy, repeated procedures, and uncertainty require separate consideration. Use this tool for classroom examples, rough safety planning, or checking straightforward time-and-distance arithmetic. Clinical imaging and therapy decisions must follow optimized protocols and the ALARA principle. Questions about occupational exposure, pregnancy, unusual incidents, or patient dose should be referred to a radiation safety officer, radiologist, or qualified medical physicist.