Radiation Dose Calculator
Compute the effective radiation dose in sieverts from absorbed dose, radiation type, and tissue weighting factor. Essential for radiological protection assessments and medical physics dosimetry.
About this calculator
Effective dose quantifies the biological risk of radiation exposure by accounting for how different radiation types and body tissues respond differently to the same absorbed energy. The formula is E = D × w_R × w_T, where D is the absorbed dose in gray (Gy), w_R is the radiation weighting factor for the type of radiation, and w_T is the tissue weighting factor for the organ exposed. The result E is expressed in sieverts (Sv). Absorbed dose measures pure energy deposition (1 Gy = 1 J/kg), while the weighting factors scale this to biological harm. For example, alpha particles carry w_R = 20, while X-rays and gamma rays have w_R = 1. Tissue weighting factors assigned by the ICRP range from 0.01 (bone surface) to 0.12 (lung, stomach, bone marrow).
How to use
A worker's lung tissue absorbs 0.05 Gy of gamma radiation. Gamma rays have a radiation weighting factor w_R = 1, and the ICRP tissue weighting factor for the lung is w_T = 0.12. Effective dose = 0.05 Gy × 1 × 0.12 = 0.006 Sv = 6 mSv. Enter 0.05 in Absorbed Dose, 1 for Radiation Type, and 0.12 for Tissue Weighting Factor. The calculator returns 0.006 Sv, which can be compared against the occupational limit of 20 mSv/year.
Frequently asked questions
What is the difference between absorbed dose, equivalent dose, and effective dose in radiation protection?
Absorbed dose (gray, Gy) measures raw energy deposited per kilogram of tissue with no weighting for biological effect. Equivalent dose (sievert, Sv) multiplies absorbed dose by the radiation weighting factor w_R to account for how damaging a particular radiation type is — alpha particles are far more damaging per gray than gamma rays. Effective dose further multiplies by the tissue weighting factor w_T to reflect that some organs are more sensitive to radiation-induced cancer than others. Effective dose is the standard quantity used in radiation protection regulations worldwide.
How do radiation weighting factors differ between alpha particles, beta particles, and gamma rays?
The ICRP assigns radiation weighting factors based on the relative biological effectiveness of each radiation type. Gamma rays, X-rays, and beta particles all have w_R = 1 because they cause similar biological damage per gray. Protons have w_R = 2, while neutrons range from 5 to 20 depending on energy. Alpha particles have the highest factor at w_R = 20 because their dense ionization track causes far greater DNA damage per unit of deposited energy, even though they cannot penetrate the skin from outside the body.
What are the safe annual radiation dose limits for workers and the general public?
The International Commission on Radiological Protection (ICRP) recommends that occupational workers receive no more than 20 mSv (0.02 Sv) per year averaged over five years, with no single year exceeding 50 mSv. The general public limit is 1 mSv per year above natural background. For comparison, natural background radiation worldwide averages about 2.4 mSv/year. A single chest CT scan delivers roughly 5–7 mSv. These limits are set to keep the lifetime risk of radiation-induced cancer below acceptable thresholds.