In radiation protection, the sievert is a derived unit of equivalent dose and effective dose. The sievert represents the equivalent biological effect of the deposit of a joule of gamma rays energy in a kilogram of human tissue. Unit of sievert is of importance in radiation protection and was named after the Swedish scientist Rolf Sievert, who did a lot of the early work on dosimetry in radiation therapy.
As was written, the sievert is used for radiation dose quantities such as equivalent dose and effective dose. Equivalent dose (symbol HT) is a dose quantity calculated for individual organs (index T – tissue). Equivalent dose is based on the absorbed dose to an organ, adjusted to account for the effectiveness of the type of radiation. Equivalent dose is given the symbol HT. The SI unit of HT is the sievert (Sv) or but rem (roentgen equivalent man) is still commonly used (1 Sv = 100 rem).
One sievert is a large amount of equivalent dose. A person who has absorbed a whole body dose of 1 Sv has absorbed one joule of energy in each kg of body tissue (in case of gamma rays).
Equivalent doses measured in industry and medicine often have usually lower doses than one sievert, and the following multiples are often used:
1 mSv (millisievert) = 1E-3 Sv
1 µSv (microsievert) = 1E-6 Sv
Conversions from the SI units to other units are as follows:
- 1 Sv = 100 rem
- 1 mSv = 100 mrem
Examples of Doses in millisieverts
We must note that radiation is all around us. In, around, and above the world we live in. It is a natural energy force that surrounds us. It is a part of our natural world that has been here since the birth of our planet. In the following points we try to express enormous ranges of radiation exposure, which can be obtained from various sources.
- 0.00005 mSv – Sleeping next to someone
- 0.00009 mSv – Living within 30 miles of a nuclear power plant for a year
- 0.0001 mSv – Eating one banana
- 0.0003 mSv – Living within 50 miles of a coal power plant for a year
- 0.01 mSv – Average daily dose received from natural background
- 0.02 mSv – Chest X-ray
- 0.04 mSv – A 5-hour airplane flight
- 0.60 mSv – mammogram
- 1 mSv – Dose limit for individual members of the public, total effective dose per annum
- 3.65 mSv – Average yearly dose received from natural background
- 5.8 mSv – Chest CT scan
- 10 mSv – Average yearly dose received from natural background in Ramsar, Iran
- 20 mSv – single full-body CT scan
- 175 mSv – Annual dose from natural radiation on a monazite beach near Guarapari, Brazil.
- 5 000 mSv – Dose that kills a human with a 50% risk within 30 days (LD50/30), if the dose is received over a very short duration.