Dosimetry
People in occupational contact with radioactive substances, or who may be exposed to radiation, routinely carry personal dosimeters.
These have been largely replaced with other devices such as Thermoluminescent dosimetry(TLD), optically stimulated luminescence(OSL), or Fluorescent Nuclear Tract Detector(FNTD) badges.
[2][3] The International Committee on Radiation Protection (ICRP) guidance states that if a personal dosimeter is worn on a position on the body representative of its exposure, assuming whole-body exposure, the value of Personal Dose Equivalent Hp(10), is sufficient to estimate an effective dose value suitable for radiological protection.
Internal dosimetry is used to evaluate the committed dose due to the intake of radionuclides into the human body.
The largest single source of radiation exposure to the general public is naturally occurring radon gas, which comprises approximately 55% of the annual background dose.
Radon is a radioactive gas generated by the decay of uranium, which is present in varying amounts in the Earth's crust.
Certain geographic areas, due to the underlying geology, continually generate radon which permeates its way to the Earth's surface.
At a dose of 1 milligray (mGy) of photon radiation, each cell nucleus is crossed by an average of 1 liberated electron track.
[9] The absorbed dose required to produce a certain biological effect varies between different types of radiation, such as photons, neutrons or alpha particles.
Stochastic effect is defined for radiation dose assessment as the probability of cancer induction and genetic damage.
In the case of estimation of stochastic effects, assuming a linear dose response, this averaging out should make no difference as the total energy imparted remains the same.
The effective dose E is designed to account for this variation by the application of specific weighting factors for each tissue (WT).
It is defined as the sum of equivalent doses to each organ (HT), each multiplied by its respective tissue weighting factor (WT).
It is not suitable for estimating stochastic risk for individual medical exposures, and is not used to assess acute radiation effects.
The worldwide average background dose for a human being is about 3.5 mSv per year [1], mostly from cosmic radiation and natural isotopes in the earth.
The largest single source of radiation exposure to the general public is naturally occurring radon gas, which comprises approximately 55% of the annual background dose.
Significant problems exist in insulating the graphite from the surrounding environment in order to measure the tiny temperature changes.
