Radiation dose is a measure of the amount of exposure to radiation. There are three kinds of dose in radiological protection. Absorbed dose is a measureable, physical quantity, while equivalent dose and effective dose are specifically for radiological protection purposes. Effective dose in particular is a central feature of radiological protection. It sums up any number of different exposures into a single number that reflects, in a general way, the overall risk. The concept may be complex, but it makes radiological protection practical to implement. Absorbed Dose: Absorbed dose is the amount of energy deposited by radiation in a mass.The mass can be anything: water, rock, air, people, etc.Absorbed dose is expressed in milligrays (mGy). Equivalent Dose: Equivalent dose is calculated for individual organs.It is based on the absorbed dose to an organ, adjusted to account for the effectiveness of the type of radiation.Equivalent dose is expressed in millisieverts (mSv) to an organ.Effective Dose: Effective dose is calculated for the whole body. It is sometimes called whole-body dose.It is the addition of equivalent doses to all organs, each adjusted to account for the sensitivity of the organ to radiation.Effective dose is expressed in millisieverts (mSv).

Effective dose equivalent is the formerly used name of effective dose and is therefore the same as effective dose. The International Commission on Radiological Protection (ICRP) used “effective dose equivalent” first in its Stockholm Statement issued in 1978, and then renamed it as “effective dose” in its Publication 60 issued in 1991. ICRU Report No. 51 issued in 1993 is also relevant here.

Supplementary Table 2 in the following paper lists historical changes in dose units:

https://www.researchgate.net/publication/262054513_Classification_of_radiation_effects_for_dose_limitation_purposes_History_current_situation_and_future_prospects

Radiation hazards include both stochastic effects and tissue reactions (formerly called non-stochastic or deterministic effects), and effective dose is used only for stochastic effects. The dose unit depends on the study design, such that in addition to effective dose and equivalent dose, organ absorbed dose has also widely been used, e.g., for specific cancer site(s) or tissue reactions.

The two definitions are not really equivalent. The differences are the risk factors for stochastic effects. The number of organs has been enlarged and the weighting factors were matched to the new scientific results.

Thank you

Absorbed dose, equivalent dose and effective dose are the quantities defined in the present version of the radiation protection system.

Dose equivalent and effective dose equivalent belong to an older version, and should not be used anymore.

Effective dose equivalent is similar to effective dose, but not identical. As Hanno Krieger says, the list of organs and the weighting factors were redefined.

The role of these doses is different in Radiological protection.

Absorbed dose (Gray) is the amount of energy deposited by radiation in a mass.

Equivalent dose (Sievert) is calculated for individual organs. It is the product of absorbed dose and radiation weighting factors (different for alpha, protons and neutrons). It is used to assess how much biological damage is expected from the absorbed dose. Equivalent dose is a dose quantity and representing the stochastic health effects of low levels of ionizing radiation on human body.

Effective dose (Sievert) is calculated for the whole body. It is product of equivalent dose and tissue weighting factors (different for Lungs, Gonads, Bone Marrow and Skin). It is the tissue-weighted sum of the equivalent doses in all specified tissues and organs of the human body and represents the stochastic health risk to the whole body. Effective dose is used to assess the potential for long-term effects that might occur in the future.

they are exactly the same thing. The effective dose equivalent was used in the old recommendations whereas effective dose is used in the current one.

The dose equivalent (DE =Q*D) became the equivalent dose (Wr*D) and the effective DE became the effective dose (Wt*Wr*D)

Effective dose equivalent and effective dose: Comparison for common projections in oral and maxillofacial radiology*

By: S.Julian and Gibbs

Effective dose (E) and Effective dose equivalent (HE) are two different quantities. Effective dose is the weighted sum (by wT) of the Equivalent doses in organs and or tissues, HT, whereas the Effective dose equivalent, HE is the weighted sum (by wT) of the Dose Equivalent HT,Q with a more limited list of organs and tissues.

Dose equivalent in an organ or tissue, HT,Q was a quantity introduced by ICRP in Publication 26 (ICRP, 1977) and replaced by equivalent dose in an organ or tissue in Publication 60 (ICRP, 1991). It uses Q instead of wR. HT,Q= QT*DT.

It is still used and pertinent in dosimetry and radiation protection for space activities. Due to the specifics of the radiation field in space, not all concepts of quantities defined for radiological protection applications on Earth are appropriate for applications in space missions, especially when risk assessment is an important task. The radiation environment in LEO for EVA or IVA has a non negligible component of atomic nuclei (up to charge Z = 92). If for all other components (proton, neutron,..). E and HE provide similar estimation of exposure, that's not the case for atomic nuclei. WR of 20 (used for Equivalent dose en effective dose) largely overestimaed the exposure compare to the Effective dose equivalent based on Q. A radiation weighting factor (wR) of 20 for all types and energies of heavy ions in the definition of equivalent dose is not justified. For heavy ions, the ratio of wR and mean quality factors averaged over the human body is up to 10 depending on the type and energy of the ion. In ICRP 123, Figure 3.13 from Sato et al. 2010 illustrates this problem. exposure being overestimated up to a factor a ten.