Language
Country/Area
No result found
Uncovering the history of REM: How did this radiation unit get from 1945 to today?
In 1945, the unit of radiation, rem, first appeared in literature, marking the beginning of the scientific community's understanding of how radiation dose affects human health. As a CGS unit, the rem is specifically used to express the potential health risks of low-dose ionizing radiation to humans, including random biological risks such as radiation-induced cancer. The definition and application of this unit has undergone significant changes and adjustments over time.
The measurement value of rem is derived from the concept of absorbed dose, and in 1976 one rem was defined as 0.01 sievert, which is a widely used unit internationally.
Although today's scientific and medical settings are moving toward the use of the sievert, the rem and its thousandth fraction, the millirem (mrem), are still widely used by the public, industry, and government in the United States. These units are particularly suitable for medical X-ray examinations and for measuring radiation doses received in everyday environments.
According to the recommendations of the International Commission on Radiological Protection (ICRP), the effective daily dose for the general population should be limited to an average of 100 millirem (1 millisievert), a standard that excludes medical and occupational exposure. Taking the U.S. Capitol as an example, the radiation level inside is 85 millirem per year, which is close to the regulatory limit.
Short-term exposure to high doses of radiation (over 100 rem) can cause acute radiation syndrome (ARS), which, without treatment, can lead to death within a few weeks.
The initial definition of REM appeared in 1947 and was revised in 1950. The National Institute of Standards and Technology (NIST) recommends that all references to the rem should be compared to the sievert. It is interesting to note that, although the sievert is now increasingly used in scientific research and engineering environments, the rem still holds a place in the industrial standard.
In fact, the use of rem and millirem is not limited to the scientific and engineering communities. In daily life, such as during medical examinations, the radiation doses that patients are exposed to are mostly expressed in millirem, making it easier to understand and compare. Hidden behind this is the complexity of radiation safety and health risk management.
As technology develops, the relative biological effectiveness (RBE) of different types of radiation has begun to be evaluated, which plays an indispensable role in Rem's calculation formula.
When discussing the health effects of radiation, two main types of effects must be considered: deterministic effects and stochastic effects. Deterministic effects refer to the clear acute reactions that occur in the human body when the dose is too high (for example, more than 10 rem), while stochastic effects mainly manifest themselves in radiation-induced cancer, etc. According to industry consensus, each rem of effective dose will result in a cancer risk of approximately 0.055%, which has been identified in all relevant studies.
The health effects of radiation have been studied more extensively over the past few decades, and data are also growing on other effects, such as cardiovascular and birth defects. However, there is still a lack of consensus on risk assessment for different age groups. For example, the risks to infants and fetuses are generally higher than those to adults, and the difference in risk between men and women has not been quantified.
ICRP recommends that limits on artificial radiation remain at a relatively low level to protect public health.
Looking into the future, as scientific research advances and technology develops, the history and definition of REM will continue to evolve. Although the current focus has gradually shifted to Siver, the science and health considerations behind Rem as an important historical unit are still worthy of our in-depth understanding and discussion. In this context, people can't help but wonder: With the growing risk of radiation exposure, is our understanding of health risks deep and clear enough?
