why are there so many units of measurement for radiation? Rads, roentgens, greys, severet, and so on?
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Because they are measuring different things. Some measure how much raw radiation something is giving off(curies, becquerels), some measure how much radiation exposure is in a specific area (roentgen, coulombs/kg), some measure how much radiation is absorbed by something else exposed to the radiation(grays, rads), some measure how much potential harm a biological entity experiences based on exposure and type(sieverts, rems).
In addition, there are multiple units of measurement for some of these things because of the same reason there are multiple units of measurement for length, force, etc. – historical vs. standardized units. A curie and a becquerel are measuring the same thing (radioactivity), but a curie is much, much, much larger because it’s older and scientific instruments kinda sucked back then, so it’s based off of what they could detect.
Rads are an English unit of radiation absorbed dose; grays are the metric unit for the same thing. They quantify how much energy was absorbed per unit mass of tissue.
Rems (English units) and sieverts (metric units) multiply rads/grays by a quality factor to calculate the effective dose. The quality factor accounts for the fact that different types of radiation is more or less damaging, and different types of tissue responds differently to radiation. Rems / sieverts are a measure of how likely it is that harmful effects such as cancer will result from exposure the radiation.
The roentgen is a very old measure of radiation exposure. It’s historically interesting, but isn’t used much any more.
There are so many units partly because we have been studying the effects of radiation on human health for well over a hundred years, and radiation itself for even longer. Early ideas about how to measure and quantify radiation and its effects have been supplanted by newer ideas and techniques (such as the metric system).
Because they are measuring different things. Some measure how much raw radiation something is giving off(curies, becquerels), some measure how much radiation exposure is in a specific area (roentgen, coulombs/kg), some measure how much radiation is absorbed by something else exposed to the radiation(grays, rads), some measure how much potential harm a biological entity experiences based on exposure and type(sieverts, rems).
In addition, there are multiple units of measurement for some of these things because of the same reason there are multiple units of measurement for length, force, etc. – historical vs. standardized units. A curie and a becquerel are measuring the same thing (radioactivity), but a curie is much, much, much larger because it’s older and scientific instruments kinda sucked back then, so it’s based off of what they could detect.
Rads are an English unit of radiation absorbed dose; grays are the metric unit for the same thing. They quantify how much energy was absorbed per unit mass of tissue.
Rems (English units) and sieverts (metric units) multiply rads/grays by a quality factor to calculate the effective dose. The quality factor accounts for the fact that different types of radiation is more or less damaging, and different types of tissue responds differently to radiation. Rems / sieverts are a measure of how likely it is that harmful effects such as cancer will result from exposure the radiation.
The roentgen is a very old measure of radiation exposure. It’s historically interesting, but isn’t used much any more.
There are so many units partly because we have been studying the effects of radiation on human health for well over a hundred years, and radiation itself for even longer. Early ideas about how to measure and quantify radiation and its effects have been supplanted by newer ideas and techniques (such as the metric system).
Because they are measuring different things. Some measure how much raw radiation something is giving off(curies, becquerels), some measure how much radiation exposure is in a specific area (roentgen, coulombs/kg), some measure how much radiation is absorbed by something else exposed to the radiation(grays, rads), some measure how much potential harm a biological entity experiences based on exposure and type(sieverts, rems).
In addition, there are multiple units of measurement for some of these things because of the same reason there are multiple units of measurement for length, force, etc. – historical vs. standardized units. A curie and a becquerel are measuring the same thing (radioactivity), but a curie is much, much, much larger because it’s older and scientific instruments kinda sucked back then, so it’s based off of what they could detect.
Rads are an English unit of radiation absorbed dose; grays are the metric unit for the same thing. They quantify how much energy was absorbed per unit mass of tissue.
Rems (English units) and sieverts (metric units) multiply rads/grays by a quality factor to calculate the effective dose. The quality factor accounts for the fact that different types of radiation is more or less damaging, and different types of tissue responds differently to radiation. Rems / sieverts are a measure of how likely it is that harmful effects such as cancer will result from exposure the radiation.
The roentgen is a very old measure of radiation exposure. It’s historically interesting, but isn’t used much any more.
There are so many units partly because we have been studying the effects of radiation on human health for well over a hundred years, and radiation itself for even longer. Early ideas about how to measure and quantify radiation and its effects have been supplanted by newer ideas and techniques (such as the metric system).
Imagine radiation is actually distance.
We have metric and imperial measurements, so two different systems. We then need to also have units for speed, area, volume, pressure etc., so we then end up with meters per second, miles per hour, square meters, hectares, cubic meters, cubic inches etc. Now to convert this back to radiation, we also have trickier ways to measure radiation than a simple linear measurement, which produces many different units from one system, let alone two or more.
As to standardisation across the world, this is as difficult as the why and how one could get America to convert to the metric system, or visa versa for Europe. Granted less people use radiation measurements on a daily basis, however there will always be people who refuses to change, and will want to use the system they did at university.
Imagine radiation is actually distance.
We have metric and imperial measurements, so two different systems. We then need to also have units for speed, area, volume, pressure etc., so we then end up with meters per second, miles per hour, square meters, hectares, cubic meters, cubic inches etc. Now to convert this back to radiation, we also have trickier ways to measure radiation than a simple linear measurement, which produces many different units from one system, let alone two or more.
As to standardisation across the world, this is as difficult as the why and how one could get America to convert to the metric system, or visa versa for Europe. Granted less people use radiation measurements on a daily basis, however there will always be people who refuses to change, and will want to use the system they did at university.
Imagine radiation is actually distance.
We have metric and imperial measurements, so two different systems. We then need to also have units for speed, area, volume, pressure etc., so we then end up with meters per second, miles per hour, square meters, hectares, cubic meters, cubic inches etc. Now to convert this back to radiation, we also have trickier ways to measure radiation than a simple linear measurement, which produces many different units from one system, let alone two or more.
As to standardisation across the world, this is as difficult as the why and how one could get America to convert to the metric system, or visa versa for Europe. Granted less people use radiation measurements on a daily basis, however there will always be people who refuses to change, and will want to use the system they did at university.
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