Why is alpha and beta radiation measured in Sievert?

[cockpitvisit]

What's the point of measuring alpha and beta radiation in Sievert?

As I understand it, one Sievert is an equivalent of 1 Joule absorbed by 1kg of body mass.

But since alpha and beta radiation barely penetrate the human skin, most of the body mass isn't irradiated at all. So the dose in Sievert says nothing about the energy absorbed by the body, either absolute or per kg of body mass.

It seems it would be more sensible to measure absorption by a square meter of human skin. Why isn't it done this way?

 

[Astronuc]

What's the point of measuring alpha and beta radiation in Sievert?

As I understand it, one Sievert is an equivalent of 1 Joule absorbed by 1kg of body mass.

But since alpha and beta radiation barely penetrate the human skin, most of the body mass isn't irradiated at all. So the dose in Sievert says nothing about the energy absorbed by the body, either absolute or per kg of body mass.

It seems it would be more sensible to measure absorption by a square meter of human skin. Why isn't it done this way?

I'll let someone with Health Physics provide details, but alpha and beta emitting isotopes can be ingested. Alphas and betas would be a problem in the lungs, where alphas can do a lot of damage to the membrane.

Alpha emitters like some isotopes of radium (226), polonium (210), and other can be absorbed by tissue and bone.
http://en.wikipedia.org/wiki/Alpha_particle#Biological_effects

Similarly, beta-emitters can be absorbed by certain organs depending on their chemistry and thus strongly irradiated surrounding cells.

Some discussion about radiation here - http://hps.org/publicinformation/ate/faqs/radiation.html

 

[raining Pete]

Well, there are a few reasons why we measure alpha and beta radiation in Sievert. First of all, Sievert is the international unit for measuring the health effects of radiation on the human body. It takes into account the type of radiation, the energy of the radiation, and the sensitivity of different organs and tissues to radiation. This allows for a more accurate assessment of the potential harm to the body from exposure to radiation.

Additionally, while it is true that alpha and beta radiation do not penetrate the human skin very deeply, they can still cause harm to the body if they are ingested or inhaled. In these cases, the radiation can reach internal organs and tissues and cause damage. Therefore, it is important to measure the potential harm to the entire body, not just the skin.

Furthermore, measuring radiation absorption by a square meter of skin would not be as accurate as using the Sievert unit. Different parts of the body have different levels of sensitivity to radiation, and not all areas of the skin have the same thickness. Using a standardized unit like the Sievert allows for a more precise measurement of the potential harm to the body.

In short, measuring alpha and beta radiation in Sievert is the most accurate and internationally recognized way to assess the potential harm to the body from radiation exposure. It takes into account various factors and provides a comprehensive measurement of the effects on the body.