Convert concentration to dose?

In summary, to get the effective dose of tritium in a human body, one would use the Mass Activity Calculator and convert the activity to disintegrations per second. This rate would need to be converted into joules per second to calculate the dose.
  • #1
Smed
36
1
How do you get from a concentration to an effective dose? For example, if you have 10-9 Ci/cm3 of tritium in a human body, then how do you get the effective dose to that body?

Thanks
 
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  • #2
Using the Mass Activity Calculator in Nucleonica (www.nucleonica.net), 10-9 Ci of tritum corresponds to 37 Bq. Also from Nucleonica, the effective dose coefficient for ingestion for tritium is 1.8x10-11 Sv/Bq. Hence the dose is 37 x 1.8x10-11 Sv per cm3 = 57 x 10-11 Sv per cm3. To obtain the total dose you then need to multiply by the volume of the human body or that part which has been exposed- I'll leave this as an exercise! If the tritium intake is by inhalation, then the effective dose coefficient for inhalation must be used. This is 2.6x10-10 Sv per Bq i.e. considerably higher than that for ingestion.
 
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  • #3
I'm not sure I follow how time plays into this. Does this process give me the Sv per second or per disintegration? If you have a decaying source, you wouldn't just get a single dose. I guess what I'm looking for is the dose rate, sorry for the confusion.
 
  • #4
Smed said:
How do you get from a concentration to an effective dose? For example, if you have 10-9 Ci/cm3 of tritium in a human body, then how do you get the effective dose to that body?

Thanks
One could integrate does rate per unit volume over time and get a does per unit volume, which of course assumes that all that is produced is absorbed. Of course, one would take into account the decay of the nuclide as well as the biological removal rate.
 
  • #5
Smed said:
I'm not sure I follow how time plays into this. Does this process give me the Sv per second or per disintegration? If you have a decaying source, you wouldn't just get a single dose. I guess what I'm looking for is the dose rate, sorry for the confusion.

Good question. Actually the effective dose coefficients are denoted by e(50). The 50 refers to the following 50 years after incorporation. Sophisticated bio-kinetic models have been developed to account for the total radiation damage to the cells from the incorporation of a radionuclide. All known effects are accounted for e.g. biological half-life, presence of daughters etc. The relationship between the Dose and the Activity is given by

Dose (Sv) = e(50) x Activity (Bq)

From this value one can estimate the risk of cancer for example. Basically the unit Sievert (Sv) is the energy deposited in the tissue.

If you would like to calculate the dose rate this requires a different approach. From the activity in Bq, one obtains the number of disintegrations per second. In each disintegration, a 20 keV electron is emitted. This electron is then absorbed in the tissue causing damage. So the rate of energy released is

Energy emission rate (keV/s) = Activity (Bq) x 20 keV

with units keV per second. This needs to be converted into joules i.e.

Energy emission rate (Joule per second) = activity x 20 x 1000 x 1.6e-19

For the activity of 37 Bq, this corresponds to

Energy emission rate (joule per second)= 37 x 20 x1000 x 1.6e-19 = 1.2 E-16

Since the "quality factor" for electrons is one, this means that the dose rate is equal to the energy emission rate i.e.
Dose Rate = 1.2 E- 16 Sieverts per second.

This is an extremely small dose rate.

For further information, I refer you to the relevant Nucleonica wiki article...
http://www.nucleonica.net/wiki/index.php/Help:Dosimetry_%26_Shielding [Broken]
 
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What is concentration and dose?

Concentration refers to the amount of a substance present in a given volume or mass of a solution. Dose, on the other hand, is the amount of a substance administered to an organism.

How do you convert concentration to dose?

To convert concentration to dose, you first need to know the desired dose and the concentration of the solution. Then, you can use the formula: Dose = Concentration x Volume. This will give you the amount of the solution needed to administer the desired dose.

What units are used for concentration and dose?

Concentration is typically measured in units such as molarity (mol/L), mass per volume (mg/mL), or percentage (%). Dose is usually measured in units of mass (mg or g) or volume (mL or L).

Why is it important to convert concentration to dose?

Converting concentration to dose is important in many scientific fields, such as medicine, pharmacology, and environmental science. It allows us to accurately measure and administer the correct amount of a substance, ensuring safety and effectiveness.

Are there any limitations to converting concentration to dose?

Yes, there are limitations to converting concentration to dose. It assumes that the substance is evenly distributed throughout the solution and that there is no loss of the substance during administration. It also does not take into account any potential interactions between the substance and the organism.

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