Calculating Total Extra Exposure from Multiple Radiation Sources

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In summary, the conversation discusses estimating the total extra exposure by taking into account the time spent near each source, the strength of the source, and its distance from the individual. An equation is provided to calculate the dose rate and absorption coefficient, and the dose rates and coefficients are given for three specific sources. The individual then uses these values to approximate their exposure and determine the total extra exposure from each source. However, there is a discussion about the accuracy of this method and the potential limitations of the setup.
  • #1
Von Neumann
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Question:

I'm looking to estimate my total extra exposure (dose above background) by taking into account account roughly how long I was near each source, the strength of the source, and its approximate distance from me. I believe it's useful to use the following equation,

[itex]\frac{dD}{dt}=\frac{dD_{0}}{dt}e^{-cx}[/itex]

where [itex]\frac{dD_{0}}{dt}[/itex] is the dose rate at x=0 and c is the absorption coefficient.

The dose rates measured at x=0 for the 3 sources, as well as the calculated absorption coefficients are

Ba-133: 277 μR/h , c=0.303/in.
Cs-137: 107 μR/h , c=0.375/in.
Co-60: 117 μR/h , c=0.360/in.

*note that the background radiation has been subtracted from the dose rates shown.

So if I take the time t spend near each source as 10 minutes, and the distance from each source as x=0 in. (as I was holding the sources as we varied the distance in the first part of the experiment) I can approximate the exposure as


[itex]\frac{dD_{0}}{dt}\cdot[/itex][itex]t[/itex]

and then sum these for from each source. So therefore I get,

Ba-133: 277 μR/h * (10 min) * (1 h/ 60 min) = 0.0462 mR
Co-60: 107 μR/h * (10 min) * (1 h/ 60 min) = 0.0195 mR
Cs-137: 117 μR/h * (10 min) * (1 h/ 60 min) = .0178 mR

Thus as my total extra exposure I get,

0.0462 mR + 0.0195 mR + 0.0178 mR = 0.0835 mR

Is this reasoning correct? Thank you in advance for any input.
 
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  • #2
Neither the dose measurement nor you received all radioactive decays, as just some fraction of them went in the direction where they got detected / absorbed in your body. In general, this fraction will be different, and depend on the setup.
as I was holding the sources
I would expect that you were holding something which was holding the sources. Even without absorber, distance to the source is crucial in the analysis.
 

FAQ: Calculating Total Extra Exposure from Multiple Radiation Sources

1. What is radiation risk and how is it estimated?

Radiation risk refers to the potential harmful effects of exposure to ionizing radiation, such as X-rays, gamma rays, and alpha and beta particles. These effects can include tissue damage, genetic mutations, and increased risk of developing cancer. Radiation risk is estimated by using scientific models and data to determine the likelihood and severity of these effects based on the amount and type of radiation exposure.

2. What factors are taken into account when estimating radiation risk?

When estimating radiation risk, factors such as the type of radiation, the duration and intensity of exposure, and the sensitivity of the individual's cells and tissues are considered. Other factors, such as age, gender, and overall health, may also play a role in determining the potential risk.

3. How is the concept of dose used in estimating radiation risk?

Dose refers to the amount of radiation a person is exposed to. It is used in estimating radiation risk by providing a measure of how much energy is absorbed by the body and how this may affect cells and tissues. The higher the dose, the higher the potential risk, but the relationship between dose and risk is not always linear and can vary depending on the type of radiation and the individual's sensitivity.

4. Can radiation risk be completely avoided?

No, radiation is a natural part of our environment and is also used in many beneficial applications, such as medical imaging and cancer treatment. However, steps can be taken to minimize exposure and reduce the potential risk, such as using protective equipment and following safety guidelines in workplaces that use radiation sources.

5. How does the general public receive information about radiation risk?

Information about radiation risk is typically disseminated through public health organizations and government agencies, as well as media outlets. These sources use scientific data and expert opinions to provide accurate and up-to-date information on the potential risks associated with different types of radiation exposure.

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