Unit 51: Radiation Dose
Practice Problems
Note: problem difficulty is ranked using a star system.
(*) One-star problems are fundamental to the unit, and can be done relatively quickly. Use these problems to introduce yourself to the material.
(**) Two-star problems are more difficult, and require an understanding of one or two key concepts. Use these problems to test your understanding of the material.
(***) Three-star problems are the most difficult, and require some creative thinking in addition to a deep familiarity with multiple key concepts. Use these problems to challenge yourself; if you can complete one of these, you’re on your way to mastering the material.
*Q51.1) A 2kg sample of tissue is subjected to 4 J of radiation. What’s the absorbed dose (in Grays)?
*Q51.2) Protons have a radiation weighting factor of 2. If a sample reaches proton radiation dose of 10 Gy, what’s the equivalent dose in Sieverts?
**Q51.3) Arrange the following scenarios in order of increasing effective dose:
A) 5Gy of protons (wᵣ = 2) on liver tissue (wₜ = 0.04)
B) 1Gy of alpha particles (wᵣ = 20) on brain tissue (wₜ = 0.01)
C) 2Gy of electrons (wᵣ = 1) on lung tissue (wₜ = 0.12)
***Q51.4) A typical chest x-ray imparts an effective dose of 7mSv to the patient. How many x-ray photons would be absorbed by a patient during such an x-ray? You may use the following values for your calculations:
wᵣ = 1 for photons,
wₜ = 0.12 for lung tissue,
X-ray wavelength of 0.1nm,
and a chest mass of 12kg.