Q: A 70-kg worker is exposed to a $$40\ \mathrm{mCi}$$ $$^{60}\mathrm{Co}$$ source for $$4.0$$ hours per day at a distance of $$4.0\ \mathrm{m}. If $$the cross-sectional area is $$1.5\ \mathrm{m}^2$$ and $$50\% of $$the gamma rays interact in the body, what is the approximate dose received in gray ($$\mathrm{Gy}$$)?

$$4.5 \times 10$$^{-4}$$\ \mathrm{Gy}$$

Q: Which of the following is the correct formula for calculating the effective dose in rem?

$$\text{Effective dose in rem} = \text{dose in rad} \times QF$$

Question 1

Which of the following types of radiation is considered the most damaging to biological tissue per unit of absorbed dose?

Accepted Answer

Alpha particles

Question 2

A laboratory worker receives an absorbed dose of $$0.02\ \mathrm{Gy}$$ from fast neutrons (quality factor $$QF = 10). $$What is the effective dose in sieverts ($$\mathrm{Sv}$$)?

Accepted Answer

$$0.2\ \mathrm{Sv}$$

Question 3

Which of the following best describes why radiation therapy sources are rotated around a patient during cancer treatment?

Accepted Answer

To minimize the dose to healthy tissue while maximizing the dose to the tumor

Question 4

A radioactive tracer is injected into a patient and detected using a gamma-ray detector. What property of the tracer allows it to be used for noninvasive scans?

Accepted Answer

It emits gamma rays that can penetrate tissue and be detected externally

Question 5

The SI unit for measuring the activity of a radioactive source is the becquerel ($$\mathrm{Bq}). $$What does $$1\ \mathrm{Bq}$$ represent?

Accepted Answer

One decay per second

Question 6

A sample emits $$4.0\ \mathrm{pCi} of$$ $$^{222}\mathrm{Rn} ($$half-life $$3.8$$ days). Using $$1\ \mathrm{Ci} = 3.7 	imes 10$$^{10}$$ decays/s, estimate the number of $$^{222}\mathrm{Rn}$$ atoms present in the sample.

Accepted Answer

$$7.05 	imes 10^4$

Question 7

Which of the following statements about ionizing radiation is correct?

Accepted Answer

Ionizing radiation can cause ionization in materials it passes through, leading to biological damage

Question 8

A detector with 70% efficiency records 720 counts per minute from a sample. What is the actual emission rate of the sample in decays per second?

Accepted Answer

17.1 decays/s

Question 9

Which of the following is the correct relationship between the absorbed dose in gray ($$\mathrm{Gy}) $$and rad?

Accepted Answer

$$1\ \mathrm{Gy} = 100\ \mathrm{rad}$$

Question 10

A worker receives a dose of $$0.3\ \mathrm{Gy}$$ from X-rays ($$QF = 1). $$What is the effective dose in sieverts?

Accepted Answer

$$0.3\ \mathrm{Sv}$$

Question 11

Which of the following is a recommended action by the Environmental Protection Agency (EPA) regarding radon exposure in homes?

Accepted Answer

Take action if radon exceeds $$4\ \mathrm{pCi/L} of $$air

Question 12

If a person receives a short dose of $$1000\ \mathrm{rem}$$, what is the likely outcome?

Accepted Answer

Almost always fatal

Question 13

Which of the following is NOT a use of radioactive tracers in medicine?

Accepted Answer

Treating bacterial infections directly

Question 14

A patient receives an absorbed dose of $$50\ \mathrm{rad}$$ from alpha particles ($$QF = 20). $$What is the effective dose in rem?

Accepted Answer

$$1000\ \mathrm{rem}$$

Question 15

Which of the following statements about the quality factor (QF) is correct?

Accepted Answer

QF is used to account for the different biological effects of various types of radiation

Question 16

A 70-kg worker is exposed to a $$40\ \mathrm{mCi}$$ $$^{60}\mathrm{Co}$$ source for $$4.0$$ hours per day at a distance of $$4.0\ \mathrm{m}. If $$the cross-sectional area is $$1.5\ \mathrm{m}^2$$ and $$50\% of $$the gamma rays interact in the body, what is the approximate dose received in gray ($$\mathrm{Gy}$$)?

Accepted Answer

$$4.5 	imes 10$$^{-4}$$\ \mathrm{Gy}$$

Question 17

Which of the following is the correct formula for calculating the effective dose in rem?

Accepted Answer

$$	ext{Effective dose in rem} = 	ext{dose in rad} 	imes QF$$

Question 18

Which of the following is a typical value for natural background radiation exposure per year?

Accepted Answer

$$0.3\ \mathrm{rem}$$

Question 19

Why is it important to measure the dose of radiation received by patients and workers?

Accepted Answer

To minimize the risk of biological damage and ensure safety

Question 20

Which of the following is the maximum recommended annual effective dose for radiation workers, according to the study materials?

Accepted Answer

$$5\ \mathrm{rem} in $$any one year

Nuclear Energy: Effects and Uses of Radiation (Dosimetry, Biological Damage, and Medical Applications)

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