20.3.3 Applications of Nuclear Chemistry

Question 1

Applications of Nuclear Chemistry

Answer 1

• There are two commonly used units of exposure to radioactivity, the rad (radiation absorbed dose) and the rem (röntgen equivalent in man).
• Radiation leads to the production, through ionization, of radicals in the body that can damage DNA and other biological molecules.
• There are productive uses of radiation such as food irradiation to kill bacteria and medical imaging such as positron emission tomography (PET).

Question 2

note

Answer 2

• There are two commonly used units of exposure to
  radioactivity, the rad (radiation absorbed dose) and the rem (röntgen equivalent in man).
• The rad is a measure of the amount of energy delivered to a given amount of tissue by radiation. The LD 50 for radiation is about 500 rads. Although, alpha (α) particles are extremely damaging, they are also easily stopped by barriers such as clothing. Less damaging gamma (γ) rays, beta (β) particles and neutrons are able to travel further into the body.
• The rem takes the damage effectiveness of different forms of radiation into account in the form of a relative biological effectiveness (RBE).
• Radiation leads to the production, through ionization, of radicals in the body that can damage DNA and other biological molecules.
• An example is illustrated of the formation of the hydroxyl radical from water. This radical will deprotonate any compound it comes into contact with including genetic molecules, or DNA.
• The body is subjected to low-level ionizing radiation all the time and has developed repair mechanisms to correct the damage. These repair mechanisms can, however, be overcome by large doses of radiation.
• There are productive uses of radiation such as food irradiation to kill bacteria and medical imaging such as positron emission tomography (PET).
• During food irradiation up to 100 krad of radiation are used to kill the bacteria in meat. The treatment does not leave the meat radioactive.
• PET uses positron emitters such as 11 C incorporated into a molecule such as glucose. A sensor measures varying levels of γ rays emitted from varying levels of concentration of the glucose. This provides information especially useful in the study of brain activity.

Question 3

Radiation is measured in (non-SI) units of radiation exposure. Which statement about radiation measurement is not correct?

Answer 3

The number of rems (röntgen equivalent in man) is the number of rads divided by the “badness factor.”

Question 4

Which statement about positron emission tomography (PET) is not correct?

Answer 4

Once 11C is ingested in the body, doctors directly observe 11C levels in the target area in the body.

Question 5

Which statement about radon is not correct?

Answer 5

Radon is not readily taken in by humans, but still poses a potential threat.

Question 6

Which statement about radiation particles is not correct?

Answer 6

γ and β are absorbed the most by living tissue. As a result, they can ultimately do the most damage, despite the fact that their “badness factor” has the lowest value.

Question 7

The term irradiation is used to describe the process of exposing something to radiation. Which statement about irradiation is not correct?

Answer 7

It is impossible for radiation to pass through a cell without doing any damage.

Question 8

Food irradiation is a useful radiation technique designed to improve the quality of food. Which statement about food irradiation is not correct?

Answer 8

One process for irradiating food involves the reaction 60Co -> 60 Ni + 0 -1 e + γ. The γ rays that pass through food can sometimes be trapped in the food tissue

Question 9

There are positive applications of radiation. Which of the following statements about food irradiation or PET, is not correct?

Answer 9

In PET procedures, doctors place elemental 11C directly into the bloodstream and then observe how it responds in the body. It typically goes through a decay process that can be monitored.

Question 10

A free radical is _____________________

Answer 10

a reactive species with an unpaired valence electron.

Question 11

Water is ionized by the reaction H2O → [H2O]+ + e−. Which statement about this event is not correct?

Answer 11

This is a beta emission reaction.

Question 12

Which statement about ionizing radiation is not correct?

Answer 12

When in the human body, the hydroxyl radical, OH  • , is highly reactive. It wants to grab a hydrogen atom to form water. It particularly wants to grab a hydrogen from another water molecule. As a result, OH  •  does not pose a major health threat to living tissue.