Tracers and Effects of Radiation

Medical Applications of Radioactivity

• Radiotracers- radioactive nuclides that can be introduced into organisms in food or drugs and subsequently traced by monitoring their radioactivity

Medical Applications of Radioactivity

• Examples:• Iodine-131 for the diagnosis and

treatment of thyroid illness• Thallium-201 damage to heart muscle

Medical Applications of Radioactivity

• Provide sensitive and nonsurgical methods for learning about biological systems, for detecting disease, and for monitoring the action and effectiveness of drugs

• Nuclides used as radiotracers have short half-lives so that they disappear rapidly from the body

Effects of Radiation

• Somatic damage – damage to the organism resulting in sickness or death

• Genetic damage – damage to the genetic machinery of reproductive cells creating problems affecting offspring.

Factors Determining Biological Damage

• 1. Energy of the radiation• 2. Penetrating ability of the

radiation• 3. Ionizing ability of the radiation• 4. Chemical properties of the

radiation source

Factors determining biological damage

1. The E of the radiation: higher energy, more damage

2. The penetrating ability: gamma- highly beta- 1cmalpha- stopped by skin

Factors determining biological damage

3. The ionizing ability – vs. is very effective at ionizing (more

damaging) is neutral and doesn’t ionize as readily

4. Chemical properties• Toxic, accumulate in body, inert. . .

Rem indicates the danger the radiation poses for humans.

Effects of Short-Term Exposures to RadiationDose (rem)0-25

25-50

100-200

500

Clinical EffectNondetectableTemporary decrease in white

blood cell countsStrong decrease in white blood cell

countsDeath of half the exposed

population w/in 30 days

Effects of Radiation

• Typical Radiation for a person in the US per year

• About 200 rems