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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
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