Radiation In Your Life Prentice-Hall Chapter 25.4 Dr. Yager

Objectives  Identify three devices that are used to detect nuclear radiation  Describe how radioisotopes are used in medicine and at home.

The Gamma People (1956)

The Atomic Man (1956)

Detecting Radiation  Radiation strikes atoms or molecules to create ions.  Ions are detected as pulses and the pulses are counted.  Radiation strength is measured in curies (Ci) or becquerel (Bq). 1 Ci = 3.7 x disintegration per second 1 Ci = 3.7 x disintegration per second 1 Bq = 1 disintegration per second 1 Bq = 1 disintegration per second

Types of Detectors  Geiger Counters  Scintillation Counters  Film Badges

Geiger Counter A Geiger Counter Inside the tube is a gas that ionizes when struck with radiation.

Film Badge

Using Radiation  Neutron Activation Analysis  Medicine  Smoke Detectors  Food Irradiation

Medical Uses  Radioactive Tracers Iodine-131 for thyroidIodine-131 for thyroid Iron-59 for anemiaIron-59 for anemia Thallium for heart muscleThallium for heart muscle  Cancer Treatment Cobalt-60 for tumorsCobalt-60 for tumors Yttrium-90 for pituitary glandYttrium-90 for pituitary gland  PET Scans (positron emission tomography)

normal thyroid enlarged thyroid

PET scan of a patient with Alzheimer's disease shows regions of high (red) and low (blue) brain activity:

Food Preservation

In a smoke detector, radiation from the Americum nuclei ionizes the nitrogen and oxygen in smoke-free air, allowing a current to flow. When smoke particles get in the way, a drop in current is detected by an electronic circuit, causing it to sound an alarm. In a smoke detector, radiation from the Americum nuclei ionizes the nitrogen and oxygen in smoke-free air, allowing a current to flow. When smoke particles get in the way, a drop in current is detected by an electronic circuit, causing it to sound an alarm.

1. Ionizing radiation can remove _______ from atoms. 1. Ionizing radiation can remove _______ from atoms. a.protons b.neutrons c.positrons d.electrons.

1. Ionizing radiation can remove _______ from atoms. 1. Ionizing radiation can remove _______ from atoms. a.protons b.neutrons c.positrons d.electrons.

2. Which of the following is NOT a device used to detect radiation? a)geiger counter b)scintillation counter c)film badge d)radioisotope

2. Which of the following is NOT a device used to detect radiation? a)geiger counter b)scintillation counter c)film badge d)radioisotope

3. Choose the correct words for the space. When a tumor is treated by radiation, more cancer cells than normal cells are killed because cancer cells ____________ than normal cells. a.are more susceptible to damage because they grow faster b.absorb more radiation because they are larger c.grow slower d.are smaller

3. Choose the correct words for the space. When a tumor is treated by radiation, more cancer cells than normal cells are killed because cancer cells ____________ than normal cells. a.are more susceptible to damage because they grow faster b.absorb more radiation because they are larger c.grow slower d.are smaller

4. How do scientists detect thyroid problems? a.with teletherapy b.by neutron activation analysis c.using an iodine-131 tracer d.using a radioisotope sealed in a gold tube

4. How do scientists detect thyroid problems? a.with teletherapy b.by neutron activation analysis c.using an iodine-131 tracer d.using a radioisotope sealed in a gold tube

What does the disintegration rate tell us? Rate = k N, where If we know the rate and half-life we can determine the amount of material. Rate= 1000 counts/sec of 99 Tc Half-life = 6 hours = sec k = 0.693/21600sec= 3.21 x10 -5 N = 1000/3.21x10 -5 = 3.1x10 7 nuclei N = 1000/3.21x10 -5 = 3.1x10 7 nuclei moles = 5.15x mol moles = 5.15x mol mass= 5.05 x10 15 g mass= 5.05 x10 15 g

Neutron activation analysis (NAA) is one of the most sensitive techniques used for qualitative and quantitative elemental analysis of multiple major, minor, and trace elements in samples from almost every conceivable field of scientific or technical interest. Neutron activation analysis (NAA) is one of the most sensitive techniques used for qualitative and quantitative elemental analysis of multiple major, minor, and trace elements in samples from almost every conceivable field of scientific or technical interest. Environmental pollutants studies Environmental pollutants studies Semiconductor materials measure ultra trace-element or impurities Semiconductor materials measure ultra trace-element or impurities Pharmaceutical materials analysis to measure ultra trace-element or impurities Pharmaceutical materials analysis to measure ultra trace-element or impurities Forensic non-destructive method to analyze evidence Forensic non-destructive method to analyze evidence Archaeological fingerprint artifacts and determine the place of origin Archaeological fingerprint artifacts and determine the place of origin Nutritional epidemiological investigate the contribution of diet, occupation, and lifestyle on chronic diseases. Nutritional epidemiological investigate the contribution of diet, occupation, and lifestyle on chronic diseases.

Neutron Activation Analysis

Surveyor Lunar Probe used alpha backscatter to analyze the surface of the moon in the 1960’s

Alpha Backscatter Analysis