Radiation In Your LifeRadiation In Your Life

Prentice-Hall Chapter 25.4Prentice-Hall Chapter 25.4

Dr. YagerDr. Yager

ObjectivesObjectives

IdentifyIdentify three devices that are three devices that are used to detect nuclear radiationused to detect nuclear radiation

DescribeDescribe how radioisotopes are how radioisotopes are used in medicine and at home.used in medicine and at home.

The Gamma People The Gamma People (1956)(1956)

                          

The Atomic Man The Atomic Man (1956)(1956)

                          

Detecting RadiationDetecting Radiation

Radiation strikes atoms or molecules to Radiation strikes atoms or molecules to create ions.create ions.

Ions are detected as pulses and the Ions are detected as pulses and the pulses are counted.pulses are counted.

Radiation strength is measured in curies Radiation strength is measured in curies (Ci) or becquerel (Bq).(Ci) or becquerel (Bq).

1 Ci = 3.7 x 101 Ci = 3.7 x 101010 disintegration per second disintegration per second

1 Bq = 1 disintegration per second1 Bq = 1 disintegration per second

Types of DetectorsTypes of Detectors

Geiger CountersGeiger Counters Scintillation CountersScintillation Counters Film BadgesFilm Badges

Geiger CounterGeiger Counter

                                                                                        

A Geiger CounterA Geiger Counter

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

Film BadgeFilm Badge

Using RadiationUsing Radiation

Neutron Activation AnalysisNeutron Activation Analysis MedicineMedicine Smoke DetectorsSmoke Detectors Food IrradiationFood Irradiation

Medical UsesMedical Uses

Radioactive TracersRadioactive Tracers• Iodine-131 for thyroid Iodine-131 for thyroid • Iron-59 for anemiaIron-59 for anemia• Thallium for heart muscleThallium for heart muscle

Cancer TreatmentCancer Treatment• Cobalt-60 for tumorsCobalt-60 for tumors• Yttrium-90 for pituitary gland Yttrium-90 for pituitary gland

PET Scans PET Scans (positron emission tomography) (positron emission tomography)

normal thyroid

enlarged thyroid

PET scan of a patientwith Alzheimer'sdisease shows regionsof high (red) andlow (blue) brainactivity:

Food Preservation

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

241 237 495 93 2Am Np He

1. Ionizing radiation can remove _______ 1. Ionizing radiation can remove _______ from atoms.from atoms.

a.a. protonsprotons

b.b. neutronsneutrons

c.c. positronspositrons

d.d. electrons.electrons.

1. Ionizing radiation can remove _______ 1. Ionizing radiation can remove _______ from atoms.from atoms.

a.a. protonsprotons

b.b. neutronsneutrons

c.c. positronspositrons

d.d. electrons.electrons.

2. Which of the following is NOT a device 2. Which of the following is NOT a device used to detect radiation?used to detect radiation?

a)a) geiger countergeiger counter

b)b) scintillation counterscintillation counter

c)c) film badgefilm badge

d)d) radioisotoperadioisotope

2. Which of the following is NOT a device 2. Which of the following is NOT a device used to detect radiation?used to detect radiation?

a)a) geiger countergeiger counter

b)b) scintillation counterscintillation counter

c)c) film badgefilm badge

d)d) radioisotoperadioisotope

3. Choose the correct words for the space. 3. Choose the correct words for the space. When a tumor is treated by radiation, When a tumor is treated by radiation, more cancer cells than normal cells are more cancer cells than normal cells are killed because cancer cells killed because cancer cells ____________ than normal cells. ____________ than normal cells.

a.a. are more susceptible to damage because they are more susceptible to damage because they grow fastergrow faster

b.b. absorb more radiation because they are largerabsorb more radiation because they are larger

c.c. grow slowergrow slower

d.d. are smallerare smaller

3. Choose the correct words for the space. 3. Choose the correct words for the space. When a tumor is treated by radiation, When a tumor is treated by radiation, more cancer cells than normal cells are more cancer cells than normal cells are killed because cancer cells killed because cancer cells ____________ than normal cells. ____________ than normal cells.

a.a. are more susceptible to damage because they are more susceptible to damage because they grow fastergrow faster

b.b. absorb more radiation because they are largerabsorb more radiation because they are larger

c.c. grow slowergrow slower

d.d. are smallerare smaller

4. How do scientists detect thyroid problems?4. How do scientists detect thyroid problems?

a.a. with teletherapywith teletherapy

b.b. by neutron activation analysisby neutron activation analysis

c.c. using an iodine-131 tracerusing an iodine-131 tracer

d.d. using a radioisotope sealed in a gold tubeusing a radioisotope sealed in a gold tube

4. How do scientists detect thyroid problems?4. How do scientists detect thyroid problems?

a.a. with teletherapywith teletherapy

b.b. by neutron activation analysisby neutron activation analysis

c.c. using an iodine-131 tracerusing an iodine-131 tracer

d.d. using a radioisotope sealed in a gold tubeusing a radioisotope sealed in a gold tube

What does the disintegration rate tell us?What does the disintegration rate tell us?

Rate = k N, whereRate = k N, where

If we know the rate and half-life we can If we know the rate and half-life we can determine the amount of material.determine the amount of material.

Rate= 1000 counts/sec of Rate= 1000 counts/sec of 9999TcTc

Half-life = 6 hours = 21600 secHalf-life = 6 hours = 21600 sec

k = 0.693/21600sec= 3.21 x10k = 0.693/21600sec= 3.21 x10-5-5

N = 1000/3.21x10N = 1000/3.21x10-5-5 = 3.1x10 = 3.1x1077 nuclei nuclei

moles = 5.15x10moles = 5.15x10-17-17mol mol

mass= 5.05 x10mass= 5.05 x101515gg

2

1t

0.693 k

Neutron activation analysis (NAA)Neutron activation analysis (NAA) is one of the most is one of the most sensitive techniques used for qualitative and sensitive techniques used for qualitative and quantitative elemental analysis of multiple major, quantitative elemental analysis of multiple major, minor, and trace elements in samples from almost minor, and trace elements in samples from almost every conceivable field of scientific or technical every conceivable field of scientific or technical interest. interest.

EnvironmentalEnvironmental pollutants studies pollutants studies Semiconductor materialsSemiconductor materials measure ultra trace-element or measure ultra trace-element or impuritiesimpurities Pharmaceutical materials analysisPharmaceutical materials analysis to measure ultra trace-element or to measure ultra trace-element or

impuritiesimpurities ForensicForensic non-destructive method to analyze non-destructive method to analyze evidenceevidence ArchaeologicalArchaeological fingerprint fingerprint artifactsartifacts and determine the place of origin and determine the place of origin Nutritional epidemiologicalNutritional epidemiological investigate the contribution of diet, investigate the contribution of diet,

occupation, and lifestyle on occupation, and lifestyle on chronic diseaseschronic diseases. .

Neutron Activation Analysis

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

Alpha Backscatter Analysis