Topics for Today What are ions? How is radiation detected? How do you stop alpha radiation? Beta? Gamma? Nuclear Medicine

Readings for Today What are ions? Sections 5.7 and 5.8 Are ions bad for you?

Readings for Today Hazards Associated with Radioactivity Section 7.8 Are ions bad for you?

Topics for Friday Nuclear Fission –The BIG difference between U-235 and U-238 –Nuclear Fission –Fission Products (Nuclear Waste and Fallout) –Quiz #2

Readings for Friday How does Nuclear Fission Work? Section 7.2.

Announcements

PRELAB QUIZ for Week #3 Due BEFORE your lab this week You will have three attempts this week (and for all the rest).

QUIZ #2 Friday. Non-memory calculators are allowed Remember to sit in the DARK colored seats!

Topics for Today What are ions? How is radiation detected? How do you stop alpha particles? Beta? Gamma rays? Nuclear Medicine

Ionizing Radiation α and β particles γ rays

Ionizing Radiation α and β particles γ rays Ionizing radiation forms ions.

Handout Ion worksheet

WHAT ARE IONS?

H2OH2O Ionizing radiation (alpha, beta, or gamma)

H2OH2O H2OH2O + + Ionizing radiation + e-e-

Is this a chemical process or a nuclear process?

Is it taking place in the nucleus?

What is an ion? A charged atom or molecule. The charge can be positive or negative. I-I- H2O+H2O+

What is an ion? A charged atom or molecule. The charge can be positive or negative. I-I- H2O+H2O+ How are ions formed?

What is an ion? A charged atom or molecule. The charge can be positive or negative. I-I- H2O+H2O+ How are ions formed? Ions are formed when there are unequal numbers of protons and electrons.

Are ions bad for you? YES?MAYBE? NO?

Are ions bad for you? YES?MAYBE NO?

Sodium in a Lake reen.aspx?file= m/prerolls/78660/2/0/1/data.xml&item=1&ti mestamp=19&id=78660http:// reen.aspx?file= m/prerolls/78660/2/0/1/data.xml&item=1&ti mestamp=19&id=78660

Ions commonly found in nature. Table Salt (sodium chloride) Limestone (calcium carbonate and magnesium carbonate) Baking Soda (sodium bicarbonate)

How is iodine utilized in your body? Chapter 11: Nutrition Minerals: Macro and Micro (page 511) How long until a sample of I-131 is “gone” from a patient’s body?

How is iodine used in your body? Two iodine atoms A gas Elemental iodine? I 2 molecule?

How is iodine used in your body? I 2 molecule? Two iodine atoms A gas Elemental iodine? Iodide Ion? OR I-I-

WHAT ARE IONS? END

How do we measure radiation?

Geiger Counter

Filled with an inert gas (usually argon).

H2OH2O H2OH2O + + Ionizing radiation + e-e- Remember…

Geiger Counter Filled with an inert gas (usually argon). ArAr + + e - Alpha, Beta, Gamma Radiation

Geiger Counter Filled with an inert gas (often argon). ArAr + + e - Detected by electronics

Geiger Counter Filled with an inert gas (often argon). ArAr + + e - Detected by electronics How is this different from a beta particle?

Penetration Depths What are the differences between alpha, beta, and gamma radiation?

Alpha Particles Po 4 2 He Pb t ½ = 138 days

Alpha Particles n p n p Po 4 2 He Pb t ½ = 138 days

Alpha radiation n p n p Alpha radiation can generally be blocked by a piece of paper.

Alpha radiation n p n p Alpha radiation can generally be blocked by a piece of paper. When is alpha radiation dangerous ?

Where might you find alpha sources in your home?

“This device contains 0.9 microcurie of americium, a radioactive material…”

Beta Source Cl  β + Ar t 1/2 = 31,000 years

Beta radiation What could stop a beta particle?

Beta radiation What could stop a beta particle?

Gamma Source Co  β + Ni t 1/2 = 5.27 years γ 0000

Gamma radiation

Ionizing Radiation SymbolMassEnergy Alpha Particle α 4Low Beta Particle β ~0Medium Gamma Ray γ 0High

Nuclear Medicine How can we use beta and gamma particles?

Review - Isotopes Some isotopes are stable, some isotopes are radioactive

Iodine 131 I - vs. 127 I -

Iodine 131 I - vs. 127 I - Where is iodine used in your body?

Thyroid The iodide ion (I - ) concentrates in your thyroid

Thyroid Produces hormones to help regulate heart rate, blood pressure, metabolism, etc…

Beta (and gamma) decay of iodine I Xe β γ I-131t ½ = 8.06 days

Review - Isotopes Which isotope of iodine will concentrate in the thyroid? 131 I - vs. 127 I -

Review - Isotopes Which isotope of iodine will concentrate in the thyroid? 131 I - vs. 127 I - I-131? I-127? Both?

Review - Isotopes Which isotope of iodine will concentrate in the thyroid? 131 I - vs. 127 I - I-131? I-127? Both! Chemically speaking, isotopes behave almost identically

In thyroid scans, patients ingest potassium iodide (KI).

Potassium ion (K + ) Iodide ion (I - )

Thyroid The iodide ion (I - ) concentrates in your thyroid Which isotope of iodine will the patient be given to ingest? I-127 or I-131?

Beta (and gamma) decay of iodine I Xe β γ I-131t ½ = 8.06 days

A gamma scintillation camera measures the gamma rays emitted from the thyroid at three directions, producing a picture of the thyroid.

This nuclear medicine technique measure the degree of function of the thyroid. –That is, how well does the thyroid take up iodine?

Figure 7.21 page 337 “The yellow and red regions show areas of I-131 concentration.”

Thyroid scans Normal Indicates thyroid problem

Any other nuclear imaging techniques?

Positron Emission Tomography (PET) Any other nuclear imaging techniques?

Positron Emission Tomography (PET) Any other nuclear imaging techniques? Also requires the use of a radioisotope.

Positron Emission Tomography (PET) What is a positron?

Positron Emission Tomography (PET) A positron is an “anti-electron,” a type of anti-matter. SAME mass as an electron OPPOSITE charge Known as β 0101

Some positron emitters… 13 N 10 min 15 O 2 min 18 F 110 min t 1/2 ALL of these isotopes are man-made

Some positron emitters… 13 N 10 min 15 O 2 min 18 F 110 min t 1/2 How does 18 F decay?

Positron Emission of 18 F F β + O Positron

Positron Emission of 18 F F β + O Positron Compare with a beta particle…

Positron Emission of 18 F F β + O Positron How does this help us image?

Annihilation Reaction An electron is never far away… eβ γ 0000 Anti- Matter MatterENERGY!! Positron Electron

Annihilation Reaction An electron is never far away… eβ γ 0000 Anti- Matter MatterENERGY!! What about the gamma rays?

Annihilation Reaction An electron is never far away… eβ γ 0000 Anti- Matter Matter Equal energy gamma rays are emitted in opposite directions.

The gamma rays are detected here!

What can we learn from PET?

A common type of scan uses 18 F “labeled” glucose.

This glucose is metabolized in your body exactly as “normal” glucose.

A common type of scan uses 18 F “labeled” glucose. This glucose is metabolized in your body exactly as “normal” glucose. With PET, we can “see” exactly where the glucose is going!

So what ? A common type of scan uses 18F “labeled” glucose. This glucose is metabolized in your body exactly as “normal” glucose. With PET, we can “see” exactly where the glucose is going!

Like with I-131 imaging of the thyroid, PET measures REAL-TIME function of an organ (brain, for example), and NOT the anatomy.

Uses of PET Used to diagnose disease Used to diagram brain function

Like with I-131 imaging of the thyroid, PET measures REAL-TIME function of an organ (brain, for example), and NOT the anatomy. Functional changes are noticed earlier than structural changes in your body.

For example Cancer cells metabolize glucose different than normal cells.