Half-Lives and More

Question 1

F18-FDG

Production?

Half-Life?

Decay?

Energy?

Answer 1

• Cyclotron
• 109.7 minutes. (110 minutes)
• Beta plus decay
• 511 KeV

Question 2

I-123 NaI

Half Life?

Energy?

Production?

Decay?

Answer 2

• 13 hours (take out the two)
• “low energy” 159 KeV (close to Tc-99m)
• Cyclotron produced
• electron capture

Question 3

Ga-67 citrate

Half-life?

Production?

Analog?

Decay?

Energy?

Answer 3

• 78 hours
• Cyclotron
• Iron analog
• electron capture
• 100, 200, 300, 400

Question 4

What is the half-life of Ga-68 DOTATATE (NETSPOT)?

Answer 4

The half-life of Ga-68 is 68 minutes. Ga-68 DOTATATE (NETSPOT) is a PET agent that is used in neuroendocrine tumor imaging. Ga-68 DOTATATE binds to somatostatin receptors with highest affinity for subtype 2 receptors (SSTR2). It binds to cells that express somatostatin receptors, including malignant cells, which overexpress SSTR2 receptors. Ga-68 is a β+ emitting radionuclide, which allows for PET imaging.

Question 5

Low Energy Collimator Radionuclides

Answer 5

• Tc-99m
• Xe-133
• Tl-201

Question 6

Medium Energy Collimator Radionuclides

Answer 6

• In-111
• Ga-67
• I-123

Question 7

High Energy Collimator Radionuclides

Answer 7

• I-131

Question 8

Tc-99m

Half-life?

Production?

Energy?

Decay?

Answer 8

• 6 hours
• ⁹⁹Mo Generator
• “Low energy” 140 KeV
• IT decay

Question 9

Xe-133

Half life?

Energy?

Production?

Decay?

Answer 9

• 125 hours (biologic is 30 seconds)
• “low energy” 81 KeV
• Nuclear Reactor
• Beta minus decay

Question 10

Thallium-201

Analog?

Half-Life?

Energy?

Production?

Decay?

Answer 10

• Potassium analog
• 73 hours
• 135 and 167 keV are gamma rays, but MAJOR imaging contribution is from decay to Mercury 201 via electron capture releasing 69 and 81 keV XRAYS.
• cyclotron
• electron capture

Question 11

Indium-111

Half-life?

Energy?

Production?

Decay?

Answer 11

• 67 hours
• “medium energy” 173 and 247 (175 and 250 to remember)
• Cyclotron
• electron capture

Question 12

I-131

Half life?

Energy?

Production?

Decay?

Answer 12

• 8 days (~1 week)
• 364 KeV (~1 year)
• Nuclear Reactor produced
• Beta minus decay

Question 13

Treatment Radionuclide Half-Lives

• Samarium-153
• Yttrium-90
• Radium-223
• Strontium-89

Answer 13

• Samarium-153 = 46 hours
• Yttrium-90 = 64 hours (~3 days)
• Radium-223 (11 days)
• Strontium-89 (50.5 days; 14 days in bones)

Question 14

Cardiac Radionuclide Half Lives

• Rubidium 82
• N-13

Answer 14

• Rubidium 82 = 75 seconds
• N-13 = 10 minutes