Filters
High-Yield Facts
- • PET imaging: 8 isotopes, all emit 511 keV annihilation photons
- • F-18: Most common PET isotope, 110 min half-life
- • Tc-99m: Most common SPECT isotope, 140 keV gamma, isomeric transition
- • Generator systems: Tc-99m (Mo-99), Ga-68 (Ge-68), Rb-82 (Sr-82)
- • Therapeutic isotopes: I-131 (thyroid), Lu-177 (NET), Y-90 (liver), Ra-223 (bone)
- • Only alpha emitter: Ra-223
Radioisotopes List
Click on any radioisotope to see detailed information. Use the filters to narrow down your search.
| Nuclide | Purpose | Half-Life | Category |
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Radioisotope Cards
Click on any card to see detailed information. Showing 0 of 23 radioisotopes.
Test Your Knowledge
High-Yield Quiz
Essential questions covering key radioisotope concepts for the ABR Core Exam.
Study Tips
- Focus on understanding the clinical applications rather than memorizing all details
- Know the key differences between PET, SPECT, and therapeutic radioisotopes
- Memorize the half-lives of common clinical isotopes (F-18, Tc-99m, I-131)
- Understand the relationship between generator parents and daughters
- Know which radioisotopes are produced by cyclotron vs. generator vs. reactor
Key Concepts for ABR Core Exam
PET Imaging Essentials
- All PET isotopes emit 511 keV photons from positron-electron annihilation
- F-18: Most common PET isotope, 110 min half-life, ideal for shipping
- Generator-produced isotopes: Ga-68 (from Ge-68) and Rb-82 (from Sr-82)
- Short half-life isotopes (C-11, N-13, O-15) require on-site cyclotron
- Zr-89 (78.4 hr half-life) ideal for antibody imaging due to slow kinetics
SPECT Imaging Essentials
- Tc-99m: Most common nuclear medicine isotope, 6 hr half-life
- Only metastable isomer: Tc-99m decays by isomeric transition
- Tc-99m production: From Mo-99/Tc-99m generator system
- I-123: Thyroid imaging (EC decay, 13 hr half-life)
- Tl-201: Cardiac imaging (EC decay, mercury X-rays)
Therapeutic Radioisotopes
- Only alpha emitter: Ra-223 (for bone metastases)
- Beta emitters: I-131, Lu-177, Y-90 (different tissue penetration)
- Production methods: All therapeutic isotopes except I-131 are produced by neutron irradiation in reactors
- I-131 production: Unique among therapeutics, produced via fission
- Y-90: Nearly pure beta emitter, highest energy (2.28 MeV)
Quality Control Isotopes
- Long half-lives: Cs-137 (30y), Ba-133 (10.5y), Co-57 (270d)
- Cs-137: 662 keV gamma from Ba-137m (higher energy)
- Co-57: 122 keV gamma (similar to Tc-99m, ideal for SPECT QC)
- Ge-68: Generator parent and PET scanner QC source
- Used for: Dose calibrator constancy, scanner calibration
Decay Modes
Beta+ Decay (β+)
A proton converts to a neutron, emitting a positron and a neutrino. Used in PET imaging.
Formula: p → n + β+ + ν
Key fact: Requires energy difference >1022 keV between parent and daughter
Beta- Decay (β-)
A neutron converts to a proton, emitting an electron and an antineutrino. Common in therapeutic radioisotopes.
Key fact: Beta particles have various energies up to a maximum value
Electron Capture (EC)
An orbital electron is captured by a proton in the nucleus, converting it to a neutron and emitting a neutrino.
Key fact: Often produces characteristic X-rays and Auger electrons
Alpha Decay (α)
Emission of a helium nucleus (2 protons and 2 neutrons). Used in targeted alpha therapy.
Key fact: Common in elements with Z>82, high LET, short range
Isomeric Transition (IT)
A metastable excited state of a nucleus decays to a more stable state, emitting a gamma ray.
Key fact: Tc-99m is the only common metastable nuclide in clinical use
Production Methods
Cyclotron
Accelerates charged particles in a spiral path to bombard target materials. Used to produce many PET isotopes like F-18.
Common isotopes: F-18, C-11, N-13, O-15, Ga-67, I-123, Tl-201, Zr-89
Generator
A long-lived parent isotope decays to a shorter-lived daughter isotope, which is eluted for medical use.
Common generators: Mo-99/Tc-99m, Ge-68/Ga-68, Sr-82/Rb-82
Reactor (Fission)
Nuclear fission produces radioisotopes as byproducts or through neutron activation of target materials.
Key isotopes: I-131, Xe-133, Cs-137, Mo-99
Reactor (Neutron Irradiation)
Target materials are bombarded with neutrons in a nuclear reactor to produce specific radioisotopes.
Key isotopes: Lu-177, Ra-223, Y-90, Ba-133
High-Yield Clusters
PET Radioisotopes (8)
All PET radioisotopes emit 511 keV annihilation photons and are produced by cyclotron or generator
SPECT Radioisotopes (6)
SPECT radioisotopes emit gamma rays with various energies
Therapeutic Radioisotopes (4)
Therapeutic radioisotopes emit beta or alpha particles
Quality Control/Generator (5)
Very long half-lives for generator parents and calibration sources
Expert Summary
For the ABR Core Exam, focus on understanding the following key concepts:
- PET Radioisotopes: All emit 511 keV photons. Most common is F-18 (110 min half-life). Generator-produced ones are Ga-68 (from Ge-68) and Rb-82 (from Sr-82). Very short half-lives (C-11, N-13, O-15) require on-site cyclotron.
- SPECT Radioisotopes: Tc-99m is the most common (6 hr half-life), produced from Mo-99 generator. It's the only one that decays by isomeric transition. Most others decay by electron capture.
- Therapeutic Radioisotopes: Ra-223 is the only alpha emitter (for bone metastases). Others (I-131, Lu-177, Y-90) are beta emitters. I-131 is uniquely produced by fission; others by neutron irradiation.
- Production Methods: Cyclotron (positron emitters, short half-lives), Generator (on-site production without cyclotron), Reactor (therapeutic isotopes, longer half-lives).
- Clinical Relevance: Focus on Tc-99m (SPECT), F-18 (PET), I-131 (therapy), which are the most widely used radioisotopes in clinical nuclear medicine.
About This Tool
This Radioisotope Learning Tool is designed to help radiology residents prepare for the American Board of Radiology (ABR) Core Exam. The tool includes comprehensive information about the 23 radioisotopes mentioned in the RISC Study Guide, organized based on clinical relevance and grouped by application type.
The information presented focuses on high-yield concepts that are most likely to appear on the ABR Core Exam, with emphasis on understanding the underlying principles rather than rote memorization of details.
How to Use This Tool
- Learn Tab: Browse radioisotopes by category, filter by various properties, and compare different isotopes side by side.
- Quiz Tab: Test your knowledge with high-yield questions or generate random questions about specific radioisotopes.
- Reference Tab: Access concise summaries of key concepts organized by topic.
ABR Core Exam Tips
- Focus on understanding the clinical applications and key properties of the most commonly used radioisotopes.
- Know the differences between PET, SPECT, and therapeutic radioisotopes.
- Understand the relationship between decay mode and imaging/therapy applications.
- Memorize the half-lives of clinically important isotopes (F-18, Tc-99m, I-131).
- Know which radioisotopes are produced by cyclotron vs. generator vs. reactor.