Notes

Question 1

H-3 Notes

Answer 1

• Tritium is a low-energy beta emitter and poses minimal external radiation hazard.
• It is a concern mainly through inhalation, ingestion, or skin absorption.

Question 2

H-3 is commonly found where

Answer 2

In radiolabeled compounds, fusion research, self-luminous devices, and nuclear reactors.

Question 3

What is C-14 used for?

Answer 3

It is used extensively in radiocarbon dating of organic materials.

Question 4

Concerns from C-14

Answer 4

As a low-energy beta emitter, it poses minimal external hazard, but internal exposure (ingestion/inhalation) is the primary concern.

Question 5

Where is C-14 found?

Answer 5

It is found in nature as a result of cosmic ray interactions in the upper atmosphere.

Question 6

Why is F-18 ideal for diagnostic imaging?

Answer 6

Because of its short half-life and positron emission.

Question 7

Concerns of F-18

Answer 7

External exposure is a concern due to the high-energy annihilation photons.

Question 8

Concerns of P-32

Answer 8

There is significant external and internal radiation hazards since P-32 is a high-energy beta emitter.

Question 9

Where is P-32 used?

Answer 9

Commonly used in molecular biology, cancer therapy, and radiotracer studies.

Question 10

Shielding for P-32

Answer 10

Due to its energetic beta emissions, shielding with acrylic or plastic is recommended (to avoid bremsstrahlung from denser materials like lead).

Question 11

Concerns with S-35

Answer 11

S-35 is a low-energy beta emitter, posing minimal external hazard.

Question 12

S-35 commonly used how?

Answer 12

In biological and biochemical research, especially in protein and nucleic acid labeling.

Question 13

S-35 Shielding

Answer 13

Due to the low energy of emissions, thin plastic shielding is sufficient.

Question 14

Concerns for Co-60

Answer 14

Significant external radiation hazard

Question 15

What is Co-60 used for?

Answer 15

Co-60 is a high-energy gamma emitter used in radiotherapy, industrial radiography, sterilization, and calibration sources.

Question 16

Shielding for Co-60

Answer 16

Dense shielding (e.g., lead or concrete) is required. shielding (e.g., lead or concrete) is required.

Question 17

Why is Co-60 good for cancer treatment?

Answer 17

Its predictable, intense gamma emissions make it valuable for dose delivery in cancer treatment.

Question 18

Concern for Sr-90

Answer 18

• No significant gamma emissions, but strong external and internal hazard from high-energy beta radiation (especially due to its daughter Y-90).
• Chemically similar to calcium, Sr-90 tends to accumulate in bone, increasing risk for bone cancer and leukemia.

Question 19

Uses for Sr-90

Answer 19

Common uses include radioisotope thermoelectric generators (RTGs) and radiotherapy.

Question 20

What is Tc-99m used for?

Answer 20

• Most widely used in diagnostic Nuc Med
• bone scans, cardiac imaging, renal scans, and tumor localization.

Question 21

Tc-99m is ideal for what imaging and why?

Answer 21

Its ideal gamma energy, short half-life, and chemical versatility make it optimal for SPECT imaging.

Question 22

Concerns with Tc-99m

Answer 22

Because of the short half-life and lack of particulate radiation, radiation exposure is minimized for patients.

Question 23

What is I-125 used for?

Answer 23

• Permanent implants for prostate brachytherapy
  *Radioimmunoassays
  *Tracer studies in research

Question 24

I-125 shielding

Answer 24

Emits low-energy photons so e.g., leaded acrylic

Question 25

I-125 concerns

Answer 25

Internal exposure is the primary concern—can concentrate in the thyroid if inhaled or ingested.

Question 26

What is I-131 used for?

Answer 26

* Thyroid imaging and ablation * Treatment of hyperthyroidism and thyroid cancer

Question 27

I-131 shielding

Answer 27

lead

Question 28

I-131 concerns

Answer 28

Emits both penetrating gamma radiation (external hazard) and high-energy beta particles (internal hazard).

Question 29

Cs-137 used for?

Answer 29

* Radiotherapy (external beam) * Industrial gauging and calibration * Environmental monitoring

Question 30

Cs-137 concerns

Answer 30

* Long half-life and energetic gamma rays make it a significant external radiation hazard. * Can contaminate the environment and persist in soil and food chains—internal exposure (e.g., ingestion) is also a concern.

Question 31

Cs-137 shielding

Answer 31

Requires dense shielding (e.g., lead or concrete).

Question 32

Ra-226 uses

Answer 32

Historically used in: *Cancer therapy (e.g., brachytherapy) * Luminous paint for watches and dials (no longer used due to safety concerns)

Question 33

Ra-226 concerns

Answer 33

* Significant internal hazard (if ingested or inhaled) due to alpha radiation. * Gamma emissions also pose an external hazard, requiring lead shielding.

Question 34

Ra-226 decay chain

Answer 34

Ra-226 is part of the uranium-238 decay chain and decays to radon-222, a radioactive gas.

Question 35

Am-241 concerns

Answer 35

Alpha emitter with some low-energy gamma radiation, making it primarily an internal hazard if inhaled or ingested.

Question 36

Am-241 used in?

Answer 36

* Smoke detectors (most common application) * Moisture/density gauges in industry * Neutron sources (when combined with beryllium)

Question 37

Am-241 shielding

Answer 37

* Alpha particles: blocked by paper or skin * Gamma rays: low-energy, but still require moderate shielding (e.g., plastic or leaded glass)

Question 38

Lu-177 used for?

Answer 38

* Lu-177 is used in targeted radionuclide therapy, especially for: - Neuroendocrine tumors (e.g., using Lu-177 DOTATATE) - Prostate cancer (e.g., Lu-177 PSMA therapy)

Question 39

What does beta emissions from Lu-177 do?

Answer 39

Deliver localized therapeutic dose to tumors.

Question 40

What does gamma emissions from Lu-177 do?

Answer 40

Allow for imaging and dosimetry using SPECT

Question 41

Shielding for Lu-177

Answer 41

Requires moderate shielding (plastic for beta; lead or leaded glass for gamma).

Question 42

Y-90 used for?

Answer 42

* Y-90 is used in targeted radiotherapy, including: - Radioembolization (e.g., Y-90 microspheres for liver cancer) - Radiolabeled monoclonal antibody therapy

Question 43

Y-90 shielding

Answer 43

Requires plastic or acrylic shielding to avoid bremsstrahlung from dense materials like lead.

Question 44

Why is Y-90 good for tumor treatment?

Answer 44

High-energy beta emission allows for localized tumor cell destruction with minimal damage to surrounding tissue.

Question 45

Why is Y-90 not used for imaging?

Answer 45

No gamma emission makes it difficult to image directly—bremsstrahlung or surrogate imaging tracers are used for verification.

Question 46

Silver zeolite is the medium of choice for iodine sampling primarily because of its:

Answer 46

low affinity for noble gas. | due to high $, silver zeolite used only during emerg fission gas sample

Question 47

Results from environmental radioactivity samples, such as in the analysis of soils and vegetation, are typically expressed in units of:

Answer 47

picocuries per gram.

Question 48

Carbon dating is possible because:

Answer 48

the specific activity of Carbon-14 in living organisms is relatively constant through time, but decays after death of the organism.

Question 49

Which radionuclide is the most radiotoxic during a space mission?

Answer 49

Pu-238

Question 50

Which of the following radionuclides in soil is the major contributor to genetically significant radiation exposure?

Answer 50

Potassium-40

Question 51

Both 137-Cs and 131-I are released as fission products by nuclear power plants. The biopathways for these two radionuclides can be traced via:

Answer 51

milk