TBI & Terrorism

Question 1

What’s the time to death from hematopoietic syndrome?

Answer 1

30-60 d

Question 2

What’s the time to death from cerebrovascular syndrome?

Answer 2

1-2 d

Question 3

What’s the time to death from GI syndrome?

Answer 3

3-16 d

Question 4

What’s the main cause of death from hematopoietic syndrome?

Answer 4

infection & hemorrhage

Question 5

What would be the first step in managing a pt exposed to 3 Gy?

Answer 5

• Recommended admission to a hospital
• Reverse air-flow isolation
• Initiation of ABX

Question 6

Which radiation dose exposure can be managed with home monitoring?

Answer 6

< 2 Gy

Question 7

What’s the LD50/60 for humans w/o supportive care?

Answer 7

2.4-4 Gy

Question 8

What’s the LD50/60 for humans w/ supportive care?

Answer 8

7.5 Gy

Question 9

What’s the exposure dose that will necessitate BM transplant?

Answer 9

7.5 - 10 Gy

Question 10

What radiation dose leads to a detectable change in blood counts?

Answer 10

1 Gy

Question 11

What’s one of the first signs of exposure to supralethal doses of radiation?

Answer 11

Immediate (within days) severe diarrhea

Question 12

What is one late toxicity/syndrome that may kill pts many months or years after exposure?

Answer 12

Pulmonary syndrome

Question 13

What’s the chronological order of blood cells rex to radiation exposure?

Answer 13

• Lymphocyte Death
• Transient Neutrophil increase f/b a massive decrease
• Granulocyte (Progenitor) Death
• Thrombocytopenia
• Anemia (mature RBC’s are very radioresistant)

Question 14

What is a classical pathological autopsy finding in the BM of pts who die of GI syndrome?

Answer 14

Mitotic arrest in the intestinal crypt cells

Question 15

What is the LD50 for GI syndrome?

Answer 15

8 Gy

Question 16

What is the LD50 for cerebrovascular syndrome?

Answer 16

20 Gy

Question 17

What is the LD50 for hematopoietic syndrome?

Answer 17

3.5 Gy

Question 18

Why do patients receiving TBI conditioning regimens not develop GI sx?

Answer 18

It’s delivered in fx and at low dose-rates

Question 19

Which organ system(s) is most at risk for life-threatening injuries from TBI conditioning regimens?

Answer 19

• Kidneys f/b
• Lungs (especially when given alongside cyclophosphamide/busulphan)

Question 20

What is Mn-SOD?

Answer 20

Manganese Superoxide Dismutase, an antioxidant

Natural free-R scavengers found in the body

Question 21

What is the synthetic drug that mimics Mn-SOD?

Answer 21

porphyrin derivate - MnTE-2-PyP(st)

Question 22

What is the mechanism of action of Mn-SOD?

Answer 22

Unknown; not yet used clinically

Question 23

What is Pentoxyfylline?

Answer 23

Used clinically to improve circulation.

Mnemonic: Oxify → improves oxygenation

Question 24

What is the MOA of Pentoxyfylline?

Answer 24

Inhibits TNF-alpha and other cytokines, preventing fibrosis.

Can potentially prevent late radiotoxicity.

Question 25

What are decorporation agents?

Answer 25

They can take radiotoxins out of the body or prevent their absorption.

Question 26

What’s the treatment for Cs-131 poisoning?

Answer 26

Prussian blue (potassium ferric hexacyanoferrate)

It binds to Cs-131 in the GI tract and promotes excretion.

Question 27

What are some common decorporation agents? Which radiotoxin do they protect against?

Answer 27

Prussian blue
Zinc or Calcium DTPA

Both protect against Cs-131

Question 28

What is a blocking agent?

Answer 28

Something that can block the uptake of a radiotoxin into a normal organ.

Question 29

What’s the role of KI in radiation toxicity?

Answer 29

Can prevent the uptake of radioactive I into the thyroid gland.

Question 30

How long is the lifecycle of platelets?

Answer 30

7-10 days

Question 31

What is the order of decontamination following exposure to radioactive material?

Answer 31

1. Open wounds
2. Nose, mouth (mucosal surfaces)
3. Intact skin

Think about it: Open wounds have direct access to the blood supply, making them the riskiest. Nose and mouth have mucosal barreiers.

Question 32

What’s the frequency of vomiting after different doses of radiation?

Answer 32

• Frequency
  – <1Gy → few instances of vomiting
  – >2Gy → most pts vomit
• Average time to vomiting is indicative of the dose
  – ↑ dose → ↓ time to vomiting
  – It’s the most sensitive in-vivo dosimeter after radiation exposure