Radiation Toxicity Flashcards Preview

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Flashcards in Radiation Toxicity Deck (13)
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1
Q

Which animals have a radiosensitivity closest to humans?

A

Dogs and rhesus monkeys; smaller animals are generally more radioresistant

2
Q

Describe the radiation toxicity prodromal syndrome

A

Neuromuscular and GI symptoms
LD50 is 3-4 Gy
Supralethal dose is 8 Gy
Starts in 5-15 min and can last days (dose dependent)

3
Q

What is the radiation cerebrovascular syndrome:

1) Dose
2) Death timing
3) Symptoms

A

1) 100 Gy
2) 24-48h
3) increased ICP due to cerebral blood vessel leakiness

4
Q

What is the radiation gastrointenstinal syndrome:

1) Dose
2) Death timing
3) Symptoms

A

1) >10 Gy
2) 3-10 days
3) nausea/vomiting, diarrhea, sepsis

5
Q

What is the radiation hematopoetic syndrome:

1) Dose
2) Death timing
3) Symptoms

A

1) >2.5 Gy (likely lethal after 4 Gy)
2) 30-60 days
3) pancytopenias, hemorrhage, fever/chills, mouth ulcers

6
Q

What is the LD50 for humans?

A

3-4 Gy without medical care

4-8 Gy with standard supportive care

7
Q

What is the timecourse of cytopenias?

A

lymphocytes drop immediately
granulocytes drop in days
platelets drop in weeks

No erythrocyte suppression

8
Q

At what dose can chromosomal aberrations in lymphocytes be seen?

A

0.25 Gy

9
Q

Is amifostine a good radioprotector?

A

Somewhat…it increases the LD50 in animals but must be given 30m before exposure and causes severe nausea and vomiting

10
Q

What are the mechanisms of late radiation toxicities?

A

vascular damage, fibrosis, damage to parenchymal cells

11
Q

What are “consequential late effecs”

A

permanent tissue damage secondary to early effects (e.g. skin necrosis requiring a graft)

12
Q

What parameter impacts acute tissue effects?

A

total dose and longer overall treatment time (Total Gy and Gy/week)

Acute reacting tissues are not very sensitive to fraction size

13
Q

What parameter impacts late tissue effects>

A

total Gy and Gy/fraction (sensitive to fraction sizes)