Unit 1.6

Question 1

Define Non-Stochastic/Deterministic Effects. Give examples.

Answer 1

Health Effects for which severity varies with the dose and for which a threshold normally exists. Examples include epilation (100s of rads) and erythema (100s of rads).

Question 2

Define Acute Radiation Syndrome

Answer 2

Biologic changes and symptoms, including death, that occur within weeks after a high-intensity total body irradiation, the earliest of which are nausea, vomiting, and diarrhea.

Question 3

Define Stochastic effects. Give examples.

Answer 3

Health Effects that occur randomly and for which the probability of the effect occurring is assumed to be a linear function of the dose without threshold. Cancer, Hereditary effects.

Question 4

What are the stages of the cell cycle in order.

Answer 4

Interphase (G1, S, G2), Mitosis including prophase, metaphase, anaphase, telophase, and cytokinesis.

Question 5

In what stages are cells most sensitive to the effects of radiation?

Answer 5

Mitosis (M) and G2 phases are most sensitive.

Question 6

In what stages are cells most resistant to the effects of radiation?

Answer 6

S phase.

Question 7

List the potential results of radiation damage on a cell.

Answer 7

Dead Mother: The cell may die.
Good Daughter: cell repairs itself and replicates normally.
Bad Daughter: cell cannot repair itself, but can survive and divides into abnormal daughter cells.
Dead Daughter: Cell repairs well enough to live but upon division, its daughters cannot survive and it dies.

Question 8

Describe direct and indirect radiation effects the cell.

Answer 8

Direct: High LET atoms create particles like Alpha and fast neutrons that directly interact with the atom and either excite it or ionize it directly, which ultimately participates in cell damage.
Indirect: Low LET atoms create particles like photons and beta particles that interact with atoms to create free radicals that ultimately lead to damage to the cell.

Question 9

Express the Law of Bergonie and Tribondeau.

Answer 9

Cells are sensitive if they are:

1. Have a high division rate.
2. Have a long dividing future.
3. Are of an unspecified type.

Question 10

List modifiers for radiation sensitivity for the whole body.

Answer 10

Chemical: Oxygen concentration, temperature.
Physical: LET, dose rate, fractionation.
Biological: Age, Gender, Health.

Question 11

What organs are generally more and less sensitive?

Answer 11

In order: Blood producing organs, Reproductive and GI tract organs, Skin, Muscle and Brain.

Question 12

List the early effects of radiation on a biologic system.

Answer 12

Nausea, vomiting, malaise, fatigue, Increased temperature, blood changes.

Question 13

What are the most radiosensitive cells in the body? The least?

Answer 13

In order: Lymphocytes, bone marrow/stem cells, intestinal crypt cells, … connective tissue, bone cells, nerve cells, brain cells, muscle cells.

Question 14

What is the threshold dose of radiation for acute radiation syndrome?

Answer 14

Whole body doses of 100 rad.

Question 15

List the 4 stages of the acute radiation syndrome.

Answer 15

Prodromal (N/V/D)
Latent: symptoms subside, hours to weeks.
Manifest Illness: Characterized by symptoms consistent with dose from prodromal symptoms to CNS effects.
Death or recovery.

Question 16

What are the three subclassifications of ARS and their respective doses?

Answer 16

Hematopoetic syndrome: 100-1000 RAD
Gastrointestinal syndrome: 1000-5000 RAD
Cerebrovascular Syndrome: >5000 RAD

Question 17

Describe Hematopoetic Syndrome.

Answer 17

Occurs between 100-1000RAD; Prodromal phase is normal N/V/D; latent phase is characterized by declining numbers of RBCs, WBCs, and PLTs. Ultimately patients get malaise, anemia, hemorrhage, and infections that cause dehydration, electrolyte abnormalities, and infections that can lead to death.

Question 18

Describe the Gastrointestinal Syndrome.

Answer 18

Occurs between 1000-5000RAD; Includes the symptoms of hematopoetic syndrome by includes depopulation of the lining of the GI tract with N/V in the manifest illness and prolonged diarrhea. Medical intervention cannot prevent death.

Question 19

Describe the Cerebrovascular Syndrome.

Answer 19

Occurs at doses >5000RAD. Characterized by Ataxia, convulsions, difficulty breathing, loos of coordination, coma and ultimate death within hours to days. Death usually results from cerebral edema and herniation.

Question 20

What is the LD 50/60 for humans?

Answer 20

An acute dose delivered to a group such that 50% will survive for 60 days without medical intervention/treatment. This is approximately 410 Rads.