General RadBio

Question 0

Non lethal DNA aberrations

Answer 0

1. Symmetric translocations

2. Small deletions

Question 1

Lethal DNA aberrations

Answer 1

1. Dicentrics
2. Rings
3. Anaphase bridges

Question 2

Changes in ____________ in peripheral blood can be used to estimate a dose of TBI. The lowest single dose that can cause these changes is:

Answer 2

Lymphocytes

0.25 Gy

Question 3

1/2 time of SLD repair (mammalian tissues)

Answer 3

1 hour

Question 4

Casaret’s classification of normal tissue radiosensitivity

Categories (4)

Answer 4

1. Vegetative intermitotic cells
2. Differentiating intermitotic cells
3. Reverting postmitotic cells
4. Fixed postmitotic cells

Question 5

Properties and examples of

Vegetative Intermitotic Cells

Answer 5

Divide regularly. No differentiation

Erythroblastosis, intestinal crypt cells, germinal cells of epidermis
High sensitivity

Question 6

Properties and examples of

Differentiating intermitotic cells

Answer 6

Divide regularly
Some differentiation between divisions

Myelocytes
Intermediate sensitivity

Question 7

Properties and examples of

Reverting postmitotic cells

Answer 7

Do not divide regularly
Variably differentiated

Liver, kidney, pancreas
Intermediate sensitivity

Question 8

Properties and examples of

Fixed postmitotic cells

Answer 8

Do not divide
Highly differentiated

Nerve cells, muscle cells
Low sensitivity

Question 9

Which DNA repair mechanism can produce antibodies by V(D)J rearrangement? Why?

Answer 9

Non- homologous end joining repair

NHEJ is error-prone. This can give an array of antibodies

Question 10

OER _______ as LET increases

Answer 10

Decreases

Question 11

OER for alpha-particles

Answer 11

1

Question 12

OER neutrons

Answer 12

1.6

Question 13

OER x-rays

Answer 13

3 for high doses

~2 for doses less than 2 Gy

Question 14

Amount of oxygen required for radiosensitization:

Answer 14

0.5% oxygen (pO2 of ~3mmHg)

This results in full radiosensitivity halfway between hypoxia and full oxygenation

Question 15

Defective Homologous Recombination leads to _______, _____, and _______.

Answer 15

chromatid and chromosome aberrations,
decreased proliferation, and
ionizing radiation sensitivity

Question 16

DNA DSBs are repaired by homologous recombination in _____ phase of the cell cycle

Answer 16

S/G2

Question 17

Defective Nonhomologous Recombination leads to _________, ______, and _____

Answer 17

chromosome aberrations,
immune deficiency, and
ionizing radiation sensitivity

Question 18

DSBs are repaired by non-homologous recombination in the ____ phase of the cell cycle

Answer 18

G1

Question 19

Occupational exposure to radiation caused an increased incidence of lung tumors in what group?

Answer 19

Uranium miners

Question 20

Occupational exposure to radiation caused an increased incidence of bone tumors in what group(s)?

Answer 20

Dial painters (ingestion of radium)
Patients irradiated for ankylosis get spondylitis
Patients injected with radium for treatment of tuberculosis

Question 21

Occupational exposure to radiation caused an increased incidence of breast cancer in what group?

Answer 21

Women treated with x-rays for postpartum mastitis

Patients fluoroscoped repeatedly for management of tuberculosis

Question 22

Occupational exposure to radiation caused an increased incidence of thyroid tumors in what group?

Answer 22

Children irradiated for benign conditions of the head and neck (ie, enlarged tonsils or thymus)
Children irradiated for tinea capitis
Children exposed to radioactive iodine at Chernobyl

Question 23

Exposure to radiation caused an increased incidence of leukemia in what group?

Answer 23

patients irradiated for ankylosing spondylitis

Question 24

Exposure to radiation caused an increased incidence of leukemia and solid tumors in what group?

Answer 24

Japanese survivors of the atomic bomb

Question 25

Relationship of hyperthermia and HIF-1

Answer 25

HT increases HIF-1 by activating NADPH oxidase

Question 26

TER = ?

Answer 26

Thermal Enhancement Ratio