Chapter 14 Radiation Biology

Which of the following statements are correct for the radionuclides used in nuclear medicine imaging?

The dose equivalent is equal to the absorbed does

the radiation weighting factor or relative tissue damage per administered gray of radiation is larger for high-LET radiation than for low-LET radiation

True or False: single-strand DNA breaks which are caused by low-dose low-LET radiation are less likely to be repaired than double- or multiple- strand breaks which are caused by high-dose low-LET radiation or high-LET radiation

False

Ranke the following phases of the cell cycle from the most radiosensitive to the least radiosensitive

1. Mitosis

2. Interphase G₁

3. Synthetic phase (S)

4. interphase G₂ (later part)

1. mitosis

2. interphase G₂ (Later part)

3. Interphase G₁

4. Synthetic phase (S)

Which of the following are true?

1. Oxygen enhance DNA damage from high-LET radiation more than it enhance DNA damage from low-LET radiation

2. The oxygen enhancement ratio for low-LET radiation is 1

3. The oxygen enhancement ratio for high-LET radiation is 2.5 to 3.5

4. All of the above

5. None of the aboe

none of the above

Connect the following doses or risk factors with their estimated values

Threshold dose in gray above which there is 100%incident of cataracts

2 Gy (200rad)

Connect the following doses or risk factors with their estimated values

Doubling dose that will increase the genetic mutation rate to twice the baseline rate

1 Gy (100rad)

Connect the following doses or risk factors with their estimated values

Excess relative risk of cancer induction per sievert of low-dose radiation exposure

0.1%

Rank the following tissues in order from most radiosensitive to most radioresistant

1. Lymphocytes

2. Neural cells

3. Spermatozoa

4. Erythrocytes

5. Intestinal crypt cells

1. Lymphocytes

2. Intestinal crypt cells

3. Spermatozoa

4. Erythrocytes

5. Neural cells

The highest risk of radiation-induced severe mental retardation occurs during which stage of embryonic and fetal development?

Early fetal development (weeks 8-15)

True or False: In general radiation exposure of the preimplantation embryo will result in either survival without malformation or death

True