MIDTERMS

Question 1

Principle stating that radiosensitivity varies with maturation and metabolism.

Answer 1

Law of Bergonie and Tribondeau

Question 2

According to this law, stem cells are most radiosensitive.

Answer 2

Bergonie and Tribondeau Law

Question 3

Measure of the rate of energy transfer from ionizing radiation to tissue.

Answer 3

Linear Energy Transfer (LET)

Question 4

Unit used to express linear energy transfer.

Answer 4

keV/μm

Question 5

Ratio comparing the biologic effectiveness of different types of radiation.

Answer 5

Relative Biologic Effectiveness (RBE)

Question 6

RBE of diagnostic x-rays.

Answer 6

1

Question 7

Relationship between LET and RBE — as LET increases, this also increases until overkill occurs.

Answer 7

RBE increases with LET

Question 8

Delivering a dose continuously over a long period.

Answer 8

Protraction

Question 9

Delivering radiation in small, equal portions over time.

Answer 9

Fractionation

Question 10

The presence of this gas makes cells more radiosensitive.

Answer 10

Oxygen

Question 11

Ratio comparing doses under oxygenated vs anoxic conditions.

Answer 11

Oxygen Enhancement Ratio (OER)

Question 12

Radiosensitivity is highest during this stage of life.

Answer 12

Embryonic or fetal stage

Question 13

Process by which tissues recover from sublethal damage through repair and repopulation.

Answer 13

Recovery

Question 14

Chemical agents that enhance radiation effects.

Answer 14

Radiosensitizers

Question 15

Chemical agents that protect cells from radiation damage.

Answer 15

Radioprotectors

Question 16

Theory suggesting small doses of radiation may have beneficial effects.

Answer 16

Radiation Hormesis

Question 17

Mathematical relationship between dose and observed tissue response.

Answer 17

Dose–Response Relationship

Question 18

Type of dose–response relationship assumed in radiation protection.

Answer 18

Linear Nonthreshold (LNT) Relationship

Question 19

Type of response showing a threshold below which no effect is observed.

Answer 19

Linear Threshold Relationship

Question 20

Graph showing a ‘S’ shape; associated with deterministic effects like skin erythema.

Answer 20

Sigmoid or Nonlinear Threshold Curve

Question 21

Low-LET radiation has an OER value of approximately this number.

Answer 21

3

Question 22

The LET of diagnostic x-rays is approximately this value in keV/μm.

Answer 22

3 keV/μm

Question 23

High LET radiation like alpha particles has an OER close to this value.

Answer 23

1

Question 24

The part of radiobiology that studies dose–effect relationships.

Answer 24

Radiation Dose–Response Relationship

Question 25

Combination of factors—physical and biologic—that determine tissue response to radiation.

Answer 25

Determinants of Radiosensitivity