LAW OF BERGONIE & TRIBONDEAU, PHYSICAL & BIOLOGICAL FACTORS THAT AFFECT RADIOSENSITIVITY

Question 1

Who promulgated the law of Bergonie and Tribondeau

Answer 1

Jean Alban Bergonie & Louis Tribondeau

Question 2

State the Law of B&T

Answer 2

Radiosensitivity of living tissue varies with maturation and metabolism

Question 3

When was the Law of B&T created?

Answer 3

1906

Question 4

What are the 4 physical factors that affect radiosensitivity?

Answer 4

Linear Energy Transfer
Relative Biologic Effectiveness
Protraction
Fractionation

Question 5

The measure of the rate at which energy is transferred from ionizing radiation to soft tissue.

Answer 5

Linear Energy Transfer

Question 6

What is the unit used to express Linear Energy Transfer?

Answer 6

expressed in units of kiloelectron volt of energy transferred per micrometer of track length in soft tissue (keV/µm).

Question 7

As the LET of radiation increases, the ability to produce biological damage also increases.

Answer 7

Relative Biologic Effectiveness

Question 8

As the LET increases, RBE _______

Answer 8

also increases

Question 9

What is the exception made in RBE?

Answer 9

There is a max value of RBE followed by a lower RBE because of overkill

Question 10

What is the LET of xrays?

Answer 10

approx 3 keV/um

Question 11

What is the RBE of xrays?

Answer 11

1

Question 12

dose of radiation is delivered over a long period of time rather than quickly, the effect of that dose is less

Answer 12

Protraction

Question 13

dose of radiation is given at equal fractions in different times

Answer 13

Fractionation

Question 14

Why is fractionation more preferred than protraction?

Answer 14

Radiation dose fractionation reduces effect because cells undergo repair and recovery between doses

Question 15

What are the different biologic factors that affect radiosensitivity?

Answer 15

Oxygen effect
Age
Recovery
Chemical Agents
Hormesis

Question 16

Tissue is more sensitive to radiation when irradiated in the oxygenated, or aerobic state than when irradiated under anoxic or hypoxic conditions

Answer 16

oxygen effect

Question 17

How do you describe the oxygen effect numerically?

Answer 17

oxygen enhancement ratio (OER)

Question 18

This biological factor states that humans are most sensitive before birth.

Answer 18

age

Question 19

After birth, sensitivity _____ until maturity, at which time humans are most resistant to radiation effects. In old age, humans again become somewhat more radiosensitive

Answer 19

decreases

Question 20

This states that human cells can recover from radiation damage only if the radiation dose is not sufficient to kill the cell before its next division - Interphase death.

Answer 20

recovery

Question 21

If given enough time, the cell will recover from the sublethal radiation damage it has sustained by ____________

Answer 21

cell repopulation

Question 22

recovery = _____ + _____

Answer 22

intracellular repair + repopulation

Question 23

this states that Some chemicals can modify the radiation response of cells, tissues, and organs. For chemical agents to be effective, they must be present at the time of irradiation. The post-irradiation application does not usually alter the degree of radiation response

Answer 23

Chemical agents

Question 24

what are the two types of chemical agents?

Answer 24

radiosensitizers

radioprotectors

Question 25

Difference between radiosensitizers and radioprotectors?

Answer 25

RS - Agents that enhance the effect of radiation are called sensitizing agents

RP - Radioprotectors are compounds used to protect the non-tumor cells from the harmful effects of radiation

Question 26

What is hormesis?

Answer 26

It refers to the radiobiologic evidence that a little bit of radiation is good for the body because it stimulates hormonal and immune responses to other toxic environmental agents