Fundamental Principles of Radiobiology Flashcards
The principal aim of the study is to
understand radiation dose-response relationships.
RADIOBIOLOGY
Some tissues are more sensitive than others to RADIATION exposure. TRU OR FALSE?
TRUE
Some tissues are less sensitive than others to radiation exposure. TRUE OR FALSE
False, more
They respond more rapidly and to low doses of radiation.
TISSUES
Tissues respond more rapidly and to high doses of radiation. TRUE OR FALSE
FALSE, Low
Reproductive cells are more sensitive than nerve cells. TRUE OR FALSE
TRUE
Nerve cells are more sensitive than reproductive cells. TRUE OR FALSE
FALSE, REPRODUCTIVE CELLS
Radiobiologic concepts were detailed in ______ by _______.
1906, TWO FRENCH SCIENTISTS
Affects the radiobiologic response of tissue.
PHYSICAL FACTORS AND BIOLOGIC FACTORS
Knowledge of these radiobiologic factors is essential for understanding the negative effects of low dose radiation exposure. TRUE OR FALSE
FALSE , POSITIVE
is essential for understanding the positive effects of low dose radiation exposure.
BIOLOGIC FACTORS
The aim of this study is to understand the radiation dose-response relationship.
FUNDAMENTAL PRINCIPLES OF RADBIOLOGY
A mathematical and graphic function that relates radiation dose to observed response
DOSE-RESPONSE RELATIONSHIP
Who theorized and observed that radiosensitivity was a function of the metabolic state of the tissue being irradiated.
BERGONIE AND TRIBONDEAU
Was a function of the metabolic state of the tissue being irradiated.
RADIOSENSITIVITY
The law states that the radiosensitivity of living tissue varies with maturation and metabolism
LAW OF BERGONIE AND TRIBONDEAU
The law of BERGONIE AND TRIBONDEAU states that the radiosensitivity of living tissue varies with _________ and __________.
MATURATION, METABOLISM
Stem cells are radiosensitive; mature cells are radioresistant. TRUE OR FALSE
TRUE
Mature cells are radiosensitive; Stem cells are radioresistant. TRUE OR FALSE
FALSE, 1. STEM CELLS
2. MATURE CELLS
Stem cells are _________; _________ are radioresistant.
RADIOSENSITIVE, MATURE CELLS
Younger tissues and organs are radioresistant. TRUE OR FALSE
FALSE, RADIOSENSITIVE
Tissues with ______ metabolic activity are ________.
HIGH, RADIOSENSITIVE
A ___ _______ rate for cells and a ____ ______ rate for tissues result in ________.
HIGH PROLIFERATION, HIGH GROWTH, INCREASED RADIOSENSITIVITY.
In diagnostic imaging, law serves to remind us that fetuses are considerably less sensitive to radiation exposure as are children compared to mature adults. TRUE OR FALSE
FALSE, MORE SENSITIVE
When one irradiates tissue, the response of the tissue is determined principally by the ___________________.
AMOUNT OF ENERGY DEPOSITED PER UNIT MASS
WHEN EQUAL DOSES ARE DELIVERED TO EQUAL SPECIMENS, the response will be the same because of other modifying factors. TRUE OR FALSE
FALSE, MAY NOT BE THE SAME
A number of _________ ______ affect the degree of radiation response.
PHYSICAL FACTORS
Is a measure of the rate at which energy is transferred from ionizing radiation to soft tissue.
LINEAR ENERGY TRANSFER
It is another method of expressing radiation quality and determining the value of the radiation weighting factor used in radiation protection
LINEAR ENERGY TRANSFER
Expressed in units of kiloelectron volt of energy transferred per micrometer of track length in soft tissue (KeV/μm).
LINEAR ENERGY TRANSFER
The LET of diagnostic x-rays is approximately _____ KeV/μm.
3
The ability of ionizing radiation to produce a biologic response ________ as the LET of radiation _________.
INCREASES, INCREASES
When LET is _____, ionization occurs frequently, increasing the probability of interaction with the target molecule.
HIGH
LET increases, biologic damage increases.
RELATIVE BIOLOGIC EFFECTIVENESS
LET increases, biologic damage decreases. TRUE OR FALSE
FALSE, INCREASES
Quantitatively described by RBE
RBE = DOSE OF STANDARD RADIATION NECESSARY TO PRODUCE A GIVEN EFFECT ÷ DOSE OF TEST RADIATION NECESSARY TO PRODUCE SAME EFFECT
Diagnosis x-rays have an RBE of ____.
1
Radiations with lower LET than diagnostic x-rays have an RBE _______.
Less than 1
Radiations with higher LET have a _____ RBE
HIGHER
If the time of irradiation is lengthened, a ____ ____ is required to produce same effect
HIGHER DOSE
The dose is delivered continuously but lower (lasts a long time)
PROTRACTION
Reduces effect because cells undergo repair and recovery between doses, used in radiation oncology
FRACTIONATION
Tissue is more sensitive to radiation when irradiated in the oxygen/aerobic state that under anoxic or hypoxic conditions
OXYGEN EFFECT
Tissue irradiation is conducted under conditions of _______ oxygenation.
FULL
Been used in radiation oncology in an attempt to enhance the radiosensitivity of nodular.
HYPERBARIC OXYGEN
Which are less radiosensitive than tumors with an adequate blood supply.
AVASCULAR TUMORS
OER is high for high LET radiation and increases in value as the LET increases. TRUE OR FALSE
FALSE, LOW LET, DECREASES IN VALUE
Humans are more sensitive to radiation before birth and old age
AGE-RELATED EFFECT
Radiosensitivity varies with height. TRUE OR FALSE
FALSE, AGE
The combined processes of intracellular repair and repopulation by surviving cells
RECOVERY
Human cells can recover from sublethal radiation damage if the dose is sufficient to kill the cell before its next cell division. TRUE OR FALSE
FALSE, IS NOT SUFFICIENT
Occurs when the cell dies before replicating
INTERPHASE DEATH
If a tissue or organs receives a sufficient radiation dose, it responds by _______. This is called _______.
SHRINKING, ATROPHY
Modify the radiation response of cells, tissues, and organs
CHEMICAL AGENTS
What are the 2 Chemical Agents
RADIOSENSITIZER & RADIOPROTECTORS
For chemical agents to be effective, they must be present at the time of _______.
IRRADIATION
Does not alter the degree of radiation response.
POSTIRRADIATION APPLICATION
This type of chemical agent is sensitizing agent
RADIOSENSITIZER
Types of chemical agents that enhance the effect of radiation
RADIOSENSITIZER
A type of Chemical agent that reduces the effect of radiation.
RADIOPROTECTORS
Chemical agent that doesn’t find human application
RADIOPROTECTORS
Theory that suggests that very low radiation doses may be beneficial
THEORY OF HORMESIS
Less than _____ mGyt (10rad) no human radiation responses have been observed
100 mGyt
A mathematical relationship between various radiation dose levels and magnitude of the observed response
RADIATION DOSE-RESPONSE RELATIONSHIP
2 important applications of radiation dose-response relationship in RADIOBIOLOGY
A.) EXPERIMENTALLY DETERMINED RELATIONSHIPS ARE USED TO DESIGN THERAPEUTIC TREATMENT FOR PATIENTS WITH CANCER
B.) EXPERIMENTALLY DETERMINED RELATIONSHIPS ARE USED TO DESIGN THERAPEUTIC TREATMENT FOR PATIENTS WITH CANCER
USED TO DESIGN THERAPEUTIC TREATMENT FOR PATIENTS WITH CANCER
RADIATION DOSE RESPONSE RELATIONSHIP
Provides the basis for radiation control activities
RADIATION DOSE-RESPONSE RELATIONSHIP
2 types of human responses to radiation exposure
EARLY OR LATE
HIGH DOSE OR LOW DOSE
DETERMINISTIC OR STOCHASTIC
Radiation responses high-dose exposure and an early response. Ex. Skin burns
DETERMINISTIC
Responses low radiation exposure and appears as a late radiation response. Ex. Leukemia, Cancer or Genetic Effects
STOCHASTIC
2 Characteristics of radiation-dose response relationship
LINEAR OR NONLINEAR
THRESHOLD OR NONTHRESHOLD
The response is directly proportionate to the radiation dose.
LINEAR DOSE-RESPONSE RELATIONSHIP
In linear dose-response relationship. When radiation dose is doubled, the response to radiation likewise is ________.
DOUBLED
The response is not directly proportional to the radiation dose
NONLINEAR DOSE-RESPONSE RELATIONSHIP
The level below which there is no response
THRESHOLD DOSE-RESPONSE RELATIONSHIP
Any dose, regardless of its size, is expected, expected to produce a response
NONTHRESHOLD DOSE-RESPONSE RELATIONSHIP
Intersects the dose axis at zero or below
NONTHRESHOLD DOSE-RESPONSE RELATIONSHIP
Indicates that no level of radiation can be considered completely safe
NONTHRESHOLD DOSE-RESPONSE RELATIONSHIP
Indicates that even without radiation exposure, that type of response, such as cancer, occurs.
THE LEVEL Rn (natural response level)
Basis for radiation protection guidelines
LINEAR NONTHRESHOLD
Basis for current dose limits
LINEAR NONTHRESHOLD
The result of extrapolation
LINEAR NONTHRESHOLD
Radiation-induced cancer
LINEAR NONTHRESHOLD
Single-hit chromosome aberration
LINEAR NONTHRESHOLD
Intercepts the dose axis at some value greater than zero
LINEAR THRESHOLD
Multihit chromosome aberration
NONLINEAR NONTHRESHOLD
A large response results from a very small radiation dose
NONLINEAR NONTHRESHOLD
Incremental doses in the low dose range produce very _______ response
LITTLE
At high doses, the same increment of dose produces a much ________ response.
LARGER
Occurs when the curve stops bending up and begins bending down
THE INFLECTION POINT
The principal interest in diagnostic imaging is to estimate response at _________ radiation dose
VERY LOW
PHYSICAL FACTOR THAT AFFECT RADIOSENSITIVITY
LET
RBE
FRACTIONATION
PROTRACTION
Factors used in radiation protection that accounts for differences in biologic effectiveness between different radiation
RADIATION WEIGHTING FACTOR
Two ways of lengthening the time of irradiation
PROTRACTION AND FRACTIONATION
The dose is delivered at the same dose in equal portions at regular intervals
FRACTIONATION
BIOLOGIC FACTOR THAT AFFECT RADIOSENSITIVITY
OXYGEN EFFECT
AGE-RELATED EFFECT
CHEMICAL AGENTS
RECOVERY
HORMESIS