therapeutic radiobiology (ALL TESTS)

components of the interphase stage of the cell cycle

G1, G2, S

a normal human has _ different chromosomes in each somatic cells

46

the control center of the cell where all cytoplasmic activities are supervised and organized is the

nucleus

stages of mitosis in order

prophase, metaphase, anaphase, telophase

one of the fundamental characteristics of directly ionizing radiation is that it has

a charge

during which stage of the cell cycle does DNA replication occur

S

oxygen molecules (solute) move from an area of high concentration in the lungs to an area of low concentration in the blood. What type of cell membrane transport does this describe

diffusion

Which molecules of the human body are most commonly acted on to produce molecular damage through the indirect action of radiation

water

_ results in genetically varied daughter cells each with a haploid number of chromosomes

Meiosis

The rate of energy loss along the track of an ionizing particle, usually expressed in keV/micrometer

LET

The addition or removal of an electron from an orbital shell within an atom

ionization

A fragment of an atom or molecule that contains an unpaired electron, making it very reactive

free radical

A change in the sequence of a cell's DNA is termed

mutation

Nitrogenous bases are purines

adenine and guanine

The building blocks of proteins are called

amino acids

Human cells contain which four major organic compounds

proteins, carbohydrates, lipids and nucleic acids

Cell cycle is considered to be the least radiosensitive

S

Organelle function to synthesize protein

ribosomes

The nucleic acids adenine only pairs with

thymine

Most occurrences of biologic damage in the treatment of photon radiation therapy are due to the action of radiation

indirect

The thin structure that surrounds the cell and serves to monitor all exchanges between intracellular and extracellular fluids and contents is termed

cell membrane

In the cell cycle, the period between one M phase and the subsequent M phase is called

interphase

If radiation damages the somatic cells of the body, the damage may be passed on to future generations in the form of genetic mutations

false

The steps or rungs of the DNA ladder-like structure are composed of

nitrogenous base pairs

How many phases of division occur during the entire process of meiosis

2

Is this true regarding double strand DNA breaks: defined as breaks in both chains of DNA

true

Shock due to severe blood loss

hypovolemic

Reproductive cells are termed cells

germ

Largest natural source of radiation contributing to the public's exposure

radon

The most frequent occurring interaction between a photon and matter in the energy range used radiation therapy is

compton scatter

In this phase, the cell checks that the DNA has been copied correctly before moving into division

G2

In this phase, the cell checks the environment to determine if it is appropriate to move toward division

G1

In this phase, the DNA is copied and replicated as the cell prepares for division

S

In this phase, the cell actively divides into two daughter cells.

M

Duration of mitosis

About 1 hour

Function of water in the cell: site of all cellular metabolic activity

True

Function of water in the cell: serves as a solvent

True

Function of water in the cell: responsible for maintaining temperature

True

Function of water in the cell: keeps the correct proportion of water in the cell

False

Source of energy for the cell

Mitochondria

Nitrogenous base mutations referring to a segment of chromosomes that breaks off and is reversed and reinserted

Inversion

Usual value quoted for annual natural background radiation dose, including radon exposure

3mSv

Chromosome damage which occurs after DNA synthesis

Chromatid aberration

Relationship between LET and RBE

Direct

Indirectly ionizing radiation: alpha particles

False

Indirectly ionizing radiation: electrons

False

Indirectly ionizing radiation: x-ray photons

True

Indirectly ionizing radiation: protons

False

Indirectly ionizing radiation: neutrons

True

RBE is influenced by: radiation dose

True

RBE is influenced by: quality of radiation

True

RBE is influenced by: fractionation

True

RBE is influenced by: tissue type

True

In division delay, cells stall in which cell cycle phase

G2

Rubin and Casarett: divide regularly and rapidly, undifferentiated

VIM

Rubin and Casarett: actively dividing and differentiating between divisions

DIM

Rubin and Casarett: irregularly dividing and differentiated

Multipotential connective tissue

Rubin and Casarett: do not normally divide but retain capability to divide

RPM

Rubin and Casarett: do not divide and are highly differentiated

Not specified

Examples include nerve cells, muscle cells, and spermatozoa

FPM

Of the possible responses of cells to radiation, which response is characterized by cells dying before entering mitosis

interphase death

Concept that accounts for the effects of fractionation, considering the different behavior of acutely and late-responding tissues through a calculation that includes alpha/beta ratio

BED

An acute change due to radiation exposure is one that is observed

within 6 months of radiation exposure

Chemical that has the most significant radiosensitizing effect

oxygen

The alpha/beta ratio is determined by a dose point on the survival curve where single event killing and multi-hit killing are equal

true

A cell survival curve that demonstrates a steep slope in association with low LET radiation exposure indicates that the cell population is

radiosensitive

Refers to the process by which cells mature both structurally and functionally

differentiation

Type of tissue/organ healing which replaces damaged cells with a different cell type

repair

The dose rate effect is most significant in relation to

low LET radiation

As the LET of radiation increases, the biologic effect (radiation damage)

increases

As dose rate is decreased, radiation damage to late responding tissues is

reduced

Permanent sterility in a male can be caused from cumulative radiation doses of

2 Gy

The primary cause of death during the hematopoietic syndrome is acute total body exposure is infection and

hemorrhage

For mammalian cells, the oxygen enhancement ratio is approximately

2-3

In the pre-implantation stage of gestation, the most common negative consequence to radiation exposure is

prenatal death

Acute or chronic change: fatigue

acute

Acute or chronic change: atrophy

chronic

Acute or chronic change: edema

acute

Acute or chronic change: stenosis

chronic

Acute or chronic change: moist desquamation

acute

Acute or chronic change: stricture

chronic

Acute or chronic change: hemorrhage

acute

Acute or chronic change: xerostomia

chronic

Acute or chronic change: obstruction

chronic

Acute or chronic change: ulceration

chronic

The dose rate effect is most influential at rates in the range of

1-100cGy/min

The rate at which energy is deposited as ionizing radiation travels through matter is termed

LET

The ratio of the dose that produces a specific biologic effect in the absence of oxygen to the dose that produces that same effect in the presence of oxygen is termed

OER

Known as hypoxic cell radiosensitizers

nitroimidazoles

The sensitizing effect of oxygen increases up to about mmHg oxygen tension, beyond which the effect levels off

20

Which fractionation schedule reduces the overall time of treatment without changing the traditional dose per fraction

accelerated fractionation

The most significant late somatic effect caused by radiation exposure is

carcinogenesis

For the mammalian cells, the 'n' number, or extrapolation number, is said to be

2-10

Sulfhydryl chemicals reduce the effect of radiation on cells by

scavenging free radicals

Defined as the dose at which 37% of a cell population survives radiation exposure

D0 (D37)

Stochastic effects are characterized as all or nothing effects

true

Stochastic effects have no threshold dose

true

Carcinogenesis, non-specific life span shortening, and genetic effects are examples of stochastic effects

true

How does dose fractionation influence sublethal damage repair

increases a cell's ability to repair sublethal damage

The organogenesis stage of gestation is generally classified as

day 10-week 6