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51 terms

Unit 6 Bushong questions

As Low As Reasonably Achievable
The largest part of the cell enclosed by the cell membrane
Late effect of radiation
A response to radiation exposure that doesnt appear for months, or even years
At what structural level do x-rays interact wih humans to produce a radiation response?
X-rays interact with electrons
How does inoizing radiation affect an atom within a large molecule?
The ionization can disrupt molecular bonds and cause the large molecule to malfunction.
What is the most abundant atom and molecule in the body?
Hydrogen, water
What is a stem cell?
The earliest stage of a cell line. An immature cell that will develop into a mature cell.
DNA is the abbreviation for what molecule?
Deoxyribonucleic acid
Which molecule is considered the genetic material of the cell?
What is the approximate dose of radiation required to produce a measurable physical change in a macromolecule?
1 Mrad (10 kGy)
List the stages of cell division of a somatic cell
G1, S, G2, M
List the stages of cell division of a genetic cell
The cell undergoes a mitosis-like divisions, and each of the resulting cells undergoes an additional mitosis-like division without DNA replication
What cell type is the most radiosensitive?
Spermatogonia and lymphocytes
What type of tissues is the least radiosensitive?
Nerve cells
List three early radiation effects and three late radiation effects in humans.
Skin erythema, organ atrophy,cytogenetic damage;
Cancer, leukemis,cataracts.
Linear energy transfer (LET)
Measure on the rate at which energy is transferred from a particular type of radiation to soft tissue. Approximately 3keV/m for diagnostic x-rays.
Standard radiation
250-500 kVp range
List 5 human groups in which radiation effects have been observed and thier effects of radiation.
Atomic bomb survivors-cancer and leukemia
American radiologist-life span shortening
Cyclotron physicist-cataracts
Radium watch dial painters- bone cancer
Patients irradiated in eutero- childhood cancer
Ankylosing spondylititis patients- leukemia
Oxygen enhancement ratio
A measure of the increased radiosensitivity of tissue in the presence of oxygen
One mode of cellular recovery from radiation damage
Threshold dose
Dose below which no effect occurs
Interphase death
Radiation effect that kills a cell before its next division
An early radiobiologist
What is the RBE formula
Rbe= Dose of standard radiation to produce an effect/ dose of test radiation to produce the same effect
What is fractionated radiation
a patient is given a dose at the same rate but broken into equal values and given over time
Why is high pressure oxygen used in radiation oncology?
To make them more radiosensitive
What is the formula for Oxygen Enhancement Ratio(OER)
OER= dose necessary under anoxic conditions/dose necessary under aerobic oxygenated conditions
How does age effect the radiosensitivity of tissue?
The younger the tissue, the more radiosensitive
When a radiobiologic expirement is conducted in vitro, what does this mean?
Outside of the human body at the cellular or molecular radiation
Name the three agents that enhance the effects of radiation.
Methotrexate, actinomycin D, vitamin K
Name 3 radioprotective agents.
Cysteine, cysteamine, and sulfhydryl goups
Are radioprotective agents used for human application?
No because they would have to be at a lethal dose.
What occurs in a nonlinear radiation dose-response relationship?
An equal amount of radiation dose will not produce an equal response.
State 2 of the corollaries to the Law of Bergonie and Tribondeau
Srem cells are more sensitive. Young tissue and organs are more radiosensitive than old tissues and organs. Tissue in a high state of metabolic ctivity has high radiosensitivity. As cellular proliferation increases, so does radiosensitivity.
What are the units of LET?
Describe how LET and RBE are related
With increasing LET, Rbe increases to a maximum value of approximately 3
Is occupational radiation exposure fractionated, or continuous?
Describe how OER and LET are related.
OER is LET-dependent. OER is highest for low LET radiation, and decreases for high LET radiation.
In vitro
Outside the body or outside the cell
Cytogenetic damage
radiation-induced structural change in chromosomes
Point mutation
Radiation damage that consists of a molecular lesion of the DNA and causes genetic mutation
Free radical
a short-lived, highly reactive, uncharged molecule that contains a single unpaired electron in the outermost shell
Target theory
The radiobiologic theory that says for a cell to die, after radiation exposure, its target molecule must be inactivated
List the effects of irradiation of macromolecules in solution in vitro.
main chain scission, cross-linking, point mutations, change in viscosity
How is solution viscosity used to determine the degree of radiation macromolecular radiation?
Viscosity drops after a high dose of radiation of macromolecules.Its a measure of the degree of main-chain scission of macromolecules.
In what phase of the cell cycle does the DNA ladder open up in the middle of each rung and consist of only a single chain
Sythesis phase
Name the three principale observable effects of DNA irradiation
Cell death, malignant disease, and genetic damage
Write the formula for radiolysis of water in which the atom of water is ionized and dissociates into two ions.
H20+ Energy in the form of radiation --> HOH+ + e-
What is the difference between vitro and in vitro?
In vitro refers to irradiation that occurs outside the body or outside the cell; in vivo irradiation is irradiation of the macromolecules in the living cell.
H2o+Radiation -->
HOH+ (dissociation)
HOH- (dissociation)
HOH+ +e-
H+ = OH*
OH- = H*
What is the difference between direct effect and indirect effect?
A direct effect exists when the ionizing radiation interacts directly with the target molecule of DNA.............