Radiation Protection Ch 7 Flashcards Preview

Radiography Spring 2016 > Radiation Protection Ch 7 > Flashcards

Flashcards in Radiation Protection Ch 7 Deck (44):

The average energy deposited per unit length of track.
-units of kiloelectron per micron

linear energy transfer


electromagnetic radiation such as x-rays and gamma rays(short wavelength, high energy waves emitted by the nuclei of radioactive substances) this penetrating electromagnetic radiation is ionizing and interacts randomly along the length of its track

Low LET radiation


includes particles that posses substantial mass and charge. This type of radiation causes dense ionization along its length of track and is more likely to interact with biologic tissue

High LET radiation


Describes the relative capabilities of radiation with differeing LETs to produce a particular biologic reaction

Relatives Biologic Effectiveness (RBE)


when irradiated in oxygenated, or aerobic state, biologic tissues is more sensitive to radiation then when it is exposed to radiation under anoxic (without oxygen) or hypoxic (low oxygen) conditions

oxygen effect


the ratio of the radiation dose required to cause a particular biologic response of cells or organism in an oxygen-deprived environment to the radiation dose required to cause an identical response under normal oxygenated conditions

Oxygen Enhancement Ratio (OER)


biologic damage occurs as a result of ionization of atoms on master or key molecules (DNA) which can cause these molecules to become inactive or functionally altered

direct action


refers to the effects produced by reactive free radicals that are created by the interaction of radiation with water molecules

indirect action


solitary atoms or most often a combination of atoms that behave as extremely reactive single entities as a result of the presence of unpaired electrons

free radicals


single strand break- commonly occur with low LET radiation

point mutations


the loss or change of a base in the DNA chain



nondivision (nonmitotic) form of cell death that occurs when cells die without attempting division during interphase portion of the cell life cycle -- programed cell death



exposing a cell to as little as 0.1 Gy(1 rad) of radiation just before it begins dividing can cause mitotic delay
- the failure of the cell to start dividing on time

mitotic delay


know the types of radiation that make up Low LET Radiation and high LET radiation

Low LET= x-ray and gamma rays (short wave length, high energy waves emitted by the nuclei of radioactive substances
High LET= includes particles that posses substantial mass and charge


know how free radicals influence biologic damage

dramatically increase


be able to describe how oxygen effects the biological tissues damaged by free radicals

Presence of oxygen in biologic tissues makes the damage produced by free radicals permanent.. Without oxygen damage produced by the indirect action of radiation on a biologic molecule may be repaired.


describe the indirect action of low LET radiation interacting with biologic tissue and causing damage

it causes damage to a cell primarily through an indirect action that involves the production of molecules called free radicals


the damage to molecules that happens when ionizing particles interact directly with vital biologic macromolecules such as DNA, RNA, proteins, and enzymes occurs from

Direct action: damage to these molecules occurs from absorption of energy through photoelectric effect and Compton interactions


what happens when free radicals act on a molecule such as DNA

the damaging action of ionizing radiation on the vital biologic macromolecule is indirect in that the radiation is not the immediate cause of injury to the macromolecule


what does the process of indirect action involve

the breakdown of a water molecule into smaller molecules, producing both ions and free radicals in the process


when does a cleaved or broken chromosome result

-when two interactions(hits) one on each of configuration
-each new portion containing unequal amounts o genetic material


know the 3 affects of ionizing radiation on chromosomes

1. radiation induced chromosome breaks
2.chromsomal fragments
3. chromosome anomalies


be able to describe the Target Theory

A master or key maintains normal cell function is believed to be present and it is necessary for the survival of the cell. Because this molecule is unique in any given cell, no similar molecules in the cell are available to replace it.. If the master molecule is inactivated by exposures to radiation the cell will die


list how damage to a cells nucleus reveals itself

1. instant death
2. reproductive death
3. apoptosis or programed cell death (interphase death)
4. mitotic death
5. mitotic or genetic death
6. interference with function
7. chromosome breakage


be able to describe instant death

occurs when a volume is irradiated with an x-ray or gamma ray dose of about 1000 Gy (100,000 rad) in a period of seconds or a few minutes


what happens to a cell when reproductive death occurs

the cell does not die but permanently loses its ability to procreate preventing the transmission of damage to future generations


when does mitotic or genetic death occur

when a cell dies after one or more divisions


what causes mitotic delay

exposing a cell to as little as .01 Gy (1 rad) of radiation just before it begins dividing can cause mitotic delay


know how radiation can interfere with a function of a cell

permanent or temporary interferences with cellular function can be brought on by radiation


what does oxygen enhance

the effects of ionizing radiation on tissue by increasing tissue radiosensitive


know the law of Bergonie and Tribondeau

the radiosensitivity of cells is directly proportional to their reproductive activity and inversely proportional to their degree of differentiation


know where the most pronounced radiation effects occur in a cell

in cells having the least maturity and specialization of differentiation; the greatest reproductive activity; and the longest mitotic phase


what is the sensitivity of a mature cell that is highly specialized in its function

the less sensitive it is to radiation


how does ionizing radiation affect blood cells

ionizing radiation adversely affects blood cells by depressive the number of cells in the peripheral circulation


know why epithelial tissue is highly radiosensitive

because the body constantly generates epithelial tissue, the cells that compromise this tissue are highly radiosensitive


know why muscle tissue is relatively insensitive

highly specialized and not divide


know what happens when a nerves tissues nucleus is destroyed?

cell dies and is not restored


know what happens when a nerves tissues is damaged?

may still ne able to function but in a partially impaired state


what dose causes severe damage to the CNS

excess of 50 Gy (5000 rad)


why the responses of male and female germ cells to ionizing radiation is different

because their processes of development from immature to mature status differ


why are mature spermatogonia (sperm cells) relatively insensitive to radiation

they are specialized and do not divide


know what can cause temporary and permanent sterility in sperm cells

TEMPORARY= radiation dose of 2 Gy (200 rad) for as long as 12 months
PERMANENT= a dose of 5 Gy or 6 Gy


Know the radiosensitivity of an ova cell

varies through lifetime. Immature = very radiosensitive, more mature has little radiosensitivity


know what causes temporary and permanent sterility in mature woman

PERMANENT= 5 Gy (500 rad)