Radiation Protection Flashcards
What is a threshold dose relationship?
Some amount of radiation is required before a measureable effect can be detected
Linear: Constant slope
Curvilinear: non linear
Sigmoidal: s shaped
What is non threshold dose response relationship?
Non threshold
Any given amount of radiation will yield a measureable effect
No amount of radiation regardless of dose is safe
What is the law of Bergonie and Tribondeau?
Cell radio sensitivity increases with increased mitotic activity
Radio sensitivity decreases with maturity
Radio sensitivity decreases with increased specificity ex. Stem cells are more radio sensitive than nerve cells
What is OER? (Oxygen enhancement ratio)
Aerobic conditions enhance the effectiveness of radiation.
Increasing oxygen increases the cells sensitivity to radiation
What is LET?
Defines rate of energy deposited per unit track length through an absorber
Amount of radiation that is transferred to the body as the X-ray beam travels through the body
As LET increases, the quality factor for a given form of radiation will increase
LET is greases for alpha particles
As LET increases the probability of a cell’s survival and recovery…
decreases
What is fractionation?
equal doses of radiation that are delivered with time interval separations
What is protraction?
radiation dose that is delivered continously but at a lower dose rate
What is radiolysis?
radiation interaction with water
positive water molecules form free radicals
free radicals can combine to form hydrogen peroxide
What is the target theory?
If the master molecule of a cell is destroyed, the cell will die.
radiaion interactions with cells are random
What is interphase death?
also know as apoptosis
cell dies without attempting to divide
What is mitotic death?
cell goes through 1 or more mitotic phaes then dies
What is mitotic delay?
mitotic activity resumes after a short delay
What is reproductive failure?
cell does not die as a result of exposrue but loses ability to procreate
What is interference of function?
radiation exposure results in a temporary permanent interruption of cellular function.
What are somatic effects?
limited to exposed population
short term occur relativley soon after exposure
nausea, vomitting, erythemia, fever
What is acute exposure?
large doses delivered over a short period of time
What is chronic exposure?
radiation delivered in small increments over a long period of time
What is carcinogenisis?
long term somatic effects of radiation
What is reproductive sterility?
doses ranging from 500-600 rad, can cause permanent sterilty
What are local somatic effects?
effects that are limited to the exposed individual to specific area
What is a general somatic effect?
effects that effect the entire body
What are high risk examinations?
abd, pelvis, coccyx, sacrum, lumbar spine and hips
Are mature sperm resistant to radiation?
yes
What is the CNS syndrome?
cardiovascular syndrome
>5000 rads
death occurs within hours
What is hemopoetic syndrome?
bone marrow syndrome
most radiosensitive system in the body
blood disorders, depressing immune system and clotting
death occurs between 3-6 weeks
What is gastrointestinal syndrome?
doses between 600-1000 rads
nausea vomitting and fatgue
death occurs approx 1 week
What is GSD? (genetic significant dose)
the dose that if delivered to everymember of a poulation would be expected to yield the same total genetic injury as the actual doses received by the various individuals
approx 20 mrem
A 0.5mm Pb lead apron will attenuate what percent of the radiation at 75 kVp?
88%
A 0.25mm Pb lead apron will attenuate what percent of the radiation at 75 kVp?
66%
