Nov 20 Notes Flashcards
RBE
relative capabilities of radiation with different types of LET’s to produce particular biological reactions
Increase in LET also does what?
Increase in biological damage risk
When is RBE not practical??
For specifiying radiation
Weighting factor
determines the ability of a dose of any kind/type of ionizing radiation to cause biological damage
Weighting factor (Wr) is used to calculate ?
EqD
Wr for xray and gamma
1
Wr for beta particles
1
Wr for neutrons(thermal)
5
Wr for high speed neutrons
20
Wr for alpha particles
20
Wt stands for
Tissue weighting factor
Tissure weighting factor
takes into account the relative risk/detriment to each specific organ and tissue
Radiation energy transfer is determined by
1)Charge 2)Mass 3)Energy
To understand the way ionizing radiation causes injury:
1)Linear energy transfer 2)Relative biological effectiveness 3)Oxygen enhancement ratio
Are males or females less radiosensitive?
Females
Oxygen has what effect on radiation?
Enhances radiation effects
Radiation and cell interactions with matter
1)passes through NC 2) Radiation damages but repaired by enzymes 3)Cell is damaged and reproduces in mutated state 4) Apoptosis
Law of Bergonie and Tribondeau
Radiosensitivity is dependent on, the # of undifferentiated cells in a tissue. Degree of mitotic activity in tissue, and length of time cells stay in active proliferation.
Sensitivity to radiation increases in?
1)immature nonspecialized cells (stem) 2)High metabolic rated cells 3)Rapidly dividing cells
List tissues decreasing in sensitivity to radiation
Lymphocytes, erthrocytes, epithelial cells, endothelial cells, connective tissue cells, bone cells, muscle cells, brain cells and nerve cells
Influencing factors of biological effects
Dose rate to tissue exposed, total dose received by the tissue exposed, type of cell irradiated, oxygenation of tissue
The size of a cell has no influence on radiation effects? True of False?
True
Indirect effect is aka
Indirect hit action,
Indirect effect causes
1)Poison water therory 2)Hydrolysis 3)Radiolysis 4)Ionization of H20 in cells 5)Pond ripple effect
The following tissues are radiosensitive:
Germinal, Hematopoetic(blood forming), Intestinal Crypt cells (cells on surface of intestine).
Early effects are
Non stochastic
Dose related effects are
Non stochastic
Late effects are
stochastic
Stochastic effects are
not dose related
Acute radiation syndrome (ars) stages are
Prodromal,latent, and manifest illness
The amount of radiation that may cause hematologic syndrome is?
100-1000 Rad or 1-10 Gy
25 rad or .25Gy can produce a measureable
hematologic depression
The amount of radiation that may cause gastrointestinal ARS
600-1000 Rad
The amount of radiation that may cause CNS syndrome is
5000 rad or more than 50Gy
