Download radiobiology: part two

RADIOBIOLOGY: PART TWO
CELLULAR EFFECTS OF
IRRADIATION
Instant death
Reproductive death
Apoptosis, programmed cell death(interphase death)
Mitotic or genetic death
Mitotic Delay
Interference of Function
Chromosome Breakage
Survival curves for Mammalian
Cells
• Shoulder indicates an area of cellular repair
with Low LET exposures
Cell radiosensisitivy and Law of
Bergonie and Tribondeau
• Blood cells
• Epithelial tissue
• Muscle Tissue
• Nervous Tissue
• Reproductive cells
• Blood Cells ???
• Find the dose for
• Whole body hematologic
depression
• What are stem or
precursor cells?
• What dose moderately to
severely deplete bone
marrow cells?
• What are the most
sensitive stems cells of
human tissue?
Blood Cells -MORE QUESTIONS
• Is death caused from
high doses to red
blood cells or white
blood cells or
platelets?Why?
• What is the lethal dose
for humans?
• What dose level can
impact lymphocytes
and why is it so low?
• Why are radiation
patients monitored
• Epithelial tissue
• Radiosensitive
• Muscle Tissue
• Insenstive
• Nervous Tissue
• When are nerve cells
most sensitive?
Reproductive cells
• Mature
spermatogoniasensitive or
insensitive? Why?
• What dose can cause
temporary sterility in
male? In female?
• What dose can cause
permanent sterility in
male? In female?
• Mature ova sensitive
or insensitive?
• What dose may
suppress male sperm
population?
• When are a woman’s
ovaries most
sensitive?
STOCHASTIC
•
•
•
•
Random
“all or nothing”
linear,nonthreshold
playing the lottery
Deterministic Effect
•
•
•
•
AKA nonstochastic or certainty effect
Nonlinear threshold curve
threshold assumed
increases with severity of dose
Dose Linear Curves (PG 112 in
Sherer, Pg.498-499 Bushong)
• Linear, non-threshold
• Linear threshold
• Nonlinear (Curvilinear, Sigmoid) Threshold
curve
• Non-linear, non threshold curve
• Linear Quadratic Non threshold
•
AGE
• The age of the biological structure
determines sensitivity
• Bergonie and Tribondeau
• Embryo-fetus-newborn-young child
• Decreases in late teens
• Stabilizes until old age
• increases in old age
GENDER
• Females tolerate 5-15% more
RECOVERY
• Cell can recover if sufficient time is given
between irradiation
• some cells have greater capacity for repair
• Sufficient radiation causes atrophy
REVIEW
PRINCIPLES OF RADIOBIOLOGY
ARE BUILT ON THE FOLLOWING:
1)RANDOM NATURE
2)RADIATION INTERACTS AT
CELLULAR LEVEL
3)FACTORS THAT ALTER THESE
INTERACTIONS