RADIOBIOLOGY: PART TWO

1
RADIOBIOLOGY PART TWO

2
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

3
Survival curves for Mammalian Cells

• Shoulder indicates an area of cellular repair
  with Low LET exposures

4
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?

5
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

6

• Epithelial tissue
• Muscle Tissue
• Nervous Tissue

• Radiosensitive
• Insenstive
• When are nerve cells most sensitive?

7
Reproductive cells

• Mature spermatogonia-sensitive 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 womans ovaries most sensitive?

8
STOCHASTIC

• Random
• all or nothing
• linear,nonthreshold
• playing the lottery

9
Deterministic Effect

• AKA nonstochastic or certainty effect
• Nonlinear threshold curve
• threshold assumed
• increases with severity of dose

10
(No Transcript)
11
Dose Linear Curves (PG 129 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

12
(No Transcript)
13

14
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

15
GENDER

• Females tolerate 5-15 more

16
RECOVERY

• Cell can recover if sufficient time is given
  between irradiation
• some cells have greater capacity for repair
• Sufficient radiation causes atrophy

17
REVIEWPRINCIPLES OF RADIOBIOLOGY ARE BUILT ON
THE FOLLOWING1)RANDOM NATURE2)RADIATION
INTERACTS AT CELLULAR LEVEL3)FACTORS THAT ALTER
THESE INTERACTIONS
18
CHEMICAL AGENTS

• Radiosensitizers-amplifies radiation effect
• Radioprotectors-inhibits