Acute Radiation Syndrome - PowerPoint PPT Presentation

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Acute Radiation Syndrome

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Acute Radiation Syndrome MUDr. Michal Jurajda, PhD. – PowerPoint PPT presentation

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Title: Acute Radiation Syndrome


1
Acute Radiation Syndrome
  • MUDr. Michal Jurajda, PhD.

2
The scope of the training
  • Radiobiology basics
  • Hematopoietic syndrome in animal as the example
    of radiation damage
  • Statistical evaluation of data

3
Ionizing radiation
  • Energetic particles or Electromagnetic waves. It
    comprises a wide part of electromagnetic spectrum
    ranging from gamma rays to short wavelength UV.
    Radiation energy above the ultraviolet range is
    called ionizing radiation because the photons
    have enough energy to knock electrons off atoms
    and break molecules.

4
Ionizing radiation
  • Ionizing of molecules and atoms within the cells
  • by direct hitting the target molecules (direct
    effects of ionization)
  • by producing free radicals that interact with
    critical cell components (indirect effects).
  • Cell response swelling, disruption of
    mitochondria, alterations in cell membrane,
    changes in the nucleus

5
Stochastic and deterministic effect of radiation
  • Definiton
  • Differences
  • Examples

6
Ionizing radiation stochastic effects
  • Effects well documented in atomic bomb survivors
  • Between 1950 and 1970, the death rate from
    leukemia alone in the most heavily exposed
    population groups of the atomic bomb survivors in
    Hiroshima and Nagasaki was 147/100000, 30 times
    the expected rate

7
  • Type of cancer that develops depends on the dose
    of radiation, the sex of the person, age at which
    exposure occured
  • Children exposed to ionizing radiation in utero
    have an increased risk for developing leukemias
    and childhood tumors, particularly 2-3 years
    after birth. This latency periond for leukemia
    extends to 5 to 10 years for certain solid
    tumours (35 years for thyroid cancer)

8
Sources of radiation
  • Natural
  • Cosmic radiation
  • Radioactive substances
  • Man made
  • Particle Accelerators
  • X-rays tubes

9
Half-time
  • Half-life is the time required for the activity
    of a radioactive material to be reduced to
    one-half its original value

10
Interaction of Ionizing Radiation with Matter
  • Photoelectric effect
  • Compton effect
  • Formation of electron-positron couples

11
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15
Protection against radiation
  • Effect of time
  • Fractionition
  • Effect of distance
  • Effect of shielding

16
Radiation effect on living subjects
  • Direct effect direct destruction of biomolecules
  • Indirect effect free radicals formation via
    radiolysis of water
  • Cell recovery
  • Correlation between dosis and effect

17
Sensibility of living systems
  • Proliferation kinetics of tissue
  • Irreversibly postmitotic organs
  • Intermitotic and premitotic tissues
  • Number of cells in proliferation
  • Every dosis of radiation leads to decrease in
    number of cells which is proportional to growth
    fraction

18
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19
Radiosensitivity alteration
  • Oxygen effect
  • Dosis fractionation
  • Alkylation cytostatics
  • Hypertermia
  • Hypotermia (protective effect)

20
Radiation responsiveness
  • Manner in which a radiosenstive tissue responds
    to irradiation
  • One of the major determinants of radiation
    responsiveness is tissue oxygenation (O2 is a
    rich source of free radicals that form and
    destroy essential cell components during
    irradiation
  • Hypoxic cells are more radioresistant
    (radiosensitisers are being investigated)

21
Deterministic effects of radiation
22
Acute radiation syndrome
  • Hematopoietic syndrome (bone marrow syndrome)
  • Gastrointestinal syndrome
  • Cardiovaskular/ CNS syndrome

23
Hormesis
  • Not accepted !!!!

24
Výška 0,1 mm
0,05 mm
0,2 mm
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