7. INTRODUCTION
Leukoencephalopathy in a 14-year-old girl with
Radiation myelopathy after radioactive
previous ALL due to the previous combinationgasabeh.com
of
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chemotherapy and radiation therapy.
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iodine therapy for spine metastasis
9. INTRODUCTION
•
Cosmic rays from space hit Earth's
atmosphere all the time. When a highenergy cosmic ray enters the
atmosphere, it can cause an "air
shower". The cosmic ray hits a
molecule in the atmosphere and
"breaks up", producing lots more subatomic particles. A real air shower can
make millions of particles. This picture
shows a simple version of an air
shower. The cosmic ray (in red, at the
top) makes lots of other particles,
many with odd names. The subatomic particles shown here include
protons (green), neutrons (orange),
pions (yellow), muons (purple),
photons (blue), and electrons &
positrons (pink).
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15. NEURAL PRECURSOR CELLS
Fike and others
have
demonstrated that
X-ray doses of 2-5
Gy cause
substantial
apoptosis of
NPCs and
continued reduction
in the
production of
immature neurons
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1Gy:is defined as the absorption of one joule of such energy by one kilogram of matter (usually human tissue)
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16. CELLULAR LEVEL
RESPONSES
Porosomes at the presynaptic membrane in synaptosomes
from rat brain neurons. (a) Electron micrograph of a single
synaptosome full of 40–50 nm synaptic vesicles.6 Scale
bar =100 nm. (b) Atomic force microscopy (AFM)
micrograph of an isolated synaptosome from rat brain.
Scale bar=100 nm. (c) AFM micrograph of a 10 nm
porosome complex at the presynaptic membrane of an
isolated synaptosome. Note the central plug and the eightprotein densities.8 (d) Electron microscopy (EM)
micrograph of a 10 nm cup-shaped neuronal porosome
with a central plug (arrowhead) and a 50 nm docked
synaptic vesicle (SV).6 (e) AFM micrograph of an insideout presynaptic membrane prepared from
However, isolated rat synaptosomes show decreased Na+uptake after 1 Gy of gamma rays
(Mullin et al., 1986) and some tissue culture gasabeh.com alterations in Ca2+ transport after 1-4
cells exhibit
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Gy of electrons (Todd and Mikkelsen, gasabeh47@gmail.com
1994) suggesting sensitivity of ion channels.
17. CELLULAR LEVEL
RESPONSES
Growth of new processes (neuritogenesis) from neurons in chick retinal explants
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is also sensitive to iron ions at doses below 0.5 Gy (Vazquez et al., 1994).
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18. ELECTRICAL OUTPUT OF NERVE
Significant decreases in the frequency and
amplitude of spikes were observed in most brain
regions after 4 – 5 Gy at times up to 6 hr, but the
hippocampus exhibited hyperexcitability along with
changes in spike train organization that may be
associated with inhibitory neuron malfunction (Monnier and
Krupp,in rabbits 1962).
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At higher doses (9 Gy) all activity was suppressed.
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19. ELECTRICAL OUTPUT OF
NERVE
The pedal-pleural ganglion of the sea slug Aplysia exhibited increased
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excitability after 10 Gy of gamma gasabeh.com
rays (Clatworthy et al., 1999).
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20. BEHAVIORAL AND COGNITIVE
EFFECTS
Morris water maze and Barnes maze
experiments indicate that
spatial memory and learning are inhibited
by doses as low as 0.1 Gy of
iron ions (Shukitt-Hale et al., 2000; Raber et
al., 2004-in rat&mice).
These behaviors are believed to be largely
associated with the hippocampus.
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21. BEHAVIORAL AND COGNITIVE
EFFECTS
In Israel, a large cohort of children (~20,000 of
average age 7 years) were treated with a mean
dose of 1.3 Gy X-rays to cause depilation of the
scalp in order to facilitate treatment of tinea capitis
fungal infections. These children later showed poorer
outcomes in high school aptitude and IQ
performance and more frequent psychiatric
disturbances in later life. (Ron et al., 1982).
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22. BEHAVIORAL AND COGNITIVE
EFFECTS
A group of 6-18 month-old Swedish children
treated for cutaneous hemangioma (strawberry
birthmarks) on the head were followed-up at the time
of comprehensive testing prior to military
enlistment (age 18 – 19 years). They showed
cognitive impairments at doses above 0.1 Gy and
up to 32% decreases in high school attendance
(corrected for social influences) after frontal lobe
X-ray doses > 0.25 Gy (Hall et al., 2004).
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