Ionizing radiation, radiation protection
Oldřich Ott, Petr Nádeníček
FN Brno_modra_obdelnik

The Electromagnetic spectrum:
nx-rays wavelength 10 - 0,001 nm


Interaction of IR with matter:
photon
ß
electric interaction (Compton scattering, photoeffect, electron-positron couple)
                           ß
                            ionisation
ß
chemical changes
     ß
biological effect
0,001 – 1 s, interaction of ions, radicals, excited atoms with biological organic molecules (DNA,
proteins)
minutes – tens years, functional and morfological changes in cells, organs and whole organism
http://stopaustinscanners.org/health/

Biological effects of IR:
stochastic
deterministic

Latence: several years for cancer
100s years for genetic effects
nno threshold
nincreasing Def – increasing probability of stochastic effects
neffect intesity do not dependent on the dose
nno effect immediately after irradiation (after several years)
ncarcinoma + genetic effects
nlesion is not related to place of irradiation
nDef (Sv)
Stochastic effects:

Stochastic effects:



nthreshold
nlesion depends on absorbed dose
nlocal effects
nradiation damage is clinical provable
nexample: cataract, erythema, infertility etc
nDekv (Sv)
Deterministic effects:

12. w
Embryo
•2 weeks – „everything or nothing“
•3.–8. w – organogenesis, risk of malformations
•8.–15. w – risk of mental handicap
•after 15. w – the same resistance as born child
•
•
•
The highest radiosensitivity – 1. third of gravidity!
8. w

•natural : artificial = 5:1
•54 % Radon (Rn)
•16 % cosmic radiation
•19 % gama radiation
•11 % inner radiation
- radionuclid 40K, 14C
•93 % medical irradiation
•1 % nuclear energy
•2 % professional irradiation
•2 % nuclear fall-out
Ionizing radiation - etiology:
11
0,3
49
9
17
0,13
Radon in building
Natural radionuclid in humans
Gama from Earth surfice
Nuclear fall-out
Medical irradiation
The rest
Radon in
building

Limits:
nRadiation employee
nDef  - 5 y  - 100 mSv
nDef  - 1 y -  50 mSv
nDekv – 1 y - lens - 150 mSv
n
nStudents
n
n6 mSv
n50 mSv
n
n
A pregnant woman – during whole pregnancy - 1 mSv

Def – 1 mSv
•several years – external irradiation from nature sources
•several years – internal irradiation from potassium in body
•< 1 year – internal irradiation from Radon in buildings
•
•severals months – external irradiation in high altitude
•
•
•100-1000 hours – external irradiation during long flight
1 mSv – 1 year limit for irradiation for person in population.

Probability of death – 50 mSv:
•irradiation of 50 mSv
•1 year work in  „industry“
•smoke 10 packs of cigaret
•15 years in household with smoker
•drink 50 bottle of good wine
•1500 km tour on the bicycle
•45 000 km travel by car
death probability - 1:10000

n
nWas the examination done?
nIs it the best type of examination?
nExplanation of problem?
nDo you necessary need this examinaton?
nDo you need the examination now?
Protection of patients:

Thank you