Risks and hazards of ionizing radiations

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Risks and hazards of ionizing radiations
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Ways of cellular damage

• ionization in the chromosomes direct damage in
  DNA
• ionization in the cytoplasm free radicals
  causing indirect damage of proteins, RNA and DNA

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Somatic radiation injury

• Diagnostic range
• threshold dose
• summation
• risk of malignancies
• ocular lens, thyroid gland
• Therapeutic range
• side effects, complications
• Nuclear accident
• Acute/chronic radiation disease

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Genetic radiation injury

• Manifests in descendants only
• No threshold dose
• Possible outcomes
• ovum or sperm cell perishes
• ovum or sperm cell is not able to (be)
  fertilize(d)
• embedment is prevented
• abortion
• congenital malformation (dominant)
• malformation manifesting in later generations
  (recessive)

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Radiation protection

• indication !!!
• pregnancy, first trimester cave!
• young women in weeks after ovulation cave!?
• technical protection
• dose reduction
• lead covers
• scattered radiation filtering
• proper collimation
• etc.

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• Absorption of x-ray is influenced by
• wave-length of radiation3
• atomic number4
• density
• thickness

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Poor contrast resolution

• Solution
• low voltage
• contrast material
• other modalities

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Contrast materials
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X-ray/CT contrast material
negative
positive water (CT)
gas (x-ray, CT) barium
iodine oil (CT)
water-soluble fat soluble
gastrointestinal intravascular
hydrophil lipophil
ionic non- ionic
monomer dimer monomer dimer
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X-ray/CT contrast materials

• bismuth
  1896
• barium
  1904
• gas - oxygen
  1905
• - air
  1918
• iodinated poppy-seed oil 1921
• tetrabromophenolphtalein 1923
• stroncium-bromide 1923
• sodium-iodide
  1924
• biiodinated organic molecules 1928
• thorium-dioxide
  1931
• triiodinated organic molecules 1950
• non-ionic triiodinated molecules 1985

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Barium

• Complication
• perforation foreign body reaction
• sterile inflammation
• superinfection
• aspiration bronchitis

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• Iodine containing i.v. contrast materials
• side effects
• heat, pain, diuresis
• complications (minor, severe)
• allergic urticaria, Quincke-oedema,
  anaphylactic shock
• osmotic thrombophlebitis, vasculitis
• chemotoxic thyreotoxic crisis, bronchial spasm,
• arrhytmia, convulsion, heart arrest
• vasovagal nausea, vomiting, hypotension

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Iodine containing i.v. contrast materials
Prevention of complications

• proper hydration
• allergy in history - premedication
• reaction in history - other CM
• poor condition - non-ionic dimer
• renal insufficiency - dialysis

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Iodine containing i.v. contrast materials
Therapy of complications

• secure vein
• management of symptoms
• fluid administration
• antiemetics
• antihistaminics
• oxygen
• bronchospasmolytics
• steroids
• epinephrine
• reanimation

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Iodine containing oral contrast materials

• Complication
• aspiration bronchial spasm
• bronchial edema
• bronchiolo-alveolitis

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MR contrast materials

• Paramagnetic gadolinium
• T 1 signal increase
• iv. administration
• Superparamagnetic (ferromagnetic) iron-oxid
• T 2 signal decrease
• iv. or GI administration
• Organ-specific CM

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US contrast materials
Gas bubbles high echogenecity

• non transpulmonal
• transpulmonal

• galactose base
• albumin base
• surface bound
• microbubble

Heart and vessels, vascularity, perfusion