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PATH2220 > 33 - Ionising Radiation > Flashcards

33 - Ionising Radiation Flashcards

1
Q

Radiation

A

Energy propagated in either electromagnetic or particulate form

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2
Q

Ionising radiation

A
  • Carries sufficient energy to produce ionisation in the tissues which absorb it (by displacing electrons from atoms)
  • Short wave length/high frequency waves
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3
Q

Electromagnetic energy

A
  • Bundles of energy propagated by wave motion
  • Continuous spectrum
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4
Q

Particulate radiation

A

Protons, neutrons, and high-speed electrons, capable of causing ionisation

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5
Q

Types of radiant energy from long wavelength, low frequency to short wavelength, high frequency

A
  • Radio waves
  • Microwaves
  • Infrared
  • Visible light
  • UV light
  • X, gamma rays
  • Cosmic rays
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6
Q

Alpha particles

A

2 protons, 2 neutrons

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7
Q

Beta particles

A

High speed positrons or electrons

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8
Q

High linear energy transfer

A

Particles which transmit large amounts of energy over short distances (eg alpha particles, high energy neutrons, beta
particles) produce severe but localised effects

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9
Q

Low linear energy transfer

A
  • Characteristic of gamma and x- rays
  • Penetrate deeply but interact with fewer molecules along the way.
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10
Q

Effects of ionising radiation on cells

A
  • Very high doses: cell death due to irreparable DNA damage
  • Lower doses: DNA synthesis interfered with
  • Altered gene expression: p53 activation may result in cell cycle arrest, often apoptosis
  • DNA synthesis without mitosis may produce cells with giant nuclei
  • DNA damage may produce chromosomal abnormalities
    -Reproductive death
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11
Q

Microscopic features of radiation injury

A
  • Nuclear changes
  • Cytoplasmic changes
  • Vascular changes
  • Fibrosis
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12
Q

Nuclear changes caused by radiation

A
  • Nucleus is more sensitive than cytoplasm
  • Swelling
  • Chromatin clumping
  • Micronuclei
  • Apoptosis
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13
Q

Cytoplasmic changes caused by radiation

A
  • Swelling
  • Vacuolation,
  • Membrane disruption
  • Organelle disintegration
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14
Q

Vascular changes caused by radiation

A
  • Early endothelial swelling
  • Necrosis of wall with haemorrhage
  • Later sclerosis → ischaemia
  • Atrophy
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15
Q

Fibrosis

A
  • Hallmark of radiation injury
  • Stromal cells more resistant
  • Often pleomorphic fibroblasts
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16
Q

Radiation injury

A

Acute vascular damage –> endothelial swelling, narrowing of lumen

17
Q

Radiation injury in the bladder

A
  • Chronic radiation cystitis
  • Dense fibrosis
  • Bizarre fibroblasts
18
Q

Genetic effects of radiation on germ cells

A
  • Chromosomal abnormalities (incompatible with life, may produce deformed babies)
  • Point mutations (affect future generations)
  • Sterility
19
Q

Somatic effects of radiation

A
  • May be acute or delayed
  • Localised or affecting total body
20
Q

Total body irradiation prodromal phase

A
  • Anorexia
  • Nausea and vomiting
  • Dose dependent
21
Q

Total body irradiation
asymptomatic latent phase

A
  • Surviving cells function as normal until mitosis
  • Dose dependent
22
Q

Total body irradiation principle phase

A
  • 1-3 successive syndromes
  • Dose dependent
23
Q

Syndromes of acute radiation sickness

A
  • Haemopoietic
  • Intestinal
  • CNS
24
Q

Haemopoietic syndrome

A
  • Loss of stem cells in marrow
  • No replacement of circulating cells.
  • Thrombocytopenia, neutropenia, anaemia.
  • Recovery by repair of non-lethal injury
25
Q

Intestinal syndrome

A
  • Damage to stem cells in crypts
  • Epithelium denuded
  • Loss of fluid, electrolytes
  • Haemorrhage, septicaemia
  • Regenerates within one week if possible
26
Q

CNS syndrome

A
  • Vascular effects: leakage and cerebral oedema
  • No neuronal injury unless massive dose
27
Q

Delayed somatic effects

A
  • Carcinogenesis
  • Abnormalities in growth and development (especially in foetus)
  • Diminished life span
28
Q

Radiation induced cancers

A
  • Thyroid
  • Leukemia
  • Lung
  • Breast
  • Skin
  • Angiosarcoma of liver
  • Oesteogenic sarcome
29
Q

Thorotrast exposure

A
  • Radiographic medium used 1930-1945 that emits alpha particles
  • Persists indefinitely in tissues
  • Associated with angiosarcoma of liver
30
Q

Effects of radiation in skin

A
  • Early changes: Blistering, necrosis, hyper/hypopigmentation
  • Chronic radiation damage: fibrosis, poor healing
  • Later: Malignant tumours (squamous cell carcinoma)
31
Q

Acute effects of radiation on lung

A
  • Radiation pneumonitis
  • DAD (diffuse alveolar damage)
32
Q

Late effects of radiation on lung

A
  • Impaired pulmonary function
  • Interstitial fibrosis
  • Carcinogenesis
33
Q

Acute effects of radiation in bone marrow

A

Panhypoplasia

34
Q

Chronic effects of radiation in bone marrow

A

Predisposition to acute and chronic myeloid leukaemia and acute lymphocytic leukaemia

35
Q

Effects of radiation on kidney

A

Ischaemic vascular effects

36
Q

Effects of radiation on gonads

A

Very susceptible, sterility common

PATH2220 (33 decks)

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