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50 Cards in this Set
- Front
- Back
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nonionizing radiation - def?
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electromag radiation that has long wavelengths and low frequencies (radio, micro, etc.)
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ionizing radiation - def?
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radiation that can actually eject electrons from atoms (high
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compare ionizing power and penetration of alpha and beta particles
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Alpha - stronger ionizing power but weaker penetration (due to greater size)
Beta - weaker ionizing power but stronger penetration (smaller size) |
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alpha particles - def?
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two protons and two neutrons
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beta particles - def?
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electrons
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why is radium no longer used to treat cancer?
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the half life is hundreds of years, and it has an ability to be concentrated in the skeleton, so people got bone tumors later on.
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roentgen - def?
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unit of charge produced by gamma rays that ionize a certain volume of air
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rad - def
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a dose of radiation that will result in absorption of 100 ergs of energy per gram of tissue
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gray - def
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dose of radiation that will produce absorption of 1 joule of energy per kg of tissue
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rem - def
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dose of radiation that causes an equivalent effect to 1 rad of xray or gamma ray
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LET - aka and def?
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Linear Energy Transfer - describes how much energy a particle transmits to tissue as it penetrates in eV/micrometer
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compare LET of alpha particles to that of gamma particles
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Alpha has a much higher LET. This means that it is not penetrating far, and interacting with lots of particles in the short distance it goes
Gamma has a tiny LET, meaning that to dissipate the same amount of energy as an alpha particle, it must penetrate much further |
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Do alpha or gamma particles produce more damage per unit of tissue affected?
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alpha, because it can't penetrate far at all, and dumps all it's energy out right away
The gamma particle penetrats deeply, giving out a tiny bit of energy to all the tissue along the way |
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RBE - aka and def?
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Relative biological effectiveness - a ratio of the LET's of a given form of radiation compared to cobalt gamma rays
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why does a single dose of radiation do more damage than several little doses that total the same amount of energy?
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because the single dose doesn't allow time for cellular repair
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why are rapidly dividing cells more vulnerable to radiation?
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because radiation primarily damages DNA, which is more accessible in dividing cells
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which phases of the cell cycle leave cells the most vulnerable to radiation?
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G2 and M
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Three things that ionizing radiation does that can lead to fibrosis?
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ischemic injury due to vascular damage
kill parenchymal cells kill stem cells |
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what is the approximate latent period between occupational or accidental exposure to radiation and the onset of cancer?
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10-20 years
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induced genetic instability - def?
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accumulation of mutations that continue to be expressed even after generations of cells, eventually leads to cancer
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LD50 - def?
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median lethal dose of radiation
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what is the approximate LD50 at 60 days?
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250-400 rads
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When radiation therapy is applied to chest or abdomen, what changes in cell counts are seen?
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neutropenia
thrombocytopenia |
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when is the fetus most susceptible to ionizing radiation (and all other teratogenic agents)?
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implantation to 9 weeks
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what are the most common fetal outcomes of maternal irradiation between 9 weeks and birth?
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CNS and reproductive abnormalities
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two common effects of radiation on infants and little kids?
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bone growth and maturation may be retarded
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describe the delayed radiation injury that happens to blood vessels
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There is an initial inflammatory reaction followed by fibrosis and severe narrowing of the lumen. This causes supplied organs to have ischemic changes and fibrosis
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radiation dermatitis - def?
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desquamation of epidermis
subcutaneous vessels become weakened and dilated skin is susceptible to infection, ulcers, and healing is slower |
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Most common thing that radiation treatments do to the heart?
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cause fibrosis of the pericardium (pericarditis
radiation induced injury to coronary arteries can cause myocardial ischemia and fibrosis |
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What are symptoms of delayed radiation injury to the lungs, and what physiological change causes them?
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dyspnea, cough, and reduced lung function - all are caused by intra-alveolar and interstitial fibrosis
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Effect of delayed radiation injury to the kidneys?
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vascular damage and fibrosis lead to renal HTN and atrophy
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Effect of delayed radiation injury to the urinary bladder?
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acute necrosis of the epith
fibrosis |
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Effect of delayed radiation injury to the GI tract?
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exfoliation of the epithelial mucosa causes infection in all areas of GI
also see fibrosis leading to strictures and obstruction |
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What happens to normal breast tissue when a pt is treated w/radiation for breast cancer?
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fibrosis w/epithelial pleomorphism
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Effect of low doses of radiation on the testes?
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suppression of meiosis and infertility
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Effect of ionizing radiation on the eyes?
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cataracts, and vascular damage to arteries
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Effect of ionizing radiation on the brain?
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focal necrosis and demyelination of the white matter
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Transverse myelitis - def?
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necrosis, demyelination and paraplegia; all caused by ionizing radiation
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What does ozone in the air absorb (light)?
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All UVC and most UVB
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Which cells in the epidermis are injured by UV light?
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Langerhans cells and keratinocytes
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Why does the skin tan when exposed to UVA and UVB?
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increased number of melanocytes
transfer of melanin to keratinocytes |
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What does UV radiation do that causes premature aging?
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degenerative changes in collagen and elastin
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What is skin damage by UVB caused by?
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generation of reactive oxygen species
damage to melanin |
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Most common kind of DNA damage due to UVB radiation?
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pyrimidine dimers between adjacent pyrimidines on the same DNA strand
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Leading cause of death for people in US up to 44 y.o.?
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Unintentional injuries (trauma)
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what characteristics differentiate a laceration vs incision?
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a laceration will have briding strands of connective tissue and/or blood vessels
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differentiate fouling vs stipling w/gunshot wounds
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Fouling only happens when the gun is 1 foot away or less (burn mark from heat and powder)
stipling happens up to 3 feet away, it's from discrete, larger particles of unburned powder |
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why would you see stellate lacerations around a gunshot entry wound?
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if the skin was very close to underlying bone, like on your head
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full-thickness burn - def?
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this means that the entire epidermis and dermis are gone, and there are no stem cells left for epithelial regeneration - includes both 3rd and 4th degree burns
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what is a first degree burn?
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means epithelial involvement only
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