Radiation Exposure & Effects Flashcards
identify the quantity
The fundamental dosimetric quantity for ionizing radiation; The energy ionizing radiation imparts to matter per unit mass
absorbed dose
identify the quantity
Biological effect caused by ionizing radiation and whose probability of occurrence is zero at small absorbed doses but will increase steeply to unity (100%) above some level of absorbed dose (the threshold)
deterministic biological effect
identify the quantity
The absorbed dose averaged over a tissue or organ (rather than at a point) and weighted for the radiation quality that is of interest
equivalent dose
identify the quantity
The sum of the weighted equivalent doses in all the tissues and organs of the body.
effective dose
identify the quantity
Expresses the relative amount of damage that a fixed amount of ionizing radiation of a given type can inflict on biological tissues.
relative biological effect
identify the quantity
Biological effect caused by ionizing radiation whose probability of occurrence increases with increasing absorbed dose, probably with no threshold, but whose severity is independent of absorbed dose.
stochastic biological effect
Which is false?
A. Higher RBE value=more damaging
B. For deterministic biological effect, there’s a threshold
C. Equivalent dose & effective dose have diff. units
C - parehong Sievert ang kanilang unit
Which is false?
A. When exposure surpass the threshold, somehow direct relationship: ↑dose exposed to, ↑DBE
B. Effective dose’s special unit name: Gray
C. Use of equivalent dose is not appropriate for large absorbed doses delivered in a relatively short period of time
B is false. unit for effective dose is Sievert.
C is true because Equivalent dose: radiation safety qty
identify the quantity
Represents the contribution of tissue or organ T to the total detriment due to all of the stochastic effects resulting from uniform irradiation of the whole body.
tissue weighing factor
Which is false?
A. The RBE may not be a continuous number
B. The probability of stochastic effects due to an equivalent dose depends on the tissue or organ irradiated.
C. The sum of all tissue weighting factors is equal to 1
A - it may be a decimal number
Which is false?
A. When exposure surpasses the threshold, higher dose of radiation means higher DBE.
B. Higher tissue weighting factor @ organs without actively dividing cells
C. BOTA
D. NOTA
B - higher TWF @ those with actively div cells
Radiation effect of energy deposition: Explain how it affects the body
Ionizing radiation is capable of depositing enough localized energy to dislodge electrons from the atoms with which it interacts –> ions and free radicals which break chemical bongs –> CELLULAR INJURY
Most radiation-caused DNA lesions are reparable, but less reparable are those produced by: A. densely ionizing radiation B. proton C. alpha particle D. NOTA
(D)
Which is false?
A. Traversal of the DNA by a single ionizing particle is not enough to cause a mutation
B. The dose-response relationship for chromosome aberrations in human blood lymphocytes can serve as a useful biological dosimeter
C. Dividing cells are radiosensitive
D. The survival of dividing cells tend to decrease exponentially with increasing dose, 1 to 2 Gy –> reduce the surviving population by 50%
A - it’s enough
Which is false?
A. Rate of atrophy is dependent on cell population dynamics within the affected tissue of surviving cells
B. Rate of atrophy is directly proportional to rate of cell division
C. Mature cells are relatively more radiosensitive compared to young dividing cells.
C - less dapat
Enumerate two types of biological effects of radiation
heritable effects
somatic effects
differentiate stochastic from non-stochastic effect
NON-stochastic or deterministic: result from depletion of progenitor cells in affected tissues and can be elicited only by doses that are large enough to kill many such cells; (+) threshold
Stochastic: in contradistinction to the mutagenic and carcinogenic effects of radiation; (-) threshold
identify effect of radiation on skin (6 Sv)
Erythema —> Epilation
identify effect of radiation on skin (10-20 Sv)
Blistering, Ulceration, Necrosis –> Fibrosis –> Atrophy
identify effect of radiation on bone marrow (2-3 Sv, within hours)
impaired immune response
identify effect of radiation on skin (2-3 Sv, 3-5 wks)
granulocytopenia & thrombocytopenia
identify effect of radiation on intestines (10 Sv)
denuded intestinal villi –> dysentery-like syndrome
identify effect of radiation on testes (0.15 Sv)
oligospermia
identify effect of radiation on testes (2-4 Sv) & oocytes (1.5-2.0 Sv)
permanent sterility
identify effect of radiation on respiratory tract (6-10 Sv)
acute pneumonitis
identify effect of radiation on eyes (> 1 Sv)
microscopic posterior polar opacity
one of the effects of radiation on the eyes is vision-impairing cataract. how can this happen? what are the doses/timeframes
2 - 3 Sv in a single brief exposure
OR
5.5 - 14 Sv accumulated over a period of months
What is acute radiation syndrome?
results from rapid exposure of a major part of the body to a dose in excess of 1 Gy
4 organ systems affected @ acute radiation syndrome. enumerate
- hematological
- gastro-intestinal
- cerebral
- pulmonary
first day after irradiation: two most common forms/features of acute radiation syndrome
nausea
vomiting
Which is false?
A. Radionuclides tend to be distributed systematically & to irradiate the body as a whole
B. Radioactive iodine concentrates in the pineal gland
C. Strontium-90 primarily injures skeletal tissues
B - thyroid gland dapat
Carcinogenic effects’ induction - which is false?
A. has been detectable only after relatively small dose equivalents (0.1 Sv)
B. varied with the type of neoplasm
C. varies with the age and sex of those exposed
A – relatively big dose equivalents dapat (0.5 Sv)
Enumerate two main mechanisms of carcinogenic effects of radiation
activation of oncogene
inactivation/loss of tumor-suppressor
oncogene activation can induce carcinogenic effect of radiation. how?
Oncogenes - genes having the potential to cause a normal cell to become cancerous; accelerate cell growth and division
Which is false?
A. Effects of radiation are only additive/synergistic with chemical carcinogens
B. Existing data is not enough to justify dose-incidence relationship
C. Heritable effects of radiation are not observed in humans
A - they may also be antagonistic :)
False about prenatal irradiation
A.susceptibility to malformation is high all throughout the prenatal period
B.effects of a given dose is the same across all developmental stages
C.there’s dose-dependent increase in the frequency of severe mental retardation
B - effects of a gien dose depend on the developmental stage of embryo/fetus
