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F08 Radiology Exam 2
Quiz 3
128
Other
Professional
10/09/2008
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Term
photons and particles
 Definition
Ionizing radiation includes ____ and _____.
Term
photons
 Definition
Gamma rays, x-rays and UV radiation are examples of _____ that cause ionizing radiation.
Term
particles
 Definition
Protons, neutrons and electrons are examples of ______ that cause ionizing radiation.
Term
atomic and molecular structure
 Definition
X-rays change the ____ and ____ structure in cells.
Term
ionization
 Definition
_____ can occur in important molecules in the cell, damaging or killing the cell.
Term
ionization
 Definition
____ can occur in water molecules, producing compounds that damage the cell.
Term
1. molecules essential for cell function and survival
2. DNA in nucleus
3. RNA
4. proteins
5. enzymes
 Definition
List 2 of the 5 critical target molecules affected by ionizing radiation.
Term
DNA in the nucleus
 Definition
____ is the most important critical target affected by ionizing radiation.
Term
Severe damage, minor damage
 Definition
___ damage to DNA cal kill the cell whereas ___ damage can alter characteristics, transforming it into a cancer cell.
Term
direct effect, indirect effect
 Definition
in the ____ effect, radiation inonizes atoms in the critical target molecules, whereas in the ____ effect, radiation ionizes water molecules, producing chemically unstable, poisonous free radicals such as hydrogen peroxide.
Term
Free radicals
 Definition
____ ____ often have an unpaired electron.
Term
Free radicals and hydrogen peroxide
 Definition
___ ____ and ____ ____ damage the target molecules as an indirect effect of ionizing radiation.
Term
water
 Definition
Most of the cell consists of ____.
Term
X-rays don't accumulate in small areas, so with x-ray exposure, most damage is caused by indirect effect.
 Definition
X-rays (DO/DON'T) accumulate in small areas, so with x-ray exposure (MOST/LEAST) damage is caused by indirect effect.
Term
chromosomal aberrations
 Definition
Following severe damage to DNA, fragments reuinite improperly, producing ______ ______. This usually results in cell death.
Term
cell death
 Definition
___ ___ is the preventing a cell from dividing.
Term
carcinogenesis
 Definition
The basis for _____ is following minor damage, subtle defects are propagated as cell divides, eventually altering the genome enough that the cells characteristics change.
Term
True!
 Definition
T/F: Radiation damage is cumulative.
Term
1. total dose of radiation
2. dose rate
3. type of radiation
4. amount of O2 in tissues
5. Sensitivity of cells in tissues
6. amount of tissue exposed
 Definition
List 3 of the 6 characteristics of radiation exposure and tissues that affect the degree of damage to the cells.
Term
False, silly! Increasing the dose increases the severity.
 Definition
T/F: Increasing the dose decreases the severity of the damage in the deterministic effect.
Term
deterministic effect
 Definition
For the ____ effect, increasing the dose increases the severity of the damage.
Term
threshold dose
 Definition
The ____ dose is the certain dose that if below there is no effect at all.
Term
True!!
 Definition
T/F: For deterministic effects, there must be a threshold dose of radiation below which no effects occur at all.
Term
threshold dose, increase in severity
 Definition
Above the ____ dose, the effects occur and ___ in severity with increasing dose.
Term
1. nausea
2. vomiting
3. diarrhea
4. bone marrow failure
5. skin burns
6. hair loss
 Definition
List 3 of the 6 deterministic effects of radiation.
Term
stochastic effects
 Definition
For ____ effects, increasing the dose increases the possibility that the effect will occur.
Term
False!! There is NO threshold dose for stochastic effects. Even at small doses there is a possibility the effect will occur.
 Definition
T/F: There is a threshold dose for stochastic effects.
Term
stochastic effects
 Definition
In _____ effects, as the doses increase, the possibility that the effect will occur also increases, but the severity of the effect doesn't increase.
Term
1. cancer in various organs (leukemia, thyroid cancer)
2. mutations
 Definition
List the 2 examples of stochastic effects of radiation.
Term
Dose rate
 Definition
___ ___ is the amount of radiation absorbed in a unit of time.
Term
Higher, less
 Definition
The (HIGHER/LOWER) dose rate causes greater damage because repair mechanisms are (MORE/LESS) effective.
Term
True!!
 Definition
T/F: X-rays are sparsely ionizing because they have no mass, so ionizations occur over larger area and are not concentrated.
Term
True!!
 Definition
T/F: Particles are densely ionizing because large mass causes many ionizations in a small area, so damage is concentrated and more severe.
Term
Linear energy transfer (LET)
 Definition
___ energy transfer measures the amount of radiation energy deposited in a volume of tissue.
Term
X-rays = low, particles = high LET
 Definition
X-rays have ___ LET and particles have ___ LET.
Term
Low, High
 Definition
___ LET causes a diffuse pattern of ionizations more likely to cause single strand DNA break and is more easily repaired whereas ___ LET is concentrated ionization in small volume and is more likely to cause double strand DNA break, therefore is not as easily repaired.
Term
Increases, free radicals
 Definition
Oxygen (INCREASES/DECREASES) the damaging effects of radiation. Oxygen binds to free radicals to form ____ _____ that destroy molecules in DNA.
Term
M (Mitosis), G1 and G2 (gaps of time), S (synthesis period)
 Definition
In the cell cycle, ____ is when cells divide, ___ and ___ are times with little cellular activity, and ___ is the period when chromosomes are replicated.
Term
M (Mitosis) and late G2 phases
 Definition
Radiation is most damaging when absorbed by cells in ___ and late ___ phases because there is little time for repair of DNA before cell division.
Term
S (Synthesis) phase
 Definition
Radiation is least damaging when absorbed by cells in the ____ phase because there is more time for repair.
Term
Most sensitive
 Definition
The Law of Bergonie and Tribondeau states that calls are (MOST/LEAST) sensitive to radiation damage when they are frequently dividing/frequently in M phase and when they are undifferentiated or primitive.
Term
vegetative intermitotic cells
 Definition
____ ____ cells divide frequently with very little differentiation between mitoses. They are mainly primitive cells such as bone marrow, precursor cells, small lymphocytes, spermatogonia, and basal epithelial cells of GI tract (including oral mucosa).
Term
Differentiating intermitotic cells
 Definition
_____ ____ cells are not as sensitive because they don't spend as much time in mitosis and differentiate between divisions. This type includes more mature bone marrow cells, oocytes and inner enamel epithelium of teeth
Term
Multipotential connective tissue cells
 Definition
____ ____ ____ cells divide more irregularly, usually only when more cells are needed. This type includes endothelial cells, fibroblasts, and other mesenchymal cells.
Term
Reverting postmitotic cells
 Definition
___ ____ cells divide infrequently and include specialized types of cells such as salivary glands, thyroid gland, liver, kidney and pancreas.
Term
fixed postmitotic cells
 Definition
___ ___ cells never divide and are fully differentiated. This type includes striated muscle cells and neurons.
Term
Neurons
 Definition
___ are the most resistant to radiation damage.
Term
Vegetative, Differentiating, Multipotential connective tissue, Reverting postmitotic, Fixed postmitotic
 Definition
List the following in order from most sensitive to least sensitive to radiation damage.
- fixed postmitotic, differentiating intermitotic cells, vegetative intermitotic, multipotential connective tissue, reverting postmitotic
Term
High, Low, Moderate
 Definition
Bone marrow, GI tract, reproductive cells and lymphoid organs have ___ sensitivity. Striated muscle and neurons have ___ sensitivity. Salivary glands, thyroid glands and fine fasculature have ____ sensitivity.
Term
Air exposure
 Definition
___ ____ represents the number of photons in a radiation beam. It also measures the number of ionizations in a kilogram of air. It does not represent the amount of radiation energy absorbed by a patient.
Term
roentgen (R), coulomb/kg, air kerma (kinetic energy released in matter)
 Definition
____ is an old unit of measuring air exposure. ____ or ___ ___ are new units of measuring air exposure.
Term
False!
 Definition
T/F: We use air exposure measurements often because it is very practical.
Term
Absorbed dose
 Definition
___ ___ measures how much energy from radiation is absorbed by tissue.
Term
True! Bone marrow absorbs more x-rays than soft tissues and enamel absorbs more x-rays than bone.
 Definition
T/F: Tissues absorb x-rays differently than air.
Term
Rad (radiation absorbed dose), Gray (Gy, 1Gy= 1J/kg)
 Definition
___ is an old unit for measuring absorbed dose. ___ is a new unit of measuring absorbed dose.
Term
100, 1, 100, 0.1
 Definition
1Gy = ___ rad(s)
1cGy = ___ rad(s)
1mGy = ____ mrad(s)
1microGy = ____ mrad(s)
Term
False! It will cause more damage
 Definition
T/F: An absorbed dose of particles will cause less damage than an equal absorbed dose of photons.
Term
equivalent dose
 Definition
___ ___ allows comparison of biologic effect of different types of radiation (such as photons vs. particles).
Term
equivalent dose
 Definition
____ ___ is equal to the absorbed dose multiplied by a radiation weighting factor (Wr) that expresses severity of damage.
Term
Rem (radiation equivalent mammal, Rem = Rad x Wr), Sieverts (Sv, Sv = Gy x Wr)
 Definition
___ is an old unit for equivalent dose. ___ is a new unit of equivalent dose.
Term
100, 1, 100, 0.1
 Definition
1 Sv = ___ rem(s)
1 cSv = ___ rem(s)
1 mSv = ___ mrem(s)
1microSv = ___ mrem(s)
Term
1, 20
 Definition
Wr for x-rays is ___ while Wr for ap=lpha particles is ___.
Term
X-rays
 Definition
____ are the standard against which all other radiations are measured.
Term
20 times more damaging
 Definition
Alpha particle are ___ times more damaging than x-rays.
Term
equivalent dose
 Definition
___ ___ is the sum of the products of all absorbed doses in tissues multiplied by radiation weighting factors.
Term
False!
 Definition
T/F: Equivalent dose takes into consideration the size of the x-ray beam and which tissues are absorbing radiation.
Term
effective dose
 Definition
___ ___ allows a comparison of the risks of biologic damage from different exposures covering different types and amounts of tissues. This usually measures risk of cancer or mutations.
Term
Sv
 Definition
Equivalent and effective dose is measured in ___.
Term
Effective dose
 Definition
____ ___ is the sum of all equivalent doses multiplied by tissue weighting factors, which are based on sensitivity of tissues to radiation damage.
Term
0.27 mSv
 Definition
US annual average effective dose of cosmic radiation = ____ mSv.
Term
0.28 mSv
 Definition
US Annual average effective dose for terrestrial radiation = ___ mSv.
Term
0.40 mSv
 Definition
US Annual average effective dose of internal(ingested) radiation = ___ mSv.
Term
Cosmic radiation (0.27 mSv/year)
 Definition
___ radiation comes from outerspace (exploding stars and solar winds).
Term
terrestrial radiation (0.28 mSv/year)
 Definition
____ radiation comes from radioactive elements in the earth (mostly K-40, Uranium-238, and thorium-232)
Term
internal/ingested radiation (0.4 mSv/year)
 Definition
___ radiation is due mainly to uranium and thorium.
Term
2.00 mSv
 Definition
US Annual average effective dose of Internal radiation (radon) = ___ mSv
Term
internal radiation (radon), radon (2.00 mSv/year)
 Definition
____ radiation is emitted by ___ a decay product of uranium, the greatest source of natural background radiation and causes lung cancer.
Term
Radon
 Definition
___ attaches to dust, ends up in lungs, causing lung cancer.
Term
0.39 mSv
 Definition
US Annual average effective dose of artificial (man-made) radiation by medical/dental diagnostic radiology = ___ mSv
Term
2.5%, 0.01 mSv
 Definition
___ % of medical/dental diagnostic radiology comes from dental x-ray exposures.
Term
nuclear medicine
 Definition
0.14 mSv is the US annual average effective dose from ____ ____.
Term
60,000 mSv
 Definition
Cancer patients experience ____ mSv.
Term
consumer products
 Definition
0.10 mSv come from ___ ___ annually.
Term
3.00 mSv for natural background, 0.6 mSv from man-made
 Definition
Average annual effective dose from natural background radiation = ____ mSv per day, from man-made radiation = ____ mSv per day
Term
83%, 17%
 Definition
___% of radiation comes from background, ___% comes from artificial sources.
Term
Maximum Permissible Dose (MPD), does not include natural etc, does include scatter
 Definition
___ ___ ___ is the dose of radiation that can be absorbed by a person per year that is currently thought NOT to increase the risk of biologic damage above normal control levels. This (does/does not) include radiation patients receive in course of diagnostic/therapeutic radiation or natural background radiation. It (does/does not) include scatter radiation received by radiographers.
Term
stochastic effects, have no threshold, so limits are lower
 Definition
MPD for ____ effects refers to whole body exposure.
Term
deterministic effects, have a threshold, so limits can be higher
 Definition
MPD for ____ effects usually refers to limited area exposure.
Term
non-occupationally exposed people
 Definition
MPD for (Occupationally/non-occupationally) exposed people is always lower.
Term
stochastic effects
 Definition
MPD of ____ effects for NOEP can be no more than 10% of dose for OEP.
Term
deterministic effects
 Definition
MPD for ____ effects of NOEP can be no more than 1/3 of dose for OEP.
Term
50 mSv/year
 Definition
MPD for OEP in regards to stochastic effects = ___ mSv/year
Term
150 mSv to lens, 500 mSv to skin/extremities
 Definition
MPD for OEP in regards to deterministic effects = ___ mSv to lens of eye and ___ mSv to skin and extremities.
Term
5 mSv infrequent, 1 mSv frequent
 Definition
MPD for NOEP in regards to stochastic effects = 5 mSv/year for ____ exposure and 1 mSv/year for ___ exposure.
Term
50 mSv
 Definition
MPD for NOEP in regards to deterministic effects = ___ mSv to lens of eye, skin and extremities.
Term
embyro-fetus
 Definition
MPD for ____ = 0.5 mSv/month or 5mSv during gestation.
Term
0.01 mSv
 Definition
Negligible individual dose = ___ mSv/year -- any attempt to reduce exposure below this level is not justified.
Term
somatic effects
 Definition
____ effects are radiation-induced damage that affects only the person irradiated, does not affect offspring. It includes all radiation effects except genetic mutations.
Term
genetic effects
 Definition
____ effects are radiation-induced damage that affects future generations and is caused by mutations in spermatogonia and oocytes.
Term
Acute somatic Effects
 Definition
____ ____ effects become apparent w/in a short time of radiation exposure. Requires large doses, include nausea, diarrhea, vomiting, skin burns, hair loss, bone marrow failure, death.
Term
prodomal period
 Definition
____ period of acute somatic effects include nasuea, vomiting, diarrhea that occur quickly after LARGE whole-body dose (at least 1Gy).
Term
latent period
 Definition
_____ period is the time between the prodomal period and onset of radiation effects, patient feels well, can last hours is high exposure (>5 Sv), or weeks for lower exposure (<2 Sv).
Term
hematopoietic syndrome
 Definition
______ _____ is when the whole body experiences doses of 2-7 Sv which kills bone marrow cells, causes bone marrow failure and leads to death in 2-3 weeks due to infections.
Term
pancytopenia
 Definition
____ is bone marrow failure.
Term
gastrointestinal syndrome
 Definition
____ syndrome occurs when whole body experiences doses of 7-15 Sv which kills GI epithelium, causing electrolyte imbalance and dehydration which leads to death in 3-5 days due to heart failure.
Term
infection, heart failure
 Definition
Hematopoietic syndrome leads to death by ____ whereas gastrointestinal syndrome leads to death by _____.
Term
cardiovascular and CNS syndrome
 Definition
____ and ___ ____ ____ syndrome is damage to neurons and fine vasculature of CNS caused by doses in excess of 50 Sv, leading to confusion, convlusions, stupid, necrosis of cardiac muscle and causes death in hours to days due to severe drop in blood pressure.
Term
radiation caries
 Definition
____ ____ are severe carious lesions on many teeth encircling the tooth at the CEJ resulting from salivary gland damage due to radiation therapy.
Term
False!! Radiation damages salivary glands (mainly serous) which results in decreased amount of saliva. Saliva then has a low pH and poor buffering ability leading to Radiation Caries.
 Definition
T/F: Radiation damages teeth.
Term
Radiation mucositis... candida albicans infection is common in these patients.
 Definition
____ _____ is when radiation therapy kills basal epithelial cells leading to red, inflamed mucosa followed by a white pseduomembrane. This condition is very painful, making it difficult for the patient to eat or drink.
Term
Osteoradionecrosis, large, poorly defined destructive lesions can occur and are often made worse by introduction of microorganisms.
 Definition
_____ is when radiation therapy damages endothelial cells which become swollen and plug up capillaries, leading to decreased blood flow and avascular necrosis mainly in mandible.
Term
Long-term somatic effects
 Definition
___ somatic effects take long time to become apparent, with a latent period that can be years or decades. Usually occurs following LARGE doses (atomic bomb, nuclear accidents, radiation therapy) but can also follow low-dose radiation.
Term
cancer
 Definition
____ is the most important long-term radiation-induced somatic effect.
Term
osteosarcoma = watch dial painters, lung cancer = uranium miners, leukemia and thyroid cancer = a-bomb/chernobyl survivors
 Definition
___ = watch dial painters ingesting radium
___ = uranium miners
___ and ____ in atomic bomb and Chernobyl survivors
Term
radiation-induced cancer
 Definition
The primary somatic risk from dental radiography is ____-____ ____ because bone marrow cells exhibit great sensitivity to radiation effects.
Term
leukemia and thyroid cancer
 Definition
The greatest cancer risk from dental radiography is ___ and ____ cancer.
Term
Cancer
 Definition
___ is a stochastic effect with no threshold, even small doses can increase frequency.
Term
False!! They should order ONLY AFTER
 Definition
T/F: Dentists should order radiographs before reviewing the patient's medical and dental history and examining the patient's oral cavity.
Term
F-speed film
 Definition
__-speed film requires approximately 40% of the radiation needed for slower film.
Term
reduce
 Definition
Rare-earth intensifying screens (reduce/increase) radiation exposure 2-4xs.
Term
35%
 Definition
Changing from 8" to 16" PID reduces dose by ____%.
Term
60%
 Definition
Using a rectangular PID reduces the radiation dose by ____% when compared to a round PID.
Term
False! It is the worst!!
 Definition
T/F: Pointed black plastic cone scatters radiation to patient and operator so it is the best PID to use.
Term
kVp
 Definition
High ___ may reduce dose to patient (according to the NERB)
Term
90%
 Definition
Using a leaded thyroid collar reduces radiation to the gland by more than ___%.
Term
False! It is the scattered radiation that is the problem.
 Definition
T/F: It is the primary beam, not the scattered radiation that puts the operator at risk.
Term
6 feet, 90-135 degrees
 Definition
If you have no barrier, you should stand at least ___ feet from the patient's head and at an angle between ___ and ____ to the direction of the central ray.
Term
As low as reasonably achievable
 Definition
ALARA stands for ___ ___ ___ ___ ___.
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