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95 Cards in this Set
- Front
- Back
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Describe the SID indicator.
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Must be provided either with a measuring tape, a digital readout, or a laser. Must be accurate within 2%.
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Describe the radiation protection devices of the collimator.
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Shutters should attenuate the beam as much as the tube housing. The x-ray beam and the light beam must coincide to within 2% of the SID.
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Describe the radiation protection devices of the positive beam limitation (PBL).
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Not required, but usually available. Must be accurate to withing 2% of the SID.
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Describe beam alignment.
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Should have indicator light to show alignment of the beam and the image receptor.
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Describe the radiation protection device of filtration.
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Total filtration must be at least 2.5 mm (inherent + added) when operated above 70 kVp. 50-70 must be at least 1.5 mm. Below 50 at least .5mm.
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Describe the radiation protection devices of reproducibility.
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With repeated exposures at the same technique, the mR or the output radiation intensity should not vary more than 5%.
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Describe the linearity.
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For the same mAs at different mA stations, output should not vary more than 10%.
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Describe the radiation protection device of the control panel.
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The exposure button should be fixed to the console, not attached to a cord.
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Describe the radiation protection devices of the portable unit.
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An apron should be assigned to each portable. The exposure switch should allow the operator to be at least 2 meters from the tube during exposure. Of course, the beam needs to be pointed away from the tech while they are at this distance.
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Describe the fluoroscopic source to tabletop distance.
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Must not be less than 38 cm (15 inches) on stationary and 30 cm (12 inches) on mobile units.
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Considering fluoroscopic equipment, describe the primary protective barrier.
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2 mm of Pb equivalent,must lock into position and be interlocked with x-ray tube during examination, cannot energize when in parked position.
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Considering fluoroscopic equipment, describe filtration.
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3.0 is preferred, but same as x ray. Tabletop can be considered added filtration.
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Considering fluoroscopic equipment, describe the collimator.
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an unexposed border should be visible on the monitor to show where the collimation borders are
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Considering fluoroscopic equipment, describe the exposure
switch. |
must have dead-man switch
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Considering fluoroscopic equipment, describe the bucky slot cover.
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.25mm Pb equivalent
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Considering fluoroscopic equipment, describe the protective curtain.
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.25 mm Pb equivalent
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Considering fluoroscopic equipment, describe the protection devices of the cumulative timer.
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5 minute with audible signal or temporary interruption of the beam
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Considering fluoroscopic equipment, describe x-ray intensity.
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Tabletop should not exceed 2.1 R/minute for each mA at 80 KVP. No high level—must not exceed 10 R/minute. With high level—must not exceed 20 R/minute.
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Primary barrier
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Any wall to which the useful beam can be directed. Concrete or brick can be used instead of lead in this situation, and as a rule of thumb, 4 inches of masonry is equal to 1/16th inch of lead.
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Secondary protective barrier
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Designed to shield against secondary radiation. Always less thick than primary protective barriers.
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Distance and barrier thickness
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The thickness of a barrier naturally depends on the distance between the source of radiation and the barrier.
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Occupancy factor and barrier thickness
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The use of the area that is being protected is of principal importance. If the area is a storeroom, the shielding would be less than if it were the reception desk.
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Workload and barrier thickness
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Shielding required depends on the level of radiation activity in that room. More exams = more shielding.
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Use factor and barrier thickness
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The percentage of time during which the x-ray beam is on and directed toward a particular protective barrier.
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KVP and barrier thickness
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The penetrability, or KVP, of the beam is considered when designing the protective barrier.
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Controlled area
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Area that is occupied primarily by radiology personnel and patients. Design limits are based on the recommended occupational dose limit.
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Uncontrolled area
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Can be occupied by anyone, so the maximum exposure rate allowed is based on the recommended dose limit for the public.
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Which materials are utilized during the design of protective shielding?
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Lead bonded to sheetrock or wood paneling, concrete, concrete block, or brick for primary barriers.
Gypsum board, glass, or lead acrylic for secondary barriers. |
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Dose Equivalent
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Radiation quantity that is used for radiation protection and that expresses dose on a common scale for all radiation. Expressed in rem or sv.
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Roentgen
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Measure of the ionization produced in air by x-rays or gamma rays. Quantity of radiation intensity expressed in roentgen, Coulumbs per kilogram, or air Kerma.
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Absorbed Dose
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The energy transferred from ionizing radiation per unit mass of irradiated material; expressed in rad or gray.
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Effective Dose Equivalent
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Sum of the products of the dose equivalent to a tissue and the weighting factors applicable to each of the tissues irradiated. The values are different for effective dose and effective dose equivalent.
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Genetically Significant Dose
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Average gonadal dose given to members of the population who are of childbearing age.
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List patient doses for these common examinations:skull, chest,c-Spine, L-Spine, abdomen, pelvis, extremity
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Abdomen: 400 mR
L-Spine: 300 mR Skull: 200mR C-Spine: 150 mR Pelvis:150 mR Extremity:50 mR Chest: 10 mR |
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Mean Marrow Dose
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Average radiation dose to the entire active bone marrow, important because bone marrow is the target organ believed responsible for radiation induced leukemias.
Gray x percent of bone marrow exposed |
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Five non-essential examinations in radiography
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Mass screening for tuberculosis
Hospital admission Pre-employment physical Periodic health examinations Emergency room CT Whole-body multislice spiral CT |
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Differentiate between instruments designed to detect versus measure radiation.
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Detector Systems are associated with circuitry; they either detect or measure or both.Detect individual work in pulse or rate mode for each individual particle- can depict energy.
Measurement systems work in integrate or current mode; averages and respond with a total dose. It doesn’t differentiate between energy or numbers, just total charge. |
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Describe film badges.
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Construction: Small piece of film sandwiched between metal filters in light tight packet housed in plastic holder.
Specificity: Radiation monitor Means to Read: Optical density of processed film is proportional to exposure Advantages: Inexpensive, easy to handle, not difficult to process. Reasonably sensitive, gives permanent record, can differentiate between scatter exposure and primary beam exposure. Disadvantages: Are sensitive to environment; cannot be worn longer than a month, only reasonably accurate; not sensitive at low KVP exposures. |
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Describe a TLD.
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Construction: Irradiated crystals: Lithium Floride
Specificity: Scintillation Detector Means to Read: Glow Curve Advantages: Respond proportionally to dose; used as personal badges, tissue equivalent recording dose more accurately; sensitive up to 5 mR; environment does not affect, can be worn up to 3 months; crystal reusable therefore more cost effective. Disadvantages: Do not respond to a single Ionizing event; information can be lost if over heated; no documentation. |
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Describe an OSD.
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Construction: Aluminum oxide is the radiation detector. The detector stimulates some electrons into an excited state. During processing, laser light stimulates these electrons, causing them to return to their ground state with the emission of visible light.
Specificity: Scintillation/ Personal Radiation monitor Means to Read: The intensity of visible light emission is proportional to dose received. Advantages: more sensitive than a TLD. Precision is better than a TLD. Wide dynamic range and excellent long-term stability. Disadvantages: Costs |
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Describe Pocket Ionization Chambers.
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Construction: Gas filled detector resembling a fountain pen that can clip on clothing
Specificity: Ionization Means to Read: Collection of amplification at the central electrode and collected in the form of a signal. Advantages: Immediate exposure reading; reasonably accurate and sensitive but have limited range Disadvantages: fairly expensive, must be charged prior to use, limited range, precision level is poor, subject to mechanical damage, no permanent record. |
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List and describe the information to be included on a personal monitoring report.
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Posting of the results of personal monitoring:
Personal Data, ID #, name, sex, SSN, DOB,type of badge, radiation quality measured,dose equivalent: deep/shallow Cumulative doses: deep, eye, shallow for calendar quarter, YTD, lifetime. |
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Describe a control monitor.
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The use of a controlled monitor is to describe how well a controlled area is sealed. It stays in the same place and never moves. It is useful when determining if a specific area receives any dose.
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Describe the five different regions of signals from gas filled detectors, and the detectors that function in each region.
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R= region of recombination, the first stage when the voltage is very low, not electrons are attracted to the central electrode. The ion pairs produced in the chamber recombine.
I= Ion chamber region, as the chamber voltage is increased, a condition is reached whereby every electron released by ionization is attracted to the central electrode and collected. The voltage range occurs between 100-300 V P= proportional region, when primary ionization are accelerated more rapidly to the central electrode causing a greater probability that they will produce additional ionization on their way to the central electrode, called secondary electrons. The total number of primary and secondary electrons at the electrode creates a large electron pulse for each primary ionization. Proportional counters are an example GM= Geiger Muller region, The region GM devices work. When a single ionizing event occurs, a cascade of secondary electrons is produced in a fashion similar to a very brief, yet violent chain reaction creating a large electron pulse. There is a quenching agent and resolving time. CD= Region of continuous discharge, if the voltage across the gas-filled chamber is increase still further, a condition is reached where by a single ionizing event completely discharges the chamber as in operation in the GM region. |
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Contact Shield
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Go directly on the patient (gonadal shield, apron etc).
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Shadow Shield
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A properly cut piece of protective material that hovers over the patient, connected to the tube. It shadows the gonads without interfering with desired anatomy.
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The monthly embryo-fetus dose limit is:
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0.5 mSv
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The occupational lens of the eye dose is:
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15 REM
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The annual occupational dose limit is:
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5 REM
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The intensity of scatter radiation at 1 meter from the patient is:
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1/1000 or 0.1% of the useful beam intensity
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The lead equivalence for a primary protective barrier is:
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1/16 inch
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The lead equivalence for a secondary barrier is:
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1/32 inch
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The normal thickness of lead equivalence for aprons in the diagnostic range is:
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0.5 mm Pb
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Which dosimeter does not usually measure exposures less than 10 mR?
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film badge
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Which dosimeter can be used for up to 3 months?
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TLD/ OSD
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Which dosimeter is most accurate and the newest technology?
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OSD
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Operates at a chamber voltage just above the region of recombination
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ionization chamber
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Contains a crystal such as cesium iodide and a photomultiplier tube
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scintillation detector
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An example is a cutie pie
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ionization chamber
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responds to a single ionizing event by producing a few secondary electrons
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proportional counters
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must have a quenching agent
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Geiger Muller
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Modern substance used for imaging anatomy as well as personnel monitoring
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scintillation detector
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An increase in chamber voltage increases output signal
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proportional counters
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Can be used to monitor inside body cavities
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TLD
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The most sensitive device used for detecting gamma radiation is:
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a scintillation counter
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Which detector is most often used to determine rates from the primary beam of radiographic equipment?
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ion chamber electrometer
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Which detector uses the avalanche effect?
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Geiger Muller counter
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The leakage of a diagnostic unit must not exceed:
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100 mR per hour at one meter
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List the stages of acute radiation syndrome in the order they occur.
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prodromal, latent, manifest illness, recovery or death
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A student radiographer under the age of 18 must not receive an annual occupational dose less than:
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0.1 REM
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The natural source of radiation, radon, contributes to what percent of the dose to the US population?
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55%
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The most common source of man made radiation is medical, which contributes to what percent of the dose to the US population?
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15%
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What is the effective dose limit recommendation for public exposure to the skin, hands, and feet?
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5 REM
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What measures ionizations in air?
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Roentgen
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What measures ionizations in body tissues?
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RAD, gray
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The roentgen measures which types of radiation?
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x ray and gamma radiation up to 3 MeV
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Which material is responsible for maintaining osmotic pressure in the cell?
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electrolytes/ mineral salts
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Beginning with G1, list the stages of the cell cycle.
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G1, S, G2, prophase, metaphase, anaphase, telophase
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DNA synthesis occurs in which stage of the cell cycle?
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S
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How long does mitosis usually last?
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1 hour
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The buildup of organic compounds in the cell is called...
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anabolism
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The breakdown of organic compounds is called...
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catabolism
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When irradiated with x rays, human cells follow which specific target theory?
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Multiple target, single hit
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Which phase of the cell cycle is considered most radioresistant?
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Late S phase
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What dose causes permanent sterility of males?
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6 gray
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Cataracts can be seen with doses as little as...
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2 gray
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Concerning radiation exposure of mammalian gonads, genetic mutation has been measured in doses as low as...
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10 rads
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The minimum testicular dose for transient infertility is approximately...
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200 rads
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The dose of x rays necessary to produce erythema in half of those exposed is about...
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600 rads
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Which type of cells would be depressed most severely by radiation?
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lymphocytes
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If radiation is delivered in utero during the organogenesis stage, which response is most likely to occur?
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Congenital abnormalities
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The average latent period for cataract induction is...
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15 years
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Approximately how many Americans will die of malignant disease from natural causes?
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20%
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Workload uses units of
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mA min/week
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The design limit for exposure of occupants in controlled areas is:
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100 mR/wk
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