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RADT456 Rad Protect.

ARRT registry review covering Radiation Protection

QuestionAnswer
Velocity of all electromagnetic radiations 3 x 10^8 (pg. 225)
Unit of measure for frequency. Hertz (Hz). (pg. 225)
More energetic radiations have ... Shorter wavelengths and higher frequencies (pg. 225)
Radiations that are energetic enough to rearrange atoms in materials through which they pass. Ionizing radiation (pg. 226)
Medical/dental x-rays and nuclear medicine studies account for approximately _____ of the man made radiation exposure in the United States. 79% (pg. 226)
Two types of interactions in which x-ray photons are produced at the anode of an x-ray tube. Bremsstrahlung (braking) and Characteristic (pg. 227)
Type of x-ray production where the negative charged electron is attracted to the positively charged nucleus of the tungsten atom, and as a result, pulled of course and redirected toward the nucleus. Bremsstrahlung Radiation (pg. 227)
X-ray production where a high-speed electron encounters a tungsten atom within the anode and ejects a k-shell electron, thereby leaving a vacancy that gets filled. Characteristic Radiation (pg. 227)
K-characteristic primary x rays from a tungsten target have _______ energy. 69 keV. (pg. 227)
Percentage of the x-ray beam that is comprised of characteristic radiation 10-30%. (pg. 227)
The gradual decrease in exposure rate as ionizing radiation passes through tissues Attenuation (pg. 227)
Type of interaction in which the total energy of an x-ray photon is used to eject an inner shell electron. Photoelectric effect (pg. 228)
Type of x-ray interaction with matter in which an x-ray photon ejects an outer shell electron. Compton scatter (pg. 228)
Linear dose response relationships are... responses that are directly related to the dose received. (pg. 230)
Dose response relationship in which the effects are not proportional to the dose. Nonlinear relationships (pg. 230)
Type of radiations that deposit less energy in cells/tissues Low LET radiations (pg. 230)
Annual U.S. background dose Approximately 3 mSv (300 mrem). (pg. 230)
Effects that occur randomly and are "all or nothing." Stochastic effects (pg. 231)
A non-threshold dose-response curve indicates There is no safe dose to radiation (pg. 231)
Effects that appear a short time after exposure, usually as a result of high doses in short periods of time, and should not be seen in diagnostic radiology. Early effects (pg. 231)
Effects that can appear years after exposure, including carcinogenesis, cataractogenesis, embryologic effects, and life-span shortening. Late effects (pg. 231)
Two categories of risks associated with exposure to ionizing radiation Deterministic and Stochastic (pg. 232)
According to the Law of Bergoni and Tribondeau, what types of tissues are particularly radiosensitive Stem (undifferentiated, or precursor) cells, young/immature tissues, and highly mitotic cells. (pg. 233)
A number assigned to different types of ionizing radiations so that their effect(s) may be better determined Radiation Weighting Factors (pg. 233)
A number that represents the relative tissue radiosensitivity of the irradiated material. Tissue Weighting Factors (pg. 233)
True or false: The radiation weighting factor is dependent upon the linear energy transfer (LET) of that particular radiation. True (pg. 233)
Product of absorbed dose and its radiation weighting factor Equivalent Dose (EqD). (pg. 233)
Effective dose formula Radiation weighting factor x tissue weighting factor x absorbed dose. (pg. 233)
The rate at which radiation deposits energy as it passes through tissue is termed... Linear Energy Transfer (LET). (pg. 234)
Principle interactions that occur between x-ray photons and body tissues in the diagnostic x-ray range. Photoelectric effect and Compton scatter. (pg. 234)
Occurs when the ionizing particle interacts directly with the key molecule (DNA) or another critical enzyme or protein (i.e. RNA). Direct Effect (pg. 234)
Which molecular effect of ionizing radiation, direct or indirect, occurs most often? Indirect effect (pg. 234)
Effect where ionizing radiation breaks water molecules into smaller molecules, often producing one or more atoms having unpaired electrons ("Free radicals"). Indirect effect (pg. 234)
Percentage of radiation induced cell damage that is repairable. 90% (pg. 235)
The most radioresistant adult somatic tissue Nerve cells (pg. 235)
As the LET of ionizing radiation increases, the radiation's ability to produce biologic damage _________. Increases (pg. 236)
The most radiosensitive cell Lymphocyte (pg. 237)
Defined as the average annual gonadal dose to the population of childbearing age and estimated to be 20 mrem. Genetically significant dose (pg. 239)
Duration in which early somatic effects become visible Minutes, hours, days, or weeks. (pg. 240)
Duration in which late somatic effects become noticeable Years after initial exposure. (pg. 240)
After a radiation dose of ________ to the skin, mild erythema will result in 1-2 days. 2 Gy or 200 rad. (pg. 241)
Exposure that can cause depletion of lymphocytes. 0.25 Gy or 25 rad threshold. (pg. 241)
Gastrointestinal syndrome (ARS) occurs at doses between... 1,000-10,000 rad (10-100 Gy). (pg. 241)
Central nervous system or cardiovascular (ARS) syndrome occurs at doses greater than .... 5,000 rad (50 Gy). (pg. 241)
Four stages of Acute Radiation Syndrome (ARS). Prodromal, latent, manifest illness, and recovery or death. (pg. 241)
Types of late somatic effects Carcinogenesis, cataractogenesis, embryological effects, lifespan shortening, reproductive risks, and systemic effects. (pg. 242)
Purpose of beam restriction Reduces patient dose, reduces production of scattered radiation, and improves image quality. (pg. 250)
Most efficient beam-restricting device Collimators. (pg. 250)
National Council on Radiation Protection and Measurements (NCRP) guidelines for collimator accuracy Must be accurate within 2% of the source-to-image-receptor distance. (pg. 252)
Technical factor that controls the quantity of ionizing radiation milliampere-seconds (mAs). (pg. 253)
Main purpose for filtration in the x-ray tube Hardens the beam to reduce patient dose. (pg. 253)
NCRP added filtration requirements for x-ray equipment. <50 kV = 0.5 mm Al equivalent 50-70 kV = 1.5 mm Al equivalent >70 kV = 2.5 mm Al equivalent. (pg. 253)
Conditions in which gonadal shielding should be used. If the gonads lie in or within 5 cm of the collimated field, the patient has reasonable reproductive potential, and if diagnostic objectives permit. (pg. 255)
True or False: Entrance skin dose is significantly greater than exit dose. True (pg. 257)
True or False: AEC can compensate for differences in screen speeds. False, it can not compensate for screen speeds outside of what it has been programmed for. (pg. 259)
Primary function of grids and air-gap technique. Remove scatter and improve radiographic contrast. (pg. 260)
Negative aspects to using grids. Increases patient dose, and higher grid ratios decrease tube/grid positioning latitude. (pg. 261)
Reproducibility for a given group of exposure factors must not exceed ______ according to NCRP guidelines. 5% (pg. 262)
NCRP guidelines for linearity state that any variation in output intensity must not exceed _____. 10% (pg. 262)
Source to skin distance in stationary fluoroscopic equipment. 15 inches (pg. 263)
Source to skin distance for mobile fluoroscopy. 12 inches (pg. 263
True or false: x-ray tube housing must keep leakage radiation to less than 100 mR/hr when measured 1 m. from the tube. True (pg. 262)
Table top intensity of the fluoroscopy beam must be fewer than ________. 10 R/min (100 mR/hr). (pg. 263)
How often should intensifying screens be cleaned? At least every 6 months. (pg. 263)
Occupation dose equivalent limit. 5 rem/y (50 mSv/y). (pg. 269)
Lead equivalent requirement for bucky-slot covers, lead curtain(drape), lead apron, and lead gloves. Minimum of 0.25 mm of lead (pg. 270 & 271)
Law that states if distance doubles, exposure dose will be cut to 1/4, and if distance is cut in half, exposure dose will be 4 times the original. Inverse square law (pg. 272)
NCRP requirements for primary protective barriers. Walls with 1/16 inch (1.5 mm.) lead thickness, and 7 feet in height. (pg. 272)
NCRP requirements for secondary protective barriers. 1/32 inch lead. (pg. 272)
Are lead aprons, gloves, and other apparel, primary or secondary barriers? Secondary (pg. 273)
Gestational dose limit to a fetus must not exceed _______. 500 mrem (5 mSv). (pg. 274)
Required length of the cord on x-ray equipment. At least long enough to allow radiographer to stand 6 feet from the x-ray tube and patient. (pg. 275)
Traditional radiation units of measurement. Roentgen, rad, and rem. (pg. 281)
SI radiation units of measurement. Air Kerma (Gya), Gray (Gyt), Sievert (Sv). (pg. 281)
Measurement of ionization in air Roentgen (pg. 281)
The term rad is an acronym for... radiation absorbed dose (the Gray is the SI unit). (pg. 282)
The accronym rem stands for ... radiation equivalent man (the sievert is the SI unit). (pg. 282)
The Code of Federal Regulations states that monitoring be provided for occupationally exposed individuals in a controlled area who are likely to receive more than ___________. 1/10 the dose-equivalent limit. (pg. 283)
Optically Stimulated Luminescense dosimeters can measure radiation doses as low as ... 1 mrem (pg. 284)
Film badges can measure radiation doses as low as... 10 mrem (pg. 285)
Thermoluminescent dosimeters can record doses as low as... 5 mrem (pg. 285)
Benefit of pocket dosimeters Immediate, on-site dose readings (pg. 285)
Disadvantage to pocket dosimeters Do not provide a permanent legal record of exposure. (pg. 286)
Occupationally exposed individuals 18 years of age and older must not receive exposure in excess of _________. 5 mrem(50 mSv)/year. (pg. 288)
A radiography student participating in clinical education before the age of 18 years must not receive an annual dose of ________. more than 0.1 rem (100 mrem). (pg. 289)
General population annual dose to ionizing radiation is ________. 0.5 rem (5 mSv)/year. (pg. 289)
Lifetime cumulative exposure for occupationally exposed individual. 1 rem x age in years (pg. 289)
Monthly occupational fetal dose limit. Not to exceed 0.05 rem (0.5 mSv). (pg. 289)
Created by: jksmith1