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Sherer Ch3
| Question | Answer |
|---|---|
| First reports of somatic damage | Europe 1896 |
| First American fatality from radiation | Clarence Madison Dally October 1904 |
| Physician reported cancer deaths from x-ray exposure first reported in? | 1910 |
| radiation exposure received by radiation workers in the course of exercising their professional responsibilities | occupational exposure |
| reddening of the skin | radiodermatitis |
| results from bone marrow failure | aplastic anemia |
| abnormal overproduction of white blood cells | leukemia |
| received quantity of rad. that causes diffuse redness over an area of skin after radiation. unit for measuring radiation exposure from 1900-1930 | skin erythema dose |
| "Roentgen" accepted unit of exposure, ICRU charged with defining unit. Established Intern'tl X-Ray & Radium Protection Commission | Second International Congress of Radiology in Stockholm Sweden, 1928 |
| appear within minutes, hours, days, or weeks of the time of radiation exposure. | short term somatic effects (acute or early effects) |
| nausea, fatigue, loss of hair, fever, diffuse redness of skin, blood disorders, shedding of the outer layer of skin | short term somatic effects (acute or early effects) of radiation exposure |
| radiation dose to which occupationally exposed persons could be continuously subjected without any apparent harmful acute effects | tolerance dose |
| dose of radiation below which an individual has a negligible chance of sustaining specific biologic damage | threshold dose |
| recommended tolerance dose daily limit by International Protection Commission & US Advisory committee 1931/1934 | .2 roentgen |
| daily dose limit in 1936 | .1 roentgen |
| Cancer, Embryologic effects (birth defects), formation of cataracts, genetic (heritable) effects | Long term (late) somatic effects of radiation exposure |
| appear months or years after radiation exposure | Long term (late) somatic effects of radiation exposure |
| Makes possible the interchange of units among all branches of science throughout the world. | International System of units (SI) |
| Maximum Permissible Dose (MPD) replaced tolerance dose for rad prot. | 1950's |
| indicated largest dose of rad an occupationally exposed person was permitted that was not anticipated to result in major adverse bio fx | MPD Maximum permissible dose (expressed in rem) |
| recommendations for dose limits based on what? | probability of harm associated with typical film badge reading should not exceed amt of harm in industries generally considered safe. |
| Rad units developed that contained factors that accounted for varied bio fx of different types of radiation | 1970's |
| when did recognition come that health consequences based upon which organs had been irradiated | 1970's |
| safe occupation are considered to have what risk of death | 10^-4/yr |
| IRCP revised tissue weighting factors based on data from recent studies of atomic bomb survivors | 1991 |
| Effective Dose (EfD) adopted | 1991 |
| takes into account type or radiation & variable sensitivity of tissues exposed to radiation | Effective Dose (EfD) |
| Measure of overall risk arising from irradiation of biologic tissue & organs | Effective Dose (EfD) |
| measurement for exposure to x-radiation & gamma radiation | Roentgen (R) |
| photon exposure that under standard conditions of pressure and temp produces a total + or - ion charge of 2.58x(10^-4) C/kg | 1 roentgen |
| unit for dose that is equivalent to any type of ionizing radiation that produces the same effect as 1 rad of x-radiation | Rem |
| what does rem stand for? | radiation equivalent man |
| what are fluoroscopic entrance rates measured in? | roentgens per minute (R/min) |
| relates the ionization produced in a small cavity within an irradiated medium to the energy absorbed in that medium | Bragg-Gray theory 1936 |
| links determination of absorbed dose in a medium to a relatively simple measurement of ionization charge | Bragg-Gray theory 1936 |
| swedish physicist best known for method of determining exposure rates at various poins near linear radium sources | Rolf Maximilian Sievert |
| amount of ionizing radiation that may strike an object such as the human body when in the vicinity of a rad source | Exposure (X) |
| deposition of energy per unit mass by ionizing radiation in the patient's body tissue | absorbed dose (D) |
| attempt to take into account the variation biologic harm that is produced by different types of rad. | Equivalent Dose (EqD) |
| attempts to summarize the overall potential for biologic damage to a human from exposure to ionizing radiation | Effective Dose (EfD) |
| radiation ionization in air | exposure |
| total electrical charge of one sign per unit mass that x-ray & gamma photons with energies up to 3MeV generate in dry air at atmosphere | exposure |
| basic unit of electric charge | Coulomb |
| quantity of electrical charge flowing past a point in a circuit 1 second when an 1 amp used | Coulomb |
| SI unit of exposure | C/kg |
| Roentgens to Coulombs/kg | R x 2.58 x (10^-4) |
| Coulombs/kg to Roentgens | C/kg รท 2.58 x (10^-4) or C/kg x 3.88x(10^3) |
| responsible for any biologic damage resulting from the tissues being exposed to radiation | absorbed dose (D) |
| factors controlling absorption of radiation | Z# of tissue, mass density of tissue, energy of incident photon |
| factors causing increased absorption | higher Z#, higher mass density, lower photon energy |
| factors causing increased transmission | lower Z#, lower mass density, higher photon energy |
| composite or weighted average of atomic numbers of the chemical elements that comprise a tissue | Effective Atomic Number (Zeff) |
| Zeff of bone | 13.8 |
| Zeff of soft tissue | 7.4 |
| in diagnostic range (23-150kVp) which absorbs more energy, bone or soft tissue? | bone |
| what happens to absorption in therapeutic range (100keV +) | difference in absorption gradually lessens, absorption decreases, scatter increases as beam energy increases. |
| which atomic numbers more likely to produce compton scatter? | none, Z# has no influence |
| relationship between mass density and effect on absorption | direct linear proportionality, double mass density, double absorption |
| energy of absorption or 1 joule (J) per kg of matter in the irradiated object | Gray (Gy) |
| SI unit of absorbed dose | Gray (Gy) |
| unit of energy, work done or energy expended when a force of 1 newton acts on a single object alone a distance of 1 meter | Joule (J) |
| Traditional unit of measure for absorbed dose | Rad (radiation absorbed dose) |
| used to indicate amount of radiant energy transferred to an irradiated object by any type of ionizing radiation. | Rad (radiation absorbed dose) |
| adjustment multiplier used in the calculation of dose equivalence to specify the ability of a dose to cause biologic damage | Quality Factor (Q) |
| amount of energy xfrd on average by incident radiation to an object per unit length of track through the object and is expressed in keV/micrometer | LET - Linear Energy Transfer |
| radiation with high LET transfers can do more biologic damage, why? | it transfers a large amount of energy into a small area |
| corresponds to type and energy of radiation for determining equivalent dose | radiation weighting factor (Wr) |
| weighting factor corresponds to what other numeric value? | quality factor |
| How do you determine EqD? | EqD = D x Wr (Sv = Gy x Wr) |
| conceptual measure for relative risk associated with irradiation of different body tissues | Tissue Weighting Factor (Wt) |
| Value that denotes the percentage of the summed stochastic risk stemming from irradiation of tissue to the all inclusive risk | Tissue Weighting Factor (Wt) |
| Tissue Weighting factor for gonads | 0.20 |
| Tissue Weighting factor for active bone marrow, colon, lung, & stomach | 0.12 |
| Tissue Weighting factor for the breast, bladder, esophagus, liver, thyroid | 0.05 |
| Tissue Weighting factor for bone surface & skin | 0.01 |
| How do you determine EfD? | EfD = D x Wr x Wt |
| describes radiation exposure of a population or group from low doses of different sources of ionizing radiation. | Collective Effective Dose (ColEfD) |
| determined as the product of the average EfD for an individual belonging to exposed population or group and the # of persons exposed | Collective Effective Dose (ColEfD) |
| 1 Sievert is equal to? | 1 J/kg (for x-ray Q=1) 100 rem 100 cSv 1000 mSv |
| 1 Gray is equal to? | 1 J/kg 100 rad 100 cGy 1000 mGy |
| 1 rad is equal to? | 1/100 J/kg 1/100 Gy 1 cGy |
| 1 rem is equal to? | 1/100 J/kg 1/100 Sv 1 cSv 10 mSv |
| 1 roentgen is equal to? | 2.58 x (10^-4) C/kg of air |
| the radiation quantity that can be used to compare the average amount of radiation received by the entire body from a specific radiologic examination with the amount received from natural background radiation | EfD |
| Zeff of air | 7.6 |
| quantity that reflects dose & volume of tissue irradiated. measured in cGy-cm^2 | Dose Area Product (DAP) |
| increases with increasing field size, even if dose remains the same | DAP |
Created by:
jen.studer
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