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RAD120 TEST 1
| Question | Answer |
|---|---|
| Two sources of ionizing radiation | - Natural (cosmic, radon, uranium) - Manmade (X-rays, nuclear power) |
| What accounts for the highest radiation dose? | Diagnostic X Rays |
| what is radiation a person receives from the sun categorized as? | natural background radiation |
| Necessary conditions for X Ray production | vacuum, source of electrons, method of acceleration, method of deceleration |
| What is potential difference? | kVp - kilovoltage peak |
| The energy of the beam is expressed in what? | kiloelectron volts (kEv) |
| 3 possible paths a beam can undergo | - total absorption - pass through with no loss of energy - undergo scattering and secondary interactions with some loss of energy |
| X ray beam collimation is used because | - image quality is improved - patient dose is decreased - it decreases scatter radiation |
| classic coherent scattering | when a low-energy X ray photon interacts with an atom as a whole, atom becomes excited and emits X ray with same energy. NO IONIZATION. |
| photoelectric effect | - occurs within diagnostic X ray energy range - Results in highest patient exposure - photon hits an atom's inner shell electron and ejects it, causing a characteristic cascade of electrons. - Incoming X ray photon is completely absorbed. - Electro |
| compton scattering | - occurs within diagnostic range of X ray energy - photon collides with outer shell electron, creating a free Compton electron (recoil) and an ion pair - photon loses some enery through collision, scatters off in random direction - when radiation inter |
| photodisintegration | a nuclear reaction where a high-energy photon (like a gamma ray) hits an atomic nucleus, gets absorbed, and causes the nucleus to become unstable, then split by ejecting a subatomic particle |
| SI unit of radioactive activity / Curie | becquerel |
| SI unit of Roentgen / exposure | coulombs per kilogram |
| SI unit of radiation absorbed dose | Gray |
| SI unit of radiation equivalent man | sievert |
| The units roentgen and couloms ps kg are measures of... | the number of ions in the air |
| RAD (unit of measurement) | conventional unit for Radiation absorbed dose, has been replaced by the gray in the SI system |
| REM (unit of measurement) | conventional unit for "radiation equivalent man," accounts for different types of radiation and their biologic effects, has been replaced by seivert |
| KERMA | - Kinetic energy released in matter, measured in joules/kg |
| NRCP | National Council on Radiation Protection and Measures |
| Annual whole body dose effective dose limit for occupational worker | 50 mSv |
| monthly dose for a pregnant tech | cannot exceed .5 mSv and 5 mSv for entire pregnancy |
| general public (infrequently exposed) | 5 mSv / year |
| age at highest sensitivity to radiation | embryonic stage |
| Law of Bergonie and Thibodeau | states that cells that divide rapidly have the greatest sensitivity |
| results of radiation hitting a cell | may kill the cell, may damage the cell with no repair, may temporarily damage the cell, may pass through cell |
| most radiosensitive cells | lymphocytes, gonads, and eyes |
| primary reason to avoid radiation to gonads | to prevent genetic effects |
| total body response to radiation | - acute radiation syndrome - late effects include cataract genesis and carcinogenesis |
| Slide 28 in Chapter 9 | |
| cardinal rules of protection | time, distance, shielding |
| what 3 things can reduce/influence patience dose? | distance, filtration, and time |
| true or false - grids help reduce patient dose | false |
| minimum filtration for tubes operating above 70 kVp | 2.5 mm |
| Shielding devices | flat contact shields, lead aprons, lead gloves, lead glasses |
| gonadal shields should be worn when? | When the gonads are in or near the useful beam |
| incidences where radiation workers wear shielding | - performing fluoroscopy - performing mobile imaging - Operating room with C-Arm |
| When doing portable exams, the technologist's best protection of self is | distance |
| True or false - use of protective barriers (ex: leaded glass) will reduce radiography personnel exposure the most | true |
| radiation control principles | - collimating to the smallest approximate field size - using highest kVp appropriate - wearing a radiation monitor - ***Using the highest appropriate mAs is NOT included *** |
| 3 types of radiation monitoring | - pocket dosimeter - Optically stimulated luminescence dosimeter (OSL) - most common - thermoluminescent dosimeter (TLD) |
| most effective method of protection for radiographer | distance |
| Law of Bergonie and Thibodeau | cells that divide rapidly have the highest sensitivities |
| most radiosensitive and least radiosensitive cells in body | fetal (most), nerve (least) |
| ARRT code of ethics | a set of moral principals and values |
| The most challenging step while solving ethical issues | selecting the best solution |
| Professionalism defined | judgement and behaviors that are expected from a person who is trained to do a job well |
| HIPAA | Health Insurance and Portability and Accountability Act - protects identifiable health information |
| MeV required for pair production | 1.022 MeV |
| What interaction with matter is responsible for image contrast? | photoelectric effect |
| what interaction causes image fog and reduced contrast? | compton |
| coherent scatter occurs at energies less than | 10 keV |
| photoelectric and compton interactions occur between | 10-150 keV |
| pair production requires ________MeV and is associated with what medicine? | 1.022, nuclear medicine |
| photodisintegration occurs at energies greater than _____ MeV and is associated with what? | 10 MeV, radiation therapy |
| photoelectric effect improves image ___________ | contrast |
| photoelectric interactions are more common with ________ kVp and _____________ atomic number materials | low kVp, high atomic number |
| in compton scattering, the photon __________ energy and _________ direction | loses energy, changes direction |
| compton scattering causes image ________ and reduced __________ | image fog, reduced contrast |
| What reduces compton scatter? | grids |
| What controls focal spot size? | filament |
| The ____ is the positive side of the x ray and contains the ______ | anode, target |
| A ______ damages DNA | direct hit |
| An ___________ produces free radicals | indirect hit |
| using the highest appropriate ______ reduces patient dose | kVp |
| using the highest appropriate mAs is ____________ a radiation protection principle | NOT |
| These doses are far greater than those received by occupational worker or patient | - bone marrow syndrome - gastrointestinal syndrome - central nervous syndrome |
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