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RADIATION BIOLOGY
| Question | Answer |
|---|---|
| Radiation protection is applied radiation | physics and radiobiology |
| The acronym for as lo as reasonably achievable is | ALARA |
| On average, the medical doses of ionizing radiation are | not greater than natural background radiation |
| The annual average dose per person from all sources is about | 360 mrems |
| The risk of 1 rad of radiation is equivalent to driving | 220 miles on a freeway |
| Two common means of expressing risk are | perceived risk and risk comparisons |
| Dr. John Cameron has recommended use of unit called the BERT, which stands for | Background Equivalent Radiation Time |
| What is the loss of life expectancy associated with each of the following risks? | |
| Smoking a cigarette | 10 minutes |
| Home accidents | 95 days |
| 1mrad of ionizing radiation | 1.5 minutes |
| Radiation work at 5rem/yr from age 20 yeard | 68 days |
| Radiation protection guidelines usually assume that there is | no threshold or level below which no effects will be seen |
| Most radiologic examinations carry a | very small risk in relation to the potential benefit |
| GSD is the abbreviation for ___________________ which is a measure of the genetic exposure to the population from ionizing radiation | genetically significant dose |
| CDRH is the abbreviation for the_____________________ which is a part of the U.S. Food and Drug administration | Center for Devices and Radiological Health |
| The safe medical devices act went into effect in 1991 and authorized civil penalties to_______________________ who do not report defects and failures in medical devices | technologists and other health care workers |
| The goal of state licensure is to_____________ from excessive ionizing radiation, not to raise professional standing of the practitioners | protect the public |
| Most state licensures laws are an outgrowth of the | Consumer-Patient Radiation Health and Safety Act of 1981 Title IX of Public Law 97-35 |
| X-Rays are a form of electromagnetic Radiation similar to light but with a wavelength that is | shorter. They have no mass or charge but behave as both waves and particles |
| X-rays are the most | penetrating electromagnetic waves. |
| They are similar to light but can not be focused by a lens nor do they reflect off a surface. They are electrically neutral. | They are heterogenous and polyenergetic. Any given photon travels in a straight line at the speed of light. |
| X-rays diverge from the source and are emitted | isotropically. |
| They ionize all matter, including | gases and can cause biologic changes |
| X-rays produce secondary and scattered radiation | when interacting with matter |
| They cause certain crystals to fluoresce and affect | photographic film |
| Approximately 99 % or greater of the kinetic energy of the projectile electrons in the x-ray tube is converted to | heat, with less than 1 % of the energy going to the production of X-rays |
| The kVp set on the machine determines the | maximum energy of the x-rays produced |
| The deceleration of electrons in the target material is called | Bremsstrahlung or braking radiation |
| Radiation produced when projectile electrons knock orbital electrons free is called | characteristic radiation |
| The radiation that passes through the window of the x-ray tube is called the useful or primary beam while radiation exiting the tube anywhere else is called | leakage radiation |
| In general diagnostic radiography, filtration is used to remove the | low energy long wavelength photons from the beam |
| As a filter, aluminum tends to absorb only low energy photons due to its | low atomic number |
| Mammography filters are made of | molybdenum or Rhodium. Which have a higher atomic number than aluminum |
| A HVL or half-value layer is a measure of the quality of a radiographic beam. As the measurement thickness of aluminum, for a HVL, increases | the harder the beam and the lower the patient dose |
| With single-phase the room mean square RMS voltage is only 70.7% of the peak voltage. The RMS value for three-phase 6-pulse is as low as 92% and the three-phase 12-pulse is near | 97% |
| Conventional fluoroscopy uses lower mA settings than conventional radiography, approximately | 1-3 mA and kVp settings of 90-120 |
| Conventional TV monitors display a resolution of about | 1-2 lp/mm. |
| Radiographic film-screen combinations are capable of displaying | 5-9 lp/mm |
| The brightness gain of image intensifiers tends to range from | 5000-20000 |
| A Linear accelerator is a device used to accelerate | subatomic particles for radiation therapy |
| Electron beams are typically used to treat | superficial tumors overlying cartilage and bone |
| In 1896 this person discovered that certain naturally ocurring substances emitted radiation | Becquerel |
| An English physicist named _____________named the radiations identified by Becquerels as alpha, beta, and gamma radiations after the first three letters of the Greek alphabet | Ernest Rutherford |
| Alpha radiation, symbolized by the Greek letter is | made up of 4 particles and does not easily penetrate matter. |
| Alpha particles are very | large and slow moving particles that carry a lot of energy. |
| Alpha particles have a mass of | 4 amu and a charge of +2. |
| They are described as a helium atom nucleus and are produced by | nuclear disentigration |
| They have a range in air of about | 1cm for each meV of energy they posess. |
| Mosdt naturally occurring Alpha particles travel | 4-8 cm |
| Beta radiation is symbolized by the Greek letter for Beta and consists of high speed | electrons with a charge of -1 or +1 |
| They are produced by | nuclear disentigration |
| Beta particles can travel approximately | 3 meters/MeV of energy in air and up to several mm in tissue |
| Positron emission tomography abbreviated PET employs the use of | positrons which are positively charged electrons |
| All electromagnetic waves travel with the same velocity | 3.0x10(^8) meters per second |
| The higher the energy of an electromagnetic wave, the | shorter the wavelength and the higher the frequency |
| X-rays are produced outside the nucleus by | accelerating electrons and having them strike a metal target |
| Gamma Rays are produced in the nucleusand are identical to x-rays in | energy, wavelength and frequency |
| Like x-rays gamma rays have no | mass, and no charge |
| The traditional unit used to measure exposure in air is the | Roentgen, abbreviated R |
| The SI Unit is coulombs per kilogram, abbreviated C/kg It is a measure of ionization in air produced by | x-radiation or gamma radiation below 3 MeV |
| The SI Unit of electric charge is the | Coulomb |
| Disadvantages of the pocket ionization chamber include: | Charge can leak on the dosimeter, causing a false reading |
| Mechanical trauma can change the reading. | Easy to misread |
| The SI unit used to express absorbed dose is the Gray (Gy) while the traditional unit | is the rad |
| The rad is defined as an energy transfer of | 100 ergs. |
| 1 rad is equal to | 0.01 gray. |
| The ratio between the number of roentgens (exposure) and the number of rads (energy transfer) is called the | f-factor. |
| The rem is an acronym for | radiation equivalent mean |
| The Si unit of biologic effect is the | Seivert abbreviated Sv |
| Rems are determined by multiplying the absorbed dose | in rad times a quality factor |
| The results are expressed as | dose equivalence |
| The most common use of rems is | for personal radiation monitoring |
| The traditional unit of radioactivity is the | curie abbreviated Ci |
| The SI Unit of radioactivity is the | Becquerel abbreviated Bq |
| Both units Curie, and Becquerel measure the rate of | nuclear disentigration (decay) of a material |
| The Curie is defined as | 3.7 x 10 (^10) disentigrations per second (dps) |
| The Becquerel is defined as | one dps of any radioactive substance |
| The time is takes for any radioactive material to decay to 50% of its original activity is known as | the half life |
| Roentgens measure exposure and are used for measuring | intensity of the radiation |
| Rads are used to measur absorbed energy and are used to | talk about dose from radiation |
| Rems are used in dosimetry and measure | biologic effects |
| 1 milliroentgen is equal to | 0.001 roentgen |
| 1 millirad is equal to | 0.001 rad |
| 1 microCurie is equal to | one millionth (10(^-6)) of a Curie |
| One centigray, abbreviated cGy is equal to | 0.01 (10(^-2)) Gray or 1 Rad |
| Dosimetry is the determination by scientific methods of the amount, rate and distribution of radiation emitted from a source of | ionizing radiation |
| Three types of field survey instruments inculde | ionization chamber, GM detector and portable scintillation detectors |
| The ionization chamber determines the amount of radiation by collecting ions in a chamber filled with | gas, usually helium or argon |
| Ionization chambers are most widely used in measuring either the dose total amount of radiation) in milliroentgens or the | exposure rate in milliroentgens per hour |
| ionization chambers are good at detecting x-rays, gamma rays and high energy beta radiation. They are not well suited for | ALPHA radiation |
| GM detector probes have a very thin window that allows for the detection of alpha, beta and gamma radiation. They are not sensitive to | very low energy alpha, beta and gamma radiation |
| GM counters are most useful in the detection rather than the | measurement of radiation sources and low level radioactive contamination |
| The scintillation counter uses a sodium iodide or cesium iodide crystal that produces small light flashes of light called scintillations upon exposure to radiation Light from the scintillation crystal is detectable by a | photomultiplier tube which converts the light flashes into electrical impulses which can be measured |
| The three basic types of personnel monitoring devices include: | film badges,TLD's and pocket ionization chambers |
| Film badges are sensitive down to about | 10 mrem (=0.1mSv) |
| Film badges have an upper sensitivity in the range of | 700-2000 rem |
| The range of stated accuracy for film badges is between | +/- 25% to +/- 50% |
| Advantages of film badges include | inexpensive, easy to handle, easy to process, permenant record of exposure, wide range of sensitivity |
| Thermoluminescent dosimeters use | lithium flouride (LiF) |
| TLD's can be worn up to | 3 months, can be reused, and are more sensitive than film badges |
| TLD's are sensitive down to about 5 mrem or | 0.05 mSv and show accuracy of around +/- 7% |
| TLD;s show the advantage of absorbing radiation approximately in the same way | human tissue absorbs radiation |
| The biggest disadvantage of TLD's is that they do not provide a | permenant record |
| A pocket ionization chamber is similar to other ion chambers and consists of | two electrodes in an air filled chamber |
| Advantages of the pocket ionization chamber include: | can be used for short periods of time, can give immediate readings, useful for monitoring personnel that are not normally monitored |
| Disadvantages of the pocket ionization chamber include: | charge can leak on the dosimeter, causing a false reading. Mechanical trauma can change the reading. Easy to misread. |
Created by:
ABIGAILDRAKE1984
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