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Rad Prot Unit 2
Sherer- Ch. 4-Radiation Monitoring
| Question | Answer |
|---|---|
| Provides an indication of the working habits and working conditions of diagnostic imaging personnel | Personnel Dosimeter |
| Serves as a basis for comparison w/ remaining badges after they have been returned for processing | Control Badge |
| Lists the deep, eye, and shallow occupational exposures of each person in a health care facility as measured by the exposed monitor. | Personnel Monitoring Report |
| Radiographic film in a film badge that is sensitive to doses ranging from .1mSv (10mrem) to as hi as 5000mSv | Radiation Dosimetry Film |
| Economical device that records whole-body radiation exposure accumulated at a low rate over a long time | Film Badge |
| Gas-filled radiation detectors that detect the presence of radiation and give a reasonably accurate measurement of exposure. | Field Radiation Survey Instruments |
| Device for monitoring occupational exposure that contains an aluminum oxide (Al2O3) detector | OSL (Optical Stimulated Luminescence) |
| Worn by a pregnant radiographer to monitor the equivalent dose to the embryo-fetus | Second Personnel Monitoring Device |
| Device with an audible system that alerts the operator to the presence of ionizing radiation | Geiger-Muller Detector |
| These are generally used in labs to detect alpha & beta radiation & small amts of other types of low-level radioactive contamination | Proportional Counter |
| The intensity of light transmitted thru a given area of the dosimetry film | Optical Density |
| What is used to calibrate radiographic & fluoroscopic units? | Ionizing chamber connected to an electrometer |
| Annual EfD limit of radiation workers in mSv and rem: | 50mSv ; 5 rem |
| A graphical plot that domonstrates the relationship of light output, or emitted thermoluminescence intensity, to temp variation | Glow Curve |
| Keeping radiation to personnel as low as reasonably achievable | ALARA |
| A weak long-lived radioisotope located on the external surface of a GM detector that is used to verify the daily consistency of the unit | Check Source |
| Sensing material found in OSL | Aluminum oxide detector |
| This is required whenever radiation workers are likely to risk receiving 10% or more of the annual EfD limit (50mSv or 5 rem) | Exposure monitoring of personnel |
| An instrument that can be used to determine the amount of radiation to which a film badge dosimeter has been exposed | Densitometer |
| This resembles an ordinary fountain pen but contains a thimble ionization chamber that measures radiation exposure | Pocket Dosimeter |
| This measures the amount of ionizing radiation exposed to a TLD badge | TLD Analyzer |
| This is an ionization chamber-type survey meter | Cutie Pie |
| This contains LiF powder or chips, which function as a sensing material | TLD |
| What is the sensing material found in TLD's? | LiF (Lithium Fluoride) |
| What are the areas of diagnostic radiology that produce the highest occupational radiation exposure for diagnostic imaging personnel | Fluoroscopy and Special Procedures |
| This is an extremity monitor worn by an imaging pro as a 2nd monitor when performing radiographic procedures that require the hands to be near the primary x-ray beam | TLD Ring Badge |
| What is used to measure the visible light emitted by the sensing material contained in a TLD AFTER exposure to ionizing radiation and heating? | Photomultiplier Tube |
| What is the most common type of personnel monitoring devices used today? | OSL's |
| Radiation survey instruments measure the total quantity of electrical charge resulting from ionization of the gases and what? | The rate the electrical charge is produced |
| Most institutions will issue personnel monitoring devices when personnel might receive what dosage in any one month? Give in mSv and mRem: | .5 mSv and 50 mrem |
| List the 5 common characteristics of Personnel monitoring instruments: (CLADS) | Cheap ; Lightweight Able 2 detect small & lg exposures reliably Durable for normal daily use Mechanical shock shouldn't affect performance |
| The head and neck area receives how much more exposure than the waist area? | 10 - 20 times |
| Personnel monitoring instruments give what 2 types of information? | Indication of working habits & conditions Measure exposure received by individual |
| List the 5 types of personnel monitoring instruments: (EFPOT) | 1. Extremity dosimeter (TLC Ring Badge) 2. Film Badge 3. Pocket Dosimeter (Ionization chambers) 4. OSL (Optically Stimulated Luminescence) 5. TLD (Thermoluminescence Dosimeter) |
| What decade did Film Badges come into use? | 1940's |
| List the 3 parts to a film badge: | Plastic film holder Assortment of metal filters Film packet |
| The plastic film holder in a film badge is made of what type of atomic # and why? | Low Atomic # to filter out low energy x-ray and gamma photons |
| The filters of a film badge give what two things? | Measurement of approximate energy reaching the badge and direction of the radiation |
| What type of film is used in a film badge? and what is the sensitivity range? | Radiation-Dosimetry Film Range .1mSv (10mrem) to 5000mSv (500 rem) |
| A Densitometer measure what on the film? | Optical Density |
| What information is contained in a Film Badge Report? | Personal Data Type of Dosimeter Radiation Quality Dose Equivalent Data Cummulative Dose Equivalent Data |
| What is the 4 ADVANTAGES of a Film Badge? (RIPE) | REASONABLY Accurate INEXPENSIVE PERMANENT Report EASY to handle |
| What are the 3 DISadvantages of a Film Badge? | Should only be used for 1 month Sensitive to heat & humidity Accuracy is + or - 20% |
| What provides the best features of traditional film and thermoluminescent dosimeters while eliminating some of the disadvantages? | OSL's |
| The readout of an OSL badge is known as what? | Glow Curve |
| After an OSL is exposed to radiation it is scanned by a laser light. What will the badge do after being scanned? | Emit a light proportional to the amount of radiation it received |
| What is the sensitivity level for an OSL Badge? | For x- & gamma rays: 1 mRem at 5keV to 40MeV to 1000 rem. |
| What is the maximum and recommended time an OSL badge is worn? | Recommended: 2 months Maximum: 1 year |
| What are the 2 types of Pocket Dosimeters? | Self-Reading Non Self-Reading |
| What is the sensitivity range for Pocket Dosimeters? | 0 to 200 mR |
| 3 Advantages of Pocket Dosimeters? | Immediate reading Easy to carry (very compact) Reasonably accurate & sensitive |
| 3 Disadvantages to Pocket Dosimeters? | Expensive Sensitive to mechanical Shock No permanent record (must be read daily) |
| What are the 2 types of crystals used in TLD's? | LiF (Lithium Fluoride) CaF2:Mn (Manganes activated Calcium Fluoride) |
| Name the levels (inside to outside) within a crystal atom used in a TLD: | Electron Shell Forbidden Zone Conduction Band |
| When Radiation hits the crystal in a TLD what happens to the electron? | It travels to the Forbidden zone after ionization and then to the conduction band after the crystal is heated to emit light. Then it returns to their proper position. |
| TLD's have several advantages and only a few disadvantages. List the advantages: | Crystal interacts w/ radiation the way human tissue does. Measure as low as 5mR Not affected by heat or humidity Can be worn up to 3 months More sensitive & accurate than a film badge |
| List the 2 disadvantages of TLD's: | High initial cost Readouts must be carefully obtained (each time)or will be lost |
| List the 2 types of Field Survey Instruments: | Gas filled Detectors Scintillation Detectors |
| 3 types of Gas Filled Detectors: (PIG) | Geiger-Muller Detectors Ionization Chambers Proportional Counters |
| Ideal Chamber Sensitivity means that an instrument can detect very _____ radiation intensities. A larger chamber is more or less sensitive? | Low; More sensitive (more gas molecules) |
| Ideal Chamber Accuracy means how well the instrument can _______ and precisely __________ the intensity of a radiation field. | Detect; Measure |
| Ideal Chamber accuracy is controlled by overall _______________. | Design |
| This type of Ionization Chamber is popular in clinical radiology, used to calibrate x-ray machines and is accurate within +/- 20%: | Cutie Pie |
| What is the radiation intensity range for the Cutie Pie? | 1mR/hr to 1R/hr |
| The Geiger-Muller Dectector is used for contamination control in what setting? | Nuclear Medicine and Portable Work |
| What type of response does the Geiger-Muller Detector have and what is the range? | Audible Response; Limited to less than 100mR/hr |
| What type of setting and detection is the Proportional Counter used? | Stationary Laboratories to detect small quantities of radioactivity. |
| In gas filled Detectors, the region whereby the voltage is so low that the electrons are not attracted to the central electrode and the ion pairs reunite, is which region? | Recombination Region |
| In Gas Filled Detectors, the region whereby all electrons are attracted to the central electrode and the voltage ranges from 100-300 volts: (Cutie Pie operates in this region) | Ion Chamber Region |
| The region after Ion Chamber region whereby as voltage is increased the electrons travel to the central electrode faster and produce more electrons per ionization (secondary electrons) | Proportional Region |
| In an ideal chamber, _________ means how well the instrument can detect and precisely measure the intensity of a radiation field. This is also controlleby by its overall design. | Accuracy |
| List the common requirements an Area Monitoring Device Should Possess. (STRALER Response AE) | SIMPLE design; TISSUE equivalent; RELIABLE & ACCURATE; LIGHTWEIGHT; ECONOMICAL; RUGGED; RESPONSE independent of rad energy; ALL types or ionizing radiation; EQUALLY sensitive to radiation from all directions |
| An ideal Ionization chamber consists of a _________ chamber of gas and a central collecting __________ that collects the electrons. | Cylindrical; Electrode |
| In the ionization chamber region, an avalanche of electrons are produced from a primary ion and a quenching agent must be added to help the atoms return to stability. Extremely sensitive-terrible accuracy. | Geiger-Muller Region |
| Within the regions of operation for Ionization Chambers, what are the only USEABLE regions: | 1. Ion Chamber Region 2. Proportional Region 3. Geiger-Muller Region |
| This ion chamber region has voltage so high that one ionization causes continuous stripping of atoms giving a continuous signal. | Region of Continuous Discharge |
| List the Ionization Chamber regions in order: | Recombination; Ion Chamber; Proportional; Geiger Muller; Continuous Discharge |
| The Field Survey Instrument devices used in Nuclear Medicine & CT with the basic principle: certain materials emit a proportional amount of light when struck by radiation. | Scintillation Detectors |
| Scintillation Phosphors can be ________, ________ or solids | Gases; Liquids |
| The Solid scintillation phospor: | Thallium activated sodium iodide Thallium activated cesium iodide |
| The Scintillation Detector assembly contains crystals that are contained in a _________ seal because they are ____________ (absorp moisture) and emit light ___________. | Hermetic; Hygroscopic; Isotropically |
| In the scintillator detector assembly, a __________ converts light into electrons (photoemission). The electrons are ____________ and amplified and end up on a _____________ and sent through a meter. | Photocathode; accelerated; collector |
Created by:
foster1317
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