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Does an ionization chamber survey meter have a wide or narrow range? What is the range?
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Gas-filled radiation detectors are used?
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Rad Protection
Chap 4
| Question | Answer |
|---|---|
| Does an ionization chamber survey meter have a wide or narrow range? What is the range? | Wide ; 0-1000 mR/hr |
| Gas-filled radiation detectors are used? | As and integration type of ionization chamber |
| What is a crystal that is used in TLD? | lithium floride |
| What kind of dector can be used to identify an unknown gamma emitter? | Multichannel crystal spectrometer |
| What normally operates in the rate mode? | an ion chamber |
| operation in which region of a gas-filled chamber results in the lowest output? | recombination |
| The resolving time of a radiation dector is the time required: | to detect sequential ionizations |
| THe amt of light emitted by a scintillation phosphor is proportional to what feature of photon energy? | absorbed |
| In thermoluminescence dosimetry, a plot of output intensity versus temp is called a: | glow curve |
| When an accurate measurement of radiation exposure is made in the air, what should be used? | ionization chamber |
| What is a characteristic of a Geiger-Mueller counter? | measures counts per min |
| What is a characteristic of scintillation dectors that are used as survey instruments? | can detect individual photons |
| Sodium iodide is a good gammay ray detector bc: | it has a high Z |
| Compared with Geiger-Mueller counters, scintillation counters: | are more sensitive to gamma rays |
| The signal detector of a gas-filled radiation detector is the: | central electrode |
| -measuring and or detecting radiation | dosimetry |
| -devices that measure radiation | dosimeters |
| When are personnel monitoring devices required? | When the personnel might recieve 10% or more of the annual dose limit |
| What is the annual dose limit? | 50 mSv ( 5 rem) |
| Which area of the body is likely to receive 10-20 times more radiation that the waist? | head and neck |
| What are 5 common characteristics of personal monitoring instruments? | lightweight & easy to carry durable able to detect and record small and large exposure in reliable manner; mechanical shock shouldn't affect performance; low in cost |
| -recommended to wear as a second monitor device when the hands are required to be near the primary beam | extermity dosimeter |
| What are the 3 parts of the film badge? | durable & lightweight; assortment of metal filters; film packet |
| What should be made of a low atomic number to filter out the low energy x-ray and gamma ray? | plastic film cover |
| -allows the measurement of the approximate energy reaching the dosimeter | filters |
| What has a sensity range from 0.1 mSv (10 mRem) to 5000 mSv (500 rem) | film badge |
| What is the instrument used to measure the optical density on the film? | densitometer |
| What are the advandages of a film badge? | inexpensive; east to handle; reasonably accurate; provides a permanent record |
| What are the disadvantages of a film badge? | can't be used longer than a month; sensitive to heat and humidity; accuracy is limited to give or take 20% |
| - provides the best features of traditional film and TLD while elimination some of the disadvantages. | OSL |
| What is the chemical compound within an OSL? | aluminum oxide |
| How is a OSL read? | scannde by a laser light; will emit light porportional to the amt of radiation it receives; light is then measured and acheived |
| What is the readout that an OSL produces? | glow curve |
| What is the range of an OSL badge? | 5 keV - 40 Mev |
| What is the maximum sensitivity of an OSL? | 1000 Rem |
| How long can an OSL badge be worn? What is reccommended? | 1 yr ; 2 mths |
| What time of dosimeter looks like a fountain pen? | pocket dosimeters |
| -works on ionization chambers and the gold leaf electroscope | pocket dosimeters |
| What is the range for pocket dosimeters? | 0-200 mR |
| What are the advantages of a pocket dosimeter? | immediate reading, easy to carry, reasonably accurate and sensitive ( but not as accurate as film badge, OSL or TDL ) |
| What are the disadvantages of a pocket dosimeter? | expensive, very sensitive to mechanical shock, no permanent record |
| -uses crystals that can undergo changes in their physcial properties | TLD |
| What is one crystal that is used in TLD? | lithium floride |
| What are the advantages of the TLD? | crystals interact with radiation as tissue would; can measure radiation as low as 5 mR; not affected by heat or humidity; can be worn up to 3 mths; more sensitive and accurate than film badge |
| What are the disadvantages to TLD? | inital high cost; readouts must be carefully obtained or results will be lost |
| What are the two types of field survey instruments? | gas filled and scintillation |
| What type of dector are: ionization chambers, proportional counters, geiger-muller counters? | gas-filled detectors |
| High sensitivity means? | that an instrument can detect very low radiation intensities |
| The larger the chamber... | the more gas molecules, the more sensitive |
| Accuracy is controlled by? | the overall design |
| What are the 7 common requirements an area monitoring device should possess? | Lightweight; rugged; reliability & accuracy; simplicity; tissue equivalence; economic |
| -is used for contamination control in nuclear medicine and portable work | geiger-muller counter |
| - has an audio response | geiger-muller counter |
| What is the range of the Geiger-muller counter? | less than 100 mR/ hr |
| -very popular in clinical radiology | cutie pie |
| what is the range of a cutie pie? | 1 mR - 1R |
| - used to calibrate x-ray machines & is accurate withing + or - 20% | cutie pie |
| -have no realistic use in radiology & used in stationary labortory assay small quantities of radioactivity | proportional counters |
| more accuracy = | less sensitivity |
| How do ionization chambers work? | radiation passes through air & ionizes atoms; negative ions are measured & reading is est |
| - unusable region | region of recombination- first stage, very low voltage |
| - highest accuracy region, second stage, region the ion chamber operate in | ion chamber region |
| -more senstitive region but less accurate, third region, instruments using this range are in a lab setting | proportional region |
| -least accurate but most sensitive; avalanche of electrons are produced from a primary ion;quenching agent ; fourth region | geiger-muller region |
| -not useful, voltage too high; fifth region | region og continuous discharge |
| Out of the 5 regions, which are useful? | ion chamber, proportional, geiger-muller |
| -these devices are used in nuclear medicine and ct | scintillation dectors |
| What can scintillation phosphors be? | gases, liquids, solids |
Created by:
erikasmith28
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