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Three types of gas-filled radiation detectors are
- ionization chambers,
- proportional counters, and
- Geiger-Muller
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What
is a pulse mode vs. a rate mode?
In the pulse mode, the presence of radiation is indicated by a ticking, chirping, or beeping sound.
In the rate mode, the instrument response is expressed in mGya/hr (mR/hr) or Gya/hr (R/hr).
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all 3 types of gas filled detectors each is based on the same principle of operation
- As radiation passes through gas,
- it ionizes atoms of the gas.
- The electrons released in ionization are detected as an electrical signal that is proportional to the radiation intensity.
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In general, the larger the chamber, the more gas molecules are available for ionization, and therefore, the more ______ is the instrument. Similarly, if the chamber is pressurized, then a greater number of molecules are available for ionization, and even higher sensitivity results.The ionization of gas is the basis for gas-filled radiati
sensitive
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Ionization chamber survey instrument-
fluoroscope, around radionuclide generators and syringes, in the vicinity of patients with therapeutic quantities of radioactive materials, and outside of protective barriers. Other, more accurate ion chambers are used for precise calibration of the output intensity of diagnostic x-ray imaging systems
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Geiger Muller Geiger counters are
used for contamination control in nuclear medicine laboratories. As portable survey instruments, they are used to detect the presence of radioactive contamination on work surfaces and laboratory apparatus. They are not particularly useful as dosimeters because they are difficult to calibrate for varying conditions of radiation
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Define skin erythema dose.
Dose of radiation, usually about 200 rad or 2 Gy, that causes redness of the skin.
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