Since ionizing radiation cannot normally be detected through the senses, instruments must be relied on and utilized for the detection and measurement of radioactive contamination and radiation fields. As a wide range of radiation-monitoring instruments are available, care must be taken to select an instrument both appropriate and efficient for the application.
Principal investigators (PI) working with beta- (e.g., C-14, S-35, P-33, P-32) or gamma-emitting radioisotopes (e.g., I-125, Cr-51) should possess or have access to a portable radiation detector with the appropriate probe. Certain labs with only sealed sources presenting a minimal radiation exposure hazard are not required to possess a radiation detector. Labs working only with H-3 are not required to possess a portable radiation detector. However, they must have access to a liquid scintillation counter for all post-experiment and monthly surveys.
All radiation detection instruments used for quantitative and qualitative measurements must be calibrated or response-checked every 12 months. Calibrations shall be performed either by EH&S, the instrument manufacturer, or a licensed calibration service provider.
Detector Type
Radioisotopes: C-14, S-35, P-33, P-32
Comments:
-Can be used to find gross surface contamination
-Does not detect H-3 or any very low energy beta
-Inefficient for detection of photons (x-rays, gamma rays)
-Typically measures in counts per minute (cpm)
Radioisotopes: Gamma or x-ray fields
Comments:
-Measures exposure rate due to gamma or xrays
-Measures exposure rate due to Bremsstrahlung radiation from beta particles
-Typically measured in μroentgen(R)/hr or mR/hr
Radioisotopes: I-125, Cr-51
Comments:
-Much more efficient at detecting gamma radiation than GM meter
-Fragile and very hygroscopic
-Measured in cpm
Radioisotopes: H-3, C-14, S-35, P-33, P-32, I-125, Cr-51
Comments:
-Able to quantify H-3
-Most sensitive detection method for beta particles, although measurement is applicable to all types of emissions
-Measured in cpm or disintegrations per minute (dpm)
Radioisotopes: I-125, Cr-51 and other gamma-emitting isotopes
Comments:
-Efficient detection method for gammaemitting isotopes
-Measured in cpm or dpm
