How to Take Measurements in Radiation Units

Radiation is measured in Röntgen (also spelled Roentgen) units (R), each of which is equal to the amount of radiation needed to liberate one electrostatic unit of positive or negatve charge (esu) in one cubic centimeter of dry air at standard temperature and pressure (STP). The average person is exposed to approximately 2 mR (1 mR or "milli-Röntgen" is equal to 1/1000 of 1 R) per week from a variety of different natural and man-made sources. A typical chest X-ray exposes the patient to about 10 mR. Measurements of radiation exposure can be taken with a Geiger counter. The counter will give you a reading of mR per hour, the equivalent exposure of standing in the given radiation field for one hour.

Things You'll Need

• Geiger counter
• Radiation source

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Instructions

• 1

  Ensure that all external cables are connected securely. Cable connectors should not be loose and should be turned completely to the right.

• 2

  Check the battery. Turn the dial on the Geiger counter to the "BAT" setting. The needle should read between the "BAT TEST" lines on the scale. If the needle is not within these parameters, change the batteries and recheck.

• 3

  Hold the Geiger counter to a radiation source of known strength. Confirm that the needle rises to the correct point, based on the radiation source you've used. If the needle does not read correctly, follow the manufacturer's recommended calibration instructions, and check again.

• 4

  Hold the Geiger counter to the source of the radiation that you are measuring. View where the needle lands on the scale and read the measurement of mR per hour.