Detection of X-rays is done using Geiger counters but it may not be able to measure the dose rate. This is due to the fact that an X-ray is a concentrated short burst radiation. Events are individually ionized in its Geiger tube and a Geiger counter measurement is performed. The events occurring during the X-ray normally take place so quickly that all of them cannot be detected by the instrument, providing a reading that does not reflect the full radiation amount. An ionization chamber will be required for a true dose rate.
Medical and X-ray machines have scatter or leakage sometimes in directions other than the target. Inappropriate shielding may cause this scatter to reach personnel causing unwanted exposure. For screening for scatter, the Radalert 100 can be placed in the location where testing has to be done while the X-ray machine is being activated. If the instrument is in Audio mode, a rapid burst of chirps or clicking will be heard and a reading higher-than-normal will be produced. Even though the measure may be a reliable measure for scatter, it is not precise.
Measurement of Radiation in Food
It is possible for Geiger counters to measure nuclear or ionizing radiation. Radiation from microcellular phones, microwave ovens, cellular phones, power lines, and electric appliances is non-ionizing electromagnetic radiation, which cannot be sensed using these instruments.
For accurate measurement of food radiation, a multi-channel analyzer is required and a special oven is also needed to ash the food for concentrating the radioactivity. Geiger counters have been used for educational, experimental and screening purposes for checking food.
Measuring radiation in food is quite tricky. The Inspector Alert and the Radalert 100 can easily detect naturally occurring radiation in potassium-rich foods such as bananas and when dried into banana chips or salt substitutes. During checking at times of nuclear accidents or testing, Strontium-90, Cesium-137 or Plutonium 239 need to be identified. The most suitable for this application is Inspector as it is highly sensitive.
The Inspector Alert efficiency for Sr-90 and Cs-137 beta is good, and it does detect the Cs-137 gamma. It can detect Pu-239, but Pu-239 can have health impacts at very low concentrations, which can be difficult to detect with any instrument.
It is important to establish a baseline measurement before screening for radiation in food. The baseline counts need to be accumulated for 12 h as explained below.
Tips for Measuring Radiation in Food
Certain tips to be followed while measuring radiation in food are:
- During measurement, the mica window of the instrument is placed directly over the measured food.
- In case of liquids or milk, the container must be filled very close to the top without glass in the way. In case all the milk is from the same source it can be concentrated by boiling sufficiently.
- The display needs to be set to Total and the counts accumulated for 12 h in each location
- The total count for the period is divided by the exact number of minutes to get the average CPM.
This information has been sourced, reviewed and adapted from materials provided by International Medcom.
For more information on this source, please visit International Medcom.