Calibration it is a set of measurement operations according to international standards in order to determine the accuracy of the device and its suitability for the purpose for which it is used. The characteristics of measuring devices and tools are determined by finding the relationship between the true value and the value that have been measured.
Medical devices must be calibrated when they are purchased new and before entering the service periodic calibration according to the recommendations of the manufacturer and after repair or maintenance of the device.
Some medical equipment, especially those that contain therapeutic energy such as pacemakers, electrosurgical units, physiotherapy stimulants, etc., must be calibrated periodically.
This means that the energy levels must be measured and whether there is a discrepancy from the levels indicated, then adjustments must be made so that the device works within the specifications.
Equipment that takes measurements is required for calibration such as electrocardiographs, laboratory equipment, patient scales, pulmonary function analyzers, etc. Also periodic standards to ensure accuracy compared to known standards.
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Measurement Technology and Metrology
Measurement technology and metrology, calibration is the comparison
of measurement values delivered by a device under test with those of a calibration standard of known accuracy. Such a standard could be another measurement device of known accuracy, a device generating the quantity to be measured such as a voltage, a sound tone, or a physical artifact, such as a meter ruler.
The outcome of the comparison can result in one of the following:
- no significant error being noted on the device under test
- a significant error being noted but no adjustment made
- an adjustment made to correct the error to an acceptable level
Strictly speaking, the term “calibration” means just the act of comparison and does not include any subsequent adjustment.
The calibration standard is normally traceable to a national or international standard held by a metrology body.
Instrument calibration prompts
Calibration may be required for the following reasons:
- a new instrument
- after an instrument has been repaired or modified
- moving from one location to another location
- when a specified time period has elapsed
- when a specified usage (operating hours) has elapsed
- before and/or after a critical measurement
- after an event, for example
- after an instrument has been exposed to a shock, vibration, or physical damage, which might potentially have compromised the integrity of its calibration
- sudden changes in weather
- whenever observations appear questionable or instrument indications do not match the output of surrogate instruments
- As specified by a requirement, e.g., customer specification, instrument manufacturer recommendation.
