2 10-20 Measurement System
10-20 MEASUREMENT SYSTEM
Introduction
The 10-20 system is an international, standardized measurement system designed to guide the placement of electrodes on the scalp. The 10-20 system gets its name from the fact that it divides the skull into regions that allow for the placement of electrodes to be 10% and 20% away from one another.
Terminology
Each electrode in the 10-20 system is identified by a unique number and letter. The numbers indicate whether the electrode is on the left or right side of the head (Odd numbers on the left, even numbers on the right). The letters identify regions of the head, for example the letter O corresponds to “Occipital” and the electrode O1 indicates the placement of an electrode on the left occipital region of the head. The following table is essential for understanding the naming of electrode position
| Abbreviation | Area | Example |
| FP | Frontopolar | FP1 (Left Frontopolar) |
| F | Frontal / Anterior Temporal | F4 (Right Frontal), F8 (Right Anterior Temporal) |
| T | Mid Temporal / Posterior Temporal | T3 (Left Mid Temporal) |
| C | Central | CZ (Central Midline) |
| P | Parietal | P4 (Right Parietal) |
| O | Occipital | O1 (Left Occipital) |
Figure 2.1.1 10-20 Measurement System Terminology & Abbreviations
トマトン124, Public domain, via Wikimedia Commons
Figure 2.1.2 10-20 Measurement System represented with placements on head.
10-20 Calculations
Understanding how to calculate interelectrode distances is an important part of the R. EEG T. exam. In this chapter, we will not be going over specifics on how to measure, it is important that you understand how the calculations are done as it is highly likely you will be asked to find distances between electrodes given a measurement of the skull. The following video will go over how to approach these problems, and provide a few practice problems that are similar to the ones you will likely see on test day.
(Insert Video 10-20 calculations)
Key Takeaways
- The 10-20 Measurement System is a standardized measurement system for the placement of electrodes in most EEG’s.
- Electrodes are named after where they are placed on the head. The number represents which hemisphere (Left/Right) and the letters represent region within that hemisphere. (FP1 = Left Frontopolar)
- Understanding how to calculate the distances between electrodes given a specific measurement will be essential on test day.
Insert H5P questions