Worse Case Precision

Example: Scanning Bed Whole Body Counter

The P4 phantom is placed in five positions, shown below:

• Normal position
• Diagonally from left to right
• Diagonally from right to left
• Extreme left side
• Extreme right side

This precision of counting will represent the worst possible case. Ideally the ratio of Worst Case Precision to normal precision, where the phantom is re-assembled in slightly different positions, should be small.