My ACR phantom has an air bubble in it. What should I do?

A small air bubble isn’t a problem. The most obvious drawback of a bubble is that once the bubble becomes large enough, you can no longer see the top of the phantom. This prevents you from measuring the phantom diameter on slice # 5 from the top to the bottom. However, unless the bubble is huge, you can do what the ACR reviewers do. You just measure the diameter of the phantom slightly to left or the right of top dead center. Start drawing the line on the edge of the water-filled part of the phantom, avoiding the bubble. Finish the measurement on the opposite side of the phantom making sure the measurement line passes through the center of the grid. However, if the bubble becomes very large, we recommend you have the phantom refilled or topped off.