Deadtime measurements with a multihole phantom: concise communication.

The performance characteristics of any Anger camera are defined by that camera's spatial and temoral resolutions. Procedures using first-past techniques--such as ejection fraction or left-to-right shunt determinations--require that deadtimes be minimal. We have evaluated a simplified method for measuring a camera's deadtime; it uses a multihole phantom consisting of a lead sheet with 196 holes, 7/16 in. diameter, arranged in a 14 X 14 matrix. Each hole can be filled with a removable lead plug. Count rates are determined following incremental removal of the plugs. Deadtime curves were generated for each of three cameras by this and standard techniques. For each camera, the three curves were virtually identical. Using the phantom, deadtimes could be determined in 15 to 20 min. This phantom provides a simple, rapid, and accurate means of determining camera deadtime and minimizing personnel radiation exposure.