We investigate the effect of motion on detectability of low-contrast objects using 2 fluoroscopic imaging techniques: 30 acq/sec (pulsed-30) and 15 acq/sec pulsed (pulsed-15). We measure detectability using a new reference/test, adaptive 9-alternative forced-choice method. For pulsed-30 (reference) and pulsed-15 (test), we measure absolute detectabilities, an equivalent perception dose (EPD) for test, and response times. Computer-generated phantoms are x-ray projections of cylinders that mimic arteries, catheters, and guide wires. In the case of the larger cylinders, motion increases absolute detectability. With the smaller cylinders, motion decreases detectability. Results from four subjects show that dose savings for pulsed- 15 is around 18% with relatively little effect of velocity or object size. In general, subjects take slightly longer to respond in the case of low acquisition fluoroscopy.