AN ADAPTIVE REFERENCE TEST PARADIGM - APPLICATION TO PULSED FLUOROSCOPY PERCEPTION/

We developed an adaptive forced-choice method whereby reference and te st presentations were alternated in order to minimize effects from var iables such as subject attention level. In our demonstration example o f an X-ray fluoroscopy perception study, we measured detectability of low-contrast objects in noisy image sequences and determined X-ray dos e levels for equivalent detectability of identical contrasts for a new test acquisition method (fluoroscopy at 15 acq/sec) as compared with a reference (conventional fluoroscopy at 30 acq/sec). In preliminary e xperiments, we found a dose savings with the test method. We derived p arameter uncertainties for the adaptive procedure and demonstrated the ir applicability with Monte Carlo simulations. Repeated experiments on a single subject demonstrated reduced standard errors due to the redu ction of day-to-day variations. It is believed that the method can be applied in a variety of situations in which one needs to compare perce ption measurements.