chapter 20, Practical Applications of Perceptual Research

Excerpt

20.1 Introduction

A lot of the work into perceptual and observer performance issues in radiologic imaging (and medical imaging in general) began as a result of a series of studies [1, 2] done after WWII. These studies were designed to determine which of four roentgenographic and photofluorographic techniques was better for mass screening of chest images for tuberculosis. What seemed to be a rather easy and practical question to answer in a fairly straightforward investigation turned out to yield results that created more questions than answers. Inter-observer and intraobserver variabilities were so high that it could not be determined which imaging method yielded better diagnostic accuracy. Prior to this study, it was generally presumed that radiologists did not differ that much from each other in their diagnoses, and that if the same image was shown to the same radiologist at two points in time the diagnosis would not differ substantially. These studies suggested otherwise—radiologists were not as consistent as previously thought. One followup study [3] even tried to get radiologists to simply describe characteristics of radiographic shadows. Again there was wide inter-observer variation and moderately high intra-observer variation even on the seemingly straightforward description of lesion characteristics. This suggested that differences∕errors in performance might lie in perceptual and cognitive factors rather than in technical factors such as bad technique or poor processing. Even today studies are being conducted that look at reader variability and ways to reduce it [4].

Since these early studies, much research has been done to elucidate the perceptual and cognitive processes involved in the reading of radiographic and other medical images. The previous chapters in this book described a variety of ways that image perception and observer performance have been investigated. Over the years, we have learned a lot about what types of errors are made [5, 6], under what circumstances they are more likely to be made [7–10], what the human visual system is actually capable of perceiving in an image [11, 12], and how to predict performance [13–15] with a variety of human visual system models. The goal of this chapter is to describe some practical applications of perceptual research in medical imaging. The intent is to provide some examples where perceptual research can or has made an impact in the clinical environment and to illustrate the general framework for extending perceptual research to practical applications. The intent is not to provide an exact methodology for doing the research or making the transition from the lab to clinic, because there really is no single correct method or formula to do this.

20.2 Bridging the gap between research and clinical practice

The American Heritage Dictionary [16] defines practical as “capable of being used or put into effect; designed to serve a purpose: useful, efficient.” In the context of medical image-perception, the first part of the definition suggests that the results of image-perception research should somehow be implemented in the clinical environment and into the real-world task of interpreting clinical images.