摘要： The “slow revolution” that brought the field of diagnostic radiology from analog film to digital imaging paved the way to important benefits that were progressively achieved in the last few decades: above all, the possibility for medical personnel to rapidly share huge amounts of patient-related information. However, some of the consequences of the analog-to-digital shift were problematic. One issue, whose importance is often underestimated, was the visual quality of the images presented to the physician. As will be described in detail herein, the requirements of the different specialties with regard to medical images span a wide range; the weakest link in the processing chain, which determines the overall quality, is frequently the display equipment. In particular, the dynamic range of the luminance that the device can emit and its relation to the typical illumination of the environment in which the device operates should be considered with care. Old analog films placed on a lightbox could yield peaks of 4000 cd/m2, and could span a luminance range of several log units: this made details well visible even in a highly illuminated room. The best medical CRT displays at the time of the digital transition, instead, had a maximum luminance in the several hundred candelas per square meter (cd/m2) range. Only later did LCDs reach 1000 cd/m2, at the price of an undesired higher luminance for “black” pixels. In this chapter we will describe a solution aimed at overcoming dynamic range problems in the visualization of medical images. We will first analyze the specific requirements for a high dynamic range (HDR) display that should operate in the medical (diagnostic) context, and the procedures that are followed in a laboratory of the US Food and Drug Administration to evaluate such a display. We will then describe in some detail an LCD composed of two stacked liquid crystal panels, a prototype of which is presently being developed at Barco.