Digital radiography is a general term describing any projection radiological system in which the image exists in digital form at some stage between acquisition and viewing. In an earlier form, radiographic films were dig itized in an attempt to enhance and redisplay information of interest. The field has evolved to its current state, in which X-ray signals are detected electronically, converted to digital form, and processed prior to being recorded and displayed. A primary goal of digital radiography is the re moval of interfering effects from secondary structures in an image, so that clinically significant details can be displayed with enhanced visibility. The achievement of this goal involves many parameters, including con trast agents, subtraction techniques, processing techniques, filtering tech niques, system noise, and quantitative aspects. It is the purpose of this book to present material by noted individuals in the field covering several of the above topics. The authors acknowledge the secretarial and editorial assistance of Mrs. Helen Taylor and the editorial assistance of Mrs. Ruth McDevitt. James G. Kereiakes Stephen R. Thomas Cincinnati, Ohio Colin G. Orton Detroit, Michigan ix Contents 1. DIGITAL RADIOGRAPHY: OVERVIEW B. A. Arnold, 1. G. Kereiakes, and S. R. Thomas 1. Introduction . . . . . . . . . 1 2. Point-Scanned Detector Systems 3 3. Line-Scanned Detector Systems 4 4. Area Detector Systems 5 4.1. Stimulable Phosphors 5 4.2. Selenium Detectors ."

Mankind has evolved in a sea of radiation. We have been bombarded constantly by X rays, y rays, UV rays, and particulate radiations from outer space, and by terrestrial radiations from the ground we walk on, from our building materials, and from our own bodies. Recently, we have become increasingly subjected to man-made radiations, especially from the medical and defense industries. All of these radiations are capable of affecting us biologically, both to our benefit and to our detriment. This book provides a thorough review of the physical and biological dosimetry of these radiations. It is targeted to those health professionals who are concerned with understanding the mechanisms fundamental to the biological action of ionizing radiation or who are involved in the application, measurement, or treatment of the effects of such radiations. The first chapter, on "Bioeffect Dosimetry in Radiation Therapy," should be of special interest to anyone involved in the treatment of cancer by radiation. It includes a brief review of the history of the manipulation of time-dose parameters in order to improve therapeutic benefit, and an up-to-date analysis of time-dose relationships designed for use in fractionated radiotherapy and brachytherapy. This is followed by two chapters reviewing and comparing national and international protocols for the precise measurement of photon and electron radiations in therapy. These chapters should be invaluable to radiation physicists responsible for treatment machine calibrations.

Mankind has evolved in a sea of radiation. We have been bombarded constantly by X rays, y rays, UV rays, and particulate radiations from outer space, and by terrestrial radiations from the ground we walk on, from our building materials, and from our own bodies. Recently, we have become increasingly subjected to man-made radiations, especially from the medical and defense industries. All of these radiations are capable of affecting us biologically, both to our benefit and to our detriment. This book provides a thorough review of the physical and biological dosimetry of these radiations. It is targeted to those health professionals who are concerned with understanding the mechanisms fundamental to the biological action of ionizing radiation or who are involved in the application, measurement, or treatment of the effects of such radiations. The first chapter, on "Bioeffect Dosimetry in Radiation Therapy," should be of special interest to anyone involved in the treatment of cancer by radiation. It includes a brief review of the history of the manipulation of time-dose parameters in order to improve therapeutic benefit, and an up-to-date analysis of time-dose relationships designed for use in fractionated radiotherapy and brachytherapy. This is followed by two chapters reviewing and comparing national and international protocols for the precise measurement of photon and electron radiations in therapy. These chapters should be invaluable to radiation physicists responsible for treatment machine calibrations.