S. James Adelstein

The value of a diagnostic test lies in its ability to detect patients with disease (its sensitivity) and to exclude patients without disease (its specificity). For tests with binary outcomes, these measures are fixed. For tests with a continuous scale of values, various cutoff points can be selected to adjust the sensitivity and specificity of the test to conform with the physician's goals. Principles of statistical decision theory and information theory suggest technics for objectively determining these cutoff points, depending upon whether the physician is concerned with health costs, with financial costs, or with the information content of the test.

Physicians have a specific responsibility toward patients who are hopelessly ill, dying, or in the end stages of an incurable disease. In a summary of current practices affecting the care of dying patients, we give particular emphasis to changes that have become commonplace since the early 1980s. Implementation of accepted policies has been deficient in certain areas, including the initiation of timely discussions with patients about dying, the solicitation and execution in advance of their directives for terminal care, the education of medical students and residents, and the formulation of institutional guidelines. The appropriate and, if necessary, aggressive use of pain-relieving substances is recommended, even when such use may result in shortened life. We emphasize the value of a sensitive approach to care--one that is adjusted continually to suit the changing needs of the patient as death approaches. Possible settings for death are reviewed, including the home, the hospital, the intensive care unit, and the nursing home. Finally, we consider the physician's response to the dying patient who is rational and desires suicide or euthanasia.

This special report aims to inform the medical community about the many challenges involved in managing radiation exposure in a way that maximizes the benefit-risk ratio. The report discusses the state of current knowledge and key questions in regard to sources of medical imaging radiation exposure, radiation risk estimation, dose reduction strategies, and regulatory options.

Although the general radiobiologic principles underlying external beam therapy and radionuclide therapy are the same, there are significant differences in the radiobiologic effects observed in mammalian cells. External beam and brachytherapy emissions are composed of photons, whereas radiations of interest in radionuclide therapy are particulate. The special features that characterize the biologic effects consequent to the traversal of charged particles through mammalian cells are explored with respect to DNA lesions and cellular responses. Information about the ways in which these radionuclides are used to treat cancers in experimental models are highlighted.