The Evaluation of Personal Radiation Exposure

Abstract

Ever since it was realized, half a century ago, that the use of x-rays and rays from radioactive substances involved a personal hazard, efforts have been made to limit exposure in order to minimize the dangers. To this end, various devices have been developed to determine just what exposures existed, for various places or persons. There have long been two aspects of the problem. The first is that of the doctor or technician who receives small doses daily, over long periods of time. These may seem entirely innocuous, but after years of such exposure, deleterious effects may become manifest. The second is that of the patient, who for diagnostic purposes is subjected to radiography and fluoroscopy to such a degree that acute or chronic radiation changes may be produced. (The patient who receives too much radiation therapy might also be included in this category.) To these two types of hazard, we must now add the problems engendered by the possibility of atomic warfare. Let us dispose promptly of the second of the above categories by pointing out that, with suitable calibration of equipment, and an understanding of the dangers on the part of those using it, this problem should disappear. At present, damage from excessive fluoroscopy is seldom seen in properly organized departments of radiology; it is much more likely to occur with non-radiologists using fluoroscopes to look for foreign bodies, set fractures, or demonstrate abnormal conditions. It may be that an educational campaign is needed here; it is not likely that any monitoring device will be of much use. With regard to the group who might receive chronic low-intensity exposures, the practice for a long time was to rely on a careful survey of the department, either with a large ionization chamber, or with dental films, or both, and then to expect that no person would go into areas not known to be safe. However, because a direct check was preferable to an indirect one, the use of dental film was extended to its being worn as a badge for some set period of time by anyone who was concerned about exposure. The film was then developed, and the dose of radiation received was evaluated by comparison with films exposed to known fractions or multiples of a roentgen. With the rapidly increasing use of artificially radioactive isotopes the individual badge has become a very important supplement to the over-all survey. Instead of the simple dental film with a paper clip across it to cast a shadow, special holders have been devised which contain two or three filters, so that the quality as well as the quantity of the radiation can be determined. Various commercial concerns, as well as the Atomic Energy Commission, offer a reliable film badge service, sending fresh films at stated intervals, receiving, developing, and measuring the exposed ones. The ultimate in such badges appears to be now in sight, with a self-developing film which can be opened and examined at any time.