Patent Number: 045047391
Section: description

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 shows a radiation shield 10 in place between a radiation source 12, depicted as a pipe containing a radioactive liquid, and a human being 14. Of course, the shape of the radiation shield 10 is merely illustrative. Several other shapes for such shields are shown in my U.S. Pat. No. 4,090,087, and many other shapes are usable and in fact in use. The subject invention is not limited in its utility to any particular shape of radiation shield. FIG. 2 shows the radiation shield 10 in plan. It has a gas inlet 16, a gas outlet 18, a pressure relief valve 20, an inlet/outlet 22 for either gas or radiation attenuating liquid, and a valve 24 controlling the inlet/outlet 22. In use, the inlet/outlet 22 is connected to a source of gas, such as an air pump, and the radiation shield 10 is inflated to form the radiation shield. During this step, the pressure relief valve 20 is set at a value (such as two pounds per square inch) which inflates the shield and which insures dimensional stability, but which does not permit an unnecessary amount of gas to be pumped into the shield. The radiation shield, which is then relatively light and easily manueverable, is then placed in a desired relationship to a radiation source. After it has been properly positioned, the inlet/outlet 22 is connected to a container of radiation attenuating liquid (such as a hydrogeneous liquid which is denser than water), and the gas is replaced with the radiation attenuating liquid. As the radiation attenuating liquid is forced into the radiation shield, it displaces the gas. The reason that the gas is preferably introduced through the inlet/outlet 22 rather than the gas inlet 16 during inflation of the radiation shield is that the weight of the line attached to the gas inlet 16 tends to pull the radiation shield over on its side when the radiation shield is only filled with gas. Of course, that is not a problem when the radiation shield is predominately filled with radiation attenuating liquid. Radiation shields of this type occasionally leak during use, losing their dimensional stability. Accordingly, after the radiation shield is in place, it is desirable to connect the gas inlet 16 to a source of gas, such as an air pump, set to provide an overpressure of gas above the radiation attenuating liquid in the shield, thereby solidifying the shield in its designed dimensional configuration. The source is conveniently triggered by a sensor which detects when the overpressure has dropped beneath a set level (for instance, one pound per square inch) and thereupon causes the overpressure to be built back up to a desired sustaining level (for instance, two pounds per square inch). When it is desired to deflate the radiation shield for storage or for transfer to another use, the gas inlet 16 is connected to a source of gas (if it is not already so connected), the valve 24 is opened, and gas is pumped into the radiation shield 10 through the gas inlet 16, forcing the radiation attenuating liquid out through the inlet/outlet 22. If desired, the pressure relief valve 20 may be set at a higher than normal value (such as 2-3 p.s.i.) or closed entirely prior to this step. However, in practice the customary two pounds per square inch overpressure has been found adequate for this purpose. After substantially all of the radiation attenuating liquid has been forced out of the radiation shield 10, the radiation shield 10 is once again light and manueverable and can be easily moved to another position. Or, if it is desired to deflate the shield for storage, the gas inlet 16 is disconnected from its source and the valve 24 and the pressure relief valve 20 are opened to atmosphere. The radiation shield 10 can then be collapsed like a giant balloon. If especially quick collapse is desired, it is even possible to connect one or more of the inlets to a vacuum pump. CAVEAT While the present invention has been illustrated by a detailed description of a preferred embodiments thereof, it will be obvious to those skilled in the art that various changes in form and detail can be made therein without departing from the true scope of the invention. For that reason, the invention must be measured by the claims appended hereto and not by the foregoing preferred embodiment.