PROPERTIES OF BETA-EMITTING ENCLOSURES

THE PROPERTIES OF CLOSED OR ALMOST-CLOSED SURFACES WITH BETA-EMITTING WALLS WILL BE STUDIED BY MEANS OF POWERFUL MONTE CARLO TRANSPORT MODELS. POSSIBLE USE OF THE ENCLOSURES IN DELIVERING AREALLY UNIFORM SURFACE DOSES TO TARGETS THAT ARE EITHER WITHIN THE ENCLOSURES OR THAT ARE EXTERNALLY APPOSED TO WINDOWS IN THE ENCLOSURE WALLS WILL BEASSESSED IN LIGHT OF THE CALCULATIONAL RESULTS. SIMPLE GEOMETRIES ONLY, E.G., SPHERICAL ENCLOSURES (RADIUS 5 TO 50 CM) CONTAINING SMALLER SPHERES AS TARGETS, WILL BE STUDIED IN PHASE I. THE INFLUENCE OF (1) SOURCE CUT-OFF ENERGY, (2) SOURCE AND TARGET RADII, (3) AND TARGET OFF-CENTERING ON SURFACE DOSE WILL BE CALCULATED AS A GUIDE IN DEVISING GEOMETRIES IN WHICH SURFACE DOSES THAT ARE INDEPENDENT, OR NEARLY SO, OF SOURCE/TARGET SIZE AND SHAPE ARE OBTAINED. SUCH INDEPENDENCE WOULD PERMIT DESIGN OF EFFICIENT, CONVENIENT, INEXPENSIVE, AND SAFE IRRADIATORS FOR RADIOBIOLOGICAL, MEDICAL, AND INDUSTRIAL PURPOSES, INCLUDINGUNIFORM IRRADIATION OF UNBOLUSED SHALLOW CELL CULTURES, TOTAL OR PARTIAL SKIN IRRADIATION OF ANIMAL AND HUMAN SUBJECTS WITH LITTLE OR NO PHOTON CONTAMINATION, AND ENERGY-EFFICIENT STERILIZATION OR OTHER PROCESSING. GENERAL GUIDELINES FOR IRRADIATOR DESIGN AND CONSTRUCTION, WHICH IN PHASE II MIGHT INCLUDE USE OF NONUNIFORM SOURCE DISTRIBUTIONS, WOULD RESULT FROM PHASE I.