DOSE DISTRIBUTION MEASUREMENTS WITH THIN TLD ARRAYS

INTERNATIONAL SENSOR TECHNOLOGY, INC. (IST) PROPOSES TO DEVELOP A THERMOLUMINESCENCE DOSIMETRY (TLD) SYSTEM FOR MEASUREMENT OF ABSORBED DOSE DISTRIBUTIONS OF IONIZING RADIATION (GAMMAS, BETAS, NEUTRONS) IN PHANTOMS. THE SYSTEMWILL EMPLOY IST-DEVELOPED TECHNOLOGY FOR LASER HEATING AND FABRICATION OF SUITABLE LARGE-AREA, THIN-FILM DOSIMETER ARRAYS. COMMERCIAL THERMOLUMINESCENCE (TL) PHOSPHORS (E.G., MAGNESIUM BORATE) WILL BE USED WITH A PRINTING TECHNIQUE FOR PRODUCING VARIOUS SPOT SIZES AND THICKNESSES ON THIN GLASS OR HIGH-TEMPERATURE POLYMER-SUBSTRATE SHEETS. NEUTRON DOSES CAN BE MEASURED USING PROTON RADIATORS AND PROTON ABSORBERS ON ALTERNATE SPOTS, OR USING A TL PHOSPHOR MADE WITH DIFFERENT ISOTOPES AT ALTERNATE LOCATIONS, FOR GAMMA-NEUTRON DISCRIMINATION. THE TLD SYSTEM WILL BE BASED ON A HIGHLY STABLE, CLOSED-LOOP, FEEDBACK-CONTROLLED 20-WATT CO2 LASER WITH A BEAM THAT HAS A UNIFORM CROSS SECTION OF VARIABLE SIZE. THETEMPORAL SHAPE OF THE LASER HEATING PULSE WILL BE TAILORED BY COMPUTER CONTROL FOR PRE-AND POSTANNEAL TREATMENTS AND RAPID HEATING OF THESE DOSIMETERS WITH MINIMAL INCANDESCENCE BACKGROUND EMISSION. A LARGE READING AREA WILL BE OBTAINED BY THE ADDITION OF SPECIAL X-Y DOSIMETER-POSITIONING MECHANISMS. THE ADVANTAGE OF THE PROPOSED TECHNOLOGY OVER CONVENTIONAL PHANTOM DOSIMETRY IS THE POSSIBILITY OF PLACING A LARGE NUMBER OF VERY SMALL DOSIMETERS IN THE FORM OF ARRAYS ON SHEETS BETWEEN THE TRANSVERSE SLICES OF HUMAN PHANTOMS OR WRAPPING THEM AROUND BONELIKE OR PROSTHETIC MATERIAL INSERTED IN THESE PHANTOMS AND RAPIDLY MEASURING THE ABSORBED DOSES IN AN AUTOMATED TLD READER.