A METHOD AND APPARATUS FOR MEASURING THE ENERGY AND/OR DOSE OF RADIATION BY RADIATION-SENSITIVE TRANSPARENT SOLID BODY MEASURING ELEMENTS

摘要

1,248,965. Lumiescent materials and uses thereof. GES. FUER KERNFORSCHUNG m.b.H. 26 Nov., 1968 [28 Nov., 1967], No. 55950/68. Heading C4S. [Also in Division G1] During readout of a dosimeter element, the intensity of fluorescence from a number of zones, which are located at different distances from the surface of the element which was subjected to the original irradiation, is measured so that information as to the energy of the original radiation can be determined before the actual dose is calculated. This because for certain radiation fields (particularly in low energy medical and technical applications) the dose absorbed by the element is energy dependent. With a cube-shaped element 1, Fig. 1, the surface which was irradiated is known, and the element is displaced at right angles to this surface (in the X direction). A masking arrangement 4 allows excitation of the element, which may be a low Z phosphate glass, by ultra-violet radiation, in the Y direction, and detection of fluorescence emitted in the Z direction by a narrow zone of the element. The detector may be a photomultiplier. The displacement may be step-by-step or continuously, in the latter case the detector being coupled to a chart recorder. In an alternative arrangement, a light conductor is moved across the fluorescent surface. In the case of a cylindrical block element, the direction of incidence of the original radiation is first detected by locating the part of the surface producing maximum fluorescence. Once this is found, fluorescence in zones spaced further and further from the originally irradiated part of the surface may be measured. A graph of intensity of fluorescence against distance (or depth) of a luminescent zone from the originally irradiated surface may then be drawn and compared with calibration curves for different energies of the original radiation, Fig. 4 (not shown), which curves have differing shapes (steeper with decreasing energies), to determine the energy and dose of the original radiation that the element was subjected to. Values for tissue equivalent doses may also be calculated therefrom. Reference is made to γ- and X-radiation and also # radiation.