GB487884A - Improvements in the measurement of roentgen rays - Google Patents

Abstract

487,884. Current meters ; Rontgenray apparatus. GROVES, W. W. (1. G. Farbenindustrie Akt.-Ges.) Jan. 1, 1937, No. 54. [Class 37] [Also in Group XX] Apparatus for measuring the quality, quantity, and dose of R÷ntgen rays comprises a pair of photoelectric cells, the ratio of current impulses produced therein being measured on ballistic instruments, the cells being provided with metallic filters of different thickness and a fluorescent screen. The cells 13, 14 are housed in a lead casing covered by a plate 20 transparent to the rays, together with a fluorescent screen 15, and lead glass filter 16. Filters 17 of different thickness are located in front of one or both cells and may be apertured so that some unfiltered rays can pass. Further, a photographic film 19 uniformly blackened to a predetermined degree can be employed to weaken the light falling on the cell in respect of weakly filtered rays. Ballistic galvanometers of the mirror type are combined to indicate on a scale of rectangular co-ordinates, the abscissae, for example, giving the intensity of unaltered rays and the ordinates the intensity of those filtered, the spot moving according to the ratio and indicating the hardness of the rays. The dosage can be defined in terms of both the intensity and quotient values. The cell surfaces are preferably equal, and screens of different sensitivity but equal electrical resistance may be used. R÷ntgen rays produced from apparatus connected to different power sources can be compared, and the standardization of photographic film sensitivity to such rays can be effected. Stencilled areas can be marked on the scale for indicating the correct dose in respect of the examination of lungs, skull, stomach, and the like. Automatic exposure can be effected by means of a further cell through relay apparatus when the spot reaches the desired area on the scale.