GB758475A - Improvements in and relating to processes, products and devices for measuring dosageof x, gamma and ultra-violet radiations - Google Patents

Abstract

758,475. Photographic dosimeter. BAROZ. N. J. M. P. F. CHASSENDE-. April 28, 1954 [April 30, 1953; April 6, 1954], No. 12264/54, Class'98 (1). Photographic material for measuring the dosage of X, gamma, and ultraviolet radiations comprises two or more photographic emulsions of which only one (the check emulsion) is substantially unaffected by the radiation to be measured and contains a latent image which becomes visible upon developing the material, the appearance of the check emulsion indicating the end of the development. The check emulsion may be one which is substantially insensitive to the radiation to be measured, or may be one which has been exposed to an illumination at least sufficient to attain after development subtantially maximum density. The check emulsion may be a silver chloride, chlorobromide, chloriodide, chlorobromide or bromiodide emulsion and may be accompanied by two other emulsions unequally sensitive to the radiation to be measured and carried on the same or separate supports, which may be of paper, film or glass. The material may be enclosed in an inner envelope of transparent plastic and an outer opaque envelope provided: The emulsions may be coated in distinct areas on a common support. The check emulsion may carry a density reference mark of ink or formed by the localised application of developer before or after formation of the latent image. The production of silver chloride, bromide and bromiodide emulsions is described. The emulsion supercoating may be of increased thickness and/or may be hardened, where a silver chloride check emulsion is used, to delay development. The inside of the opaque envelope may be provided with a coating like that used for carbon papers to facilitate the inscription of identification marks. The photographic material may be self-developing. As shown, a support carries a photographic paper 2 suitable for the range 0-150 Roentgens of gamma radiation, a paper 3 suitable for 100-600 Roentgens, a check photographic paper 1 which has been exposed to light, and a density scale 4 calibrated so that it can be compared with the densities of papers 2 and 3 to determine the dosage. The paper 1 may constitute the density scale if the original latent image is produced by exposure under a sensitometric step-wedge, and it may be detached from the other papers.