Bordier Radiometer

BORDIER RADIOMETER (Bordier) is an improved version of the Freund radiometer for measuring the quantity of X-rays emitted by a tube. Since working with the Freund radiometer was complicated by the need to constantly have a freshly prepared 2% solution of iodoform in chloroform, Bordier and Gallimard in 1906 proposed adding an alcoholic solution of potash to the iodoform solution to avoid this. They prepared ampoules with 1 cubic centimeter of such a solution mixed with an alcoholic potash solution. As a unit of dose, they proposed the quantity of X-rays which, falling perpendicularly on 1 cubic centimeter of the solution, liberates 0.1 mg of iodine; they designated this unit as "J". They judged the amount of liberated iodine by the degree of coloration of the solution, which was compared with a scale having 12 different shades. 1 "J" is approximately equal to 1.5 Holzknecht units. The shortcomings of this radiometer lie in the fact that it is more sensitive to hard rays (due to the high atomic number of iodine), then the amount of liberated iodine depends on the amount of water in the solution, and finally, the liberation of iodine continues even after the cessation of illumination. At present, the Bordier radiometer is no longer used. The Bordier chromoradiometer is a variant of photochemical dosimeters in X-ray therapy. It represents a modification of the Sabouraud and Noire radiometer and makes it possible to measure not only the erythema dose but also a larger one. It consists of a scale representing 5 cardboard strips (with various shades from light green to dark brown) in which small squares are cut out, corresponding to a definite dose from 0 to IV according to Bordier (1 Bordier = 1 Sabouraud). One of the reactive plates attached to this chromoradiometer is placed on the illuminated surface and, after illumination, is inserted into the cut-out openings of the scale; the matching shade of the scale indicates the magnitude of the dose. This chromoradiometer is currently used in practical work, mainly in France, and has the disadvantage of being more sensitive to hard rays, and therefore its readings can only be evaluated by taking into account the quality of the rays.

M. Manikov.