Film available on the market can be sensitized by special processing. We achieved further sensitization of high-sensitivity x-ray film by using a technique of simple auxiliary exposure. The photographic speed of the sensitizing film was 1.5 times greater than that of the original film. When the sensitizing film is combined with a super-high-sensitivity intensifying screen, the total relative speed reaches 2400, a value that up to now has never been realized in a radiographic system. Our sensitization technique is very useful for decreasing medical radiation doses. Moreover, using the increase in density obtained by sensitization, we estimated the number of latent sub-image specks, which is related to the sensitizing effect.
