The determination of the point of time in processing archived X-ray films

The point of time, in which archived X-ray films were processed, can be proved with the determination of the remaining content of thiosulphate.The methylene blue method of DIN 19069 (equivalent to ISO 18917) was adapted to X-ray films.The range of time is in about two and a half year,in which the remaining content of thiosulphate is correlatable to the point of time in processing. This range of time covers the range, in which "radiological bodies" control the results of constancy testing. This method brings the "radiological bodies" in a better position to decide wether the recommended time of processing is true or not, when test images according DIN 6868-3 and/or the sensitometric step wedges according DIN 6868-2 are checked.