X-ray photographic method for determination of stable iodine in tissues

A new x-ray photographic technique for imaging of small concentrations of iodine in tissues is presented. The method is based on the use of two x-ray beams of slightly different energies, which are obtained from the same primary source by appropriate use of critical absorbers. The beam energies are chosen so that the more energetic one is high enough to excite K x rays of the element under study while the less energetic beam is just below the required excitation energy. Two x-ray pictures are taken using the beams consecutively; thereafter, a difference picture is made by subtracting photographically the lower energy beam picture from that of higher energy. The difference picture then displays the distribution of the element to be imaged. This method is sensitive to iodine concentrations less than 100 microgram/mm2.