TREATMENT (see RADIOLOGY RADIOTHERAPY). The X-rays are used extensively in medical treatment. They are valuable in many forms of skin disease, particularly those of a chronic character. They have a favourable influence upon en largements of the lymphatic glands, of the spleen and of the thyroid gland. They give useful palliative effects in certain forms of malignant disease, and some permanent cures of cancerous conditions have been obtained by their use. In rodent ulcer, which presents features allied to cancer, there is no doubt of the efficacy of X-ray treatment for bringing about a complete cure in the majority of cases, provided that the disease has not advanced too deeply into the tissues.
The idea of using X-rays in the treatment of disease arose from recognition of the injurious effects which followed pro longed application of the rays for diagnostic purposes. Many early workers with X-rays noted the production of an inflamma tion of the skin, or a falling out of the hair over parts which had been subjected to X-rays, and Leopold Freund, of Vienna, has stated that his first attempts to utilize X-rays in treatment were made in 1896 to cure a hairy mole and were prompted by what he had read of such occurrences. A definite action of the rays upon the skin having been observed, their employment in the treatment of skin diseases followed as a natural corollary. Amongst the earliest investigators of the possible therapeutic effects of X-rays the names of Schiff, Freund, Kienbock, Holtz knecht, Sjogren and Stenbeck may be mentioned. In Great Brit ain C. R. C. Lyster, Sir Malcolm Morris, E. Dore and J. H. Sequeira were amongst the earliest investigators.
by which the quality of the rays emitted by a tube at any moment could be determined, and in 1902 Holtzknecht brought out the first quantitative device, a chromo-radiometer, which enabled the dose administered to a patient to be observed, and recorded for future guidance. Holtzknecht also drew up a scale of units by means of which the indications of his apparatus could be inter preted. The units of Holtzknecht are still used to express the dosage of X-rays, though his apparatus has been superseded. Holtzknecht's method of measurement consisted in observing the change of colour in certain pastilles when exposed to X-rays, and his apparatus consisted of a scale of tints, and a number of pastilles of a yellow tint which acquired a green colour during exposure. The composition of these was kept a secret, but analy sis revealed in them the presence of potassium sulphate combined with celluloid or gelatine. The pastilles were laid upon the sur face under treatment, and their change of colour was compared at intervals with the scale of standard tints.