The cumulative effect of the X-ray is re markable. A certain number of minutes ex posure has the same effect whether applied at one time or in divided doses extending over two or three weeks. This is what makes it so dangerous to the operator if he is frequently exposed to the X-ray. Even though each ex posure for a picture or treatment may be bene ficial to the successive patients and although from the operator's being at a greater distance, he is exposed each time to a much smaller dose than any of the patients, the cumulative effect upon him is disastrous. Many X-ray operators have died from cancer originating from this cause. The only safety for the operator lies in being shielded from the rays by a brick wall or very heavy lead. An operator is very foolish In think that he is going to use the X-ray so seldom that he does not need to be shielded from it. If he does good work he will soon find that he has benefited many patients at the expense of irreparable injury to himself. The semis] of incubation is another interesting nature of the X-ray effect upon the human hody. In treating skin cancers, a reaction is produced somewhat similar to a slight sun burn and this does not appear at the time of the exposure but all the way from four to 20 days afterward.
The dosage of the X-ray necessarily implies the appropriate quality as represented for in stance, on the Benoist scale of penetration and also the appropriate quantity of X-rays meas ured usually as applied at the surface of the body. One unit of quantity is the Holzknecht unit H and about SH is an erythema dose. Another unit is Tint B, Sahouraud, which is the same erythema dose. Another is Dien kick's X unit and 10X is an erythema dose. The erythema dose is that amount of X-ray which will produce redness of the skin with out ulceration. It first became a standard of c in Sabouraud's treatment of ring worm of scalp. In that disease the germs are difficult to kill because they are adherent to the roots of the hairs deep down in the hair follicles. A single erythema dose causes the hairs to fall out carrying the germs with them. Of course an antiseptic lotion must be em ployed to prevent reinfection of other hairs from those which have fallen out. After a
single correct dose the disease is permanently cured and the hair all returns. Repeated doses of the X-ray are sometimes employed for the permanent removal of superfluous hair hut not all authorities recommend this use of the X-ray.
The X-ray has led to one of the most im r,ortant discoveries in modern medicine. It has shown that many diseases of the woe of rheumatism, arthritis, neuritis and myositis, also endocarditis, digestive troubles including ulcer of the stomach and many other symptoms and lesions of a varied character frequently have their origin in tooth infection. A blind ab scrag may exist for years at the apex of the root of a tooth and poison the system all that time. It may give no pain or swelling and its presence may be unknown to the patient or the dentist and still he the cause of painful or even fatal illness. Such infection is readily disclosed by an X-ray examination and easily cured by the dentist. The patient is fortunate if this is done while the systemic infection is slight and of a nature to certainly get well after the discovery and elimination of the den tal infection. Of course after the onset of a fatal illness is not the time to discover that it was caused by an infected tooth. There are almost always mild indications which suggest the desirability of an X-ray examination of the teeth in time to prevent the more serious effects of tooth infection. One of the effects of a great many mild exposures in the case of X-ray operators is sterility. This is an addi tional reason why the operator should be shielded. And one of the diseases in which X-ray exposures are curative is fibroid tumor of the uterus with hemorrhage as a serious symptom. The cases of this disease which are most successfully treated are those in which the X-ray exposures bring on an artificial menopause.
X-ray operators who are not shielded are liable to blood changes resembling anemia or lencarmia, but this effect is not so generally produced as the X-ray keratoses with a tend ency to change into cancer, and tho sterility.