Eberhart's Manual of High Frequency Currents
Noble M. Eberhart, M.D., Ph.D., D.C.L., 1911
Chapter Ten
High Frequency X-ray; Its Nature; Generation and Therapeutic Indications.
Explanatory. This is intended as an elementary chapter on the X-ray for the possessor of a small or portable high frequency outfit who wishes at times also to avail himself of its X-ray possibilities.Scope of Portable Outfits. Portable outfits are constructed on the Tesla type, and it is surprising how well some of them light up the X-ray tube. They are suitable for the treatment of skin diseases and all superficial lesions. This includes practically all of the conditions in which the X-ray is really effective. For radiographic purposes the manufacturers only claim them to be capable of skiagraphing the extremities, although some of them make satisfactory pictures of thicker parts. Their portability is at times of considerable advantage. They are not claimed to take the place of the larger equipment in the office of the radiologist, but bring the use of the X-ray and high frequency within the reach of many physicians who wish to employ it in connection with their regular work. They are not suited to the requirements of the X-ray specialist.
Nature of the X-ray. The X-ray was discovered by Roentgen in 1895. It possesses the property of penetrating supposedly opaque bodies, but cannot be seen by our eyes, nor felt as it passes through the body. It is produced by means of a tube exhausted to a vacuum of one-millionth of an atmosphere.
The Tube. For high frequency coils a special X-ray tube is required. These are of various shapes, some monopolar and some bipolar. One form is shown in Fig. 62. The metal disk in the center is called the target or anti-cathode and at this point the X-ray is generated. According to the degree of vacuum existing in the tube it is spoken of as high, medium, or low. The higher the tube the greater penetration its rays possess.
Adjusting the Tube. There are gauges for measuring the penetration of the tube.
To accomplish results in X-ray treatment the rays must be stopped and absorbed by the area including the lesion treated. For this reason the higher the vacuum and therefore the greater the penetration of the rays the farther away the tube must be placed from the part treated.
The average distance for a low tube is from 4 to 8 inches; medium tube, 8 to 12 inches; high tube, 12 to 20 or more inches.
Protecting Patient and Operator. As an overdose of the X-ray is injurious, it is necessary to guard against indiscriminate exposure of the patient and also of the operator.
Fig. 60 - Large Office Ozone Generator.
The simplest method is the use of a protective shield to encircle the tube, permitting the exit of the rays only through a small aperture that may be regulated as required.
In addition the use of leadfoil or sheet lead to cover all parts which are to be protected from the ray is customary.
The Fluoroscope. In order to see the findings of the X-ray a screen is employed containing barium platinum cyanide, a substance which shines or fluoresces when exposed to the X-ray. Interposing an object between this screen and the X-ray tube produces a shadow on the screen commensurate with the amount of the ray which has been prevented from reaching the screen. We have, therefore, a shadow picture showing the relative density of the object traversed by the X-ray.
The Skiagraph. The rays act upon the bromide of silver gelatin coating on photographic plates in the same manner as ordinary light. When a plate takes the relative position of the fluoroscopic screen the resultant picture is called a radiograph, or skiagraph, and affords a permanent record of the condition shown.
The X-ray plates have a heavier coating than ordinary photographic plates and are enclosed in two envelopes so that they may be handled in daylight. The flaps on the envelopes are on the nonsensitive side of the plate. The plate is placed on the table, the part to be skiagraphed resting on the plate and the tube some distance above, the target being directly over the center or the part radiographed.
Fig. 61 - High Frequency Coil Giving All Modalities.
As the rays diverge from th point on the target where they are produced, the image on the plate is always enlarged. The nearer the part is to the tube the greater the magnification.
Fig. 62 - High Frequency X-ray Tube.
Fig. 63 -Proper Position of Tube. Plate and Hand for a Skiagraph.
In order to obtain a picture without distortion of the image the following rule must be kept in mind: An imaginary line from the point on the target where the ray is generated to the center of the plate, must be perpendicular to the plate and pass through the center of the part skiagraphed.
Fig. 63 show the proper relationship of the tube, plate and hand for a skiagraph of the latter.
The length of exposure is from a few seconds to several minutes, according to the apparatus employed and the density of the parts. A few experimental pictures will enable the physician to determine the approximate time for his individual outfit.
The method for developing is the same as for ordinary photographic plates, but takes much longer, averaging about ten to twenty minutes.
Dental Films. For skiagraphs of teeth, a film is used. Two small films wrapped in two opaque paper coverings is the way they are supplied to the doctor. The film is held inside the mouth, back of he teeth, the smooth side of the paper toward the tube. Head is adjusted so that the line from target to film is in accordance with the rule given above. With small machines it will be necessary to experiment to get the time of exposure. It will average 30 to 60 seconds. The films are developed, washed and dried; the one retained by the radiographer, the other by the patient.
Diseases Grouped According to Technique. In treating with the X-ray the average number of treatments is three per week. The length of exposure during the first two weeks should not be over five minutes each time to guard against possible idiosyncrasy to the ray.
Fig. 64 - Portable X-Ray and High Frequency Coil.
After two weeks the treatment may be lengthened to seven, or, in some cases, ten minutes, and continued until improvement takes place or the characteristic reaction appears.
In the former instance, the frequency of the treatment is gradually decreased; in the latter it is suspended entirely for a few treatments until the signs of dermatitis have subsided, when it is resumed as before, providing the evidences of disease have not disappeared with the reaction.
With a low tube the tube-wall is from five to eight inches from the surface treated; medium tube eight to twelve inches; high tube twelve to twenty inches.
A number of diseases suitable for X-ray treatment are given herewith, grouped according to the vacuum of tube best suited to their treatment. The lower the tube the quicker the reaction produced. Some diseases are included under two headings., where it is a matter of choice, either method yielding results.
Low Tube.
Acne, eczema, epithelioma, lupus, rodent ulcer.
Medium Tube.
Acne, blastomycosis, cancer (superficial), favus, goitre, hyperidrosis, keloid, nevus, pruritus, psoriasis, sarcoma, sycosis, trachoma, tuberculous glands, neuralgia.
High Tube.
Alopecia areata, cancer (deep seated), leukemia.
X-ray Burns. An X-ray burn or dermatitis is the result of an overdose of the ray. The earlier symptoms are itching, redness and pigmentation. By keeping these in mind it will be possible to avoid severe burns.
Fig. 64a - A Method of Applying Diathermy to the Chest.
Mild burns should be let alone and they will subside of their own accord. In severe forms the condition is an X-ray gangrene or necrosis and calls for surgical measures.
