Lewis L. Haas

Changes in the Central Nervous System Following Irradiation with 23-mev X-Rays from the Betatron

During the past three years, studies have been in progress to determine and analyze the effects of x-rays on the normal brain of the monkey and on tumors of the central nervous system of man. Although these studies have been carried out primarily with 23-mev x-rays, produced by the University of Illinois betatron, additional comparative studies utilizing 200 and 400 kv. x-rays have also been undertaken. Our findings, to date, would indicate that the brain of both monkey and man is more radioresponsive than previously supposed, and that the pathological changes produced by these radiations are due to a direct effect upon the neural elements. These observations are definitely contradictory to the observations made by previous investigators (1–5) who have irradiated the central nervous system of a variety of animal species, including man (6). In general, these authors have concluded (a) that the central nervous system is highly radioresistant, in that it requires many thousands of roentgens to produce any re...

Modification of the Depth Dose Curves of Various Radiations by Interposed Bone

Physical depth dose measurements were performed in presence of interposed bone at various energies. The obtained empirical data show the resulting modifications of the standard depth dose curves by intervening bone. The data are arranged in four groups of radiations, according to the basic differences in the type of modifications: (1) 50 to 100 kVp, (2) 140 to 400 kVp X rays, (3) 22·5 MeV betatron X rays, and (4) 13 to 18 MeV electron beams. The data are reported mainly for practical, clinical use, and they may help the radiologist physician in calculating the depth dose behind bony layers in his specific physical and anatomical situations. Physical explanations, comparison with theoretical calculations and with data published by others were at this time omitted.

Betatron cancer therapy.

In the last few years we have all witnessed with varying degrees of interest a tremendous increase in the upper limits of supravoltage energies for possible therapeutic application. A variety of radiations have become available, some in adequate quantity for the first time. We have been using a 24,000,000-volt betatron which yields a very powerful beam of x-rays and a less well developed external beam of electrons (3, 6). Most of our work in the last year and a half has been with the x-ray beam, although at present we are diverting some of our attention to engineering problems and animal tissue effects of the electron beam. The betatron x-ray beam offers some very appealing distribution advantages in tissue (4). In Figure 1 is shown the distribution of density in a film phantom with a 200-kv. beam path and with the 24,000,000-volt betatron x-ray beam path. In the latter the sparing effect on the superficial tissues at the site of entrance of the beam (on the left in the illustration), the concentration of...

The Posterior Condylar Fossa, Foramen and Canal, and the Jugular Foramen

Variations of the posterior condylar fossa and jugular foramen are not adequately known in roentgen practice and are frequently the source of diagnostic difficulties and misinterpretations. Misinterpretation of posterior condylar fossa variations has occasionally even led to surgical intervention for a presumed jugular glomus tumor. It seems desirable, therefore, to analyze the roentgen anatomy of these structures. The condylar fossae are situated at either side of the foramen magnum behind the occipital condyles (Fig. 1, A) and accommodate the superior posterior part of the lateral mass of the atlas when the head is bent backward (see Cunningham or other anatomical text). The posterior condylar canal opens through a foramen into the fossa (Fig. 1, B), transmitting an emissary vein from the suboccipital venous plexus to the sigmoid sinus, or at times to the jugular bulb. Fossa, canal, and foramen are all inconstant formations. The fossa is best visualized radiologically on the occipital oblique and poster...

Preliminary Clinical Experience with the Betatron

The betatron is primarily a physics research tool and industrial x-ray machine. We are exploring its medical possibilities and realize that it will be a long-term project. The present report high-lights some of our progress, some of the obstacles encountered, and some of the early biological effects we have observed. As its name implies, the betatron is an agency for producing high-energy electrons, i.e., beta particles. The desirability of great acceleration of electrons and the limitations of ordinary transformers for this purpose were recognized many years ago. As far back as 1922 the general idea of speeding electrons in a magnetic field was recognized as feasible. Since that time many university and industrial groups have tackled the problem, and in 1940 Kerst (1) succeeded in accelerating and guiding electrons into a useful beam of x-rays. At present we are converting these high-speed electrons into extremely powerful x-rays but, as Uhlmann and Skaggs (2) have shown, electrons can be brought out as ...

Neck roentgenograms in the diagnosis of esophageal carcinoma.

Esophageal carcinoma is usually diagnosed radiographically by analysis of the intraluminal defects as shown in the barium-filled esophagus. The direct roentgen signs which are so frequently visible on the plain film are often neglected, though they may significantly alter the therapeutic indications and prognosis, and may aid in determining progression or regression of the disease. The direct roentgen signs differ with the various segments of the esophagus. For lesions of the cervical and upper thoracic esophagus, sagittal and lateral neck roentgenograms are a valuable diagnostic aid (a) when intramural or extra-esophageal tumor extension exceeds the intraluminal changes as visualized in the barium-filled esophagus; (b) when there is inadequate barium filling of the esophagus, either for technical reasons or because of severe dysphagia or vomiting, and when, because of stenosis, the entire length of the lesion cannot be outlined; (c) when the barium meal is contraindicated by danger of hemorrhage or perfo...

Tumor outline of esophageal carcinoma.

The roentgen diagnosis of carcinoma of the esophagus is usually based upon the alterations seen in the barium-filled lumen, such as filling defects produced by the fungating tumor, excavations due to necrotic ulcers, obstruction, suprastenotic dilatation, perforation, and indentations by para-esophageal lymph node metastases. The extension of the tumor is usually determined from the length of the lesion as indicated by the filling defect, and this is the basis for surgical indications and statistics. This procedure is unsatisfactory, since it fails to outline the tumor in its lateral extent and therefore does not satisfy the general principles of tumor localization, for which all the dimensions of the lesion should be determined: length, width, and depth. The intramural and/or extra-esophageal extension may significantly affect therapeutic indications and prognosis. Also, the added knowledge of lateral or depth extension may influence radiation technic and selection of fields. For these reasons it would b...

A more rapid method of isodose analysis.

The dose in the center of a tumor is commonly denoted as tumor dose. Less frequently doses at one or more peripheral points of the tumor are also determined, e.g., the points A and B in cervix cases. In general, a complete isodose analysis of the whole irradiated body part is not performed. Such an analysis is limited to theoretical and scientific problems, and as Chamberlain advocates, to difficult and unusual cases (see Radiology 55: 67–68, 1950). The procedure is admittedly time-consuming. Chamberlain has estimated the required time in individual cases as about eight hours. This is in dose agreement with our experience on betatron cases, in which frequently 6 to 8, and sometimes 9 fields have been used, the time required being about seven hours. The medical application of the betatron and of other high-energy sources has produced entirely new problems in treatment planning, since the physical dose distribution is quite different, and the exit dose is relatively large. The field selection, therefore, di...