Paul C. Aebersold

A Preliminary Report on the Use of Fast Neutrons in the Treatment of Malignant Disease1

THE production of fast neutrons in therapeutic intensities and the successful collimation of them into beams has made a new method of treatment of cancer available. It has not been used long enough to report on results. Many radiologists expressed a desire to know how they were being used. Hence, we agreed to make a preliminary report on the method. Neutrons are electrically neutral particles of matter, each having approximately the same weight as a proton (the nucleus of the hydrogen atom). Chadwick (1) discovered their existence in 1932. For the treatments here reported, they were produced by bombarding a target of beryllium with deuterons (nuclei of heavy hydrogen or deuterium) with energies of eight million volts. The deuterons were given their energies in the Lawrence cyclotron, The method of operating the cyclotron to produce neutrons, and some of the properties of neutrons were described by E. O. Lawrence (2) to the Radiological Society of North America in 1936. In brief, the cyclotron repeatedly a...

Comparative Effects of Neutrons and X-rays on Three Tumors Irradiated in vitro.

Summary and Conclusions 1. The comparative effect of X-rays and neutrons on the survival of 3 mouse tumors was studied. 2. Both X-ray and neutron irradiation in vitro resulted in delaying the appearance of the tumors—mammary carcinoma being the most affected. 3. Some cases of regressions in the growth of lymphoma were noted after neutron and X-ray irradiation. 4. When the doses at the 50% survival point were compared, the X-ray/neutron ratios of the 3 tumors, lymphoma, mammary carcinoma, and lymphosarcoma, were found to be 5.8, 6.1, and 7.5 respectively. These ratios do not seem to indicate a significant difference in the sensitivity of the tumors to the radiations, but do show that per unit of ionization neutrons are more biologically destructive than X-rays.

PRODUCTION AND AVAILABILITY OF RADIOISOTOPES

Radioisotopes as tracer atoms and as uniquely applicable sources of radiation have become important working tools of clinical investigation. Indeed, they have already been established as permanent tools, indispensable to many investigations. They provide a new and dynamic power of perception-an ultra-sensitive way of following certain atoms. Their application has led to the development of new and unique techniques for studying the metabolism of a wide variety of elements and biochemical compounds, diagnosing and treating disease and studying the behavior and role of pharmaceuticals and other medicinal agents. However, the greatest value of isotopes is expected to be derived from their contribution to the over-all advance of medical knowledge.

The Cyclotron: A Nuclear Transformer1

Although the cyclotron is popularly known as an “atom smasher,” it is in more scientific terms a “nuclear transformer,” for it deals not as much with the atoms themselves as with the ten thousand times smaller nuclei of the atoms, and instead of smashing them completely it transforms them into new forms. Atomic Structure To appreciate the action involved in “atom smashing,” or man-made transformations of nuclei, we need first to picture the atom as a whole and then to enlarge upon its tiny center, the nucleus. An atom may be conceived as being an infinitesimally small solar system, as shown schematically in Figure 1.2 While the diameter of the solar system is about one hundred thousand million times greater than the height of a man, that of an atom is only about one one hundred thousand millionth as large as a man. Or roughly, man is mid-way in the scale of size between the solar system and an atom. The atom is so small that in one cubic centimeter of air, which we consider as being quite tenuous, there a...

The U.S.A. research program on low-dose radiation processing of food

Tnw new U. S. Atomic Energy Commission research program on low-dose radiation aims at developing techniques for providing freshlike fish and fruits far from harvest areas. Relatively low doses of radiation will be used to inhibit the growth of microbes for days or weeks during the usual conditions of distribution and storage of perishable foods. Low-dose preservation, known also as radiation pasteurization, would in particular avoid the necessity for freezing perishable foods that are to be sold within a short time. The process, thus, is potentially highly advantageous in extending the marketing life of highly perishable products for shipment to remote areas. Consideration will also be given to the very low-dose uses such as control of sprout inhibition, disinfestation of grain and control of insects for quarantine purposes. The U.S. Atomic Energy Commissions program for low-dose radiation processing of food is complementary to the program of the U. S. Army Quartermaster Corps for radiation sterilization of food. In the Army program, foods are irradiated with high doses of radiation capable of completely destroying bacteria and permitting food preservation without refrigeration for months. The sterilization program is primarily designed to improve the logistics and acceptability of military rations, but ultimately may have civilian applications as well. It is expected that radiation processing of food will eventually find its place among the historic food preservation processes of drying, salting, canning, freezing and such contemporary developments as freeze drying. This latter process is in an accelerating phase of initial commercial success, despite previous doubts based on estimates of high unit cost and low quality. A particular product or process finds acceptance when there is unique application, through the competitive action of the market place. The USAEC low-dose radiation pasteurization program has the purpose of defining the relevant products and processes prior to this final market test.

Isotopes and Their Application to Peacetime Use of Atomic Energy

As chief of the Isotopes Division of the Atomic Energy Commissions operations at Oak Ridge, Dr. Aebersold is eminently qualified to speak about the substantial achievements in this important field of atomic energy development. This article is based on a speech delivered before the AAAS in Chicago, Dec. 29, 1947.

PROGRESS AGAINST CANCER WITH RADIOISOTOPES

The international availability of radioisotopes produced by nuclear reactors was first announced almost seven years ago at the Fourth meeting of this Congress. It was recognized that this international release would greatly benefit the study and treatment of cancer. Initially available only from the United States, these radioisotopes soon could be procured from Great Britain, Canada, France, and later from Norway. Presently they will be available from reactors in many nations, including Brazil. With modern air transportation, physicians anywhere in the world can be supplied with useful radioisotopes. It is appropriate therefore to evaluate the progress made against cancer with the use of radioisotopes and to look at their potentialities in the. future. The unique properties of radioisotopes fit them for an important role against cancer. Because of their effectiveness as tracer atoms and also as radiation sources, radioisotopes find widespread use in research, diagnosis and therapy (Tables 1-4). Over 47,000 shipments have been made within the United States to about 2,100 institutions, approximately 700 of which are medical. Over 40 per cent of the medical use is in the field of cancer. Over 2,700 shipments have been sent from the United States to 43 other countries, mostly for medical purposes. United States exports are now exceeded in number by those from Harwell in England; other nations, also, are exporting radioisotopes. These figures indicate the widespread acceptance of these relatively new tools. Because this work is so extensive, it is possible here to survey briefly only major or representative uses in the cancer field. To make a thorough critical survey of all the literature would be a formidable task. Moreover, the world literature on isotopes in cancer is so voluminous that it has been necessary to confine most of the present discussion to work performed in the United States. This is, however, presented only as representative of the great number of studies and applications in other countries. The use of radioisotopes as sources of a variety of radiations has diversified the field of radiotherapy which originated with the discovery of radium and x-rays. Of more importance, however, is the unique advantage of radioisotopes as sensitive and specific tracer atoms, which makes them powerful tools in the study of life processes. Their greatest long-term contribution may hence be in cancer research.

Isotopes for medicine.

This year marks two important anniversaries for radioactivity in the fields of biology and medicine: (1) the golden anniversary of the discovery of radium for use in radiation treatment and (2) the silver anniversary of the use of radioactive atoms for tracing stable atoms—that is, of the tracer atom technic. Fifty years ago radium was discovered by Pierre and Marie Curie in France. This led to the wide and valuable use of radioactivity for radiation treatment of certain diseases, particularly cancer. Twenty-five years ago Hevesy in Denmark first used radioactivity to trace the course and behavior of a stable element in a biologic system. This was the inception of the technic of tracing the atoms of stable elements by means of their radioactive counterparts—the radioactive isotopes of that element. The first tracer experiments were done with the naturally occurring radioactive isotopes and were limited to the tracing of the heavy