ROENTGEN RAYS AGAINST CANCER—TRUMP 
generator which has been designed 
since the war in Dr. Van de Graaff’s 
laboratory is being reproduced in 
several of the world’s principal nuclear 
research laboratories, among them 
Cockcroft’s National Nuclear Labora- 
tory at Harwell, England, Joliot’s 
laboratory in the College de France in 
Paris, and the National Research 
Council’s Chalk River Laboratory in 
Canada. Several dozen electrostatic 
accelerators scattered about the world, 
notably including those designed by 
Prof. R. G. Herb at the University of 
Wisconsin, have been used in research 
which has made important contribu- 
tions to the knowledge of nuclear 
processes. 
Back in 1934 the realization that 
electrostatically generated voltages 
could also be used in the production 
of unusually penetrating X-rays for 
deep therapy led to the opportunity to 
build the 1-million volt air-insulated 
generator for the Huntington Memo- 
rial Hospital. This machine and its 
building were financed by the Godfrey 
M. Hyams Trust, a Boston philan- 
thropy which has continued loyally to 
support the high-voltage medical work 
at M. 1. FT: On March 1, 1937, the 
first patient was treated at the Hunt- 
ington, and during the subsequent 4% 
years well over 1,000 patients were 
given complete treatment series. This 
pioneering effort in radiology disclosed 
at an early date the great benefits that 
could be derived in avoiding skin 
damage and increasing the depth dose 
by use of roentgen rays produced by 
several times the standard voltage. 
In 1939 development of a compact 1,- 
million-volt gas-insulated X-ray source 
was undertaken for the Massachusetts 
General Hospital. This generator was 
placed in use in April 1940, and has 
since been in continuous clinical use. 
Between 15 and 25 patients are treated 
daily with the equipment developed 
and built at M. I. T., and the voltages 
now generally used with this apparatus 
lie in the range between 1% and 1% 
million volts. This work has further 
confirmed the desirability of super- 
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voltages in the treatment of certain 
types of malignancies and has empha- 
sized the need to investigate the effi- 
cacy of roentgen rays produced at still 
higher energy levels. The electrical 
engineering group at M. I. T. extended 
its efforts to the development of a 
higher-voltage X-ray source for Phila- 
delphia’s American Oncologic Hos- 
pital. The first generator for Onco- 
logic, completed during the war, was 
requisitioned by the United States 
Army for nuclear research at Chicago. 
Its successor, a tiltable 2-million-volt 
unit now nearly ready for delivery, is 
the most compact supervoltage X-ray 
source yet seen. Meanwhile, the 
supervoltage X-ray generator at Tech- 
nology has made possible the extension 
of pioneering clinical researches to 3 
million volts and is now being modified 
to bring the voltage to 5 million volts. 
Present Therapy Spectrum 
At no time in medical history have 
sO many types of ionizing radiation 
been available for therapy and re- 
search. Artificially radioactive sub- 
stances produced within the nuclear 
pile or by the cyclotron, roentgen rays 
produced by betatrons with energies 
up to 100 million volts, high-energy 
cathode rays, and _ well-collimated 
beams of neutrons and protons are all 
under investigation or proposed for 
use on the deep-tumor problem. 
Artificially radioactive substances are 
of unique and fundamental impor- 
tance as tracers in biological and clini- 
cal research, but only a few materials 
such as radio-iodine and radio-phos- 
phorus have thus far found limited 
therapeutic use. Roentgen rays with 
energies much higher than a few 
million volts may actually become less 
desirable for therapy because of the 
increasing narrowness of the radiation 
beam at the very high energies and 
the seriously high exit dose which once 
again produces skin damage. High- 
energy cathode rays, which behave 
like bullets in the sense that they pro- 
duce no damage in the body beyond 
their maximum range, are still too new 
