The Doctor Consults the Physicist
Wisdom crieth without. . . . Length of days is in her right hand.
THE wonders which medical workers have already brought about in the diagnosis and treatment of disease give hope that a time may come when the physician will be able to analyze most illness as soon as it starts, and cure it before damage results. How soon this ‘golden age of healing’ arrives will depend greatly on how close is the collaboration between research workers in medicine and those who work in the sciences on which medicine depends. The physician has long relied on the chemist for curative drugs, and on the physicist for diagnostic instruments and healing rays. In the one field new materials and in the other new devices are being produced in increasing numbers, helping to make imminent new miracles of medicine.
The X-ray and the microscope have extended the vision of the medical observer until he can see through ten inches of living flesh or into a single tissue cell, yet similar but much more powerful tools still await development. Modern electrical devices enable him to listen to faint murmurings of the life processes, or to measure feeble currents arising from heart and brain and nerve, yet electrical body measurements are but little understood. Now newly discovered atomic rays are being brought to help him destroy malignant invaders of the human system, and there is every reason to believe that even more important curative rays await discovery.
Much of the aid which physics gives to medicine is of a deliberate sort: ‘Here is a job to be done,’ says medicine; ‘This is how to do it,’ says physics. But connections which are more striking can be traced between medical life-saving and some of the apparently impractical fundamental researches of the modern physicist. X-rays and radium, which have saved thousands of lives in the few years they have been available, are two early examples. To-day discoveries are being made which promise to be even more fruitful in their turn.
The X-ray was stumbled on by Roentgen, a physicist, who had no inkling that the outcome of his experiments would turn out to be so fruitful in relieving human suffering. Yet it would be incorrect to say that the X-ray became available to mankind as the result of an accident. As well say that the sportsman landing a giant tarpon off the coast of Florida made his catch by accident because he could not predict in advance exactly w hat sort of fish he would hook. Most great experimental discoveries are made in a similar way. The accident, if such it must be called, is a planned accident, which could never occur if the scientist did not place himself in position for the lightning of discovery to strike.
Cancer now causes about 135,000 deaths each year in the United States, but there is hope that eventually most of such deaths can be prevented. During 1934, 76 per cent of the cancer patients in the principal hospitals in England were treated by radiation from X-ray tubes and from radium. The ray treatment would be far more effective than it is if only unhealthy cells were affected; but to reach internal cancers the rays must first traverse normal tissue, in which they produce electron bullets that fly in all directions, and an undesirable number of healthy cells may thus be killed. Rays are wanted which will be more penetrating.
Even if radium could always be used effectively, there is not enough radium in the world to fill the present need. Not much more than two pounds — roughly $18,000,000 worth — is now available; and even this much radium, if gathered together and applied to one patient, would hardly be sufficient to treat some of the deep-seated malignancies which are found. Much comfort can therefore be derived from the knowledge that new super-giant X-ray tubes can be designed to produce rays that will outradiate radium.
For bombarding malignant growths, X-ray tubes are needed which will stand much higher voltages than do those used for X-ray picture taking. The higher the voltage on the tube, the more penetrating are the X-rays produced, within present practical limits. Cancers on the surface of the body can be treated with X-rays produced at 100,000 to 200,000 volts, but a malignancy which lies deeper may be better attacked by rays from tubes which operate on much higher voltages. The principal rays from radium are equivalent to those from an X-ray tube running on only two million volts. Since the immediate plans of the atom smashers call for tubes which will stand five to ten million volts — and they have already reached three million — medical investigators naturally have a weather eye cocked to watch their success.
Several large hospitals in the United States now possess X-ray tubes to which a million or more volts can be applied safely. Some of these great tubes are twice the height of a man, and each of them will furnish rays in quantity equivalent to those given out by more than two pounds of radium — $20,000,000 worth. Mere interest payments on the investment in so much radium would come to $100 for an hour’s treatment, yet the power to operate the most efficient of these giant X-ray outfits for an hour costs less than thirty cents.
A three-million-volt X-ray tube of the type which has been built for atom smashing can be applied readily to medical purposes. Since such a tube produces not only more rays but more useful rays than those of any obtainable amount of radium, deeper-lying tumors might be reached with its aid, and treatment times greatly shortened. Such an X-ray outfit would cost less than many a sportsman’s toy.
Millions of volts sound rather alarming to a patient, but danger from electric shock has been completely eliminated in these giant tubes. All dangerous and scientific-looking gadgets can be kept bottled up in a room into which no one need go while the apparatus is running. The X-rays can be sent through the bottom of the tube into a room below, where the patient reclines comfortably amid attractive surroundings during the short periods required for treatment.
Some doctors believe that high-speed electrons may turn out to be even more useful than X-rays or radium emanations in treating cancer. The faster an electron moves, within limits, the less does it affect tissue through which it passes, just as a fast bullet breaks a cleaner hole through a windowpane than does a slow one. High-speed electrons might then be expected to have less effect on the healthy tissue cells in the first part of their paths, and to do their destructive work mostly on the diseased cells at the end of their flight, like shells with fuses set to explode them in the enemy’s trenches. However, much higher voltages than have been available previously are necessary to generate electrons with sufficient speed to supplement X-rays for cancer treatment. Electron rays from a three-million-volt tube would be useful, but ten-million-volt electron rays are expected to be better. The atom-splitting physicists are now close to being able to provide these; and when they, the engineers, and the doctors can get into closer coöperation on the problem, unfortunate sufferers should have all the rays they need.
Radium is the best-known radioactive element, but the radium atom is only one of forty kinds of atoms found in nature which are unstable and which must eventually, at some unpredictable time, explode. Radium has had wide use in the treatment of malignancies, but unfortunately, as a result of the many cures associated with it, the word has come to have magical significance, and tonic remedies containing radium have had wide sale as nostrums, some of which are extremely dangerous.
Careful distinction should be made between the use of radium for cancer treatment, in which only the emitted rays are used, and the actual introduction of radium into the body. Ten cents’ worth of radium is enough to kill a man if it gets into his bones. Eating five dollars’ worth or breathing fifty cents’ worth of radium salts will accomplish this. As little as one ten-millionth of an ounce of radium deposited in the bones has been found to cause death within ten years.
Fortunately many of the so-called radioactive waters which are sold as medicine contain a negligible amount of radium and are harmless, though their value may be open to question. But there are some which do contain radium in relatively large quantities, and these are slow but deadly poison. A few unfortunates who have drunk ‘radium waters’ have found themselves apparently improving in health for a time, presumably as the result of a stimulating irritation of the blood-cell-producing centres. But shortly thereafter, when enough of the radium has become fixed in the body, a poisoning process of a particularly horrible kind may set in, for the radium atoms lodge in the bones and from this vantage place can bombard the cells of the body to death.
Radium is chemically like the calcium from which bones are made, and the unsuspecting blood stream willingly deposits radium atoms wherever calcium atoms are needed for building purposes. Soon the deception becomes apparent, however, for previously healthy bones, attacked from within, begin to fester and decay. Even after an atom of radium has exploded, the damage it can do is not complete, for it changes into an atom of radon, which can again explode, and over and over the same atom, like a sixball Roman candle, can shoot out its violently destructive rays. It is of no use to wait for all of the radium atoms which have been taken into the body to explode, for only half of them will have done so by the end of 1690 years. The only hope is to get some of them out, and this can be done more readily if it be attempted soon after they have been absorbed.
In a number of cases of radium poisoning it has been found possible literally to rinse some of the dangerous atoms out of the patient’s bones. First he is given a medical treatment which causes his bones to lose calcium, and as the calcium departs some of the radium, in keeping with its masquerade, is forced out with it. The patient is kept in bed, and before his bones are appreciably softened the treatment is reversed and the body is encouraged to take up fresh clean calcium to rebuild them. When the bones are sound again the first procedure can be repeated. This rinsing process can be carried out again and again until the patient improves.
The closest coöperation between physician and physicist is necessary for such treatment. The physicist is needed to make delicate measurements with sensitive detectors which tell, at every instant, just how much radium still remains in the various parts of the patient’s body, how much is being eliminated through his breath, and how much through his other eliminative processes. Such control of the treatment is made possible only by the sensitive instruments which have recently been developed for research on cosmic rays, on atom splitting, and on radioactivity. Measurements made with them cause no discomfort to the patient, as their extreme sensitivity makes possible measurements on the radium content of his body by means of a detector placed as much as a yard away.
To achieve such sensitivity all the resources of modern vacuum-tube amplifiers must be invoked, and to them must be added other tricks which have been developed to pick up the tiny burst of energy which is freed when a single atom explodes. A pebble from a slingshot can explode a percussion cap, which in turn can explode enough dynamite to blow up a mountain. So the energy of the exploding atom can be turned cunningly into channels that will produce an electrical result which is cataclysmic in comparison with the cause that touched it off. So sensitive have these instruments been made that they record a continuous rattat-tat when carried above an ordinary sidewalk, in the concrete of which not more than one atom in a thousand billion is radioactive. Small wonder they will detect the presence of less than one cent’s worth of radium in the human body.
While such instruments were developed primarily for studying atomic processes, their medical application is obvious. One can easily imagine the joy of a patient suffering from incipient radium poisoning when the instruments show
that as the result of a course of special treatments he is eliminating radium eight times as fast as previously, and that the amount of radium left in his body is gradually being lowered to a safe level.
The creation of new kinds of atoms is commonly supposed to have been quite thoroughly completed some years ago, whether in 4004 B.C. or long before PreCambrian days. As this is written, however, atoms of varieties never before found are being artificially produced in physical laboratories throughout the world at a rate almost too fast to follow. Youths whose cheeks are still downy, who but a few years ago were struggling through the bewilderments of the elementary physics textbooks, are discovering new building blocks of the universe. These discoveries will eventually produce profound effects on chemistry and medicine.
The physicist has succeeded in permanently changing one kind of material into another kind — true transmutation of the elements — by bombarding ordinary matter with atomic bullets. But, contrary to the dreams of the alchemists, the new atoms which result from a transmutation are at present of little interest except from an academic standpoint. Far more important are the new varieties of temporary atoms which have been found to be produced as an intermediate step. These atoms are mortal, manmade, not in nature’s plan.
Such temporary atoms duplicate the atoms of chemistry, but show surprising properties of instability. They may last but an hour, a day, or a month, and are like ghosts allowed to walk the earth but briefly, after which they must depart. They are much more real than ghosts while they last, however, for no chemist can distinguish them from their normal counterparts. Only deep within their hearts do they differ, and, when the hour for their departure strikes, the tiny atomic cataclysm which results can be read on sensitive detectors that record the minute explosion as surely as an earthquake recorder will mark the explosion of a ton of dynamite.
Since these tricky atoms are chemically indistinguishable from normal atoms of the same material, they can be used as atomic spies to follow the movements of swarms of normal atoms with which they can be mixed. The airplane machine-gunner finds advantage in having every tenth bullet a tracer which leaves a track of smoke behind it and so marks the path of all the bullets; in the same way the chemist and the biologist, to say nothing of workers in other sciences, should find tracer atoms effective. Mixing undetected with their fellow atoms, these behave normally until the hour of inevitable explosion arrives for each. Then, like an Oriental spy sworn to selfimmolation, each reveals its presence as it is destroyed and so betrays the location of its atomic comrades.
The explosion which marks the end of such a temporary atom results in certain cases in the ejection of an electron traveling as fast as four hundred million miles an hour — fast enough to encircle the earth while one snaps a finger. Such an electron is for all practical purposes identical with one produced in a millionvolt vacuum tube. Gamma rays, equivalent to the X-rays from a high-voltage tube, are also emitted by the exploding atom. Instead of its being necessary for a patient who is to be treated with Xrays or electrons to rest under a gigantic tube, ordinary table salt or other suitably chosen harmless material can be exposed for a few minutes to rays from such a tube, can thus be made artificially radioactive, and can then be applied to the proper spot on the patient. Exact dosage is made easy, for only as many radioactive atoms are produced in the salt as are needed, and if the material is left in place on the patient too long no harm results, most of the atoms having already exploded.
Another feature of the new radioactive atoms which has aroused medical interest is that suggested by the concentration of iodine by the thyroid gland. Some physicians who have worked on the problem believe that when iodine is fed to a patient practically all of it is concentrated in the thyroid gland within twenty-five minutes. Radioactive iodine atoms can be made by bombarding iodine with protons, the hearts of ordinary hydrogen atoms. If such activated iodine, mixed with ordinary iodine, be fed to a patient, the physician should be able to follow the course of all the iodine atoms through the patient’s system by counting the atomic explosions which will be registered on various detectors placed in suitable positions around him.
Now suppose that a particular patient has a malignant disease of the thyroid gland which needs radioactive treatment. The radio-iodine atoms emit rays which are quite as effective as those of radium, and the bombarding atoms should be carried in the blood directly to the spot where they are needed. Exactly the proper amount of radio-iodine, costing only a few cents to produce in one of the new atom-splitting machines, could then be given to the patient, so that when almost every atom has exploded, and has done its minute bit of cell blasting, the proper treatment would have been completed. As each radio-iodine atom disintegrates, it changes to xenon, an absolutely inert gas which is harmlessly carried off in the blood stream.
With electrons and protons, deuterons, and even heavier atomic particles available to be hurled against each of the more than four hundred varieties of atoms which the physicist has found included among the ninety elements of the chemist, dozens of new kinds of useful temporary atoms doubtless remain to be discovered. Already nearly two hundred new varieties of temporary atoms have been produced by physicists in the course of atomic transmutations, and it seems probable that every known element can be produced in one or two temporary radioactive forms. Some have already been created in four or five forms. As higher speeds for atomic bullets are achieved, increasing numbers of new super-chemical reactions should be found.
The world’s supply of radium and other naturally radioactive atoms is limited, but the supply of atoms which can be made radioactive is as unlimited as man’s capacity to build machines with which to produce such atoms. Better atomic artillery is rapidly being mobilized, and we can shortly expect greatly increased efficiency in producing curative materials of the radioactive type.
To-day in America a thousand times as many microscopes are in use as were available sixty years ago. Every past improvement in the microscope has resulted in further progress in the identification of the bacteria which are responsible for disease. Medicine would be greatly benefited by new microscopes which would give clear enlargements of more than four thousand diameters; ten thousand diameters would be very desirable; or better, while we are wishing, a hundred thousand.
The provision of such microscopes, if we ever get them, must lie with physics, for the difficulty is not with the presentday instruments so much as with light waves themselves. A wave of yellow light, though only one fifty-thousandth of an inch long, is yet too coarse to reveal much about a particle of matter smaller than itself, just as the daintiest finger is far too coarse to be used in lieu of a needle for playing a phonograph record. To feel the shape of an object satisfactorily with our eyes through the medium of light waves, these waves must be comparable in size with, or smaller than, the detail which is to be seen with their aid.
A partial solution is to sharpen up the seeing by using shorter light waves. These waves, being of the invisible ultraviolet variety, cannot pass through ordinary glass lenses. Invisibility makes little difference, for ultraviolet rays can still be photographed, and special kinds of glass have been devised which will transmit them. Ultraviolet microscopes giving magnifications as great as six thousand diameters have been constructed and are in fairly common use. But a microscope which is to operate with still shorter light waves must be placed in a vacuum or in an atmosphere of helium or hydrogen gas, because air and water are entirely opaque to these waves.
Light, in addition to being useful for seeing, has its own curative effects. Some physicians consider the sun the greatest of all healing agencies, but sunlight is not always available. Lamps have now been developed which can be made to radiate not only waves of every one of the visible and invisible colors which the sun sends us, but others as well which were never known before. Many of these new light rays are found to have definite germkilling or curative properties, while others have not yet been tested for possible biological effects.
The spectroscopes and light filters which the physicist has developed to study the structure of matter and the relationships of matter and energy have proved very useful in separating light into its component parts for medical use. When a beam of white light produces a curative or stimulating effect, there is always the possibility that only the blue or the red light contained in the white beam was responsible for the effect. When the basic colors have been separated and tried individually, sometimes one color has been found partially to offset effects produced by another, a greater effect being produced by a part of the light than by all of it.
Infrared rays, consisting of waves somewhat longer than those which we can see as visible light, penetrate the skin well and are absorbed in the underlying tissue, where they soothe cramped muscles and tired nerves. Their application increases the flow of blood and appears beneficial in neuralgic and arthritic conditions.
Production of vitamin D is closely linked to light, and it is no longer necessary to rely on the ability of the codfish to store in his liver the energy of sunlight which has been gathered up by the saltwater algæ on which have fed the small fish which he eats. By exposing specific food materials to light under controlled conditions, the vitamin can be concentrated more effectively than by any codfish.
The medical use of light has met with such popular response that many fads have developed, some of which have been carried to extremes. Indiscriminate exposure of large areas of the body to intense light may do much more harm than good. What is needed is more really scientific study of the effects of light of different colors, both visible and invisible, on human physiology and psychology. For the developments of the light-emitting, the light-analyzing, and the light-measuring devices still needed for this purpose, medicine looks to the physicist.
The whirling force which causes a youngster to cling so tightly to the neck of his wooden horse on a merry-goround, and the ticket taker of the carrousel to lean inward at such a precarious angle as he makes his rounds, comes effectively to the assistance of medicine in the separation of viruses too delicate to handle otherwise. Mud will settle from murky water merely on standing, but the same mud will take much longer to settle from a viscous substance like honey. Centrifugal forces much greater than the pull of gravity can be used to speed up the separation of the mud from the honey, merely by whirling the mixture in a circle. If whirled two thousand times in a second, each mud particle will feel a pull 300,000 times its own weight gently but compellingly urging it toward the outside of its container. Such a pull will quickly separate blood cells from the serum in which they float. A grain of wheat whirled at so giddy a rate behaves as though it weighed ten pounds. Small wonder that even a tiny clump of molecules finds such weighty considerations worthy of respect.
Small rotating tops have recently been developed which will spin a tiny vial of biological serum at speeds up to a million revolutions a minute. To attain such speeds, friction must be reduced to a minimum, and the top, as it spins, touches nothing solid, but is balanced in a whirling jet of air. The limitation which prevents attainment of still higher speeds is the difficulty of getting materials which will stand the great forces involved — the top itself tends to be torn apart by the terrific pull on its own substance. Yet, even at the highest practical speed, a flashing light has been arranged to make the whirling tube seem to stand still, and an observer, looking through a microscope, has calmly watched a cell being pulled apart while it whirled under his nose at more than three thousand miles an hour.
Mechanics, as exemplified in the centrifuge, is the oldest branch of physics, but what of electricity, one of the newest? The body probably has more electric currents flowing through it than has a telephone switchboard, but most of these currents are weak and difficult to measure, and the body is poorly equipped with terminal contacts. Variations in health and in the tone of various organs are undoubtedly reflected in changes of these currents, but as yet electrical methods of diagnosis have been but slightly developed. How tired a person feels, and his general state of health, seem to be tied up in some mysterious fashion with differences between the resistance of his body to the passage of an alternating current and its resistance to a direct current. Just why this relationship exists, and how it can be used, are as yet not apparent.
In the treatment of disease the position of electricity is more secure. The electric knife has caused great progress in surgery. High-frequency alternating current is sprayed into the tissue from the edge of the knife, and as the tissue is cut the edges of the wound are electrically disinfected and seared, a process which reduces bleeding and promotes healing. In brain operations the radio knife has been found especially useful, for with it electric current can be sent through tumors to shrivel and destroy them, and the dried tissue can be removed through small openings in the skull. In cancer operations this knife may give greater safety, for cancerous cells which might be set free for distribution through the body in the blood stream can be killed by the heat and current, and the ends of the blood vessels which might carry them off are seared shut. The radio knife operates by means of alternating current of very high frequency, and is a direct development of the investigations which made radio telegraphy possible.
Only in recent years have doctors come to realize that a fever may not be the result of an illness, but an attempt of the body to cure the illness. Many kinds of germs die at temperatures slightly above normal body temperatures. Doctors have even inoculated patients with malaria germs to produce intermittent fevers — the malaria was less disagreeable and easier to cure than the original disease. When it is found that a vacuum tube can produce just as good a fever as a malaria germ, with no malaria to be cured afterward, there is cause for rejoicing.
The heat generated by high-frequency currents first came markedly to attention when radio men who were working near high-power oscillating tubes developed temporary fevers. After all, if the insides of vacuum tubes could be heated white-hot by such means, why could not the insides of a patient thus be warmed to a lesser degree?
Listing the contributions of physics to the new medicine could be continued almost indefinitely. Tiny super-candid cameras which, with their own lights attached, can be swallowed by a patient and used to snap a number of views of the inside of his stomach before they are fished up again; electrical speedometers, invented specifically to measure cosmic rays, which immediately turn out useful for counting the rapid heartheats of a rat; electrical stethoscopes and brainwave measurers which give such an accurate measure of the state of vitality of a patient deep under the influence of drugs that mental cases hitherto considered incurable can safely be treated — hundreds of such examples can be brought forward to emphasize the great importance to mankind of close coöperation between physician and physicist.
Medicine is growing in effectiveness as it progresses from the status of an art to that of a science. Progress in a science depends to a great degree on the tools which it can forge to aid it in uncovering truth. For many years the chief tools of the physician were his own five senses, but human eyes have bounded vision, human hands have limited strength. With eyes that see where before was only darkness, with ears that hear revealing sound in the midst of former silence, the modern healer finds in no mere poetic sense that ‘ his strength is as the strength of ten.’ These more-than-human eyes and ears, this beneficent sharpening of the senses, it is the province of physics and the purpose of physicists to continue to supply.