Since the discovery of the x-ray in 1895, it has become one of the greatest aids of the medical profession. Its greatest use is for diagnostic purposes, but it may also be used for treatment. Diagnostic x-ray is a great adjunct to other diagnostic procedures and often provides the only test necessary to confirm or rule out a certain suspected disease. Your surgeon may order x-ray procedures in your case. If so, you will want to know a little about them. Many physicians have x-ray equipment in their offices, but for the major procedures you will be referred to the x-ray department of the hospital or the radiologist’s office.
The production and use of the x-ray in the medical profession is called radiology or roentgenology (after Wilhelm Roentgen, who discovered it). Films exposed by use of x-rays are called radiographs or roentgenographs, or more commonly are referred to as “x-ray pictures,” or “x-rays,” although this latter term should be reserved for the ray itself. The specialist who deals exclusively with radiology is called a radiologist or roentgenologist.
The x-ray is a penetrating, invisible ray or beam emitted from an x-ray machine, or emitted from a radioactive metal, such as radium. The ray is the same from either. The mechanism of the x-ray machine in producing the ray is quite complicated and not relevant here to understanding its uses. Suffice it to say that the modem x-ray machine is a delicate instrument which emits the x-ray in such a precise and well-con- trolled manner that the specific required amount on the exact area of the body for each procedure can be produced without fear of destruction of tissue. The x-ray machine is used for both diagnostic and therapeutic procedures, while the use of radium is limited to specific therapeutic procedures.
An x-ray picture of any area of the body is produced by directing the x-ray at that part of the body with a photographic film on the opposite side of the part. Since ordinary light will also expose the film, it is encased in darkness. The rays pass through the body and the encasement to rccord the images of the parts on the photographic plate. The film is then removed from its casing in darkness and developed just as any other photographic film.
The radiograph so produced is actually a record of the densities of the parts of the body photographed. The x-ray penetrates the body parts inversely proportional to their density; that is, it passes with ease through the soft tissues parts, but is almost totally blocked by the hard, dense, bony parts. The area on the film where there were no interposed body parts will be very dark, as it was totally exposed. On the other hand, the area of film underlying a bone will be very light, as little x-ray could penetrate the dense structure. The radiograph is essentially, then, a study in black and white of an area of the body, the blackest parts representing the least dense structures and the whitest parts representing the most dense structures. On any one x-ray film there can be seen all degrees of densities, and many body structures can be visualized completely by simple radiographs.
There are numerous variations in techniques and various devices employed to modify each x-ray picture, depending on the tissue or the organ to be studied. Many advances have been made in recent years in radiological techniques and equipment which make clearer images on the x-ray plates and make it possible to study almost any organ. Most of these are by special devices on the x-ray equipment and improvements and variations in techniques.
Since x-ray films show the parts in one plane only, often several views of the same area taken at different angles are necessary to ascertain the complete anatomical condition. Another means of studying the parts in their dimensions is by the use of stereoscopic techniques. This method entails taking two exposures simultaneously at slightly different angles and then placing the films in a special optical device whereby they are viewed by the interpreter with the images superimposed on one another; this gives the effect of seeing the parts in three dimension, and exact anatomical relationship can be determined. There are many other special techniques and devices used to make certain studies more complete.
Fluoroscopy is visualization of internal structures of the body by passing x-rays through the body and observing the shadow on a fluorescent screen. The part of the patient’s body to be fluoroscoped is placed against the fluorescent screen and the x-ray source is directed toward the body. The rays pass through the body and outline the images on the screen. The observer stands behind the screen and can see the images so cast through the screen. Fluoroscopy must be done in a dark room. This, again, is a matter of the densities of the various parts. The more dense structures will not allow as much x-ray to pass through, and therefore these shadows will not fluoresce on the screen as much as in other areas where the tissues are less dense and allow more x-ray to penetrate. Fluoroscopy gives no permanent record for future study as does the radiograph, nor are the images quite so distinct, but fluoroscopy is useful to study the movements of parts, which cannot be done by radiographs. Often the combination of x-ray pictures and fluoroscopic study gives the complete story of an organ’s anatomy and function. Interpretation of both the radiographs and the fluoroscopy requires training and experience. These procedures are done only by a physician.
One of the chief uses of x-ray procedures is for the study of bones. X-ray pictures are taken at several angles to determine the relationship of the fragments in broken bones and their relationship to the adjacent tissue. Radiographs are taken before and after reduction of fractures and during their course of treatment to determine the extent of healing at various stages. Fluoroscopy may be employed during the operation of reducing a broken bone to see that it is aligned correctly. Besides fractures, all other lesions of bones may be diagnosed as well, such as bone tumors, infections, dislocations, and other deformities. Bones ranging in size from the very small bones of the face and at the base of the skull to the very large bones of the pelvis may be studied in detail by use of the x-ray.
X-ray plates of the chest are a most important tool in the diagnosis of diseases of the lungs and heart and allied structures. Since the lungs are filled with air, they are of little density and x-ray penetrates well; the rib cage about the lungs is of greater density and less x-ray passes through to the film. This leaves the lungs well outlined on the x-ray film, and these homogeneous lung fields may be studied in detail. Any abnormal opacity in the lung areas can be correlated with the physical examination findings and the symptoms to make an accurate diagnosis. Typical opaque shadows are found for each disease of the lungs.
The heart is more dense than the lungs, so its silhouette is well outlined against the surrounding lung tissues. The exact shape of the heart can be seen, to determine whether any one chamber is dilated or enlarged; the exact position of the heart in the chest is visible, and by measurements with special corrections for distortion, the exact heart size can be calculated.
The trachea (windpipe) can be seen on chest films from the neck down to its branches into the lungs, since it contains a column of air which appears as a darker outline on the film. The great vessels leading off from the heart are demonstrated on chest films by the same manner the heart is silhouetted against the surrounding lungs. The actions of the heart, lungs, and diaphragm can be studied by fluoroscopic procedures, and this is often a necessary diagnostic step in diseases of these organs.
Radiographs of the abdomen are often a great adjunct to establishing a diagnosis. The stomach and the large bowel normally may contain air, which outlines the size, position, and shape of these structures by the dark air shadow. In diseases such as intestinal obstruction the small bowel may also contain air demonstrable on x-ray films. The kidney and occasionally the spleen shadows may be seen on the abdominal film.
In cases of pregnancy, the fetus (unborn baby) inside the enlarging uterus (womb) may be studied. The position of the fetus is often important just prior to delivery, and the size of the fetus in relation to the size of the mother’s pelvic passageway can be determined accurately by measurements on the film with corrections for distortions. The methods for determining this are very specific and several views are required. In some cases it is necessary to know the exact site of the placenta (afterbirth), and this can usually be determined by simple radiographs taken at varied angles.
Another important use of x-ray is for the localization of foreign bodies within any area of the body. Naturally, if the foreign body is of the same density as the tissue in which it is imbedded, radiographs will not show it, but in cases where the foreign matter is more or less dense than its surrounding structures, radiographs will be of great import. By taking x-ray pictures at different angles the exact location may be determined, whether it be a bullet lodged in an extremity, an article swallowed by a child, or whatever the case.
The use of various contrast media aids in the radiological study of certain organs and conditions. These substances which are opaque to x-ray actually block the x-rays from passing through. By filling a cavity with such material, the exact outline of the cavity is silhouetted on the x-ray film or fluoroscopic screen. This is one of the greatest diagnostic means in modern medicine, and several different liquids may be employed. Barium is the one most often used for the study of the gastrointestinal tract. The barium enema, or lower G.I. series, is an extremely valuable procedure for diagnosing conditions of the rectum and large bowel (colon). The patient is prepared with an ordinary enema so that his colon is empty. Then the barium solution is introduced by rectal tube. The fluoroscopic observations are made and x-ray films exposed. The barium enema is then expelled and further observations and radiographs may be made. This procedure outlines the rectum and the large bowel in their entirety and may even fill the lower part of the small intestine and the apptndix so that they too may be visualized as well.
The upper G.I. series is for the study of the esophagus, stomach, and small intestine. The patient must be prepared for the procedure. Since fluoroscopy is necessary to ascertain the function of the organs by watching the barium contents move along the G.I. tract, the procedure is done in a dark room. The patient is placed behind the fluoroscopic screen with the examiner in front of the screen. A glass of the barium is held by the patient, and he is told when to take a swallow of it. The examiner watches the course of the barium down the esophagus and into the stomach. Multiple short observations are made so as not to expose the patient to excess x-radiation. From time to time x-ray photographs are made for permanent record and later study of the patterns so produced. The examiner may press on and gently manipulate the patient’s abdomen frequently. After the study of the esophagus and initial studies of the stomach are made, an interval of time is allowed for the contents to move farther along the digestive tract. Then further observations are made, either by radiographs alone or in combination with fluoroscopy. Frequent further studies are made as the barium moves farther down the intestine. Often studies up to 8 hours or longer are made. Fluoroscopy and radiographs are both of import in upper and lower G.I. studies.
Both anatomy and function are ascertained by the G.I. series. The entire system is outlined and any changes in shape, position, caliber, and motility of the esophagus, stomach, and intestines may be noted. Ulcers of the digestive system are often found by this diagnostic method, as well as many other conditions.
If a G.I. series is planned for you, try to realize how valuable it may be. Preparation is extremely important to successful results. You will be given simple written instructions about your preparation. These will include an enema, minor dietary restrictions, and probably a cathartic. Follow your instructions specifically.
Contrast media are also used in other body cavities. Myelography (spinal canal outlining) is the introduction of a radiopaque substance into the spinal canal by lumbar puncture (see Fig. 3) and studying the chamber so outlined by fluoroscopy and radiographs. The urinary bladder is frequently examined by introducing a contrast medium into the bladder via catheter and analyzing the image exposed on an x-ray film. This is called a cystogram (bladder outline). The kidneys are likewise commonly studied by inserting catheters through the bladder up the ureters (tube from kidney to bladder) to the kidneys. An opaque material is then injected through these, and an x-ray plate outlines the system. This is called a retrograde pyelo- gram (reverse kidney outline). Other organs that may be studied by direct introduction of a contrast medium are the bronchial tube (bronchogram), arteries (arteriogram), veins (venogram), joints (arthrogram), and tubes (salpingogram). Almost any body cavity may be studied by this method. Abnormal openings are also often filled with an opaque medium to outline on an x-ray plate their extent and communications.
In some cases air will serve as an excellent contrast medium. A pneumoencephalogram (air-brain outline) is the replacement of spinal fluid with air to demonstrate the various brain cavities (ventricles) by x-ray studies.
Certain other substances are employed for examination of internal organs. A gallbladder series can determine the anatomy and function of this organ. It is performed by giving the patient a specific dye substance which is absorbed and deposited into the bile. After a few hours the gallbladder becomes visible on an x-ray plate, for the substance is opaque to x-ray and is localized in the bile which is held by the gallbladder. The shape, size, and position of the bladder can be seen on the film. If gallstones are present within the organ, they are silhouetted within the gallbladder shadow. If the gallbladder does not properly fill with the opaque dye, function of the organ is known to be impaired. Function of the filled organ is tested by giving a “fatty meal” which stimulates the gallbladder to empty its bile. If it does not empty properly, malfunction exists. A film study of the gallbladder so produced is called a cholecystogram (gallbladder outline). Several exposures are made.
Another specific material can be used to study the kidneys. This material when injected (usually in the vein) is excreted by the kidneys. It is opaque to x-ray, so as it collects in the kidneys and bladder the outline can be seen on a radiograph. Exposures are made at intervals a few minutes apart so that the excretory process can be analyzed. Any disturbance in function is elicited, as well as any anatomical abnormality. This is called an intravenous pyelogram (in- vein-kidney outline). Rarely the liver and spleen are studied by a similar method.
All of these special x-ray studies require preparation of the patient. If your doctor orders any of these for you, you will be given a sheet of specific written instructions. Carrying out the instructions accurately is a most important part of the procedure. Do exactly as the instructions indicate, so that the studies will be complete and accurate in every detail.
When you are having an x-ray film taken, you must be very co-operative with the x-ray technician. He has many things to consider with each exposure. Positioning of the patient is extremely important. The specific study your doctor orders will determine the settings the technician uses. The exposure depends on the amperage and voltage used, the thickness of the part examined, the distance of the film from the x-ray source, and the time of the exposure. The technician must have all settings correct to obtain the proper results. Your co-operation with the technician will contribute to accurate results.
X-ray films are always interpreted by a physician. Your own doctor will examine your films, but this will be supplemented by a formal written report from the radiologist if the studies are made at the hospital. This becomes a part of your permanent record. Your doctor may deem it fitting to explain part of your case to you by use of your x-rays, but patients are not allowed to view their films by themselves. The interpretation of x-rays is very complicated. The patient is not qualified to analyze any part of them, and erroneous conclusions are detrimental. Your doctor will tell you the results of your films, and if he wants you to see them with him, he will arrange it. Do not be offended if you do not see your films. The chances are that the films would mean little to you. They are hospital property and are kept indefinitely.
With the early uses of x-rays, burns of the tissues were occasionally encountered. However, such burns are rare today because x-ray is better controlled. X-ray burns from diagnostic procedures are today unheard of. You have nothing to fear from any of the diagnostic fluoroscopic or radiographic procedures. Do not let old tales of deleterious effects deter you from the x-ray studies your doctor needs in your case.
The x-ray has been found also to have a certain ability to control the growth of human tissues. In this capacity it serves as a treatment agent and is termed therapeutic radiology. The source of x-ray may be from an x-ray machine so set and directed to administer a specific amount to a specific area. Or it may be that x-ray emitted from the rare metal radium, which is placed in the near vicinity of the area to be treated for a specified length of time. Therapeutic x-ray is of value in the treatment of certain forms of cancer and other new growths, many types of skin disease, and certain inflammatory processes. This is a highly technical medical specialty, and x-ray treatments are rendered only by the radiologist. Confirmation of the diagnosis is required before x-ray treatment can be initiated, and the dosages are calculated very precisely by the radiologist. One or several treatments may be needed, depending on the case. Surgeons often employ x-ray treatments before or after an operation; or, in some cases, treatment is entirely by x-radiation. Both diagnostic and therapeutic x-ray are important aids to the field of surgery.