The creation of 'cyberspace,' or the sharing of information through email, on the Internet and on websites, has had a profound impact on nearly every field of human endeavor. Medical science, and particularly Radiology, has been particularly affected and enhanced by new technology. Radiology, by its very nature, has always been a leader in the use of emerging technology in the medical field. Now, new technology developed during the growth and expansion of the Internet is giving Radiology the opportunity to expand as never before.
What is Radiology
Radiology is the branch of medical science devoted to the use of a variety of energy sources in the diagnosis and treatment of disease, including x-ray, ultrasound, magnetic resonance, and nuclear energy. Diagnostic imaging allows practitioners to create images of internal body structures, including bones, tissues and organs. This usually necessitates a balance between using the correct amount of energy needed to produce an image with the optimum diagnostic information for the physician and maintaining minimal risk to the patient. Thus, Radiology provides a non-invasive method of viewing internal body structures and allowing diagnosis without the need for exploratory surgery.
The Radiologist and the Radiology Technologist are the two main professionals in Radiology. The Radiologist is a diagnostic physician who works either as a consultant to primary physicians, or, depending on the type of disease present, Radiologists may act as primary physicians themselves. Radiologists read and interpret diagnostic images, advise on the best diagnostic tests to perform, supervise radiographic examinations and perform radiographic treatments.
In the early days of Radiology, physicians were often considered 'general radiologists,' both performing radiographic examinations and providing therapy. Since the 1970s the field of Radiology has grown so dramatically that the Radiologist cannot remain active in the entire field. Initially, Radiologists began to specialize in either diagnostic or therapeutic radiology. With the continued expansion of the field however, Radiologists now specialize in areas such as neuroaudiology, interventional radiology, ultrasound, MRI and CT specialists, mammography, etc., as well as radionuclide and nuclear medicine specialists.
In many cases, the actual diagnostic images are taken by Radiology Technologists for later interpretation by Radiologists. Radiology Technicians must deal directly with the patients to ensure that images provide sufficient diagnostic information, but must also guard the patient from overexposure to radiation.
Methods of Diagnostic Imaging
Radiologists and Radiology Technologists use a variety of techniques for diagnostic imaging, including x-rays, mammography, ultra-sound, MRI and CT scans, among others. X-rays are the oldest of these techniques and have been in use for over one hundred years. Images produced using this technique are the result of passing electromagnetic energy beams through the body. Different body tissues allow these beams to pass through at different rates, with softer tissues allowing the rapid transfer of energy, while denser tissues such as bone slow the transfer of energy. The images thus produced reveal the internal structure of bones and tissue, revealing injury or the presence of tumors.
Mammography also uses x-ray technology but at particularly low levels. Mammography reveals abnormal changes in the density and structure of breast tissues. Mammograms are differentiated into two types: screening and diagnostic. Screening mammograms are used with women who have had no previous signs of breast cancer. Diagnostic mammograms are used when changes to the breast tissue have been found in screening mammograms, to measure and monitor areas of concern. Mammograms can reveal changes to the breast such as the presence of unusual tissue masses or lumps, and mineral deposits called calcifications.
Another form of diagnostic imaging, ultrasound, uses sound waves, which are passed through the body to create images. Used primarily to view internal organs, particularly the heart, or during pregnancy to monitory fetal development, the sound waves passed through the body and are recorded using a computer, which displays the image on the screen. Doppler Ultrasound is a particular kind of ultrasound imaging that is used primarily on the neck, arms and legs to provide images of blood flow. Other types of ultrasound include vascular, echocardiogram, abdominal, renal, pelvic, thyroid, and prostrate. Interventional ultrasound is sometimes used during surgery or biopsy.
Magnetic Resonance Imaging, or MRI, creates high-resolution images by using a magnet, radio frequencies and computer aided images to produce low energy electromagnetic waves (Andrew 1995). These waves show bodily structures. MRI is particularly popular due to the minimal affect it has on the body. In the past it was sometimes uncomfortable for the patient as it required the patient to be placed inside a long slender tube, often causing claustrophobia, but newer scanners no longer have this requirement. MRIs can be used to monitor blood flow, examine organs, including the liver, heart, and brain, detect injuries and reveal the presence of tumors.
X-ray imaging in conjunction with computer technology can also be used to create Computed Tomography imaging, or CAT scans. This technology produces an image of a cross section of a bodily structure in a thin slice. Used correctly, this technology can provide a three dimensional image of great clarity (Mayo Clinic, par. 5). A CT scan is a method of using x-ray technology while minimizing the effects of x-rays on the body. CT scans often include the use of a dye or other substance injected into the body through an IV in order to make certain structures stand out in the image.
History of Radiology
Wilhelm Conrad Roentgen, a professor at Wuerzburg University in Germany, first discovered x-rays in 1985. Roentgen was experimenting with fluorescent light using a cathode-ray tube when he noticed, when high voltages of electricity were applied, that a green glow was coming from nearby objects. After much investigation, Roentgen was able to use this method to produce an image of the bones in his wife's hand. In 1901 Roentgen was awarded the Nobel prize for physics for a discovery that changed the course of medical science (Eisenberg and Powell 1992).
Roentgren's initial machine for creating x-rays was easily reproduced, but was later modified by Sir William Crookes (Thomas, par 2). Creating x-rays using this machine was widely demonstrated to both scientific and lay audiences. This phenomenon caused considerable astonishment in both sectors of society and considerable demonstration was required before its validity was widely accepted and believed. Its application to medical science was quickly understood, however, and, as technological advancements improved the initial mechanism, hospitals and clinics began to use it as standard practice. This expansion of technology was limited, however, by the lack of availability of electricity in hospital buildings.
Other early difficulties in the use of x-ray technology included inadequate shielding for both patients and technicians, and the use of high levels of radiation when producing images. Radiation burns and dermatitis were common in the early days of x-ray technology. Because the results of high levels of radiation exposure often developed slowly, the cause of the problem was often not known. While x-ray imaging of hands and feet caused few problems, early attempts to create images of denser body areas produced disastrous results and even deaths.
Peripheral radiography was not a problem where the body part was thin. Radiography of the trunk was to prove technically more demanding and the shadows produced were much more difficult to interpret. Harnack had three assistants, Reginald Blackall, Ernest Wilson and Harold Suggars. Ernest Wilson joined in 1898 to help with the X-ray work and to perform clinical photography and developed signs of injury within a few months. By 1903 they all had radiation injuries. Wilson died of his injuries in 1911 and took a series of photographs of his hands showing progressive bony damage leading to malignancy. Harnack ultimately had both hands amputated. Suggars and Blackall worked for longer and helped to establish the College of Radiographers (Thomas, par 7).
After a great number of these early tragedies occurred, safeguards and procedures were finally developed that allowed the safe use of x-ray technology.
Early diagnostic images using x-rays were initially created using glass plates. The development of photographic film enhanced the use of x-rays making them both easier to read and easier to store (Goodwin, Quimby and Morgan, 1970).
During the initial phase of diagnostic imaging, radiologists and radiological technicians were recruited from general medical staff. Images were difficult to read and no training was available. Physicians were often left to wonder what the shadowy images represented. Gradually, medical personnel began to specialize in this branch of medicine and training courses were set up, with the eventual creation, in 1920, of the Society of Radiographers (NDT Resource Center).
Karl Dussik first used ultrasound, which had been developed during the first and second World Wars with the use of submarines, as a tool of medical diagnostics in the 1930s. Ultrasound was first used to destroy tumors. Later, John Wild developed the hand held ultrasound device that became popularly used in the 1950s. Ian Donald began using ultrasound in 1955 to diagnose tumors and breast lesions, which brought ultrasound into popular use in radiology (NDT Resource Center).