Radiography was established as an essential complementary examination for the practice of health services. But to allow the evaluation of bone fractures, lung tissue, heart dimensions, intestinal walls and many other structures of the human body, progress began as early as the 19th century. X-rays were discovered in 1895 by Wilhelm Conrad Roentgen in Germany, who made the first radiographic image in history: the x-ray of his wife’s right hand. Since then, radiography has evolved a lot, and today it is capable of generating increasingly sharper images with the emission of a much smaller amount of radiation and a shorter exposure, mainly with digital radiography.
Conventional radiography uses the emission of radiation photons (in the case of X-rays) and their interaction with the materials of the human body to generate images. The emitted X-rays are partially absorbed by the organism, but some of them manage to pass through matter, colliding with the radiographic film… At that time, it sensitises the silver salts and burns them. As each structure of the human body (be it adipose tissue, thigh, bone, sandy lung tissue, etc.) absorbs a different amount of radiation, the film burns according to that standard. In this way, an overlay image is generated of all the structures crossed by the rays on the way.
For the image to be visible, developing the film and generating representations in shades of grey is necessary. In this palette, the shades closest to white represent dense materials that absorb all the radiation and prevent the film from burning. The darker tones indicate that most X-rays managed to pass through the structure and burn the movie, representing the less dense structures.
How is digital radiography done?
In direct digital radiography, x-rays are captured by a radiation-sensitive circuit board that generates a digital image and sends it to the computer through electrical signals; the idea is processed and reaches health professionals. They can be stored or printed. In indirect digital radiography, the rays are captured by a phosphor plate that needs to be scanned so that the image is transmitted to the most diverse locations in the same way as direct radiography.
disadvantages of conventional radiography
The correct amount of radiation is necessary for an excellent image to be generated from conventional radiography; the right amount of radiation is needed. An error in the dose can cause a significantly or poorly penetrated idea, which will not allow the identification of lesions with certainty. But, even if you use the perfect technique, considering that the sharpness and contrast of the conventional radiographic image are naturally lower, the patient is exposed to a more significant amount of radiation than in digital radiography for a photo with the same quality.
In addition to being one more stage (it needs more professionals), the film development process generates substances that contribute to environmental pollution… And the film itself ends up discarded over the years, generating garbage. Although the revelation process takes less than an hour, it does not compare with the agility of the digital system that produces the images in a few seconds.
The advantages of conventional radiography
As it is a well-established technology, conventional radiography can be performed with cheaper and simpler devices without requiring specialised knowledge of the process. It is enough to position the film and the patient well, with the emission of x-rays in the correct quantity in the predetermined time. For this reason, small health or imaging centres can already carry out the exam, increasing access for the population.
The disadvantages of radiography
Because it is a recent technology, it requires a more excellent investment in equipment and upgrading technicians who must be ready to work with computerised image processing.
Superior in terms of sharpness, contrast, detail and density differentiation, the digital system’s image generates less rigorous radiation exposure than conventional radiography. This already reduces the risks of the exam for the patient and leaves the work environment safer for the technician. Also, since the image is generated immediately on the computer, you can quickly go to the radiologist. This soon professional issues the medical report to a remote specialist or to the doctor responsible for the patient within the institution, who can make the diagnosis and start the appropriate treatment, giving more agility and efficiency throughout the care process.
All this mobility of the digital X-ray file is facilitated by the Digital Storage and Communication System ( PACS ) integrated into the Radiology Information System (RIS), used throughout the world by services in the medical area, following the quality models established by the Digital Imaging and Communications in Medicine ( DICOM ). In this way, the institution’s processing and transportation time improve productivity.
Another great advantage of digital radiography is the possible image processing by the computer, which allows contrast adjustment, histogram equalisation and even image reduction to favour the identification of lesions—all without the use of films and polluting substances, which shows that digital radiology is more sustainable.