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Evolution of tomography and its effects on imaging specialties
Imaging in medicine dates its origin to 1895 when X-ray was discovered by Roentgen. Obviously, this exciting and novel technology opened a new and unprecedented era in medicine, which continued throughout the 20th century and is still a major element of the day-to-day practice of the discipline of radiology. Some limited and modest efforts were made during the mid 20th century to employ tomographic methodologies, which eventually led to the introduction of X-ray computed tomography by Sir Godfrey Hounsfield in 1973. 1-7 The extraordinary power of this approach and its superiority over conventional planar imaging techniques became apparent within the first few months after its application in several intracranial disorders.
While the value of plain film radiography of the skull had been questioned for decades, X-ray CT images of the head were embraced as the standard of care for a multitude of neurosurgical and neurological diseases as the technology spread to the medical community over the ensuing years. We must mention that the concept of modern tomography was born at the University of Pennsylvania in the early 60's, when David Kuhl and Roy Edwards were able to reconstruct tomographic images of the head and the body by utilizing radiotracers. The impact of this modality in detecting central nervous disorders became apparent when sophisticated single photon emission computed tomography (SPECT) instruments were designed and built in the late 60's and early 70's and subsequently employed to assess a variety of diseases of the brain. These images were acquired to detect blood-brain barrier abnormalities with [^sup 99m^Tc]pertechnetate. We had noted frequently that many lesions, which were missed by conventional planar imaging techniques, were readily detectable by SPECT. We were convinced then, as we are today, that planar imaging in nuclear medicine is a suboptimal technique and cannot successfully compete with tomographic methodologies in the today's practice of medicine.
As the technology for X-ray computed tomography (CT) matured over the years, the superiority of tomographic imaging over planar radiology for assessing disease processes anywhere in the body has become increasingly apparent to the practicing radiologist.8-10 Examination of anatomic sites such as the chest and abdomen by X-ray CT has added a major and exciting dimension to the practice...