Computed Tomography: A Brief Historical Perspective

Abstract

Radiology, diagnostic imaging, organ imaging, call it what you will, logically may be regarded as part of the physical examination of a patient. It is a more extreme example of the process that started with the invention of the stethoscope, the process of augmentation of our senses. This process may be extended beyond our normal senses so we may now appreciate the electrical activity of the brain or the heart, using the electro-encephalogram or electro-cardiogram. The very complexity of the technical processes involved, however, tends to make us see them as remote from the diagnostic relationship of patient and doctor.

The diagnosis of diseases of the brain provides us with a unique example of the role of these "augmented senses". The inaccessibility and delicate nature of the brain restrict the diagnostic tools we may use. The presence of a rigid bony box, the skull, protecting the brain prevents us from using our senses directly to examine the organ. Indeed, if we could examine it in our usual manner, the brain tissue might be destroyed by the use of percussion or palpation. The relative opaqueness of bone to X-rays limits the use of almost all plain radiographs. It is this very limitation that has provided an incentive to devise techniques to demonstrate the brain without damaging the brain tissue.