INTRODUCTION

Endoscopes, lasers and radiological equipment all utilize the harnessing and manipulation of the physical properties of the electromagnetic spectrum, especially light. Although they have become commonplace in operating theatres, the rapid development of technology in the latter part of this century has greatly increased the scope of surgical practice. Most of this technology has been developed in other fields and then adapted for medical use later. In practice, the application of such technology greatly improves surgical technique and allows much more information to be gathered and utilized by the operation of ever more sophisticated hardware. The rapid increase in its use has not only had the benefit of safer and more successful surgery but has also expanded the range of procedures available. A more recent consideration is the trend towards less invasive and non-invasive surgery where such technology, although initially very expensive, can greatly benefit patients by involving them in less trauma and thus decreasing the time spent in hospital. This also reduces the cost of treatment.

THE ELECTROMAGNETIC SPECTRUM

Having briefly placed these particular tools into context as far as their use in surgery is concerned, we can now examine the underlying scientific and technological principles involved in their use.

To fully appreciate the fundamentals of the electromagnetic spectrum we must understand a little about particle physics, quantum theory and the theory of special relativity. Although the in-depth examination of these subjects is essential to the pure physicist it can be a little daunting to those of us who merely use the technology. However, if we are to understand how these tools work it is first important to examine the behaviour and characteristics of light. Light is the medium by which visual information about the universe is transmitted via the eye to the brain. This is what we all know and experience as visual light but it occupies only a small area within the spectrum of electromagnetic energy (Fig. 11.1).