Uncertainty

The measured or calculated values of almost all quantities of interest in radiation oncology (and in most other walks of life) cannot be known exactly, but have some degree of uncertainty associated with them. The exceptions are the so-called “denumerable” quantities – things which can be counted such as the number of digits on your right hand. The analysis of the uncertainties in non-denumerable quantities is not an academic exercise, but, rather, is central to the conduct of radiation therapy – not least because it is a life or death matter for patients. As you will see, the following chapters are suffused with talk of uncertainty and the need to estimate it. It is for this reason that I have placed this chapter near the beginning of this book.