Nuclear imaging Advances and trends

' 'One picture is worth more than a thousand words''. The validity of this expression, which is a leitmotiv in the publicity sector, is not limited to the strategy underlying advertisements. It certainly also applies to the commanding role images play in diagnostic medicine. To draw lines of development in imaging instruments, one must start where the arsenal of nuclear medicine equipment stands today. In this article, nuclear imaging instruments that are likely to be of interest to the nuclear medicine community of developing countries are emphasized. The rectilinear scanner was the earliest instrument with which one created an image of a radioactive distribution inside the body. It still is a common — and reliable — piece of equipment in many nuclear medicine centres in the Third World. The scanner consists of a detector fitted with a lead collimator, which focuses the radiation-sensitive field of view to a narrow spot below it. The detector is being moved along a meandering path oyer the selected area where a radioactive tracer is distributed — for example, the organ to be imaged in the patient. The amount of radioactivity measured at each position is simultaneously recorded with a printing device attached at the other end of the moving detector assembly. After the total area has been scanned, the total pattern of printed dashes, the "scan", is a life-size presentation of the tracer distribution.