Spiral Versus Helical

Spiral or helical CT: right or wrong?

 From: Willi A. Kalender, PhD

 Siemens Medical Systems

 Henkestrasse 127, D-91050 Erlangen, Germany

 Editor:

The term spiral computed tomography (CT) was first made public at the 1989 RSNA scientific assembly (1). Peter Vock, MD, from Switzerland and myself, not native speakers of the English language, had had some trouble in deciding on the name for the technique. Both spiral and helical appeared to be acceptable to us—helical was possibly more precise (which is very important to the Swiss), and spiral was more readily understandable. Authoritative dictionaries of the English language told us that both terms were correct. Having walked up and down spiral staircases with spiral binders under our arms without any problems, we believed that the term spiral might be more readily understood and accepted intuitively. Indeed, the term was accepted. However, in several of our communications, we stressed that spiral and helical can be considered as synonyms (2).

Apparently, a controversy arose in the past 1-2 years, as documented by letters to editors of scientific journals (3,4). The authors made very intelligent and acceptable statements voting for either one of the terms. I think that the discussion is unnecessary. There is no right or wrong term; both terms should be kept as synonyms.

Last, but not least, for yet another reason I recommend that the scientific community and their journals stay away from deciding that one term is right and the other one is wrong. There are some commercial implications and interests connected to the terms, and any decision might be misinterpreted. For what I hope are understandable reasons, I will continue to use the original term spiral CT in my communications; however, it shall not imply a decision about which term is right and which term is wrong.