Using a Consistent System of Units

One frustration that persists in making judgements about technical matters is that it has not yet been possible to develop a consistent system of units. People are creatures of habit and tend to use those units with which they are familiar. Old and useful textbooks and reference materials use old units that are out of fashion. Many millions of hours have been spent in engineering and science classes converting from English to Metric or from "old" International System of Units (SI) to "new" SI units.

It is irritating to need to refer to a book of conversion factors with a calculator handy just to obtain useful information. We regret that we have no solution to the problem in a global sense, but when we use numbers in this letter we will attempt to consistently use modern SI units.

We will include tables to help people familiar with other systems to be able to use the numbers.

For this issue, the following table may be helpful.

quantity measured old unit symbol new unit symbol relationship

Dose rad rad gray Gy 1 rad = .01 Gy
100 rad = 1 Gy

Dose equivalent rem rem sievert Sv 1 rem = .01 Sv
100 rem = 1 Sv

Radioactivity curie Ci becquerel Bq 1 Ci = 3.7e10 Bq
1 pCi/l = 37 Bq/m3

quantity measured	old unit	symbol	new unit	symbol	relationship
Dose	rad	rad	gray	Gy	1 rad = .01 Gy 100 rad = 1 Gy
Dose equivalent	rem	rem	sievert	Sv	1 rem = .01 Sv 100 rem = 1 Sv
Radioactivity	curie	Ci	becquerel	Bq	1 Ci = 3.7e10 Bq 1 pCi/l = 37 Bq/m3

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