A thermoluminescent dosimeter might look very similar to a film badge
personnel dosimeter, but it operates completely differently.
Crucially the photograph shows the men, Ronald Coates, John Carr, Peter Cutforth and Harry Rowlands wearing dosimeters, film badges
used to measure radiation exposure.
Monitoring is performed with personnel dosimeters such as pocket dosimeters, film badges
and thermoluminescent dosimeters.
When the radiologic technologist participates in any type of fluoroscopy, it is extremely important that the film badge
is worn correctly to ascertain true occupational exposure.
That's why people who work around radiation are required to wear film badges
that measure cumulative radiation exposure.
They had radiation levels recorded by film badges
but most test participants did not.
Uncertainties in dose estimates in the worker cohorts are caused by sampling variation in measurements from film badges
and thermoluminescent dosimeters, adjustments made to doses below the limit of detection, and attenuation of externally measured dose by shielding (Gilbert 1998; Gilbert and Fix 1995).
The light weight portable monitor gives an immediate indication of exposure to ionizing radiation without waiting for film badges
to be developed.