A series of wipe tests must be taken in all areas where activity is handled in unsealed form on a routine basis. The location of wipe tests should be indicated on the survey form and should be chosen for maximum probability of contamination, e.g. areas where individual doses are drawn up, incoming packages received, frequent pipetting carried out.
Floors, particularly adjacent to doorways, lead syringe shields, and door and drawer handles should also be wipe tested frequently. Care should be taken that cross contamination does not occur.
A gamma-scintillation counter (e.g. NaI well counter), should be used for pure gamma emitters. Make sure that the analyzer threshold is set below the lowest gamma energy used in the lab (usually I125). Low energy beta emitters will require liquid scintillation counting for wipe assay.
Measure the background count rate under the same counting conditions used with the wipes and record. An individual wipe test should routinely cover approximately 100 cm2. Ideally, any contamination more than a few disintegration's per minute (DPM) should be cleaned up; however, a more usual level at which cleanup is initiated is about 600 DPM.