Urine Sample Results - doe-std-1136-20040134

DOE-STD-1136-2004

Guide of Good Practices for Occupational Radiological Protection in Uranium Facilities

Chest-wall thickness has a significant impact on chest counting. Corrections are commonly made

using a height-to-weight ratio or ultrasonic methods (Kruchten and Anderson 1990).

Corrections may be required to address apparent detection in one tissue resulting from photon

crossfire from another tissue. For example, chest counting is performed primarily to estimate activity in the

lung. Yet, there is substantial bone over the lungs (rib cage, sternum) and behind the lungs (vertebrae).

Plutonium and uranium are both bone-seeking radionuclides which will deposit on those bone surfaces and

can interfere with chest counting. It is possible for a person having a systemic burden of uranium from a

wound in the finger to manifest a positive chest count from material translocated to the skeleton, axillary

lymph nodes, or liver (Carbaugh et al. 1989; Graham and Kirkham 1983; Jeffries and Gunston 1986).

Interpreting such a chest count as a lung burden can render dose estimates somewhat inaccurate.

When comparing in vivo measurements made over many years, it is important to make sure that the

measurements are, in fact, comparable. One consideration is to make sure that corrections have been

consistently applied to all similar measurements. It is not unusual for measurement systems to be replaced

or to change the algorithms used for calculating results over time. Step changes in data can occur and

should be addressed in monitoring long-term detectable trends (Carbaugh et al. 1988).

In vivo wound counting for uranium is usually one facet of special bioassay. While a portable alpha

survey meter may show if surface contamination is present at the wound site or contamination of the

wounding object, alpha detectors are not capable of measuring imbedded activity or activity masked by

blood or serum. Thus, uranium facilities should have available a wound counter utilizing a thin sodium

iodide or semi-conductor (e.g., planar germanium) detector. Such detectors are capable of measuring the

low-energy photons emitted from uranium. The ability to accurately quantify wound activity is highly

variable, depending on the calibration of the equipment and how deeply imbedded material is in the

wound. If the object causing a wound and blood smears taken at the time of a wound show no detectable

activity, then a wound count also showing no detectable activity is probably sufficient to rule out an intake.

If the wounding object or the blood smears show detectable activity, special urine samples should be

obtained regardless of the wound count result. In this latter circumstance, lack of detectable activity on a

wound count could be attributable to deeply imbedded material at the wound site or to rapid transportation

of material from the wound to the systemic compartment.

5.7.2 Urine Sample Results

Detection of uranium activity in a routine or special urine sample using commonly available

radiochemical measurement techniques should be investigated as a potential intake. A data review

should be made to determine if the sample result was correctly determined, and batch QC sample data

should be verified.

If the result is near the Lc, it is possible that statistical fluctuation of the measurement process could

account for the apparent detection. Recounting the final sample preparation once or twice can be a helpful

technique to verify a result or classify it as a false-positive. If the first recount also detects the analyte, it

can be concluded that the sample does contain the analyte (the likelihood of two consecutive false

positives at a 5% type I error per measurement is 0.0025, or 0.25%.) If the first recount does not detect the

analyte, a second recount can be performed as a tie -breaker.

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