CONTRIBUTION OF MEASUREMENT METHODOLOGY TO THE ACCUMULATION OF I$sup 131$ IN THE THYROID

Journal Article · Sat Jun 15 04:00:00 EDT 1963 · Schweiz. Med. Wochschr.

OSTI ID:4141353

Luethy, H

The effects of measurement distance, field size, collimator shielding, scattered radiation, and use of filters were studied by means of a phantom with two types of commercial NaI probes. The optimum measurement distance varies with the probe used because of the differences in scattered radiation from the crystal casings and collimator shielding. Source-crystal distances should be measured from the crystal face. The field size, defined as the distance over which the count from a point source amonnts to 90% or more of the value at the central axis, was 9 and 11 cm at distances of 30 and 40 cm, respectively. The optimal thickness of lead filters ranges from 0.8 to 2 mm. Uncentainty as to the true depth of I/sup 131/ thyroidal deposition probably does not introduce more than a 5% measurement error. Correction for extra-thyroidal I/sup 131/ activity by thigh measurements is important for early periods after administration. Measurements on five patients showed thai the nonthyroidal neck activity was from 1.2 to 1.7 times that of the thigh. Corrections for body background are more reproducible when a 2.5-mm lead shield is placed directly on the collimator opening instead of over the thyroid region. (BBB)

• Research Organization: Buergerspital, Basel
• NSA Number: NSA-18-003443
• OSTI ID: 4141353
• Journal Information: Schweiz. Med. Wochschr., Journal Name: Schweiz. Med. Wochschr. Vol. Vol: 93
• Country of Publication: Country unknown/Code not available
• Language: German

Related Subjects

BIOLOGY AND MEDICINE
CRYSTALS
ERRORS
FILTERS
IODINE 131
MAN
MEASURED VALUES
MOCKUP
QUANTITY RATIO
SCATTERING
SHIELDING
SODIUM IODIDES
THICKNESS
THYROID
USES
VARIATIONS