Deadtime is a time interval during which a radiation counting instrument that is processing incident radiation is insensitive to additional radiation. At higher count rates, losses caused by deadtime limitations degrade quantitative data. Absolute count-rate accuracy requires mathematical corrections for deadtime losses.

Under clinical conditions, the deadtime of a scintillation camera is a function of radiation scatter within the source and its surroundings. Therefore, a scatter phantom which simulates in-vivo forward and backscatter characteristics of 99mTc gamma rays is required for the extrinsic measurement of a scintillation camera’s deadtime. The Dual-Source Scatter Phantom produces a spectrum typical of that observed from 99mTc in the myocardium.

A deadtime measurement can be accomplished easily in about 15 minutes. Equipment required include the phantom and two 99mTc test tube sources for which accurate calibration is not necessary. After measuring the count rates of the sources, individually and combined, the deadtime can be determined by using a calculator with natural log functions.

Features

For deadtime measurements

Simulates in-vivo scatter conditions needed to measure gamma camera deadtime

Specifications Material: Acrylic Dimensions: 6 (w) x 8 (d) x 8 in (h) (15 x 20 x 20 cm) Hole dimensions: 1.7 cm Ø x 12 cm deep. The two holes are used to hold the radioactive sources and are spaced 5 cm apart (center-tocenter) at a distance of 5 cm from the face of the phantom Weight: 16.4 lb (7 kg)