The validity of an equivalent point source (EPS) assumption used in quantitative scanning
- 1 May 1975
- journal article
- Published by IOP Publishing in Physics in Medicine & Biology
- Vol. 20 (3), 455-464
- https://doi.org/10.1088/0031-9155/20/3/009
Abstract
Most methods used to estimate the absolute organ content of a gamma-emitting radionuclide from external counting measurements assume that the depth distribution of activity is equivalent to a point source of the same activity located at an 'effective' depth. A theoretical analysis is presented which shows that this assumption is not correct for a dual opposed detector system, because of self-attenuation of the photons by the organ (or source). Experimental varification is also given, and it indicates that the error caused by this assumption is normally less than 10%, although it can be very large in special cases.Keywords
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