Path:Index:History
Although the first instance of SPECT was when Kuhl and
Edwards produced the first tomographs from emission data in 1963,
the history of SPECT detectors begins earlier.
In the 1940's crude spatial information about
radioactive source distributions within the brain were produced using a
single detector positioned at various locations around the head.
Ben
Classen improved this method in the 1950's when he invented the
rectilinear scanner. This device produced planar images by mechanically
scanning a detector in a raster-like pattern over the area of interest.
By today's standards, this technique required very long imaging times because
of the sequential nature of the scanning.
A pin-hole in lead was used to project a gamma ray image
of the source distribution in 1953 by Hal Anger. The image was projected
onto a scintillating screen with photographic film behind it. This technique
required extremely long exposure times because of the huge inefficiencies
in the system (principally due to losses in the film). The inefficiencies
in the system resulted in extremely high radiation doses to patients.
In the late 1950's, Anger replaced the film and
screen with a single NaI crystal and PMT array. This formed the basis for
the "Anger Camera" which is now the standard clinical nuclear imaging device.
Modern Anger Cameras use a lead collimator perforated with many parallel,
converging or diverging holes instead of the original pin-hole configuration.
Kuhl and Edwards were the first to present tomographic
images produced using the Anger Camera in 1963.
Everett, Fleming, Todd and Nightengale suggested the
use of the Compton effect for gamma-radiation imaging in 1977. This
technique is currently in use in astronomy. It's adaptation to SPECT is
non-trivial because of the vastly different source distributions and geometry
involved.
The investigation of the Compton Camera for SPECT began
in 1983. Manbir Singh and David Doria proposed and experimented
with a basic design using solid state detectors, performed an analysis
of possible detector materials, and produced a small prototype for testing.
The illustration and information on this page are adapted from "Physics
in Nuclear Medicine" by Sorenson and Phelps