First Clinical Positron Imaging
Device - 1952

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Figure 1: First clinical positron imaging device. Drs. Brownell (left) and Aronow are shown with scanner (1953).

The success of our prototype positron scanner led us to develop a scanner designed specifically for brain imaging (Figure 1). This instrument followed the general concepts of the instrument build in 1950 but included many refinements. It produced both a coincidence scan as well as an unbalance scan. The unbalance of the two detectors was used to create an unbalance image using two symbols to record any unbalance in the single channel rates of the two detectors. The unbalance scan produced a low resolution image but was remarkable sensitive in determining whether a tumor existed, particularly if the tumor was to the right or left of midline of the brain. Figure 2 shows the two scans of a patient with recurring brain tumor.

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Figure 2: Coincidence and unbalance scans of patient with recurring brain tumor. Coincidence scan (a) of a patient showing recurrence of tumor under previous operation site, and unbalance scan (b) showing asymmetry to the left. (Reproduced from Brownell and Sweet 1953).