The PET-CT scanner, or Positron emission tomography-computed tomography, is a combination of the PET scanner and the CT scanner. The concept collects data from both the PET and CT scanners in one scan session combined in a single gantry system, in order to produce a single superposed image. This is useful since PET scans are best for the spatial distribution of metabolic or biochemical activity in the body, and CT scans are best for anatomical imaging.


The PET scanner was introduced in the early 1960’s, and the CT scanner introduced in the early 1970’s. It wasn’t until the 90’s, however, that the idea to combine to two for even better image quality was considered. Until the invention of the PET-CT, medical doctors were often frustrated for years, attempting to match two different scans from the PET or CT scanners and studying them in order to determine the exact location of a tumor, for example.


The idea for the PET-CT scanner came about from an earlier low-cost PET scanner that comprised rotating banks of bismuth germinate (BGO) block detectors that were developed by David W. Townsend at the University of Geneva in 1991. There were gaps between the banks of the BGO detectors, which offered the possibility to incorporate a different imaging modality within the PET scanner. It was then that Swiss oncology surgeon Dr. Rudi Egeli suggested that they add the CT scanner in the gaps in order to provide more anatomical information that was familiar to surgeons.


The difference between PET, CT, and PET-CT scanners


Dr. Townsend moved to the University of Pittsburgh in 1993, in order to work with Dr. Ron Nutt, who was then the president of CTI PET systems in Knoxville, Tennessee.  They received NIH funding in order to complete the PET-CT prototype, but it wasn’t until seven years later, however, that the first prototype PET-CT scanner was completed and installed at the University of Pittsburgh Medical Center.


The first commercial PET-CT scanner to be announced was the GE Discovery LS in 2001 and incorporated a 4-slice CT scanner, which, at the time, was the highest end CT available in terms of the number of detector rows.


Dr. Townsend and Dr. Nutt were highlighted in Time magazine in 2000, by naming the PET-CT scanner the Medical Invention of the Year.


Currently, five manufacturers offer PET-CT scanners: GE, Hitachi, Philips, Toshiba, and Siemens.


CT scanners and PET scanners are triumphs of the medical community in their own right, but when you put the two together, you get something even more special: the missing piece to a puzzle that baffled the medical community for years.


Luckily, we have Dr. Townsend and Dr. Nutt to thank for their incredible contribution to the medical world. If you would like to speak to one of our highly skilled professionals about one of Amber’s refurbished PET-CT scanners, give us a call or contact us here today.



Reference: Combined PET/CT: the historical perspective

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