Standardized phantoms exist for X-ray machines, CT scanners, and other imaging modalities to calibrate devices regularly. X-ray phantoms, for example, absorb X-rays in predictable ways, consisting of materials that mimic how the human body attenuates such electromagnetic radiation. But, making a calibration phantom for positron emission tomography (PET) scanners is very different from other phantoms because it has to replicate how radioactive tracers look like after being injected into a patient. Germanium is loaded into a special vessel and a PET scanner is used to observe the changing radioactive glow from day to day, providing a value against which to adjust the scanner. These exist, but there is no standard phantom that can be used in PET scanners from different manufacturers.
Sanders Medical Products, a company that builds PET phantoms for GE Healthcare, partnered with the National Institute of Standards and Technology (NIST) to create standardized phantoms that meet NIST’s standards specifically for PET/MRI scanners. The new devices reportedly use a more direct way of measuring the amount of germanium remaining as it decays, according to NIST.
The new phantoms will be shipping with all of GE’s PET/MRI machines and will be available for purchase by other manufacturers. The hope is that PET scanners will become easier to manage while providing more consistent scans from day to day, helping clinicians more accurately monitor tumors.
The collaboration is now working on finalizing PET phantoms for other varieties of scanners.