In therapies for cancer and blood disorders, PET/CT scanners are commonly used for patient diagnosis and treatment monitoring. Children, however, are especially sensitive to radiation, making PET/CT scans more risky. One way to address this is to increase the sensitivity of the scanner. This can be achieved by increasing the field-of-view: with every doubling of the scanner field, the sensitivity is quadrupled.

This is the approach taken by the PET20.0 scanner – which has a 2 m field-of-view, affording a 20-fold increase in sensitivity when compared to current PET scanners. The advantage of total-body scanning, explains PET20.0 developer Stefaan Vandenberghe of Ghent University, is "the combination of very high sensitivity due to the large axial acceptance angle, and the very good and uniform spatial resolution of 2 mm".

Current versus total-body PET/CT scan. Credit: Stien Stessens

The inner diameter of the detector will be 65 cm, with an axial length of 1 m and the option to extend this by a further metre. The compact gantry is planned to have a transverse outer diameter of less than 2 m. The design is expected to be able to perform a total body scan in around just 20 s   rapid enough to be undertaken within a single breath hold for nearly all patients.

When finished, the scanner will be installed in the Ghent University Hospital. The researchers anticipate completing the PET20.0 scanner by 2020, with little technical challenges to overcome on the hardware side. The only drawback is that the machine is expected to cost around 6–7 million USD, about three times more than current PET-CT scanners, and just above the commercial price of a simultaneous time-of-flight PET/MR.

In comparison with the EXPLORER PET system – a full-body scanner being developed at the University of California Davis – the PET20.0 will have a shorter axial field-of-view (with 1 m detectors only). The use of monolithic detector crystals with advanced positioning methods will offer improved spatial resolution: 2.0 mm with PET20.0, compared with 3.5 mm in the EXPLORER.

Alongside improving imaging quality for juvenile patients, the researchers report that the PET20.0 will find unique applications in monitoring the impact of innovative treatment plans –in such areas as chemotherapy and conventional radiotherapy – as well as for conducting fundamental research into the functioning of humans, animals and other biological matter.

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