Period 1 dec 2015 – june 2017
The project started with the pinhole concept as suggested in the proposal. This system was simulated in constructed in a physical prototype. Using this, image quality was evaluated for different collimators of the set-up. While successful test were conducted they also exposed flaws of the concept in terms of limited sensitivity and image resolution. As alternative a second concept was formulated, that places the gamma camera behind a x-ray flat panel detector and relies on the fact the x-ray is detector is mainly sensitive for the x-ray photons and partial transparent to the gamma photons. The gamma is equipped with a cone beam collimator so guarantees perfect overlap of the x-ray and nuclear images. For this a new prototype was constructed with the help of Philips Medical Systems. This company showed interest in our work and decided to support it with knowledge about x-ray imaging and by making x-ray parts available on loan for the project.
Period 2 July 2017 – June 2018
During this period the second prototype was further developed to show case its ability to do live x-ray/nuclear imaging in 2D and also in 3D. The live 2D experiments were documented and published. For the 3D part, reconstruction algorithm needed to be developed, implemented and evaluated. We have also shown that dosimetry is even possible at very low levels of radio-activity. As indicated by the work in the previous period, motion of organs is a detrimental factor in (quantitative) imaging. This can be compensated by exploiting the specific x-ray and nuclear capabilities of our concept as we have reported. Since in the interventional setting time is even more of critical factor as in the diagnostic setting we also investigated the possibilities of speeding up the acquisition. Especially when lung shunting is to be evaluated the acquisition can be as short as 1 minute.
Besides reconstruction and simulations, we have also worked on the hardware, mainly the performance of the detector. We have researched the detrimental impact of the x-ray flux on the gamma camera and come up with a number of solutions, which were however too costly for our budget. Therefore a simpler design using an off focus collimator was tested and implemented.
Period 3 July 2018 – Dec 2021
In this period all the scientific work of the earlier stages of the project comes together, and the main objective is to come, at the end of the project, to a new clinical-grade scanner, which can be employed in a clinical setting to demonstrate the performance of our innovations. This required the construction of a C-arm gantry, that is able to hold the relatively heavy dual layer detector (150kg), the preparation of a Medical Device Dossier (constituting almost 1000 documents), approval of the Institutional Review Board for Medical Ethics clearance of applying the new technology in a patient study and finally the clinical study itself. Altogether this was a major achievement of our team, as few academic groups are used to complete the route from bench to bedside. I am very proud that we managed this and can now demonstrate our technology in clinical setting. We get enthusiastic response from both health care professionals and patients, and both value the potential to improve the quality of the intervention and the increased comfort and speed of the procedure. Besides this study we have disseminated the results of our work in a patent and more than 10 journal papers including top journals as Radiology.
