by
Gus Iversen, Editor in Chief | September 10, 2019
From the September 2019 issue of HealthCare Business News magazine
If you’re a regular reader of HealthCare Business News magazine, the name John Boone might be familiar to you. A couple of years ago we sat down with him to talk about a novel breast scanning CT system he developed alongside colleagues at UC Davis. We recently reached out to him again to discuss another CT innovation — ultrahigh-resolution.
Boone is a researcher, educator, and clinical medical physicist with long-standing interests in CT technology. He is former president of the American Association of Physicists in Medicine (AAPM), and currently chairs the CT subcommittee for this organization. He is also the primary author of the ICRU (International Commission on Radiation Units) Report 87, “Patient dose and image quality assessment in computed tomography”.
HCB News: In April, UC Davis Health announced that it was performing clinical imaging exams using an ultrahigh-res CT scanner. Can you tell us a bit about the technology and how it came to be acquired by the facility?
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John Boone: About 2 years ago, I was approached by an executive from (then) Toshiba, about the potential of siting this new high-resolution CT scanner at UC Davis. I was immediately excited about the prospect of evaluating this new technology — and as a leader in the research administration of my academic radiology department, I saw the opportunity for my young academic radiologist colleagues to have an opportunity to evaluate and report on this technology in a series of clinical protocols spanning applications from neuroradiology to musculoskeletal radiology — and that was the primary motivating factor for me in this project.
This CT scanner (which is now the Canon Aquilion Precision) has high-resolution features, which, in my opinion as a medical physicist specialized in CT technology are a game changer for CT imaging — perhaps not for every CT examination, but for a number of imaging applications I believe the high-resolution capabilities will lead to more accurate diagnoses and better patient care. The system has a 40 mm-wide detector (measured at the isocenter, per industry standards), with 160 – 0.25 mm wide detector arrays along the long axis of the scanner (the Z dimension). There are 4 different acquisition modes, which the manufacturer refers to as normal resolution, high resolution, super high-resolution, and ultrahigh-resolution modes. Of course, the size of the detector elements is not the only resolution-limiting factor, and this scanner has 7 different focal spot sizes that can be used, unlike any whole-body clinical CT scanner I have seen in the past. Obviously, the smaller focal spots need to be used with the higher resolution detector modes to actually achieve high-resolution images. The system is capable of reconstructing images with 0.15 mm pixel dimensions, with imaging matrices of 512 x 512, 1024 x 1024, and 2048 x 2048. The MTF, which is the traditional measure of spatial resolution in imaging systems, has a limiting resolution for clinical operation on the order of 3.2 pairs per millimeter, which is consistent with the 150 µm voxel dimensions.
