Detector advance could lead to cheaper, easier medical scans

New ultrafast photon detectors enable fast processing of information from positron emission or X-ray scans without the requirement for tomography to rebuild images. This image reveals a brain phantom (design) scanned by positron emission utilizing the brand-new technology. Credit: Simon Cherry, UC Davis

Researchers in the U.S. and Japan have actually shown the very first speculative cross-sectional medical image that does not need tomography, a mathematical procedure utilized to rebuild images in CT and PET scans . The work, released Oct. 14 in Nature Photonics, could lead to cheaper, easier and more precise medical imaging.

The advance was enabled by advancement of brand-new, ultrafast photon detectors, stated Simon Cherry, teacher of biomedical engineering and of radiology at the University of California, Davis and senior author on the paper.

“We’re literally imaging at the speed of light, which is something of a holy grail in our field,” Cherry stated.

Experimental work was led by Sun Il Kwon, job researcher in the UC Davis Department of Biomedical Engineering and Ryosuke Ota at Hamamatsu Photonics, Japan, where the brand-new photon detector technology was established. Other partners consisted of research study groups led by Professor Yoichi Tamagawa at the University of Fukui, and by Professor Tomoyuki Hasegawa at Kitasato University.

The procedure of tomography is needed to mathematically rebuild cross-sectional images from the information in imaging that utilizes X-rays or gamma rays. In PET scans, particles tagged with trace quantities of a radioactive isotope are injected and used up by organs and tissues in the body. The isotope, such as fluorine-18, is unsteady and produces positrons as it decomposes.

Ultrafast photon detection

Whenever among these positrons experiences an electron in the body, they wipe out each other and all at once release 2 annihilation photons. Tracking the origin and trajectory of these photons in theory produces a picture of the tissues tagged with isotopes. But previously, scientists were not able to do that without the additional action of tomographic restoration, since detectors were too sluggish to specifically identify the arrival times of 2 photons and hence identify their place based upon their time distinction.

When the annihilation photons strike the detector, they create Cherenkov photons that produce the signal. Cherry and his fellow scientists found out how to identify these Cherenkov photonså with a typical timing accuracy of 32 picoseconds. This implied they could identify where the annihilation photons emerged with a spatial accuracy of 4.8 millimeters. This level of speed and precision made it possible for the research study group to produce cross-sectional pictures of a radioactive isotope straight from the annihilation photons without having to utilize tomography.

In their paper, the scientists explain numerous tests they performed with their brand-new method, consisting of on a test item that simulates the human brain. They feel great that this treatment is eventually scalable to the level required for scientific diagnostics and has the capacity to produce greater quality images utilizing a lower radiation dosage. Images can likewise be developed quicker with this approach, possibly even in genuine time throughout the PET scan, as no after-the-fact restoration is required.

PET scans are presently pricey and are technically restricted in some methods, as the complete details present in the travel time of the annihilation photons is not caught by existing scientific scanners. This brand-new discovery includes a compact devices setup and could lead to affordable, simple and precise scans of the body utilizing radioactive isotopes.

Additional coauthors are: Eric Berg at UC Davis; Fumio Hashimoto and Tomohide Omura, Hamamatsu Photonics; Kyohei Nakajima and Izumi Ogawa, University of Fukui.

Look what’s within: Full-body motion pictures from EXPLORER scanner

More details:
Sun Il Kwon et al, Ultrafast timing allows reconstruction-free positron emission imaging, Nature Photonics (2021). DOI: 10.1038/s41566-021-00871-2

Detector advance could lead to cheaper, easier medical scans (2021, October 29)
recovered 31 October 2021

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