Multi-energy CT (also known as spectral CT) exploits the attenuation variations observed when composite materials are imaged by X-rays of differing energies. The article's authors, from Philips Research in Germany and Philips Healthcare in Israel, demonstrated spectral CT imaging of a phantom containing PMMA, calcium-hydroxyapatite, water, and varying concentrations of gadolinium- and iodine-based contrast agents.
The researchers - headed up by Philips' Jens-Peter Schlomka - generated separate images showing the attenuation due to photoelectric absorption, Compton scattering, iodine and gadolinium. Calculated concentrations of the contrast agents based on their observed attenuation matched well with the actual doses used. This quantitative imaging is a major differentiator of spectral CT over conventional or dual-energy CT (see also: Spectral CT picks out multiple materials).
"This work represented a major step forward in taking spectral CT from a theoretical concept to an imaging tool to help improve diagnosis and therapy planning for many of the world's major diseases," Schlomka told medicalphysicsweb. "We have learnt from the feedback that we have received so far that this paper has helped convince many people of the feasibility of spectral CT imaging."
Since the PMB paper was published last year, the researchers have enhanced the spectral CT system's scanning hardware and image reconstruction software to offer better image quality and easier object handling. They are now working to speed up the system - a key challenge in developing a clinical spectral CT scanner.
The enhanced spectral CT prototype has been employed to study phantom models and tissue samples, in the search for novel spectral CT contrast agents. "We initially targeted the structural and functional imaging capabilities of spectral CT for cardiovascular diseases, but the principles can be transferred to other clinical application areas such as oncology," explained Schlomka.
"I recently switched position from being an 'active' researcher to managing other researchers, heading the X-ray imaging group within Philips Research in Aachen, Germany," Schlomka added. "Receiving this prize makes me proud, of course; it is a great achievement for me on the finishing line of my career as an active researcher."
Top choices
The Roberts Prize is a joint award from IOP Publishing, the publishers of PMB, and the journal owners, the Institute of Physics and Engineering in Medicine (IPEM). Starting with a shortlist of the best 10 research papers published in 2008 (based on the referees' quality assessments), an IPEM college of jurors choose a winner, which was then endorsed by the Editorial Board.
This year, it was a close contest between the top two papers, with the Board particularly commending the runner-up (Phys. Med. Biol. 53 6291). The second-place paper, by Chao Wang et al, describes arc-modulated radiation therapy (AMRT), an alternative method of delivering intensity-modulated radiotherapy. The article describes an AMRT treatment planning scheme, and details the verification of this scheme with multiple clinical cases (see also: Single-arc IMRT: variations on a theme).
The following ten articles (listed in alphabetical order) were shortlisted for the 2008 Roberts Prize:
- S Cho et al 2008 Analytical properties of time-of-flight PET data Phys. Med. Biol. 53 2809
- M Hamann et al 2008 Evaluation of a low-dose/slow-rotating SPECT-CT system Phys. Med. Biol. 53 2495
- E Kim et al 2008 Improving the quantitative accuracy of optical-emission computed tomography by incorporating an attenuation correction: application to HIF1 imaging Phys. Med. Biol. 53 5371
- P Kimstrand et al 2008 Parametrization and application of scatter kernels for modelling scanned proton beam collimator scatter dose Phys. Med. Biol. 53 3405
- Y Kyriakou et al 2008 Simultaneous misalignment correction for approximate circular cone-beam computed tomography Phys. Med. Biol. 53 6267
- J P Schlomka et al 2008 Experimental feasibility of multi-energy photon-counting K-edge imaging in pre-clinical computed tomography Phys. Med. Biol. 53 4031
- R Serduc et al 2008 Characterization and quantification of cerebral edema induced by synchrotron x-ray microbeam radiation therapy Phys. Med. Biol. 53 1153
- C Vignal et al 2008 Measuring brain hemodynamic changes in a songbird: responses to hypercapnia measured with functional MRI and near-infrared spectroscopy Phys. Med. Biol. 53 2457
- C Wang et al 2008 Arc-modulated radiation therapy (AMRT): a single-arc form of intensity-modulated arc therapy Phys. Med. Biol. 53 6291
- A Wunderlich and F Noo 2008 Image covariance and lesion detectability in direct fan-beam x-ray computed tomography Phys. Med. Biol. 53 2471
More information on the shortlisted papers can be found here.