OBJECTIVE: Computed tomography (CT) uses radiographical density to depict different materials; although different elements have different absorption fingerprints across the range of diagnostic X-ray energies, this spectral absorption information is lost in conventional CT. The recent development of dual energy CT (DECT) allows extraction of this information to a useful but limited extent. However, the advent of new photon counting chips that have energy resolution capabilities has put multi-energy or spectral CT (SCT) on the clinical horizon. METHODS: This paper uses a prototype SCT system to demonstrate how CT density measurements vary with kilovoltage. RESULTS: While radiologists learn about linear attenuation curves during radiology training, they do not usually need a detailed understanding of this phenomenon in their clinical practice. However SCT requires a paradigm shift in how radiologists think about CT density. CONCLUSION: Because radiologists are already familiar with the Hounsfield Unit (HU), it is proposed that a modified HU be used that includes the mean energy used to obtain the image, as a conceptual bridge between conventional CT and SCT. A suggested format would be: HU(keV). KEY POINTS: • Spectral computed tomography uses K-edge and slope effects to identify element signatures. • New visualisation tools will be required to efficiently display spectral CT information. • This paper demonstrates HU variation with keV using the Medipix3 chip. • HU ( keV ) is a suggested format when stating spectral HU measurements.
OBJECTIVE: Computed tomography (CT) uses radiographical density to depict different materials; although different elements have different absorption fingerprints across the range of diagnostic X-ray energies, this spectral absorption information is lost in conventional CT. The recent development of dual energy CT (DECT) allows extraction of this information to a useful but limited extent. However, the advent of new photon counting chips that have energy resolution capabilities has put multi-energy or spectral CT (SCT) on the clinical horizon. METHODS: This paper uses a prototype SCT system to demonstrate how CT density measurements vary with kilovoltage. RESULTS: While radiologists learn about linear attenuation curves during radiology training, they do not usually need a detailed understanding of this phenomenon in their clinical practice. However SCT requires a paradigm shift in how radiologists think about CT density. CONCLUSION: Because radiologists are already familiar with the Hounsfield Unit (HU), it is proposed that a modified HU be used that includes the mean energy used to obtain the image, as a conceptual bridge between conventional CT and SCT. A suggested format would be: HU(keV). KEY POINTS: • Spectral computed tomography uses K-edge and slope effects to identify element signatures. • New visualisation tools will be required to efficiently display spectral CT information. • This paper demonstrates HU variation with keV using the Medipix3 chip. • HU ( keV ) is a suggested format when stating spectral HU measurements.
Authors: Dipanjan Pan; Ewald Roessl; Jens-Peter Schlomka; Shelton D Caruthers; Angana Senpan; Mike J Scott; John S Allen; Huiying Zhang; Grace Hu; Patrick J Gaffney; Eric T Choi; Volker Rasche; Samuel A Wickline; Roland Proksa; Gregory M Lanza Journal: Angew Chem Int Ed Engl Date: 2010-12-10 Impact factor: 15.336
Authors: Daniel T Boll; Martin H Hoffmann; Nadine Huber; Andrea S Bossert; Andrik J Aschoff; Thorsten R Fleiter Journal: J Comput Assist Tomogr Date: 2006 Sep-Oct Impact factor: 1.826
Authors: V Raptopoulos; A Karellas; J Bernstein; F R Reale; C Constantinou; J K Zawacki Journal: AJR Am J Roentgenol Date: 1991-10 Impact factor: 3.959
Authors: N G Anderson; A P Butler; N J A Scott; N J Cook; J S Butzer; N Schleich; M Firsching; R Grasset; N de Ruiter; M Campbell; P H Butler Journal: Eur Radiol Date: 2010-03-23 Impact factor: 5.315
Authors: David P Cormode; Ewald Roessl; Axel Thran; Torjus Skajaa; Ronald E Gordon; Jens-Peter Schlomka; Valentin Fuster; Edward A Fisher; Willem J M Mulder; Roland Proksa; Zahi A Fayad Journal: Radiology Date: 2010-07-28 Impact factor: 11.105
Authors: R Zainon; J P Ronaldson; T Janmale; N J Scott; T M Buckenham; A P H Butler; P H Butler; R M Doesburg; S P Gieseg; J A Roake; N G Anderson Journal: Eur Radiol Date: 2012-07-04 Impact factor: 5.315