Introduction

Dual-energy computed tomography (DECT) was first discussed in 1973 by Sir Godfrey Hounsfield.* In the last decade, CT vendors have introduced different techniques for dual-energy scanning following Sir Hounsfield’s approach. These scanning techniques, although promising, have inherent limitations as they require:

• Upfront selection of a dual-energy scan mode rather than a conventional scan mode

• Dose penalties

• Limited scan field of view (FOV)

• Limited gantry rotation time

• Restrictions on patient size

Due to these limitations, DECT was not widely adopted and found only slow inclusion over the years of select protocols (e.g., for evaluation of pulmonary emboli, kidney stones, and gout) into routine clinical practice.

The Philips IQon Spectral CT is the first and only detector-based spectral CT scanner. Instead of scanning the same slice at two different kVp settings, the IQon Spectral CT uses conventional scanning at a single kVp setting, and differentiates energy levels of X-ray photons after transmission through the patient’s body using a proprietary NanoPanel Prism detector and a novel spectral reconstruction technique.

The unique approach of the IQon Spectral CT to spectral scanning enables every routine CT scan to be a spectral scan, without requiring a prior selection of scan mode, change in workflow, impact on dose, restriction of field of view (FOV), increase in gantry rotation time, or limit to patient size. The IQon Spectral CT increases a radiologist’s diagnostic confidence by providing multiple layers of spectral data that improve tissue visualization and characterization with the potential to expand the clinical utility of CT.

This clinical image case book is a result of a collaborative effort from the growing IQon Spectral CT user community that aims to make spectral CT a standard of care. Together, they have assembled a comprehensive overview of this advanced technology and its applications in different clinical areas.

Cases will also highlight the benefits this technology has provided healthcare organizations around the world, and additional chapters will focus on the future of CT and advanced technology yet to come.

We hope you find the material useful for your practice, and an inspiration to make the switch from routine CT to Spectral CT.

Emmanuel Coche, MD, PhD Head of Department of Radiology, Scientific coordinator of the project Cliniques Universitaires St-Luc, Brussels, Belgium