Technical prerequisites and imaging protocols for CT perfusion imaging in oncology

• Use of low kV provides the largest leverage to reduce radiation dose of dynamic contrast enhanced CT to a reasonable level.
• High temporal sampling, short scan times and optimized injection protocols are highly required for accurate quantitative analysis of dynamic contrast enhanced CT data.
• Functional and morphological assessment from single volume dynamic contrast enhanced CT scan appears feasible.

The aim of this review article is to define the technical prerequisites of modern state-of-the-art CT perfusion imaging in oncology at reasonable dose levels. The focus is mainly on abdominal and thoracic tumor imaging, as they pose the largest challenges with respect to attenuation and patient motion. We will show that low kV dynamic scanning in conjunction with detection technology optimized for low photon fluxes has the highest impact on reducing dose independently of other choices made in the protocol selection. We discuss, derived from relatively simple first principles, on what appropriate temporal sampling and total scan duration depend on and why optimized contrast medium injection protocols are also essential in limiting dose. Finally we will examine the possibility of simultaneously extracting standard morphological and functional information from one single 4D examination as a potential enabler for a more widespread use of dynamic contrast enhanced CT in oncology.