Table 1.
Available approaches to dual-energy computed tomography
| DECT system | Principle | Technical considerations | Clinical considerations |
|---|---|---|---|
| Spectral detector DECT (SDCT) | Two vertically stacked scintillator layers | DECT information temporally and spatially matched Basis decomposition in projection domain DECT information available for all examinations (including challenges for computational and workflow requirements) Greater overlap between energy spectra (as compared with the other DECT approaches) |
DECT information obtained for every patient and available retrospectively No need for prospective protocol decision (regarding DECT) Conventional images without dose/quality compromise |
| Dual-source DECT (DSCT) | Two tube-detector pairs are offset by approximately 90° to each other | Adjustable tube voltage for either tube (including modification of spectral overlap) Possibility to combine both tubes for fast single energy combinations Spatial offset between acquisitions Basis decomposition in image domain only |
Requirement for prospective protocol decision (regarding DECT) DECT information is not retrospectively available Dose/image quality compromise for conventional images if acquired as DECT |
| Rapid-kVp-switching DECT | Tube voltage changes rapidly between low and high kVp | May be used in single-energy mode Basis decomposition after angular interpolation within projection domain Temporal offset between acquisitions |
No dose modulation in dual energy mode Requirement for prospective protocol decision (regarding DECT) DECT information is not retrospectively available |
| Split-beam DECT | Half of the tube output is filtered (in z-direction) and corresponding detector rows are read out separately | May be used in single-energy mode Large spatial and temporal offset between acquisitions Basis decomposition in image domain only |
Possible to upgrade existing CT scanners Requirement for prospective protocol decision (regarding DECT) DECT information is not retrospectively available Dose/image quality compromise for conventional images if acquired as DECT |