Dual-source CT scanner

Since the introduction of a dual source CT scanner, several dual energy applications operating the two tubes of the scanner at different potentials have been described. The simultaneous acquisition of images at 80 and 140 kVp allows for material differentiation and subtraction of iodine from the dataset. Clinical use of this technique enhances diagnostic capabilities of abdominal MDCT. 

Fig. 1.5a,b. Schematic illustration of a dual-source CT (DSCT) system using two tubes and two corresponding detectors offset by 90°. A scanner of this type provides temporal resolution equivalent to a qiuirter of the gantry rotation time, independent of the patient s heart rate. In a technical realization, one detector (a) covers the entire scan field of view with a diameter of 50 cm, while the other detector (b) is restricted to a smaller, central field of view... 

These results indicate that the dependency of image quahty on the average heart rate decreases with the increasing temporal resolution of the CT scanners. Another conclusion from these studies is that until the use of 64-shce CT for noninvasive coronary imaging, the administration of (3-receptor antagonists is advisable when the heart rate exceeds a certain threshold (60 or 65 bpm). With dual-source CT, heart rate control through the use of beta-blockers is no longer required (Fig. 15.2). 

The evolution in CT technology over nearly two decades has been impressive. Single-sHce hehcal CT was introduced in 1989. It was another 10 years before 4-shce CT was introduced. After that, it took only 3 years until the release of 16-slice CT, and another 2 years until the release of 64-shce CT. The next step was dual-source CT, which was introduced only 1 year after 64 detector rows became commercially available. Today, we experience a new situation with the community of vendors providing a diversity of different approaches. CT scanners with a dedicated cardiac functionahty of 2008 have a bandwidth of detector sizes ranging from 2 cm (32 detector rows) up to 16 cm (320 detector rows) and range from a rotational speed of 350ms to 270 ms. 

The most recent development in CT scanners is dualsource technology. Two separate X-ray sources and two detector systems are arranged perpendicular to each other, and rotate around the body. Initially, the design was chosen to improve the temporal resolution for cardiac imaging. However, if these two tubes run at different kV levels, elements with different order numbers such as calcium and iodine may be separated by their different dual energy indices. As... 

After the introduction of multislice CT in 1992 with the advent of dual-slice scanners, this technology was improved in 1998 by the implementation of 4-slice, in 2000 with 8-slice, in 2002 with 16-slice, and in 2004 with 64-slice scanners. Development continues and at the turn of 2006 the first 64-slice dual-source devices with a very high temporal and spatial resolution were installed thus one seems to observe a 2-year cycle for the launch of new CT... 

Because of these still-existing limitations, further CT scanner technology developments ensued. As a result, the dual-source 64-sHce CT scaimer was introduced. This CT system offers a high temporal resolution of 83 ms in a monosegment reconstruction mode, which has dispensed the necessity for administering P-blocking medication for heart rate reduction prior to CT coronary angiography (Achenbach et al. 2006 Johnson et al. 2006 Scheffel et al. 2006). 

---