In multislice CT, additional parameters such as z-axis filter were introduced. In addition, significant alteration has been observed in the concept of scan pitch. For these reasons, it was suspected that the parameter selection in multislice CT will be a complicated and confusing subject compared with single-slice helical scan. This hypothesis seemed especially true for Aquilion because it has the wide range of selection in slice thickness (0.5x4, 1.0x4, 2.0x4, 3.0x4, 4.0x4, 5.0x4, 8.0x4, 10x2) and scanning pitch (2.5 to 6).
Fortunately, this hypothesis for Aquilion was not work. We have developed entirely new method for the selection of scan parameters for routine examination of multislice CT. Basic concept consists of three parts.
*Single breath-holding scan for all the CT exam.
*Effective slice thickness based on detector aperture
*"Patient-first" instead of "machine first"
The actual process of parameter selection is as follows;
1. Set scanning range on scanogram.
2. Set scanning time (= breath-holding time)
3. Automated setting of slice thickness and scanning pitch.
4. Scan start
This new method is simple enough to be used by less experienced technologist, or even by "on-duty technologist" who are not familiar with CT operation. More important is the conceptual change introduced by P-COPS. Until now, scanning parameters of CT and MRI were regulated mainly by the specification of the machine, and a patient are requested to adapt the condition of the machine. P-COPS will bring a patient in the center position of CT examination.
It is important to understand that, the scanner should be fast enough to cover a sufficient scanning area, and should equipped with wide range of selectability in slice thickness and scanning pitch in order to extract full advantages of P-COPS.