The benefits of more slices (6 vs 64)
In this comparison we compare the performance of two systems.
One has 6 slices (like an Emotion 6), the other has 64 slices (like a Sensation 64). However, since the increase in performance in terms of slices is almost linear other devices may also be considered.
Of course slice thickness and rotation times also play a role. To keep the comparison as simple as possible we assume a slices thickness of 1mm and a rotation time of 1sec. per full rotation.
Image quality is one of the most important, if not the most important factor to be considered because only with good image quality a doubtless diagnose can be made.
Although the layer thickness plays a greater role here a larger number of lines also allows a larger image. Thus entire organs are assembled from fewer individual images. This results in an image with fewer artifacts which usually occur at the interfaces between two images. Especially with moving organs like the heart this makes a big difference.
The scan time is reduced linearly with the number of slices. This means a 6-slice-scan takes 10.66 times as long for the same task as a 64-slice-scan.
An area of 30cm is to be scanned.
The 6-slice-scanner covers 0.6mm per second and thus takes 50 seconds.
The 64-slice-scanner covers 6.4mm per second and therefore only needs about 4.7 seconds.
Therefore in facilities with a high volume of patients high slice CT systems are a clear advantage as a lot more patients can be served in within the same time.
Although tubes for a 64-slice device are usually much more expensive to buy they are also much more profitable to use. The more slices the device has the shorter one must scan. That means that for each scan a tube accumulates less scan seconds to it‘s count which represent the generally recognized value for tube wear and come along with a high decline in value.
The operatin costs for a 30cm scan can be up to 10€. And even with smaller scans this makes a big difference after a few thousand patients.