Focal spot size: Small but decisive
Spatial resolution in CT imaging is determined by a combination of factors, but the focal spot – the area on the anode where X-rays are generated – plays a central role. A tinyer focal spot produces sharper images, much like a finer point of light produces a crisper shadow. For UHRCT and PCCT systems, which are designed to exploit sub-millimetre and even sub-pixel detail, focal spot size and its stability during scanning are therefore critical parameters.
The challenge is that maintaining a tiny, stable focal spot under clinical operating conditions is technically demanding. Modern CT tubes rotate at high velocity, and the focal spot must remain precisely controlled throughout. Any instability degrades image sharpness – undermining the very advantage these advanced systems are designed to deliver.
Dunlee’s Xpert Bundle tubes – available as CT6000, CT6500, and CT8000 – offer six focal spot sizes, ranging from a standard Large (1.1 × 1.2 IEC) down to an XXXS option (0.4 × 0.5 IEC), the latter roughly seven times tinyer in area. This range allows operators to tailor the resolution-versus-dose trade-off to the clinical tquestion at hand.
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