Bart Carelsen, Presenter: Nothing to Disclose

Henk Willem Venema PhD, Abstract Co-Author: Nothing to Disclose

Marcel van Herk PhD, Abstract Co-Author: Nothing to Disclose

Patricia van Kemenade PhD, Abstract Co-Author: Nothing to Disclose

Wilko Grolman, Abstract Co-Author: Nothing to Disclose

Geert J. Streekstra PhD, Abstract Co-Author: Nothing to Disclose

Intra-operative 3D Rotational X-ray (3D-RX) with a Mobile C-arm supports the surgeon to achieve an optimal operation result. In today's 3D-RX clinical observation studies image quality (IQ) is determined subjectively by detection of anatomical landmarks which essentially comprises detection of small bone details. In contrast to this we objectively determined the IQ of a mobile 3D-RX device by measurement of contrast-to-noise ratio (CNR), spatial resolution and effective dose of a mobile 3D-RX system in comparison to a multi-slice CT scanner (MSCT). We also investigated a first order approximation of detectability of small bony details based on a slightly modified Rose model.

The point spread function (PSF), contrast and noise of a 3D-RX scanner (BV Pulsera 3D, Philips Medical Systems) were measured using a custom made RX phantom. Scans were made with 95, 225 and 450 projection images and with different fields of views (spheres of 90, 125 and 180 mm). For comparison we used MSCT with standard mastoid, orbit and skeleton protocols. The dose was estimated using PCXMC and ImPACTCT dosimetry software. The visibility of small details consisting of bone in soft tissue was determined by calculating the signal-to-noise ratio of the details after blurring with the experimentally determined PSF.

The mean spatial resolution of MSCT (FWHM of the PSF 0.3-0.4 mm) is slightly better than 3D-RX (FWHM of the PSF 0.4-0.9 mm) for most settings as is the CNR. However, effective dose is much higher for MSCT. Smaller bone details can be detected with MSCT (range 0.1-0.3mm) than with 3D-RX (range 0.3-0.6mm). Clinical relevant details, like the long process of the incus in the middle ear (diameter 0.6 mm) can be visualized with both systems.

The proposed method quantifies the most relevant imaging parameters of 3D-RX and CT to allow comparison, verification and optimal use. For high-contrast details the IQ of 3D-RX approximates that of MSCT. Small details of bone in soft tissue and tissue in air that are relevant for bone surgery are visualised adequately at low dose.

We investigated the ability of a mobile 3D-RX system for imaging small high contrast details in comparison with MSCT.

Carelsen, B, Venema, H, van Herk, M, van Kemenade, P, Grolman, W, Streekstra, G, Imaging Small Details Performance of a Mobile 3D Rotational X-ray Device.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5010386.html