Viwas

□ Fig. 6.23. Transferring the complete table top with patient onto the operating table column tient remains on the head plate without having to be re-bedded. All head plates developed for the AWIGS and VIWAS system are radiolucent. This means that CT scans, C-arm scans and angiograms can be carried out without any interfering artefacts. All head plates are adapted directly to the transfer board, so that the patient does not lose his position between the head plate and the table top.

Practical application in Innsbruck clinic -18 months of clinical experience

»The system was used from January 2002 to the end of June 2003 for 1058 patients. The CT was used intraopera-tively in 15% of the cases. Stereotactic procedures (biopsies, deep brain stimulation, abscess drainage, radiosur-gery) were the main areas of application. Here the AWIGS system allows for intraoperative acquisition of top quality CT scans, with the following positive effects on neurosur-gery:

4 The operating time for stereotactic procedures can be reduced because it is no longer necessary to re-bed the patient.

4 Intraoperative imaging with identification of residual tumours and at-risk structures. Here intraoperative use of the CT takes less than 20 min« [1].

VIWAS (Vascular Interventional Workplace for Advanced Surgery), brother to the AWIGS system, was specially developed for interventional radiology, vascular surgery and cardiosurgery. The system makes it possible to use imaging procedures such as C-arm or angiography system directly at the operating table without having to interrupt the procedure to change the positioning of the patient.

6.2.4.1 VIWAS in combination with an angiography system

Special functions for the VIWAS system such as longitudinal and transverse displacement offer optimum possibilities for positioning the scanning units.

As with the AWIGS system, the patient is placed on the radiolucent transfer board, which is compatible with the transporter and with the operating table. The transfer functions between transporter and operating table are the same as for the AWIGS.

The VIWAS system avoids the problems encountered with previous operating tables in the intraoperative use of scanning units. This is thanks to two columns which carry the table top. Both columns can be moved under the table top independent of each other, leaving generous scope for using the C-arm. The scanning unit can be placed once between the columns. Instead of the arduous procedure of manoeuvring the C-arm, the patient is »floated« on the table top to the scanning unit by a joystick with longitudinal and transverse movements, as on an angiography table. The completely radiolucent one-section table top offers artefact-free scanning through 360° specially for intraoperative scanning of aortic an-eurysms.

The table top moves longitudinally on a linear guide system; transverse movements of up to 10 cm are possible

Fig. 6.25. Single-section table top VIWAS with angiography system

to both sides. Individual rails can be fitted to the frame of the table top to take accessories (O Fig. 6.25).

6.2.4.2 VIWAS in combination with a sliding gantry

The VIWAS can be extended in combination with a mobile CT unit, a so-called sliding gantry. Here the transfer board is pulled out to a scan length of 1.50 m for intraoperative scanning, and the CT unit moves to the patient accordingly. Subsequently the operation can be continued on a specially developed one-section table top. This brand new product was presented for the first time at the Medica 2002.

Both systems work without mutual monitoring. The patient is held manually at the scanning position under the fresh air panel. After the interlocking device of the table top has been released, the operating table columns are moved away from under the patient by the sliding gantry. The patient board is now available in a length of 1.50 m for scanning under the laminar flow. To take the pictures, the sliding gantry moves across the patient on the extended transfer board.

In addition, the special board can also be used for procedures with a C-arm or angiography system (O Fig. 6.26).

6.2.5 Prospects

The compatibility of the AWIGS and VIWAS systems with a standard Alphamaquet operating column makes them suitable for a wide range of surgical applications. Depending on the type of operation and the surgeon's requirements in terms of positioning the patient, the table top can be chosen before the operation: the one-section or three-section table top or the special table top for a sliding gantry and the one-section table top for a standard Alpha-maquet column 1150.

Intraoperative updates of the image data and the possibility of producing a new set of primary data offer both the surgeon and the patient an enhanced quality of care, together with a reduction in patient transfers and the integration of improved workflows.

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