Does "spreading" skin dose by rotating the C-arm during an intervention work?

PURPOSE: To determine if C-arm rotation is beneficial for reducing peak skin dose (PSD) in interventional radiology (IR) and, if so, under what circumstances.

MATERIALS AND

METHODS

The Monte Carlo method was used to perform ray tracing for detailed analyses of the effect of C-arm rotation on PSD across a range of patient sizes, C-arm configurations, and procedure types. Automatic dose-rate control curves on modern fluoroscopic systems were measured for input into the simulations.

RESULTS

Rotating the C-arm to reduce the PSD is in most cases contraindicated and results in increased PSD when the C-arm is rotated from an original posteroanterior projection, in some cases resulting in a PSD increase by a factor of 5 or more. When prophylactic rotation was performed before a procedure, however, and the C-arm was rotated between opposed, distinct oblique angles, substantial reduction in PSD was achieved for patients of any size.

CONCLUSIONS

Rotating the C-arm during a procedure with the aim of "spreading" dose on the skin of the patient may not result in a reduction in PSD and may increase PSD. However, when used as a prophylactic measure combined with tight x-ray beam collimation, C-arm rotation can be used as a tool to reduce PSD. Tight collimation greatly increases the benefit of C-arm rotation.