Your C-Arm May Be Dose Optimised but Is Your Surgical Procedure? The Evaluation and Dose Optimisation of Positioning...

Positioning aids are frequently used in image guided surgery (IGS). This study evaluates the impact of positioning aids on radiation dose and image quality (IQ) in IGS and the potential for dose optimised imaging via the choice of positioning aid type selected for clinical use.

Foam and gel positioning aids were evaluated in this study. Anthropomorphic phantoms were used to simulate clinically relevant procedures. Patient and staff radiation exposure were estimated via incident air kerma rate and scatter dose rate measurements, respectively. Perspex phantoms were used to assess the impact of the positioning aid location within the field of view (FOV) on radiation dose, via the reference entrance point air kerma rate displayed on the C-arm. IQ was analysed objectively via contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) measurements.

An average dose rate reduction of 24% and 27% were measured for the simulated patient and surgeon locations, respectively, when gel was replaced with foam, over all anthropomorphic phantom sizes and procedures. A maximum increase in dose rate of 3% for foam and 57% for gel were calculated with a change in positioning aid location within the FOV. In most instances, an improvement in CNR and SNR was observed with the replacement of gel with foam positioning aids.

The present study demonstrates that the choice of positioning aids used in IGS can significantly impact radiation dose and IQ. With collaboration between radiographers and the perioperative team, it is recommended sites optimise their selection of positioning aids in IGS.