The radiation dose dilemma in the hybrid operating room

Abstract

The of the hybrid Operation room (an operation room combined with advanced radiological X-ray equipment) is gaining popularity, as it is now the preferred room to perform (complex) endovascular aortic procedures. The fixed C-arms equipped in these rooms make it possible to gain very high image quality, add the use of advanced 3D imaging techniques to the procedure, while the room is optimized for the use of X-ray radiation. Moreover, with a hybrid OR, including these advanced imaging options, combined with evolving stent graft designs, more patients with an aortic aneurysm become eligible for an endovascular aneurysm repair (EVAR), resulting in the fact that both more EVARS, as well as that more complex EVARs, are nowadays performed. Unfortunately, the transition from a standard operation room with a mobile C-arm towards a Hybrid OR with a fixed C-arm is also complicated by the much higher radiation dose rates as a result of using fixed C-arms. When the operating team does not adapt their working habits, they will be at risk to absorb much high radiation dose per procedure, and they are at risk to reach their yearly dose limits when working in a hybrid operating environment. In this thesis, we studied the radiation dose outcomes at three different levels, and for each level, we studied both the effects of radiation exposure to the patient, as well as the effects of the absorbed radiation doses to the surgical staff. The first level included the cumulative radiation dose outcomes per type of procedure. Using the cumulative radiation dose outcomes, we were able to analyse the efficiently for new radiation and imaging techniques on reducing the radiation dose rate. We have shown that for noncomplex (for example bifurcated EVARs) radiation dose can double when a similar process is performed in a Hybrid OR vs. a standard OR. Additionally, we studied the efficacy of new techniques which may be able to reduce the intraoperative dose, for example, an advanced image processing upgrade which can reduce the radiation in the Hybrid OR or the use of new imaging strategies such as 3D road mapping using contrast-enhanced Cone beam CT. In the second level ,we studied which procedural steps during the variety of EVAR procedures accords for very high radiation dose and which EVAR steps are relatively safe. The primary goal of this study was to analyse radiation dose fluctuations during the procedure and to extract the procedural steps that accord to relatively high radiation dose exposure and analyse which EVAR procedural steps are relatively safe. In the third and deepest level, we studied the effect of a variety of radiation dose predictors, such as BMI, C-arm angulation and rotation, and field size on the initial intraoperative radiation dose rate. This level was independent of the specific procedure in which the image was used, but dose rates were analysed for each acquired image or X-ray run. The outcomes of these radiation prediction models were translated to an instant patient radiation risk chart and an instant operator radiation risk chart. These charts included the predicted radiation dose for both the patient and the operator, as well as the predicted time they can use these settings until dose thresholds are reached (2 Gray skin threshold for patient sand 20 milliSieverts/year for the operator). These radiation risks charts visualized the X-ray radiation dose behaviour including the exponentially, multifactorial and fluctuation, and creates awareness of the radiation dose exposure during EVARs in the hybrid operation room.