Using a survey specifically designed for users of CT scanners, we propose an econometric model investigating the determinants of user innovation. In line with the literature on user innovation, we highlight the importance of user experience including factors such as time spent on devices and the variety of device generations which the user has had experience with. One striking result is that early users are less likely to be innovative with their CT scanners than followers. Slack is found to be negatively related to user innovators who are more likely to modify their CT scanner when their utilization rate is high. Monetary and non-monetary incentives as well as market size matter but our results suggest that they are more likely to be important after the achievement of innovation by users. Instead, before such innovation, users are found to be more influenced by other potential userinnovators or colleagues’ commitment. Finally, our paper contributes to the literature showing both the positive effects of in-house R&D spillovers and for-profit governance as well as the negative effect of leasing contracts on the likelihood of CT users innovating.