Assessment of abdominal organ dose and image quality in varying arc trajectory interventional C-arm cone beam CT

Purpose: The aim of this study was to investigate the effect of varying arc exposure trajectory on radiation dose to radiosensitive organs and to assess image quality in abdominal C-arm cone beam computed tomography (CBCT) interventional procedures using a latest generation system.Methods: An anthropomorphic phantom that simulates the average adult individual was used. Individual-specific Monte Carlo (MC) simulation dosimetry was performed to estimate organ doses (OD) in abdominal C-arm CBCT. Seven examination protocols prescribed by the system for vascular and soft tissue CBCT, were simulated. These protocols are differentiated in the range of the arc exposure trajectory and the level of radiation dose delivered to the patient. OD was estimated for liver, adrenals, kidneys, pancreas, stomach, gall bladder, spleen, bone and skin. Image noise, signal to noise ratio (SNR), contrast to noise ratio (CNR) and in-plane spatial resolution were assessed using CT-specific image quality assessment phantoms. Results: OD was found to depend on the range of arc trajectory and was higher for posterior located organs. In vascular protocols OD ranged from 4.75 mGy for skin to 0.60 mGy for bone. Image noise was higher in vascular protocols than in soft tissue ones. SNR and CNR were significantly modified among different soft tissue protocols (P < 0.05). In-plane spatial resolution was found 0.80 lp/mm in vascular as opposed to 0.41 lp/mm in soft tissue protocols.Conclusions: The current results may be used to estimate OD for different examination protocols and enable operators choose the appropriate acquisition protocol on the preprogrammed interventional task.

Automated summary

This study investigated the effects of varying arc exposure trajectories on radiation dose and image quality in abdominal C-arm CBCT interventional procedures. The results showed that the arc trajectory affected organ doses, with higher doses for posterior located organs. Image noise was higher in vascular protocols compared to soft tissue protocols, and there were significant differences in SNR, CNR, and in-plane spatial resolution among different soft tissue protocols.