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Abstract: Purpose: To develop a 4DCT reconstruction technique that improves time resolution when the anatomy moves with respiration. Method: A cone-beam CT (CBCT) scan is performed and a breathing signal is acquired. At the same time a set of simulated CBCT projections is created from a prior source CT deformed by a time-dependent parametric deformation model. The model parameters are iteratively adjusted until the simulated projections optimally resemble the acquired images. This concept was tested with three different simulated deformation scenarios approximating a moving lung tumor with rigid and elastic deformation and a 3D anatomical expansion/contraction. Results: The known deformation was accurately reconstructed in all three scenarios. The method is reasonably robust to noise and contrast mismatch in the projections Conclusion: Matching simulated to actual CBCT projections can adequately constrain a 4D model of breathing-induced motion that occurs during acquisition of the CBCT data.

Introduction:The effective sterilization of isolators prior to placement of germ-free birds/eggs is crucial to ensuring that the environment is free of potential contaminants. With the use of formaldehyde for sterilization becoming less popular owing to its carcinogenicity, the need for an alternative agent with the same efficacy is essential in the preparation of isolators. Chlorine dioxide dry gas has previously been shown to be a highly effective sterilization method, providing a promising alternative for germ-free avian egg facilities.Methods:Polyvinyl chloride (PVC; n= 32) and stainless-steel production isolators (n= 7) were sterilized using approximately 4 h of exposure to chlorine dioxide (PVC isolator) and after approximately 6 h of exposure to chlorine dioxide (stainless-steel production isolator).Results:Each isolator type was sterilized effectively using chlorine dioxide. Samples collected for microbiological analysis from the isolators after sterilization confirmed that the isolators were sterilized and remained sterile for at least 3 weeks after sterilization.Discussion:The results of this study highlight the first use of chlorine dioxide dry gas for germ-free avian sterilization practices, augmenting on its use as a fogging agent seen in germ-free mice practices. As described in previous animal laboratory studies, values >1440 ppm-h cycle achieved in this study provided consistently adequate antimicrobial efficacy for the sterilization of germ-free egg facilities.Conclusion:Chlorine dioxide dry gas is a highly effective sterilization solution for germ-free avian egg facilities, providing long-lasting sterility to isolators without the safety concerns associated with other fumigants such as formaldehyde.