title: The Effect of Contrast Material on Radiation Dose at CT: Part I. Incorporation of Contrast Material Dynamics in Anthropomorphic Phantoms.
abstract: Purpose To develop a method to incorporate the propagation of contrast material into computational anthropomorphic phantoms for estimation of organ dose at computed tomography (CT). Materials and Methods A patient-specific physiologically based pharmacokinetic (PBPK) model of the human cardiovascular system was incorporated into 58 extended cardiac-torso (XCAT) patient phantoms. The PBPK model comprised compartmental models of vessels and organs unique to each XCAT model. For typical injection protocols, the dynamics of the contrast material in the body were described according to a series of patient-specific iodine mass-balance differential equations, the solutions to which provided the contrast material concentration time curves for each compartment. Each organ was assigned to a corresponding time-varying iodinated contrast agent to create the contrast material-enhanced five-dimensional XCAT models, in which the fifth dimension represents the dynamics of contrast material. To validate the accuracy of the models, simulated aortic and hepatic contrast-enhancement results throughout the models were compared with previously published clinical data by using the percentage of discrepancy in the mean, time to 90% peak, peak value, and slope of enhancement in a paired t test at the 95% significance level. Results The PBPK model allowed effective prediction of the time-varying concentration curves of various contrast material administrations in each organ for different patient models. The contrast-enhancement results were in agreement with results of previously published clinical data, with mean percentage, time to 90% peak, peak value, and slope of less than 10% (P > .74), 4%, 7%, and 14% for uniphasic and 12% (P > .56), 4%, 12%, and 14% for biphasic injection protocols, respectively. The exception was hepatic enhancement results calculated for a uniphasic injection protocol for which the discrepancy was less than 25%. Conclusion A technique to model the propagation of contrast material in XCAT human models was developed. The models with added contrast material propagation can be applied to simulate contrast-enhanced CT examinations.©RSNA, 2017 Online supplemental material is available for this article.
authors.affiliation: From the Carl E. Ravin Advanced Imaging Laboratories (P.S., W.P.S., E.S.) and Departments of Radiology (P.S., D.M., R.C.N., E.S.), Medical Physics Graduate Program (W.P.S., E.S.), and Biomedical Engineering, Electrical and Computer Engineering, and Physics (E.S.), Duke University Medical Center, 2424 Erwin Rd, Suite 302, Durham, NC 27705; and Department of Physics, NC State University, Raleigh, NC (P.S.).
authors.forename: Pooyan
authors.initials: P
authors.lastname: Sahbaee
authors.affiliation: From the Carl E. Ravin Advanced Imaging Laboratories (P.S., W.P.S., E.S.) and Departments of Radiology (P.S., D.M., R.C.N., E.S.), Medical Physics Graduate Program (W.P.S., E.S.), and Biomedical Engineering, Electrical and Computer Engineering, and Physics (E.S.), Duke University Medical Center, 2424 Erwin Rd, Suite 302, Durham, NC 27705; and Department of Physics, NC State University, Raleigh, NC (P.S.).
authors.forename: W Paul
authors.initials: WP
authors.lastname: Segars
authors.affiliation: From the Carl E. Ravin Advanced Imaging Laboratories (P.S., W.P.S., E.S.) and Departments of Radiology (P.S., D.M., R.C.N., E.S.), Medical Physics Graduate Program (W.P.S., E.S.), and Biomedical Engineering, Electrical and Computer Engineering, and Physics (E.S.), Duke University Medical Center, 2424 Erwin Rd, Suite 302, Durham, NC 27705; and Department of Physics, NC State University, Raleigh, NC (P.S.).
authors.forename: Daniele
authors.initials: D
authors.lastname: Marin
authors.affiliation: From the Carl E. Ravin Advanced Imaging Laboratories (P.S., W.P.S., E.S.) and Departments of Radiology (P.S., D.M., R.C.N., E.S.), Medical Physics Graduate Program (W.P.S., E.S.), and Biomedical Engineering, Electrical and Computer Engineering, and Physics (E.S.), Duke University Medical Center, 2424 Erwin Rd, Suite 302, Durham, NC 27705; and Department of Physics, NC State University, Raleigh, NC (P.S.).
authors.forename: Rendon C
authors.initials: RC
authors.lastname: Nelson
authors.affiliation: From the Carl E. Ravin Advanced Imaging Laboratories (P.S., W.P.S., E.S.) and Departments of Radiology (P.S., D.M., R.C.N., E.S.), Medical Physics Graduate Program (W.P.S., E.S.), and Biomedical Engineering, Electrical and Computer Engineering, and Physics (E.S.), Duke University Medical Center, 2424 Erwin Rd, Suite 302, Durham, NC 27705; and Department of Physics, NC State University, Raleigh, NC (P.S.).
authors.forename: Ehsan
authors.initials: E
authors.lastname: Samei
mesh_terms: D003287:Contrast Media / Q000493:pharmacokinetics*; D008954:Models, Biological; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media