Viewing angles (aortic annulus seen edge on)
If the aortic axis has C-arm (spherical) coordinates (θa,ϕa), where θa is positive for LAO and negative for RAO (longitude), and ϕa is positive for cranial and negative for caudal (latitude), then the C-arm coordinates (θ,ϕ) perpendicular to the aortic axis are given by:
Fleischmann D, Dao C, Blake T, Miller DC, Fischbein M, Fearon W. "Computed tomography-based prediction of angiographic deployment angles reduces contrast medium volume and procedure time for transcatheter aortic valve replacement (TAVR)." Presented at RSNA, Chicago, 2012-11-27.
Blake T, Dao C, Boas FE, Fearon W, Miller D, Fleischmann D. "CT-based instantaneous calculation of viewing angles for device deployment in patients undergoing transcatheter aortic valve replacement (TAVR)." Presented at RSNA, Chicago, 2012-11-27.
Fleischmann D, Dao C, Blake T, Boas FE, Liang D, Yeung, A, Fearon W, Fischbein M, Miller DC. (2012) "Computed tomography based prediction of angiographic deployment angles may reduce procedure time and contrast medium volume for transcatheter aortic valve replacement." J Am Coll Cardiol. 59(13s1):E1199-E1199.