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. Author manuscript; available in PMC: 2014 Jan 1.
Published in final edited form as: Osteoarthritis Cartilage. 2012 Oct 23;21(1):110–116. doi: 10.1016/j.joca.2012.10.011

Fig. 1.

Fig. 1

Example longitudinal measurements of the ACR phantom (A) length (site 1) and (B) diameter (site 4) from slice 5 (25 mm off-isocenter). In both (A) and (B), the solid green line represents the nominal value (148.0 mm length; 190.0 mm diameter). In (B), the four measurement directions are individually identified: A/P (dark blue diamond), left/right (L/R; pink square), left upper to right lower diagonal (diag up; yellow triangle), and left lower to right upper diagonal (diag down; blue circle). No ACR phantom changes occurred during the measurement period, however the MR system upgrade (black arrow) occurred in April 2010 for site 1 and in September 2005 for site 4. This change is more apparent in the length measurement (A). Actual ACR phantom length is 148.0 mm and diameter 190.0 mm.