Enhanced CR image of prosthetic femoral head with outline drawn for the calculation of its Radius of Curvature.
An AP image of a 46 year old female patient's prosthetic hip (the Prosthetic Femoral Head area) was obtained. A piece of 035J Guide Wire was placed in the vertical Y-direction below the patient (placed onto the bed), and another piece of guide wire was placed in the horizontal X-direction on top of the patient. Outlining of the enhanced CR image was used for the calculation of Radius of Curvature by software. The distance between the two wires was 200mm (20cm).
Top wire thickness = 0.89mm => 4.8884 pixels => .1821 mm/pixel.
Bottom wire thickness = 0.89mm => 5.3616 pixels => .166 mm/pixel.
%-error per-cm of displacement = ((1-(0.1821/0.1660))*100%)/(20cm) = 0.48% per-cm displacement.
Assuming the prosthetic femoral head lies half way up from the table,
Average Radius of Curvature, R, of prosthetic femoral head,
R = 86.49 pixel*0.17405mm/pixel = 15.05mm (±STD = 2.10% in-plane and ±0.48% per-cm displacement between planes).
All these are now calculated by a given subroutine (with documentation provided in the IET User Manual).
© 2010 Image Enhancement Technology Ltd