Purpose : To establish a more effective false profile (FP) radiography standard via theoretical consideration of patients' non-inspection-side foot position. Problem : Existing FP radiography admits to two difficulties : 1) A 65-degree pelvic rotation results in differing inter-femoral head distances in individual patients, and 2) the desired angle of rotation of the pelvis is difficult to maintain throughout the examination period. Method : The following investigations were performed in this study : 1) inter-femoral head distance using computed tomography (CT) images; 2) optimum outside rotation angle of the non-inspection side for standing comfort; and 3) optimum foot position of the non-inspection side. Results : 1) CT examination revealed an average inter-femoral head distance of 28.7 mm in males and 40.3mm in females, with a maximum distance of 57.5 mm and minimum distance of 44.1mm. 2) Investigation established the optimum outside angle of rotation to be 60 degrees. 3) Investigation revealed that the optimum foot position requires that the patient's heel be retracted 3 cm along the axis created by a pelvic rotation of 65 degrees. CT was used to verify the accuracy of the FP view method. CT comparison revealed that X-rays are able to obtain a view quite similar in quality to that of CT. Conclusion : It is of utmost importance in FP radiography to establish the optimum foot position for a pelvic rotation value of 65 degrees.
