426 C. R. BARDEEN 



2. POSITION OF THE BODY IN RADIOGRAPHY OF THE HEART 



In the orthodiagraphic studies the position of the patient is 

 determined by the convenience of the operator and patient and 

 general physiological considerations. It makes no particular 

 difference whether the tube is behind or in front of the patient. 

 In teleroentgenography it is important to have the heart as near 

 the plate ^s possible and hence as a rule the patient should face 

 the plate. It is difficult to place the tube two meters from the 

 plate when the patient is in the supine position. The prone 

 position is inconvenient and somewhat unnatural. A sitting or 

 standing position as a rule is more convenient and comfortable. 

 I have found the best position for routine work to be the sitting 

 position in which the patient leans slightly forward against a 

 plate holder with an inclination of 20° from the vertical. The 

 ventral surface of the gladiolus of the sternum should be approxi- 

 mately parallel with the surface of the x-ray plate. This position 



In the two-distances method of estimating the size of the heart two pictures 

 are taken one with the target a shorter distance from the plate than the other. 

 The most convenient distances are one and two meters. When these distances 

 are chosen the following formulae may be used: 



_ 200 A - 200 a 

 2 A- a 



X = distance of plane of the heart contour from the plate 

 A = square root of area of heart silhouette in picture taken at one meter 

 a = square root of area of heart silhouette in picture taken at two meters. 

 If desired a given diameter may be used instead of the square root of the area. 



(2) 



A .a 



X = 



2 A-a 



X = diameter of the heart 



A = diameter of the heart silhouette at one meter 

 a = diameter of the heart silhouette at two meters 



(3) 

 , _ a2 (200-a;)2 

 2002 

 X- = area enclosed by heart contour 

 o- = area of silhouette at two meters 

 200— X = distance from the target to the plane of the heart contour. 



