3-16. SIZE OF FILM
Images are captured with digital fluoroscopy. Digital printers are capable of
printing multiple images on each film. In addition, the unprinted digital image is still
available on the image archiving system. In selecting the size of film, the following
factors must be considered:
a. The particular region to be radiographed and the extent of coverage desired.
b. The size of the patient. In an angiocardiographic examination, for example,
an 8 x 10-inch film may suffice for an infant, but a large film (usually 14 x 17-inch) would
be required for an adult.
3-17. THE CR
a. If, in a given situation, the subject to be radiographed is placed in a specified
position with the objective of accomplishing a certain radiograph, the projection can be
made only according to the following CR relationships:
With the CR directed from a vertical relationship.
With the CR directed from a horizontal relationship.
b. Assume, for example, that the patient is in the supine position on the x-ray
table and it is desired to obtain AP and lateral projections of the leg with the position of
the patient and the part remaining unchanged throughout the procedure. This
necessitates the use of two types of CR projections: a vertical CR projection for the AP
and a horizontal CR projection for the lateral. However, if the patient is in the standing
position and the same projections (AP and lateral) are required, a horizontal CR
projection must be used in each case.
3-18. RADIOGRAPHIC EXPOSURE FACTORS
a. As a general rule, the exposure technique for angiographic examinations will
require an increase of about 10 percent over the kVp values normally used for
comparable radiographs in routine radiography. The mAs values should be adjusted to
produce the desired film density. The shortest practicable exposure times should be