A tube angle of positive 60[degrees] is used and the central ray
enters through the infraorbital foramen.
perpendicular to the IR and centered to the MSP at a level of T7 was determined by palpating her vertebra prominens at the level of T1 and then using the hand-spread method to place the central ray
7 inches below T1.
The mammographer then directs the central ray
from the superior to the inferior lateral aspect of the breast, midway between the nipple and the lateral breast tissue.[7,20] (See Fig.
The median coronal plane of the patient must be parallel with the film and perpendicular to the central ray
. The central ray
must be perpendicular to the chest and the cassette.
A perpendicular central ray
was directed through the acetabulum.
Table 1 shows the proportion of exposures recorded through the focused grid as a function of focal film distance changes and the degree of off-centeredness to the central ray
. An elevated degree of grid "cutoff" due to off-focal distance is evident.
The central ray
is directed perpendicular through the glenoliumeral joint. (See Fig.
The central ray
should be parallel to the spine with a 12 [degrees] caudal tilt.
In optics, an aperture is the maximum diameter of a light beam that can pass through an optical system, blocking the unfocused peripheral lights rays and focussing the central rays
more closely on the fovea; this results in a sharper image and a more flexible depth of focus.
In atypical type of cleft hand, the central rays
either are missing or have deficient components.