RADIOGRAPHY

RADIOGRAPHY 

1. Angulation of the central ray may be required

If structures are overlying or underlying the area to be demonstrated (eg, the medial femoral condyle obscuring the joint space in the lateral knee projection), central ray angulation is employed (eg, 5° cephalad angulation to see the joint space in the lateral knee). If structures would be foreshortened or self-superimposed (eg, the scaphoid in a PA wrist), central ray angulation may be employed to place the structure more closely parallel with the IR. Another example is the oblique cervical spine, where cephalad or caudad angulation is required to "open" the intervertebral foramina.

2. which of the part is well demonstrated in the oblique position of the cervical?

Intervertebral foramina

The cervical intervertebral foramina form a 45° angle with the MSP, and therefore are well visualized in a 45° oblique position. Apophyseal joints are formed by articulating surfaces of the inferior articular facet of one vertebra with the superior articular facet of the vertebra below; they are well demonstrated in the lateral position of the cervical spine. The intervertebral disk spaces are best demonstrated in the lateral position

3. Base -plus fog

Base-plus fog is the small amount of measurable density on unexposed and processed x-ray film. This fog is a result of environmental, background radiation that is present during film manufacture, transportation, and storage. The (usually blue) tint, given the base to enhance contrast, adds more density. Finally, the emulsion receives further fog as the film is chemically processed. Base-plus fog should not exceed 0.2D.

 4.  ossification in long bone

Bones are classified as long, short, flat, and irregular. Many of the bones making up the 

extremities are long bones. Long bones have a shaft and two extremities (ends). The shaft (or 

diaphysis) of long bones is the primary ossification center during bone development. It is composed of compact tissue and covered with a membrane called periosteum. Within the shaft is the medullary cavity, which contains bone marrow and is lined by the membrane called endosteum. In the adult, yellow marrow occupies the shaft, and red marrow is found within the proximal and distal extremities of long bones. The secondary ossification center, the epiphysis, is separated from the diaphysis in early life by a layer of cartilage, the epiphyseal plate. As bone growth takes place, the epiphysis becomes part of the larger portion of bone and the epiphyseal plate disappears, but a characteristic line remains and is thereafter recognizable as the epiphyseal line.