MEASURING THE SOURCE-TO-IMAGE RECEPTOR DISTANCE
Set the source-to-image receptor distance (SID) as indicated in item g of the
order of procedure chart. As indicated in the chart that follows, the SID is measured
either to the tabletop or to the Bucky (Potter-Bucky diaphragm) tray. (See the glossary
at the back of this text for definitions of terms such as SID and Bucky tray.)
THE SID IS MEASURED:
To the tabletop
This concludes the introductory portion of the lesson that is relevant to all of
the positions covered in this text. The remainder of this lesson is devoted to
actual positioning for specific projections of the lower extremities.
a. General. The foot is a common site of injury for soldiers. Injury to the foot
can result from dropping something on the foot, jogging, jumping, or disease. The way
in which the foot is constructed requires that special considerations must be made when
radiographing it to properly demonstrate the bones of the foot.
b. The Bones of the Foot. As you review the anatomical drawings of the foot
on the next few pages, take note of the 7 tarsal bones, the 5 metatarsals, and the
14 phalanges. Note that the phalanges are arranged in three rows, known as the
proximal, middle, and distal rows.
THE TARSAL. BONES
Os calcis (calcaneus).