In general, follow this principle: Obtain plain films before
obtaining films that require contrast. Each hospital has its own
guidelines for patient preps. Consult the radiology department before ordering
any x-ray that requires a prep. Examinations that require no specific
bowel preparation are routine CXR, flat and upright abdominal films,
cystograms, C-spines, skull series, extremity films, CT scans of
the head and chest, and many others.
Studies that usually require preps such as enemas, laxatives,
or oral contrast agents or those that require that the patient be
NPO before the examination include upper GI series, small-bowel
follow-through (SBFT), barium enema, IVP, and others. IV contrast
studies are discussed below.
Includes posteroanterior (PA) and lateral chest films. (PA means
the film is placed in front of the patient with the beam coming
from the back.) Evaluation of pulmonary, cardiac, and mediastinal diseases
and traumatic injury. See How to Read a Chest X-Ray, and Figures 15–1 and 15–2.
Structures seen on a posteroanterior (PA) chest x-ray.
1 = first rib; 2–10 = posterior aspect
of ribs 2–10; AK = aortic knob; APW = aortopulmonary
window, BS = breast shadow (labeled only on right); C = carina;
CA = colonic air; CPA = costophrenic angle, DA = descending
aorta; GA = gastric air; LHB = left heart border
(Note: Most of the left heart border
represents the left ventricle; the superior aspect of the left heart
border represents the left atrial appendage.); LPA = left
pulmonary artery; RC = right clavicle (left clavicle not
labeled); RHB = right heart border (Note: The
right heart border represents the right atrium.); RHD = right
hemidiaphragm (left hemidiaphragm not labeled); RPA = right
pulmonary artery; T = tracheal air column.
Structures seen on a lateral chest x-ray. A = aorta;
CPA = posterior costophrenic angle; LHD = left hemidiaphragm;
PHB = posterior heart border (Note: The
posterior heart border represents the left atrium superiorly and
left ventricle inferiorly; the anterior heart border is not clearly
defined on this film but represents the right ventricle.); RA = retrosternal
airspace; RHD = right hemidiaphragm; RMF = right
major fissure (left major fissure and minor fissures not well visualized
on these films but can occasionally be seen); S = scapula;
T = tracheal air column.
Visualization of small pneumothorax
Allows small amounts of pleural effusion or subpulmonic effusion
to layer out; as little as 175 mL of pleural fluid can be detected