SCIENTIFIC IMPORTANCE OF X-RAYS—GARLAND 193 
nosis of established cases of joint disease (chronic rheumatism, gout, 
specific infection). Bleeding in and about joint areas, such as occurs 
in hemophiliacs, presents fairly characteristic changes. 
Respiratory system.—If{ roentgenology had made no other con- 
tribution to medicine than the ability to study the shadows cast by 
the lungs in living individuals it would have performed a tremendous 
boon. But before considering this portion of the system, let us com- 
mence at the upper portion of the respiratory tract, namely the nose 
and nasal accessory sinuses. ‘The cartilages, bones, and even the skin 
of the nose can be radiographed with simplicity, and various injuries 
and other conditions accurately diagnosed. The nasal accessory 
sinuses, nasal passages, and adjacent areas can be recorded and various 
conditions ranging from sinusitis to cancer detected. The air pas- 
sages leading from the nose to the lungs can be portrayed and the 
true and false vocal cords may be studied both fluoroscopically and 
radiographically. A special technique known as body-section roent- 
genography (laminography or tomography) permits the obtaining 
of films of such areas as the cords relatively free from underlying or 
overlying shadows. In this method the tube and film are moved 
synchronously but in opposite directions about a fulcrum, the loca- 
tion of which depends on the height above the X-ray table of the area 
to be studied. 
All types and varieties of diseases of the lungs and pleura are 
amenable to X-ray diagnosis, and many require such examination 
for their elucidation. Communicable diseases such as active lung 
tuberculosis provide an excellent example. In recent years the train- 
ing of increased numbers of physicians in radiology plus the develop- 
ment of special X-ray apparatus has permitted mass surveys of 
hundreds of thousands of individuals. The best method involves 
the use of standard (14- by 17-inch) films. A slightly less expensive 
and currently popular method is the photofluorographic one, in 
which the fluoroscopic image is photographed on small or roll film 
(35-millimeter, 70-millimeter, or 100-millimeter widths, depending 
on the type of equipment). The film comes in rolls of from 35 to 
100 frames, permitting a like number of exposures. Some of the 
newer units have built-in photoelectric cells by which the X-ray 
exposures are timed automatically. This strip film is processed in 
special developer, then dried and viewed either in a magnifying trans. 
illuminator or by means of a projection unit. The detail in the films 
is naturally not as great as in the conventional 14- by 17-inch film 
but it is sufficiently good to permit screening of lungs for significant 
lesions. The prime object in the method is to detect cases of open 
pulmonary tuberculosis, that is, patients with cavities or other lesions 
from which they cough bacilli and so innocently infect their fellow 
