Page 365 - Sensors and Control Systems in Manufacturing

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seriously affected by stray light from the laser itself; it also allows
simple alignment and operation in full room light. The Microfluor
detector has already been used to determine the extent of adduct for-
mation and base modification in DNA so that the effects of carcino-
gens on living cells can be studied. Future uses of the sensor will
include DNA sequencing and protein sequencing. With direct or indi-
rect fluorescence detection, researchers are using this technique to
study the chemical contents of individual living cells. This capability
may allow pharmaceutical products to be tested on single cells rather
than a whole organism, with improved speed and safety.

6.29.2 Sensors for Early Detection and Treatment of Lung
Tumors
A quick accurate method for early detection of lung cancer would
raise chances of patient survival from less than 50 percent to 80 or 90
percent. Until now, small cancer cells deep in the lung have been
impossible to detect before they form tumors large enough to show
up in x-rays. Researchers at Los Alamos National Laboratory in col-
laboration with other institutions, including the Johns Hopkins school
of medicine and St. Mary’s Hospital in Grand Junction, Colorado, are
developing methods for finding and treating lung cancer in its earli-
est stages.
A detection sensor involves a porphyrin, one of an unusual fam-
ily of chemicals that is found naturally in the body and concentrates
in cancer cells. The chemical is added to a sample of sputum coughed
up from the lung. When exposed to ultraviolet or laser light, cells in
the porphyrin-treated sputum glow a bright red. When the sample is
viewed under the microscope, the amount and intensity of fluores-
cence in the cells determines the presence of cancer.
The first clinical test of a detection technique using porphyrin
was done by LANL and St. Mary’s Hospital in 1988. Four different
porphyrins were tested on sputum samples from two former miners,
one known to have lung cancer and one with no detectable cancer.
One of the porphyrins was concentrated in certain cells only in the
sputum of the miner with lung cancer. Other tests concluded that
these were cancer cells. Later, a blind study of sputum samples from
12 patients, 8 of whom had lung cancer in various stages of develop-
ment, identified all the cancer patients as well as a ninth originally
thought to be free of cancer. Further tests showed that this patient
also had lung cancer.
Identifying the ninth patient prompted a new study in which the
procedure was evaluated for its ability to detect precancerous cells in
the lung. In this study, historical sputum samples obtained from
Johns Hopkins were treated with the porphyrin. Precancerous condi-
tions that chest x-rays had not detected were identified in samples
from patients who later developed the disease. Although further