04-01-2013, 03:59 PM
Exhaled breath analysis of lung cancer patients using metal oxide sensors
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INTRODUCTION
Smell used to be a common diagnostic tool in medicine and physicians were trained to
use their sense of smell during medical training. Latterly, odour diagnostics have been
relegated to secondary status as a diagnostic method. Array based on gas sensor technology
now offers the potential of a robust analytical approach to odour measurement for medical use.
The technology has been used to examine odours emitted from the body such as from breath,
wounds, and body fluids and identify possible problems such as Gastrointestinal, Sinus,
Infection, Diabetes, Liver problems. In addition, this technology could be adapted to use inside
human body to detect stomach diseases.
The exhaled breath analysis to screen lung cancer using metal oxide gas sensors is
based on of many clinical inventions on lung cancer detection such as: Metabolomx, a
diagnostic company focused on the detection of the metabolomics signature of cancer from
exhaled breath, and also inventions of A professor at the Russell Berrie Nanotechnology
Institute of the Technion-Israel Institute of Technology, Hossam Haick developed an artificial
nose that detects disease biomarkers passing from the bloodstream to the lungs and out through
the breath.
Breath sampling is completely noninvasive and provides a potentially useful approach
to screening lung cancer.Breath analysis can be used as a diagnostic tool because increased or
decreased concentrations of some compounds have been associated with various diseases or
altered metabolism.
Dept of ECE, GSSSIETW, Mysore Page 1
Exhaled breath analysis of lung cancer patients using metal oxide sensors
What is in the exhaled breath?
More than 100 compounds have been identified in normal human breath by gas
chromatography and mass spectrometry. These volatile organic compounds (VOCs) are
produced by metabolic processes and partition from the blood stream via the alveolar
pulmonary membrane into the alveolar air. This implies that the concentration measured in
breath is related to the concentration in blood. Breath analysis can be used as a diagnostic tool
because increased or decreased concentrations of some compounds have been associated with
various diseases or altered metabolism.
Exhaled breath is largely composed of nitrogen, oxygen, carbon dioxide, water, and
inert gases. Trace components—volatile substances that are generated in the body or absorbed
from the environment—present in the nmol/l–pmol/l (parts per billion volume-parts per trillion
volumes) range make up the rest of the breath. The exogenous volatiles are inhaled into and
absorbed through the lungs or absorbed through the skin. They originate from many solvents
and petroleum based products. The endogenous volatiles are generated by the cellular
biochemical processes of the body. Thus, measurement of VOCs in the breath can provide a
window into the biochemical processes of the body.
Exhaled breath of a lung cancer patient
For the pattern of breath VOCs of patients with lung cancer to be unique, the
biochemical processes that lead to their generation or metabolism must be different in lung
cancer patients than in those without lung cancer.
CONTEMPORARY METHODS FOR SCREENING LUNG CANCER
Lung cancer screening refers to strategies used to identify early lung cancers before
they cause symptoms, at a point where they are more likely to be curable. Before screening for
any type of cancer can be carried out, doctors must have an accurate and safe test to use. The
test must be reliable in picking up cancers that are there. And it must not give false positive
results. A false positive result means that a test makes it look as though a cancer could be
present when it isn’t. For screening to be introduced, we need a test that is simple, quick, not
too expensive and not harmful. Lung cancer is often picked up on chest X-ray. But by the time
it is diagnosed this way, it is often quite advanced. Researchers are trying to find other
screening tests that may help to diagnose lung cancer earlier. At present the following
screening methods are used for screening people at high risk of lung cancer: Chest X-ray,
Spiral CT scan and Bronchoscopy.
The following are the disadvantages of chest X-ray:
· The X-ray may or may not show an abnormality.
· Types of abnormalities seen in lung cancer include a small nodule or nodules or a large
mass.
· Not all abnormalities observed on a chest X-ray are cancers. For example, some people
develop scarring and calcium deposits in their lungs that may look like tumors on a
chest X-ray.
· The lungs are very sensitive to radiation and frequent X-rays may cause lung damage