International Light Technologies ILT1400, Инструкция по эксплуатации, Страница: 24 / 31

For a more empirical calculation of the Effective Dose
of UVA, simply place the detector in the booth at the level
of the patient’s skin and put the ILT1400 in ‘INTEGRATE’
mode. The instrument will automatically calculate the
ongoing accumulated dose in Joules/cm
2
. Remember to
press ‘HOLD’ if you wish to terminate or pause the
integration. If you hit ‘HOLD’ a second time, the
instrument will unfreeze the display and return to the
uninterrupted integration, allowing intermediate readings to
be taken. Constant monitoring of fluorescent exposure
booths is necessary, both to ensure a safe, effective
ultraviolet dosage and to evaluate when the fluorescent
lamps need replacement. As mentioned above, after only
6000 hours of use, a patient will need to be exposed for up
to three times as long to accumulate the same treatment
dose.
8.2.4 Phototherapy - UVB
Ultraviolet-B radiation consists of any light in the
spectral band between 280 and 315 nm. For many
phototherapy applications, this “Actinic” radiation can be
replaced by UVA, since UVB often irritates or damages
the skin, leading to skin cancer. For certain skin disorders,
however, moderate doses of UVB light combined with
certain drugs can be remarkably beneficial. Psoriasis, a
skin irritation condition, can be controlled in this manner.
Close monitoring of UVB lamp output and doses is
ESSENTIAL, considering the dangers of overexposure as
well as the lamp degradation problem mentioned above.
Also, remember to always wear protective eye wear when
working with short wavelength sources.
The technique for measuring UVB wavelength light is
similar to the UVA radiometric irradiance dose measurement
described above. The UVB detector should be placed at the
same reference plane as the patient’s skin. Be sure to use
your UVB detector (SEL240/UVB1/TD, for example), not
your UVA detector, for measuring UVB light. UVB light is
much more dangerous than UVA, and your UVA detector
will not sense any UVB light. Typical lamps may have a
large UVA component, leading to misleading results if the
wrong detector is used. All International Light
Technologies detectors are clearly marked with detector type
and serial number. If ever in doubt, simply check the
engraved labels on the individual filter rings to be sure you
are using the proper detector.
8.2.5
Hyperbilirubinemia Phototherapy - Blue
Visible
Jaundice is a very common condition requiring medical
attention in newborns. The yellow coloration of the skin and
sclera in newborns with jaundice is the result of accumulation
of unconjugated bilirubin, often referred to as neonatal
hyperbilirubinemia.
Phototherapy is the primary treatment in neonates with
unconjugated hyperbilirubinemia. Phototherapy employs blue
wavelengths of light to alter unconjugated bilirubin in the skin.
Our Hyperbilirubinemia probe is designed to match the
wavelength specific photo-oxidation response of bilirubin to
provide optimal measurement of the therapeutic radiation.
As with most phototherapy applications, it is important to
place the detector in the same reference plane as the
patient’s skin. The fact that blue light is visible mislead s
most people into believing that it is much safer than
ultraviolet light. Excessive doses of blue light constitute a
significant health hazard. The U.S. National Institute of
Occupational Safety and Health (NIOSH) has accurately
defined the “Blue Hazard” wavelength band, and the
maximum allowable daily dosage. Refer to NIOSH research
publications for more information on Blue Hazards.
Another important factor to consider when exposing patients
to intense blue light is the fact that many fluorescent
hyperbilirubinemia lamps emit a significant amount of
radiation in the UVA band (315 - 400 nm), which is not
sensed by a bilirubin probe. We strongly recommend the use
of protective eye wear, especially by medical technicians,
who may not realize the ambient dose radiation they are
exposed to over time.
8.2.6 ACGIH and NIOSH Actinic UV Hazard
ACGIH has extensively researched the effect of light at
specific wavelengths on human skin. They accurately define
the hazardous effects of ultraviolet light as a function of
wavelength. This weighted spectral effect plot is referred to
as the Actinic hazard function, with the relative hazard
proportionally weighted from 200 nm to 315 nm (maximum
hazard at 270 nm). NIOSH also recommends the use of the
ACGIH standards to define hazardous working conditions.
ACGIH updated the Actinic function by logarithmically
extending this hazard data through the UVA to 400 nm.
This revision is an important consideration. Although the
effect of the UVA band is proportionally much less than that
of the UVB and UVC bands, an intense UVA source poses a
significant Actinic threat. We have custom designed our
Actinic filter using thin film techniques to precisely match
the new Actinic hazard function curve released by ACGIH,
out to 400 nm. This is essential for accurate Effective
Irradiance measurements. The ILT1400 combined with
SEL240/T2ACT displays Effective Watts/cm
2 , providing
immediate, direct hazard readings when compared to
Threshold Limit Values.
8.2.7 IES Luckeish and DIN Germicidal / UVC
The germicidal band is precisely defined by IES
Luckeish and DIN standard curves. Light in this wavelength
band acts as a germicide, killing germs and microorganisms.
Many hospital operating rooms employ mercury arc lamps,
shining germicidal light inside an open wound as the
operation takes place to kill environmental germs. Almost
98% of a Low Pressure Mercury lamp output occurs at
precisely 254 nm. The peak of the effective irradiance
curve, however, is at 265 nm. Light from a Mercury lamp
has only 85% of the effect that an equal amount of 265 nm
light would have. Our SEL240/T2ACT5 germicidal detector
weights the effect of all light in this band to its actual
germicidal effect, regardless of the type of source used. A
narrow band detector measuring only light at 254 nm can
also be used (XRL140T254)
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