Health > Protective measures against dangers resulting from the use of radium, roentgen and ultra-violet rays

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here again, is the greatest possible distance. The preparations should therefore not
be carried in the hand but should be manipulated with forceps, preferably made of
wood, and carried from place to place in long-handled containers. The last-named
precaution applies to gamma-ray preparations as well.
The cathode rays also fall under this heading, since they are similar in nature
to beta rays and can now be produced with considerable energy values by high-output
tubes with Lenard windows. Though their use for medical (therapeutic) purposes and
in technical processes (e.g., sterilisation) is still in the initial stages, they may be
utilised on a wider scale in the course of time. The cathode rays produced with high
voltages approximate, in respect of their kinetic energy, to the beta rays of radio¬
active substances, and give extraordinarily powerful, even though comparatively
superficial, biological effects. Owing to their low power of penetration protection is a
comparatively simple matter — glass screens and the like, for instance, being sufficient.
The simultaneously generated X-rays should, however, also be taken into account.
Special protective measures against alpha rays need hardly engage our attention,
since they are absorbed by very thin casing and reach but a short distance through
the air.
In the case of ultra-violet rays (artificial sunlight, analysis lamps, etc.) the
precautionary measures may be limited to protection for the eyes; regulations
concerning measurement and dosage would, however, be very welcome in the case of
ultra-violet light as well, since, here again, injuries may be inflicted by overdoses.
9. Protective Measures against Scattered X-Rays.
So far, the observations made have reference to direct radiation, the primary
radiation as it leaves the target of a Roentgen tube or a radio-active preparation. It is
screened off so far as possible by the tube holders, protective cylinders, lead casings, etc.,
and narrowed down to the particular cone of radiation required for the purpose in
view.
Apart from these casings, protection must hence also be provided to arrest the
applied radiation after it has passed through the patient, through the product to be
examined, etc. For this purpose, a protective screen must be mounted behind the
radiated substance (behind the patient). In therapeutic radiation, sheet-lead is placed
under the treatment bed, or the patient is laid upon a thick slab of lead rubber. In
screening examinations, the fluorescent screen must be covered with lead glass of
adequate protective value, whilst, in X-ray photography, the Roentgen cassette is
usually provided with a metal bottom. The thickness of the protective material must be
adjusted to the power and penetration of the rays.
All bodies on which short-wave radiation impinges are known, however, them¬
selves to give off radiation consisting of electronic radiation, fluorescent radiation
and scattered radiation. The first two kinds of radiation may be disregarded so far as
protection is concerned. Not so, however, the scattered radiation, which may be quite
considerable in certain circumstances. Scattered radiation must again be subdivided
into two kinds, the classical, and Compton’s scattered radiation. The former consists
of primary radiation which has merely been deflected from its original path, the
latter, however, of rays which have simultaneously undergone an increase of wave
length. The classical scattered radiation predominates in the case of soft Roentgen-rays,
Compton’s radiation in the case of short-wave X-rays and gamma-rays. So far as
protection against radiation is concerned, the increase of wave length may be
disregarded.
The strength and power of penetration of scattered radiation depends upon the