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

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radiation charts, determine the dose, etc.; this is solely the business of the qualified
doctor and radiologist; the assistants must, however, have a general idea of the structure
of the human body, they must master the physical basis of dose measurement, they
must be able to compute the dose for a particular case and must have experience in the
controlling and adjusting of the various apparatus. Only if they have undergone
adequate preliminary training, will they be able to give valuable assistance to the
doctor and possibly safeguard the patient against danger in certain cases.
The extensive training thus required can clearly be provided only in large estab¬
lishments, such as universities for example. In Germany, suitable courses are given
at approved institutes, which provide for eighteen months’ practical and theoretical
study, on the conclusion of which an examination is held under State supervision,
there follows six months’ practical work, after which the State diploma is granted.
The standards set at the examination are extremely high; it is hence all the more
necessary that the roentgenologist should himself be adequately trained in order that
he may be in a position to supervise the work of the assistants.
5. Dosage Questions.
The most essential safeguard for the patient lies in correctly performed accurate
dosage, which should extend also to the diagnostic use of rays. Owing to the introduction
of the international unit, dose measurement has been placed on a very much sounder
footing in recent years, although it must not be overlooked that the choice of an ioni¬
sation unit as a basis has introduced a number of difficulties into the problem.
The mode of expression used in r unit dose specifications lacks that direct appea
to sense perception which has made the skin unit dose so widely popular ; r unit dosage
also lacks that natural upper limit which is set to the skin unit dose by the capacity
of the skin. Owing to the realisation of this fact, demands have recently been made
n930 Congress of the German Rontgengesellschaft) for a dose unit, apart from the
r unit which will be more readily understandable by doctors than a mere numerical
value If the advocates of this measure proposed the term “ tolerance dose this really
amounts to nothing more than what has previously been termed the skin unit dose,
for, in the course of years, the latter term has lost its original meaning as a strictly
defined amount of radiation, and has only retained its biological meaning as the limit
of tolerance of the normal human skin. When expressed in r units this limit is known
to be variable and changes with the intensity of the radiation (biological additional
dose, time factor), so that, as the intensity is reduced and as the permd over which
administration extends is prolonged, increasing r values correspond to the skin unit
dose for one and the same effect. . .. .
A further complication arises out of the fact that, at the present moment, it mus
be regarded as questionable, to say the least, whether the dose giving a particular
biological reaction corresponds to one and the same value in r units with differen
qualities of radiation. The underlying idea in the introduction of th®
as the basis of dose measurement was that, the mean atomic number of the tissue
substances on the one hand and of the air on the other being practically identical, the
absorption of rays, and thereby the effect, would be likely to vary in the same way
when the quality of the rays changed. In other words, when the dose was measured
in r units, the effect would be independent of the quality of the radiation. Apart from
i The expression “ tolerance dose ” is, as a matter of fact, already used to indicate a dose which
can be absorbed indefinitely without injury.