摘要:

I Knew Sir James Mackenzie Davidson personally, and he was always an inspiration to us in those early days of radiology.I remember well once asking him how he got such good results in his kidney cases, and his answer was, “One tube for each case.” Tubes were then seventeen and sixpence each, so that answer could hardly apply nowadays.Mackenzie Davidson was always trying to-day to do something which seemed impossible, to-morrow he succeeded. This was his constant attitude towards radiological problems and accounts in a large measure for his remarkable successes. I am sure my subject of to-day would have greatly pleased him.Mackenzie Davidson came prominently before us early radiologists by his invention of the motordriven paddle mercury break. Many of you probably have never seen or even heard of it. This, Fig. 1, is an illustration of it. I have one of his earliest models in what I call my “junk room,” and in which I have preserved all sorts of ancient apparatus. I should like here to suggest that in addition to our Mackenzie Davidson Library we should have a Mackenzie Davidson Museum.Mackenzie Davidson was the inventor of many other pieces of apparatus, including the cross thread localiser, which is so familiar to you all, and the lead-lined protective tube-box. The inspiration for the latter, I believe, came from the north.

DOI:10.1259/0007-1285-13-150-185

出版商:The British Institute of Radiology    

年代:1940

数据来源: WILEY

摘要:

A survey of the published data from the N.P.L. and some sixteen other research centres in this country and abroad, on the rates of X-ray emission from X-ray generators of nine different types operating at voltages from 200 kV to 2,000 kV, shows that the X-ray output of a tube in röntgens (r) is predictable at any practicable voltage under standard conditions of operation, whether for “reflection” or “transmission” X-ray targets. It further appears that the maximum X-ray output from a present-day 2-million volt tube is comparable with the gamma-ray output from about 16,000 grammes of radium.The paper next deals with a method of calculating the progressive X-ray absorption by materials, based on Kramers' formula for X-ray emission and a graphical method of solution, utilising theoretical data for the components of the absorption coefficients of a “narrow” beam of X rays, at a series of selected wavelengths in the continuous spectrum. The derived transmission curves for different exciting voltages are illustrated by the case of lead filtration, particularly in its application to ensuring adequate protection for X-ray workers, on the basis of the accepted tolerance dosage-rate of 10-5r/sec. The good agreement of such calculated lead protection values with experimental observations, since published elsewhere for a range of exciting voltages up to 1 million, suggests the feasibility of forecasting the degree of lead protection required for an even higher range of X-ray voltages.A somewhat similar procedure is followed in the case of a narrow beam of gamma rays from radium B and C, utilising published data for the energy distribution and absorption coefficients of the several components of the line spectrum of the rays. The calculated transmission curve, which again fits in well with experimental observations carried out at the Laboratory, corresponds, incidentally, to an X-ray beam excited by about 3,000 kV.By similar means, the “lead equivalents” of various materials can be calculated for a wide range of X-ray voltages, the method being exemplified for a barium-sulphate concrete, the lead-equivalent curve of which, in common with other protective materials, increases with the voltage to a maximum at about 90 kV, followed by a minimum at 200–300 kV, afterwards rising steadily up to very high voltages. Experimental observations which we have conducted with 50 to 400 kV X rays are in satisfactory agreement with such computed curves, and appear to justify the calculations for higher voltages. Gamma-ray measurements are in similar agreement with calculation, the results finding a place on the X-ray lead-equivalent curves at between 3,500 and 4,500 kV, depending on the thickness of the specimen.

DOI:10.1259/0007-1285-13-150-193

出版商:The British Institute of Radiology    

年代:1940

数据来源: WILEY

摘要:

The skeletal changes found in workers exposed to fluorine compounds were first described in 1932 by Flemming Møller and Gudjonsson.1During the examination of cryolite workers for pulmonary manifestations of exposure to dust, their attention was directed to a peculiar form of bone sclerosis, occurring in a certain percentage of workers who had been exposed to cryolite dust for a number of years.Cryolite is a double fluoride of sodium and aluminium, occurring naturally, chiefly in Iceland and North America. The raw material is quarried on a large scale in Iceland, and shipped to Copenhagen, where it is crushed and refined before being used as a source of metallic aluminium.The original investigation by Flemming Møller and Gudjonsson was followed by an extensive research into the effects of fluorine by Roholm.3In an excellent monograph, in which the whole subject is studied from the clinical, biochemical and experimental aspects, Roholm gives a complete survey of the toxic effects of fluorine. The monograph is also notable for a very complete bibliography.Bishop,4in America, described a case of fluorine intoxication occurring in a worker engaged in the manufacture of a chemical fertiliser, in which fluorine was present as a contaminant. Shortt6(quoted by Flemming Møller) reported cases of osteosclerosis occurring in natives of India, where the drinking water contained considerable quantities of fluorine.Cases of “mottled teeth” have been reported in Europe and America.

DOI:10.1259/0007-1285-13-150-213

出版商:The British Institute of Radiology    

年代:1940

数据来源: WILEY

摘要:

The term “cephalhæmatoma” is generally used for traumatic lesions of the skull, acquired during the labour or at the early childhood, and causing a subperiosteal hæmorrhage on the outer and inner surface of the cranium. In the later stages, by new formation of bone along the detached periosteum, as well as inside the hæmatoma, a marked thickening and deformity of the skull may develop. The most common localisation of the cephalhæmatoma is the right parietal protuberance; rarer it is seen on the left parietal or on the occipital bone; a frontal localisation seems to be very unusual. X-ray pictures of cephalhæmatomas show characteristic features: a localised thickening of the bone, protrusion of the outer and inner wall of the skull, a dense, spongy, or cystic structure of the lump.

DOI:10.1259/0007-1285-13-150-218

出版商:The British Institute of Radiology    

年代:1940

数据来源: WILEY

摘要:

American Journal of Cancer, January, February, March 1940.American Journal of Orthodontics and Oral Surgery, February, March, April 1940.

DOI:10.1259/0007-1285-13-150-220-a

出版商:The British Institute of Radiology    

年代:1940

数据来源: WILEY