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Secondary beta radiation is given off from a platinum tube or needle containing radium, even when the platinum is sufficiently thick to cut off all primary beta radiation. It has been suggested that this secondary beta radiation plays a not unimportant part in therapy when a platinum needle containing radium is placed in a tumour. The following experiments were carried out to see whether this secondary beta radiation could be detected biologically. Two radium applicators were used (a) containing 110·2 mgrs. of radium bromide and (b) 111·2 mgrs. The applicators were square and of 4 sq. cm. and the screen 0·12 mm. of silver. They were further screened with 3 mm. of lead covered with zinc oxide adhesive plaster on the outside. A series of exposures were first carried out to find the lethal dose for Jensen's rat sarcoma in vitro using applicator A. This was found to be in the neighbourhood of 200 minutes. The first experiment was made with an exposure of 109 minutes. The conditions are shown in Fig. 1. The pi...

In a previous paper, published by one of us (S. R.) in the Proceedings of the Royal Society, B. Vol. 95, 1923, experiments were recorded showing that, if the skin of a rat was exposed to a beam of X rays limited to wave-lengths ranging from ·45 to ·30 A., definite changes subsequently occurred in the hair and skin, and that once the dose was large enough to produce an obvious effect, the reaction increased with the dose. When the wave-length of the X rays was diminished to ·168 A., much the same effects were produced, but not until six times as much energy had been absorbed. When exposing tumours (Jensen's rat sarcoma), a similar phenomenon was observed, but in this case to cause the same effect with the two groups of wave-lengths, only 2·6 times as much energy of the short wave-length had to be absorbed. In the paper mentioned, attention was drawn to some of the difficulties of X-ray measurement. After testing a variety of ionisation chambers, the results showed that the differential action could be enti...

During the last year or two it has become the usual custom, when embedding radium tubes into malignant growths, to use very much smaller concentrations of radium. Often tubes or needles are used containing about one milligram of radium element per centimeter length of tube; these are sometimes left in a week or longer. It seems an important point to know how much more the concentration can be reduced, and the tubes still be capable of causing the disappearance of malignant growths, when the reduction in the quantity of radium is made up by a proportional increase in the length of the exposure. Jensen's Rat Sarcoma has been used for most of the experiments recorded here. In most cases the rats have had a tumour on both flanks so that one could be used as a control; measurements of the tumours have been taken twice a week so that the effect of the irradiation can be easily detected. Platinum tubes of various sizes containing either radium or radon have been inserted into quickly growing tumours. After a def...

Several years ago1 we carried out some experiments which showed that the grafts of Jensen's rat sarcoma grew more readily in the normal tissue of a rat than in the adjoining tissue which had been exposed to X-rays or radium. This fact has been observed, too, in clinical treatment. Handley has reported on a patient in whom he attempted, with some success, to block the lines of spread of malignant disease by exposing the probable paths of dissemination to γ rays.2 The experiments which are now recorded were planned to find out how far it might be possible to check an actively growing Jensen's rat sarcoma by irradiating merely the tissue surrounding the tumour, while the tumour itself was kept clear of all irradiation. This is subsequently referred to as irradiation of the tumour bed. The rats were inoculated rather superficially, high up in the flank, so that it was possible, when irradiating the surrounding tissue, to button the tumour through a hole in a piece of lint, then sew up the lint so that the tum...

It is a common clinical experience that tumours treated with γ or X radiation subsequently become resistant to these radiations. This has been demonstrated experimentally by Russ, using Jensen's rat sarcoma (J. R. S) and X radiation. By previous treatment he raised the lethal in vitro dose 2·5 times. I have repeated this experiment with γ rays. Chart 1 shows that whereas J.R.S. originally did not grow after exposures longer than 153 minutes, it survived an exposure of 350 minutes after being twice exposed to γ rays. Similar results were obtained with slow rat sarcoma (S.R.S.) Both clinical and experimental evidence, therefore, indicate that in the treatment of tumours with X or γ radiation, endeavour should be made to cause the tumour to disappear at the initial treatment and thus avoid the necessity of second or third treatments, when the tumour cells will be more resistant to those radiations than they were originally. These findings have a bearing on another common clinical experience at the Radium Ins...

The effects of severe ischaemic shock and of various shock-producing and other chemicals on 32P uptake and on nucleic acid synthesis in the Jensen rat sarcoma were investigated. The possibility was considered that the apparent effect of X-ray irradiation on nucleic acid synthesis might be due, in part, to a slight degree of stress produced by the fastening of the animals under the X-ray applicator. When this complicating factor is avoided, it is found that a dose of 2000 r X rays causes a 50 per cent decrease in DNA synthesis in the Jensen rat sarcoma but has no effect on 32P uptake into RNA.