A British Medical Association Lecture ON RADIUM THERAPY
Authors: R. Knox
Journal: BMJ (1922)

THE subject on which I lhave been asked to speak covers so mnucli ground that it will be-possible only to deal with broad principles and give an indication.of the mvlue of radium in treatment-more particularly in the treatment of malignant disease, for it is in this field thiat so much has been expected from the use of radium.New awg! powers are not at--first properly appre- ciated, miss .piss'througi -the stages-of overestimation, depreciation, and'possibly rejection, before tlleir true value is arrived at.Whenani ageat whic.appears to act upon all structures with whlichi it comes; in contact is employed, the difficulties-inc ease proportionately wfth its effect upon these structures, and thie grea,test care rhust be exercised in all attempt's -to estimate its, value.The radio-active bodies belong to -tlis class, and it is very difficullt even approxi- mately to estimlate fieir value.. The ranae of thlerapentic activity of radiations is an exceedingly Wide one, exteindiing from the ultra-violet to tlle penetrating gamma rays of radium.Tthe fundamental'principle -of radiation the'rapeutics -i1 easily understood,it it is realized that the-vave length of the radiation is the determiniDigy factor.Whien thie correct wave length for a particular depthi hias been estimated, it is then merely a matter of time-tlhat i, dirration of tihe cxp'osure-to produce a particular effect upon tlle tissues.Tlie effect of radiations is dependent upon the powm,er of absorption the tissues possess for these particular wave lengtlhs, and tlhe absorption of tlle radiations causes changes in the cells, whiclh may vary in their degree; amongst otliers chemical clhages may result wlichl lhave a far-reaeching effect upon tlle organismi.In order to obtain effects over a wide range of morbid processes, it is necessary to have at our disposal radiations of all wave lengths, so that any coudition may be treated.Inx rays and radium we possess tllc particular values required.Large quantities of radium may be used witlh advantage, as,for example, at tile Middlesex Hospital, wlhere 5A gr;ams lhave been used for varying times in the treatment of malignant disease.Relative Values of X Raiys aCndl Radium.A great deal of unnecessary discuission lias taken place on thle relative values of x rays and radium rays, the assumption beina that these agents act differently ou the tissues.The matter will be more clearly understood if we assume that we are dealing withi radiations wlichi have a very wide range of wave lengthi, thle gamma ray from radium representing thle extreme limit of penetrating power.Given an equal wave length froim eithier agent the effect will be the same.The x-ray value has been, up to the present, limited by the inability of the apparatus to generate thie highl voltage necessary to produce x rays equal to the gamma ray from radiurn.So far it has only been possible to use voltages from 200,000 to 300,000; the voltage required to produce x rays equal to the liar(lest gamma rays is approximately between one and two millions.Neverthieless, the voltages of 250,000 give us a very useful radiation, wlicl, if applied in sufficient intensity, may give very good thlerapeutic results.For example, cancer of thle cervix uteri mav be influenced by massive doses of rays administered thlroughi several ports of entry.The dose mav lhave to be very prolonged, from five to eighit hou"rs at a single treatment.Good effects are claimed for this particular techinique.Radium is more applicable to the growtlh, and gives very brilliant results; these are, hlowever, ptirely local, and are not permanent.The use of both agents wouldi appear to be a rational procedure.By this method-of attack it is possible to obtain the maximura effect from botli agents, the radium acting from a local focus, and spreading outwards to the periphery, wihile the x rays are 'Iiied from the periphierv to a central focus point.The tissues are thoroughly sattirated and simultaneouslv attacked fromi all points.it is possible that in this way p'eriphieral extension of tlheniew growths may be chieclked.SuLperficial lesions a're the most favourable for treatment, in so far as they can be kept under continuial observation and progress noted; occasionally it is possible to remove a piece