. Radiography, X-ray therapeutics and radium therapy . d. A milliamperemeter measuring approxi-mately the quantity of current passing throughthe tube, is an essentia] if reliable work is tobe expected. It should be of the very bestDArsonval moving-coil dead-beat precisiontype, which is provided with two readings,viz., 0-5 and 0-50 On the lower reading-each one-fifth part of a milliampere is clearlyregistered, while on the higher reading eachdivision of the scale represents two all ordinary work only one or two milli-amperes are utilised through the focus tube, sothat the l
. Radiography, X-ray therapeutics and radium therapy . d. A milliamperemeter measuring approxi-mately the quantity of current passing throughthe tube, is an essentia] if reliable work is tobe expected. It should be of the very bestDArsonval moving-coil dead-beat precisiontype, which is provided with two readings,viz., 0-5 and 0-50 On the lower reading-each one-fifth part of a milliampere is clearlyregistered, while on the higher reading eachdivision of the scale represents two all ordinary work only one or two milli-amperes are utilised through the focus tube, sothat the lower reading serves admirably, while ^Siemens!?61 for very heavy discharges the higher reading is called into use. The milliamperemeter enables the operator to estimateapproximately the hardness of the tube, as the variations may be detectedby the fluctuations of the recording needle. As the tube hardens theamount of current passing through diminishes and vice versa. In treatmentit may be used as a guide to the length of the exposure if care has been. 268 RADIATION THERAPEUTICS taken to note the condition of the tube as to hardness and quantity of current when a particular dose is being given. The Qualimeter of Bauer is a useful adjunct to a treatment outfit,enabling one at a glance to estimate approxi-mately the degree of hardness of the tube. Bauers Qualimeter.—The instrument is sus-pended from the wall of the protective houseor protective screen, and indicates the hard-ness of the focus tube on a scale. It does notdepend, as in other scales, on the comparison ofdifferent tints. This instrument is connected by a wire tothe negative terminal of the coil or the cathodeof the tube. It is a static electrometer andcondenser which indicates automatically thepotential of the cathode, and hence the qualityof the X-rays. The apparatus consists of twowings, which swing between two fixed wings and plates are equally charged sothat a repulsion takes place between them. Thei
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